WO2016021709A1 - 網膜神経節細胞の作製方法 - Google Patents
網膜神経節細胞の作製方法 Download PDFInfo
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Definitions
- the present invention relates to a method for producing retinal ganglion cells, and more specifically, to a method for inducing differentiation from pluripotent stem cells by producing retinal ganglion cells with extended axons.
- glaucoma is listed as one of the leading causes of blindness in developed countries. According to the 2002 WHO statistics, there are 37 million people with blindness according to WHO standards worldwide, of which 12% are 450%. Tens of thousands have been blinded by glaucoma. In Japan, about 20% of visually impaired people are due to glaucoma, which is the leading cause of blindness. Moreover, there is a survey result that the prevalence of glaucoma in Japanese over 40 years old is about 5%, and it is known that the prevalence of glaucoma increases with age. It is expected that the number of patients will continue to increase in the future as we enter society.
- the pathology of glaucoma is cell death of retinal ganglion cells associated with optic disc depression, the treatment is focused on protecting retinal ganglion cells.
- the first measure for protecting retinal ganglion cells is to lower intraocular pressure, and lowering intraocular pressure with eye drops is the first choice for glaucoma treatment.
- eye drops have achieved a certain degree of reduction in intraocular pressure, there are many cases in which the progression of glaucoma cannot be sufficiently stopped only by a decrease in intraocular pressure, and eye drops only prevent progression. It doesn't stay and it can't achieve fundamental treatment.
- Non-Patent Document 1 reports that the entire retina was successfully regenerated by three-dimensionally culturing human ES cells.
- retinal ganglion cells were induced 30 days after the start of induction from human ES cells, and retinal ganglion cells were identified in the inner retinal layer by immunostaining of Brn3b, a marker of retinal ganglion cells. It is described that it has been confirmed that even retinal photoreceptor cells are induced after 100 days or more.
- Non-Patent Document 2 the 3D and 2D cultures of iPS cells are repeatedly performed to create an ocular vesicle-like structure, and then the 3D culture is continued in a floating state to construct the retina.
- a method of inducing retinal progenitor cells that become individual cell components is described.
- the layer structure of the retina cannot be formed, the induction rate of each cell component constituting the retina is low, and the retinal ganglion cell has not reached axon extension.
- Patent Document 1 describes a method for producing a retinal layer-specific nerve cell by causing a Notch signal pathway inhibitor to act on retinal progenitor cells contained in retinal tissue induced to differentiate from pluripotent stem cells by suspension culture.
- a Notch signal pathway inhibitor to act on retinal progenitor cells contained in retinal tissue induced to differentiate from pluripotent stem cells by suspension culture.
- the cells confirmed in the manufactured retinal tissue contained some ganglion cells, most of them were photoreceptor cells.
- the first thing to consider when performing regenerative medicine is the integrity of the cells. Even if immunostaining for a marker specific to retinal ganglion cells is positive or expression of the marker gene is observed, it is unlikely that the marker can be applied to therapy without axonal elongation. Therefore, the methods known so far have not been able to regenerate a retinal nerve fiber layer in which clinically applicable axons are elongated and arranged. In addition, the induction rate and the number of days until induction are not satisfactory in practice.
- An object of the present invention is to provide a method for inducing differentiation of retinal ganglion cells in a clinically applicable form from pluripotent stem cells.
- the inventors of the present invention continued the suspension culture while adjusting the serum concentration and the neuronal differentiation inducing factor for the cell mass that was induced to differentiate from the suspension culture from the pluripotent stem cells.
- this retinal ganglion cell when this retinal ganglion cell was transplanted into the recipient retina, it engrafted in the retina, and axon elongation was observed in it. Furthermore, the retinal ganglion cell expresses all marker molecules unique to the retinal ganglion cell or axon, and the axon has a characteristic structure including various neurofilaments, Tau, etc. It has also been confirmed to have functions of axonal flow (antegrade, retrograde) and electrophysiological reaction (action potential and action current), and it can function and be used sufficiently as a screening system for retinal optic neuropathy treatments. I got the knowledge. The present invention has been completed based on such findings.
- the present invention includes the following inventions.
- a method for producing a retinal ganglion cell with an axon extended comprising: (2) The method according to (1), wherein the pluripotent stem cell is an induced pluripotent stem cell (iPS cell) or an embryonic stem cell (ES cell).
- iPS cell induced pluripotent stem cell
- ES cell embryonic stem cell
- a retinal neuroprotective drug comprising contacting a test substance with the culture of retinal ganglion cells according to (5), and evaluating the protective or regenerative effect of the test substance on retinal ganglion cells, Retinal nerve regeneration drug screening method.
- a method for treating an ocular disease that damages retinal ganglion cells comprising administering to a mammal a therapeutically effective amount of the culture of retinal ganglion cells according to (5).
- the treatment method according to (9), wherein the ocular disease that damages retinal ganglion cells is selected from glaucoma disease, congenital optic nerve atrophy, optic nerve hypoplasia, ischemic disorder, or retinal disease.
- a retinal ganglion cell in which an axon is extended which is a form applicable to actual clinical practice, is inserted from a pluripotent stem cell in a short period of time, and a gene is inserted from the outside. And can be easily produced.
- the retinal ganglion cells produced by the method of the present invention can be used for cell replacement therapy for transplantation to a damaged site of the retinal nerve.
- cell replacement therapy using the retinal ganglion cells is compared with retinal pigment epithelial cells, which are currently being applied to humans, and cell replacement therapy using the expected visual cells.
- retinal ganglion cells screening for drugs such as a glaucoma therapeutic drug (for example, “retinal neuroprotective drug” that delays retinal nerve cell death or “retinal nerve regenerative drug” that promotes retinal nerve plasticity or regeneration).
- a glaucoma therapeutic drug for example, “retinal neuroprotective drug” that delays retinal nerve cell death or “retinal nerve regenerative drug” that promotes retinal nerve plasticity or regeneration.
- the immunostaining image by the anti- Rx antibody of the embryoid body (24 days after the differentiation induction start) differentiation-induced from the human iPS (hiPS) cell is shown.
- the stereomicroscope (100 times) photograph of the embryoid body The 40th after the differentiation induction start and the 13th day after the adhesion culture start) induced differentiation from the human iPS (hiPS) cell is shown.
- the immunostaining image by the anti-Brn3b antibody of the embryoid body induced differentiation from human iPS (hiPS) cells (40 days after the start of differentiation induction, 13 days after the start of adhesion culture) is shown.
- the time-dependent change of the expression level of the retinal differentiation-related marker genes (Brn3b, Rx, Pax6) of embryoid bodies induced to differentiate from human iPS cells is shown.
- a stereomicroscope (100 times) photograph of an embryoid body (18 days after initiation of differentiation induction and 5 days after initiation of adhesion culture) induced to differentiate from mouse ES (mES) cells is shown.
- FIG. 1 An immunostained image with an anti-Brn3b antibody of an embryoid body (18 days after initiation of differentiation induction and 5 days after initiation of adhesion culture) induced to differentiate from mouse ES (mES) cells is shown.
- the time-dependent change of the expression level of the retinal differentiation related marker gene (Brn3b, Rx, Pax6) of the embryoid body induced to differentiate from mouse ES cells is shown.
- the result of the sustained release test of the nerve inhibitory factor (Sema3A) with respect to the retinal ganglion cell produced from the human iPS cell by the method of this invention is shown.
- 10A shows transcription factors (Rx) involved in retinal formation on day 6 (D6), day 18 (D18), day 24 (D24), and day 34 (D34) after initiation of differentiation induction from human iPS cells.
- Rx transcription factors
- D6 day 6
- D18 day 18
- D24 day 24
- D34 day 34
- RT-PCR expression error bar: mean ⁇ SD of three independent tests, vertical axis: strip Logarithmic scale).
- the mRNA expression level is corrected with respect to the expression level of HPRT1, and is expressed as a relative amount with the mRNA expression level on day 0 after the start of differentiation induction being 1.
- FIG. 10B shows Rx, Pax6, Math5, Brn3b, and Crx in the optic vesicle (OV) on embryoid bodies (EB) on day 24 (D24) and day 34 (D34) after initiation of differentiation induction from human iPS cells.
- Scale bar 100 ⁇ m
- FIG. 11A and FIG. 11B show HE-stained images of axons radiated from the outer edge of the cell clamp corresponding to the eye follicle (OV) protruding from the embryoid body (EB) (FIG. 11A: horizontal plane, FIG. 11B). : Vertical plane, scale bar: 80 ⁇ m).
- FIG. 11C shows an electron micrograph of the cell body of the retinal ganglion cell corresponding to part c of FIG. 11B (arrow: rough endoplasmic reticulum, triangular arrow: axon projection, scale bar: 5 ⁇ m).
- FIG. 11D shows an electron micrograph of the retinal ganglion cell axon corresponding to the portion d of FIG. 11B (scale bar: 5 ⁇ m).
- FIG. 12A shows the results of RT-PCR expression analysis of retinal ganglion cell-specific markers (Brn3b, Math5, Islet1, Sncg, Tuj1) in embryoid bodies 34 days after initiation of differentiation induction from human iPS cells (error) Bar: mean ⁇ SD of 3 independent tests, vertical axis: semi-log scale).
- the mRNA expression level is corrected with respect to the expression level of HPRT1, and is expressed as a relative amount with the mRNA expression level on day 0 after the start of differentiation induction being 1.
- FIG. 12B shows immunostained images of retinal ganglion cell-specific markers (Brn3b, Math5, Islet, Sncg, Tuj1) in the embryoid body 34 days after initiation of differentiation induction from human iPS cells (scale bar: 100 ⁇ m).
- FIG. 13A is an electron micrograph of three regions of embryoid bodies (RGCR: retinal ganglion cell region, OVR: optic vesicle region, MBEB: embryoid body main body) 34 days after initiation of differentiation induction from human iPS cells. (Scale bar: 100 ⁇ m).
- FIG. 13A is an electron micrograph of three regions of embryoid bodies (RGCR: retinal ganglion cell region, OVR: optic vesicle region, MBEB: embryoid body main body) 34 days after initiation of differentiation induction from human iPS cells. (Scale bar: 100 ⁇ m).
- FIG. 13B shows retinal nerve markers (Brn3b, Islet1, Chx10, Crx) in the above three regions of retinal ganglion cells (RGCR: retinal ganglion cell region, OVR: ocular vesicle region, MBEB: embryoid body main body).
- RGCR retinal ganglion cell region
- OVR ocular vesicle region
- MBEB embryoid body main body.
- the results of expression analysis by RT-PCR are shown (error bar: mean ⁇ SD of three independent tests. Vertical axis: semilogarithmic scale).
- the mRNA expression level is corrected with respect to the expression level of HPRT1, and is expressed as a relative amount with the mRNA expression level on day 0 after the start of induction being 1.
- FIG. 14A shows the results of RT-PCR expression analysis of neurofilament markers (Tau, NFL, NFM, NFH) in embryoid bodies on day 34 (D34) and day 50 (D50) after initiation of differentiation induction from human iPS cells. Indicates. The mRNA expression level is corrected with respect to the expression level of HPRT1, and is expressed as a relative amount with the NFH mRNA expression level 34 days after the start of differentiation induction being 1.
- FIG. 14B shows an immunostained image of a neurofilament marker (Tau, NFL / NFM, NFH) in an embryoid body on day 34 (D34) after initiation of differentiation induction from human iPS cells (scale bar: 100 ⁇ m).
- FIG. 14A shows the results of RT-PCR expression analysis of neurofilament markers (Tau, NFL, NFM, NFH) in embryoid bodies on day 34 (D34) and day 50 (D50) after initiation of differentiation induction from human iPS cells.
- FIG. 15 shows that embryoid bodies (GFP (control), NTRK1, and mitochondrial specific protein were introduced into the cell body by electroporation on day 34 after the start of differentiation induction from human iPS cells, and cholera toxin was colonized with a micropipette. The results of antegrade axonal flow are shown below.
- FIG. 16 shows the results of electrophysiological analysis of retinal ganglion cells induced to differentiate from human iPS cells.
- FIG. 16A shows micrographs of retinal ganglion cells stained with Lucifer Yellow CH (triangular arrow: dendritic process, arrow: axon process).
- FIG. 16B shows action potential recording of retinal ganglion cells (whole-cell recording).
- FIG. 16C shows retinal ganglion cell activity current recordings (upper panel: activity current, middle panel: attenuation by tetrodotoxin, lower panel: recovery by washing, scale bar: 30 ⁇ m).
- FIG. 17A shows a stereoscopic microscope image and an apoptotic staining image of a cell model of glaucoma.
- FIG. 17B shows the results of RT-PCR expression analysis of apoptosis-related markers (Bax, Caspase3) in a cell model of glaucoma.
- FIG. 18 shows the results of evaluating the effects of neurotrophic factors (BDNF, CNTF) on glaucoma cell models by RT-PCR expression analysis of apoptosis-related markers (Bax, Caspase8, Bcl2).
- FIG. 19A shows a stereomicroscopic image of a cell model of an iris / optic nerve dysplasia disease (c.774 + 1G> T mutation: a cell induced to differentiate from an iridosis (Pax6 mutation) disease iPS cell, Q227X: nothing Iris (Pax6 mutation) disease: cells induced to differentiate from iPS cells, control: cells induced to differentiate from normal iPS cells).
- FIG. 19A shows a stereomicroscopic image of a cell model of an iris / optic nerve dysplasia disease (c.774 + 1G> T mutation: a cell induced to differentiate from an iridosis (Pax6 mutation) disease iPS cell, Q227X: nothing
- FIG. 19B shows the results of RT-PCR expression analysis of retinal ganglion cell formation genes (Brn3b, Math5) in a cell model of aniridia / optic nerve dysgenesis (c.774 + 1G> T mutation: aniridia) (Pax6 mutation) cells induced to differentiate from diseased iPS cells, Q227X: cells induced to differentiate from aniridia (Pax6 mutation) diseased iPS cells, control: cells induced to differentiate from normal iPS cells).
- FIG. 20A shows the results of microscopic observation of the effect of neurotrophic factors (BDNF, CNTF) on the cell model of aniridia (c.774 + 1G> T mutation) disease (promotion of axon growth).
- FIG. 20B shows the effect of neurotrophic factors (BDNF, CNTF) on cell models of aniridia (c.774 + 1G> T mutation), transcription factors (Brn3b, Math5, Islet1, Tuj1) and retinal ganglion cell formation.
- the result evaluated by the expression analysis by RT-PCR of the structural gene (Tau, NFL) of a retinal nerve fiber is shown.
- FIG. 21A shows the results of microscopic observation of the effect of neurotrophic factors (BDNF, CNTF) on retinal ganglion cells (normal cell model) prepared from human iPS cells (promotion of axon growth).
- FIG. 21B shows the effect of neurotrophic factors (BDNF, CNTF) on retinal ganglion cells (normal cell model) prepared from human iPS cells by RT-PCR expression analysis of retinal ganglion cell-specific markers (Brn3b). The evaluation results are shown.
- FIG. 22A shows the results of microscopic observation of the effect of a neurosuppressive factor (Sema3A) on retinal ganglion cells (normal cell model) prepared from human iPS cells.
- FIG. 22B evaluated the effect of a neurosuppressive factor (Sema3A) on retinal ganglion cells (normal cell model) prepared from human iPS cells by RT-PCR expression analysis of a retinal ganglion cell-specific marker (Brn3b). Results are shown.
- FIG. 1A neurotrophic factors
- FIG. 23 shows the results of a transplantation test of retinal ganglion cells prepared by the method of the present invention into the mouse eye.
- FIG. 24A shows a stereoscopic microscope photograph (40 ⁇ ) of an embryoid body (30 days after initiation of differentiation induction, 3 days after initiation of adhesion culture) induced to differentiate from human ES (hES) cells.
- FIG. 24B shows transcription factors (Rx, Pax6, Chx10, and Rx, Pax6, Chx10, which are involved in retinal differentiation in embryoid bodies on the 24th and 34th days after initiation of differentiation induction from human ES (hES) cells (7 days after the start of adhesion culture). The expression analysis result by RT-PCR of Brn3b) is shown.
- FIG. 25A shows a stereoscopic microscope (40 ⁇ ) photograph of an embryoid body (22 days after initiation of differentiation induction, 8 days after initiation of adhesion culture) induced to differentiate from mouse iPS (miPS) cells.
- FIG. 25B shows transcription factors (Rx, Pax6, Chx10, Math5, Brn3a, Brn3b) involved in retinal differentiation in embryoid bodies on day 14 (at the start of adhesion culture) of differentiation induction from mouse iPS (miPS) cells). The expression analysis result by RT-PCR is shown.
- FIG. 26 shows the observation results of antegrade axonal flow of retinal ganglion cells induced to differentiate from mouse ES (mES) cells or mouse iPS (miPS) cells (10 after administration of cholera toxin in the central part of the eye follicle). Minutes, 30 minutes).
- mES mouse ES
- miPS mouse iPS
- FIG. 27 shows micrographs (triangular arrow: dendritic process, arrow: axon process) and activity of retinal ganglion cells (differentiation induction from mouse ES (mES) cells or mouse iPS (miPS) cells) stained with Lucifer Yellow CH. Potential recording (whole-cell recording).
- FIG. 28 shows observation results of antegrade axonal flow of retinal ganglion cells induced to differentiate from human iPS (hiPS) cells (10 minutes, 1 hour, 2 hours after administration of cholera toxin in the central part of the eye follicle). ).
- FIG. 29 shows the observation results of antegrade axonal flow of retinal ganglion cells induced to differentiate from human ES (hES) cells (10 minutes, 1 hour, 2 hours after administration of cholera toxin in the central part of the eye follicle). ).
- FIG. 30 shows the results of electrophysiological analysis of retinal ganglion cells differentiated from human ES cells.
- FIG. 30A shows an electron micrograph of cells punctured with patch clamp electrodes.
- FIG. 30B shows a photomicrograph of retinal ganglion cells stained with Procion Yellow after detection of electrophysiological reaction.
- FIG. 30C shows action potential recording of retinal ganglion cells (whole-cell recording).
- FIG. 30D shows activity current recordings of retinal ganglion cells (upper panel: active current, middle panel: attenuation by tetrodotoxin, lower panel: recovery by washing).
- the comparative examination result of the conditions which induce differentiation of a retinal ganglion cell from a human iPS cell is shown (A. Transition day to adhesion culture (18th day, 27th day, 35th day), B. Medium amount of adhesion culture ( 250 ⁇ l, 400 ⁇ l), C. Presence or absence of excision of the eye vesicle from the embryoid body during adhesion).
- the comparative examination result of the conditions which induce differentiation of a retinal ganglion cell from a human iPS (hiPS) cell is shown (D. addition of neurotrophic factor (BDNF) (+,-), E. addition of retinoic acid (RA) (+ ,-), F. Oxygen concentration during suspension culture).
- BDNF neurotrophic factor
- RA retinoic acid
- the present invention relates to a method for producing a retinal ganglion cell in which an axon is elongated, the method comprising (a) culturing pluripotent stem cells in suspension culture to produce a retinal progenitor. A step of inducing differentiation into somatic cells, (b) a step of inducing differentiation into retinal ganglion cells by suspension culture of the retinal progenitor cells obtained in step (a), and (c) in step (b) A step of adhesion-culturing the obtained retinal ganglion cells to extend axons.
- the “pluripotent stem cell” has the ability to differentiate into all cells existing in the living body derived from ectoderm, mesoderm and endoderm (multipotency) and also has the ability to proliferate.
- the pluripotent stem cells used in the present invention are obtained by artificial pluripotent stem cells (Induced Pluripotent Stem cell; iPS cells), embryonic stem cells (ES cells), somatic stem cells (tissue-specific stem cells), and nuclear transfer These include embryonic stem cells derived from cloned embryos (ntES cells), sperm stem cells (GS cells), embryonic germ cells (EG cells), and adult pluripotent stem cells (MAPC cells), but iPS cells and ES cells preferable.
- iPS cells Induced Pluripotent Stem cell
- ES cells embryonic stem cells
- somatic stem cells tissue-specific stem cells
- nuclear transfer include embryonic stem cells derived from cloned embryos (ntES cells), sperm stem cells
- the “pluripotent stem cell” used in the present invention is preferably derived from a mammal.
- mammals include humans, monkeys, mice, rats, hamsters, guinea pigs, rabbits, dogs, cats, sheep, pigs, cows and the like.
- an “artificial pluripotent stem cell” can be prepared by introducing a specific reprogramming (initialization) factor into a somatic cell such as a skin cell in the form of DNA or protein.
- a somatic cell such as a skin cell in the form of DNA or protein.
- iPS cells were first established by Yamanaka et al. by introducing four factors OCT3 / 4, SOX2, KLF4, and C-MYC into mouse fibroblasts (K. Takahashihand S. Yamanaka (2006) Cell, 126). Then, human iPS cells were also established by introducing the same four factors into human fibroblasts (K. Takahashi et al. (2007), Cell, 131: 861-872) . Also, among the four factors, the method that does not include C-MYC (M. Nakagawa et al., (2008) Nat. Biotechnol. 26: 101-106) Change some of the four factors to other factors IPS cells have also been successfully established by methods, such as adding other factors to the four factors (J. Yu et al. (2007), Science, 318: 1917-1920, etc.).
- reprogramming factors may be introduced into somatic cells in the form of proteins, for example by means of lipofection, binding to cell membrane permeable peptides, microinjection, or in the form of DNA
- the vector may be introduced into a somatic cell by a technique such as a vector such as a virus, a plasmid, or an artificial chromosome, a lipofection, a liposome, or a microinjection technique.
- virus vectors include retrovirus vectors, lentivirus vectors, adenovirus vectors, adeno-associated virus vectors, Sendai virus vectors, and the like.
- the artificial chromosome vector examples include human artificial chromosome (HAC), yeast artificial chromosome (YAC), and bacterial artificial chromosome (BAC, PAC) vector.
- HAC human artificial chromosome
- YAC yeast artificial chromosome
- BAC bacterial artificial chromosome
- plasmid a plasmid for mammalian cells can be used, and the vector can contain a control sequence such as a promoter, an enhancer, a ribosome binding sequence, a terminator, and a polyadenylation site so that the reprogramming factor can be expressed.
- selectable marker sequences such as drug resistance genes (eg, kanamycin resistance gene, ampicillin resistance gene, puromycin resistance gene), thymidine kinase gene, diphtheria toxin gene, green fluorescent protein (GFP), ⁇ -glucuronidase ( GUS), reporter gene sequences such as FLAG, and the like.
- drug resistance genes eg, kanamycin resistance gene, ampicillin resistance gene, puromycin resistance gene
- thymidine kinase gene diphtheria toxin gene
- GFP green fluorescent protein
- GUS ⁇ -glucuronidase
- reporter gene sequences such as FLAG, and the like.
- LoxP at each end of those genes. It may have an array.
- the “iPS cells” used in the present invention are not particularly limited in terms of origin, reprogramming factor to be introduced, introduction method, and the like. As long as the purpose of the present invention is not impaired, all iPS cells produced by known methods are used. However, the origin is preferably derived from human, more preferably derived from a patient who requires retinal ganglion cells differentiated from the iPS cells.
- the “iPS cells” used in the present invention may be prepared by a known method implemented in the above-mentioned field, but can also be obtained from public institutions such as RIKEN BioResource Center (RIKEN BRC). is there.
- RIKEN BRC RIKEN BioResource Center
- embryonic stem cells are pluripotency established from the inner cell mass of an early embryo (eg, blastocyst) of mammals such as humans and mice, and the proliferation ability by self-replication. Stem cells.
- ES cells are also preferably derived from the aforementioned mammals, but mouse-derived ES cells are preferred because of their availability, and human-derived ES cells are preferred for human treatment.
- ES cells can be used from ES cells provided by public institutions or commercially available.
- mouse-derived ES cells include C57 / BL6 cells, EB3 cells, E14 cells, D3 cells, CCE cells, R1 cells, 129SV cells, J1 cells, RF8 cells, RIKEN BioResource Center (RIKEN BRC), ATCC ( American Type Culture), Dainippon Sumitomo Pharma Co., Ltd. (Osaka, Japan), etc.
- Human ES cells can be obtained from the Research Center for Stem Cell Medicine, Institute for Regenerative Medicine, Kyoto University, WiCell Research Institute (Madison, USA), etc.
- an “embryoid body” refers to an aggregate (cell mass) of cells formed by culturing pluripotent stem cells, and a cell mass including retinal progenitor cells, A cell mass including retinal ganglion cells and a cell mass including all retinal ganglion cells in which axons are extended shall be indicated.
- a retinal ganglion cell with an axon extended produced from a pluripotent stem cell by the method of the present invention is characterized by the axon extension and its specific marker Brn3b.
- the retinal ganglion cell is one of the cells that make up the retina. In the retina in the living body, the cells are arranged in layers from the outside to the inside in the order of visual cells, horizontal cells, bipolar cells, amacrine cells, ganglion cells, and Müller cells. It is out.
- the term “axon is extended” as used herein means that one long axon extends from the cell body of the retinal ganglion cell, and the axon extended from each cell is accompanied in the same direction. The form which is doing.
- a retinal ganglion cell with an axon extended produced from a pluripotent stem cell by the method of the present invention is provided as a culture containing the same.
- the ratio of “retinal ganglion cells with extended axons” in the cell mass contained in this culture is preferably 80% or more, more preferably 85% or more, still more preferably 90% or more, and most preferably 95% or more. .
- pluripotent stem cells are cultured in suspension to induce differentiation into retinal progenitor cells.
- feeder cells such as MEF (mouse fetal fiber), SNL, SNLP, etc. Medium etc.
- MEF mouse fetal fiber
- SNL retinal ganglion cells
- SNLP SNLP
- the “retinal progenitor cell” obtained in step (a) refers to a progenitor cell that can differentiate into a mature retinal cell of a photoreceptor cell, a horizontal cell, a bipolar cell, an amacrine cell, or a ganglion cell.
- the “suspension culture” performed in the step (a) refers to a three-dimensional culture performed under non-adhesive conditions with respect to the incubator, and agglutination suspension culture is preferable.
- a cell mass of pluripotent stem cells is formed, and differentiation from the cell mass to a target cell can be induced.
- Aggregation suspension culture is a serum-free aggregation suspension culture method (SFEB: Serum-free-Floating culture of Embryoid Bodies-like aggregates; atesWatanabe K., Sasai Y., et.al.
- the incubator used in suspension culture is not particularly limited, and examples thereof include flasks, dishes, microplates, chambers, tubes, and roller bottles. These incubators used in suspension culture are preferably non-cell-adhesive. Therefore, it is preferable to use a hydrophobic material for the incubator or to coat the surface with a coating agent (for example, a polyhydroxyethyl methacrylate copolymer) for preventing cell adsorption.
- a coating agent for example, a polyhydroxyethyl methacrylate copolymer
- the culture conditions such as the culture temperature and CO 2 concentration of the suspension culture can be appropriately set depending on the type of stem cells used.
- the culture temperature is, for example, about 30-40 ° C., preferably about 37 ° C.
- the CO 2 concentration is, for example, about 1-10%, preferably about 5%.
- Suspension culture varies depending on the type of pluripotent stem cells used.
- SFEBq Human-free Floating
- Rho kinase inhibitor medium culture of Embryoid Bodies-like aggregates with quick
- the number of days for culturing in step (a) varies depending on the type of pluripotent stem cells to be used, but when the number of days is counted with the culture start date as the day 0 of differentiation induction, in the case of human pluripotent stem cells, after the start of differentiation induction Until the 18th day, in the case of mouse pluripotent stem cells, it is carried out until the 7th day after the start of differentiation induction.
- These culture days are merely examples, and can be changed within a range of 1 to 3 days based on the above days.
- an aggregate of pluripotent stem cells is formed in a serum-free medium (medium 1), and then the cell aggregate is treated with serum-free serum containing a basement membrane preparation.
- Culture is carried out in a medium (medium 2), and further cultured in a serum medium (medium 3) containing a basement membrane preparation.
- the culture in medium 1 is 1 to 2 days after the start of differentiation induction
- the culture in medium 2 is days 2 to 12 after the start of differentiation induction.
- the culture in medium 3 is carried out from the 12th day to the 18th day after the initiation of differentiation.
- the treatment is performed only in a serum-free medium (medium 2) containing a basement membrane preparation until the seventh day after initiation of differentiation induction.
- the media 1, 2, and 3 used in step (a) are referred to as “retinal differentiation media”.
- the “retinal differentiation medium (RDM medium)” in step (a) can be prepared using a medium used for culturing animal cells as a basic medium.
- the basic medium includes components (inorganic salts, amino acids, glucose, vitamins, etc.) necessary for cell survival, and is not particularly limited as long as it is a basic medium known to those skilled in the art.
- D-MEM Dulbecco's Modified Eagle's Medium
- Dulbecco's Modified Eagle's Medium Nutient Mixture F-12 (D-MEM / F-12) medium
- G-MEM Glasgow MEM
- BME BasalBaMedium Eagle
- MEM Minimum EssentialsMedium
- EMEM Eagle's minimal essential medium
- RPMI 1640 Medium 199, ⁇ Fi
- a medium and a mixed medium thereof examples of such basic media.
- the “serum-free medium” of the culture media 1 and 2 refers to a medium that does not contain unconditioned or unpurified animal serum in the above basic medium.
- the “serum-free medium” may contain a serum replacement.
- Such “serum substitutes” include KSR (Knockout serum replacement), collagen precursor, albumin, transferrin, insulin, progesterone, putrescine, trace elements (such as sodium selenate), and mixtures thereof, and nerves KnockOut Serum Replacement TM (KSR, manufactured by Invitrogen), N2 Supplement TM (Gibco, etc.), B27 Supplement TM (Gibco, etc.), Chemically-defined Lipid concentrated (Gibco) Etc.) are preferably used.
- the “basement membrane preparation” used for the above-mentioned culture media 2 and 3 refers to cell morphology, differentiation, proliferation, movement, functional expression, etc. when predetermined cells having basement membrane-forming ability are seeded and cultured thereon.
- a preparation containing a basement membrane component having a function of controlling As the basement membrane preparation a commercially available product containing extracellular matrix molecules such as known laminin, type IV collagen, heparan sulfate proteoglycan, entactin (for example, “Matrigel TM ” from BD Bioscience) may be used as the basement membrane preparation. it can.
- the concentration of the basement membrane preparation in the medium is preferably about 0.1 to 5%, and more preferably about 0.5 to 2%, for example, when Matrigel is used.
- the “serum medium” of medium 3 refers to a medium containing animal serum in the above basic medium.
- mammalian serum such as bovine serum, fetal bovine serum, horse serum, human serum and the like can be used.
- the serum concentration in the medium is preferably about 0.1 to 10%, more preferably about 1 to 10%, and further preferably about 1 to 5%.
- the concentration of pluripotent stem cells in the retinal differentiation medium in step (a) is not particularly limited as long as a uniform aggregate (cell mass) of pluripotent stem cells is formed.
- a uniform aggregate (cell mass) of pluripotent stem cells is formed.
- about 1 ⁇ 10 3 to 3 ⁇ 10 4 cells are preferable per well, more preferably about 5 ⁇ 10 3 to about 2 ⁇ 10 4 cells, and about 9 ⁇ 10 3 cells. Is more preferable.
- components necessary for cell differentiation induction, proliferation, and maintenance may be added to the above basic medium.
- components include non-essential amino acids (glycine, serine, glutamine, etc.), glutamine, and the like.
- Alternative products such as GlutaMAX TM ), pyruvate, cytokines such as growth factors (FGF, PDGF, TGF- ⁇ , EGF, etc.), reducing agents (such as 2-mercaptoethanol, 3'-thiolglycerol), antibiotics (streptomycin, Penicillin, etc.), vitamins (ascorbic acid, d-biotin, etc.), buffering agents (HEPES, etc.), and antioxidants.
- Suitable components for inducing differentiation in step (a) include serum substitutes such as KSR, non-essential amino acids, 2-mercaptoethanol, sodium pyruvate and the like. Therefore, it is preferable to use a serum-free medium (G-MEM or D-MEM, 0.1 mM 2-mercaptoethanol, 0.1 mM non-essential amino acid Mix, 1 mM sodium pyruvate) supplemented with an appropriate amount of commercially available KSR as the medium 1.
- G-MEM or D-MEM 0.1 mM 2-mercaptoethanol, 0.1 mM non-essential amino acid Mix, 1 mM sodium pyruvate
- the concentration of KSR in the serum-free medium is preferably about 1 to 20%, more preferably about 10 to 20%.
- ROCK Ra-associated Coiled forming Kinase
- a ROCK inhibitor Rostanabe et al., Nat.
- the concentration of the ROCK inhibitor in the medium is not particularly limited as long as it can suppress the death of stem cells and improve the survival rate, but is preferably about 1 ⁇ M to 50 ⁇ M, more preferably about 5 ⁇ M to 30 ⁇ M.
- a Wnt signal inhibitor is added to the medium 1.
- the Wnt signal inhibitor is not particularly limited as long as it can suppress signal transduction mediated by Wnt.
- IWR-1-endo IWR-1e
- IWP-2 IWP-2
- Dkk1 Cerberus protein
- Wnt receptor Body inhibitors soluble Wnt receptors
- Wnt antibodies and the like.
- the concentration of the Wnt signal inhibitor in the medium is not particularly limited as long as an embryoid body of pluripotent stem cells can be formed.
- a normal Wnt signal inhibitor such as IWR-1e
- About 0.1 ⁇ M to 100 ⁇ M is preferable, and about 1 ⁇ M to 10 ⁇ M is more preferable.
- the medium 2 may be one obtained by adding a basement membrane preparation to the medium 1, or one obtained by adding a basement membrane preparation to a new serum-free medium. Note that the ROCK inhibitor is preferably removed when the culture in the medium 1 is completed.
- the medium 3 is preferably a new medium in which serum is added to the above serum-free medium (G-MEM or D-MEM, 0.1 mM 2-mercaptoethanol, 0.1 mM non-essential amino acid Mix, 1 mM sodium pyruvate).
- a Shh (Sonic hedgehog) signal activator and a Wnt signal activator are added to the medium 3 to promote the generation of retinal progenitor cells (Rx positive).
- the Shh signal activator is not particularly limited as long as it can enhance signal transduction mediated by Shh.
- the Shh signal activator include proteins belonging to the hedgehog family (for example, Shh), Shh receptors, Shh receptor agonists, Purmorphamine, SAG and the like.
- the concentration of the Shh signal activator in the medium is preferably about 0.1 nM to 10 ⁇ M, more preferably about 10 nM to 1 ⁇ M.
- the Wnt signal activator typically corresponds to what is known as a GSK3 ⁇ inhibitor, for example, BIO (GSK-3 ⁇ inhibitor IX; 6-bromoindirubin 3′-oxime) which is an indirubin derivative, SB216763 (3- (2,4-dichlorophenyl) -4- (1-methyl-1H-indol-3-yl) -1H-pyrrole-2,5-dione), a phenylimide bromomethyl ketone compound, which is a maleimide derivative GSK-3 ⁇ inhibitor VII (4-dibromoacetophenone), CHIR99021, 6-[(2- ⁇ [4- (2,4-dichlorophenyl) -5- (4-methylimidazol-2-yl) pyrimidin-2-yl ] Amino ⁇ ethyl) amino] pyridine-3-carbonitrile (WO1999 / 65897) and L803-mts (GSK-3 ⁇ peptide inhibitor; Myr-N-G
- the Shh signal activator and the Wnt signal activator may be added simultaneously with the start of culture in the medium 3, or may be added 2 to 3 days after the start of culture in the medium 3.
- Confirmation that differentiation has been induced from pluripotent stem cells to retinal progenitor cells by step (a) can be performed with a marker that is specifically expressed in retinal progenitor cells.
- retinal progenitor cell markers include Rx, Pax6, Chx10, and Six3, and these markers may be used alone or in combination.
- the expression of the marker can be confirmed by immunostaining the marker protein or measuring the expression level of the marker gene by RT-PCR method.
- the retinal progenitor cells obtained in the step (a) are suspended in a serum-free medium (serum-free retinal maturation medium) and further cultured in a serum medium (serum retinal maturation medium).
- serum-free medium serum-free retinal maturation medium
- serum retinal maturation medium serum retinal maturation medium
- the number of days for suspension culture in step (b) varies depending on the type of pluripotent stem cells used.
- culture in serum-free retinal maturation medium is from day 18 to day 24 after the start of differentiation induction, and culture in serum retinal maturation medium is from day 24 to day 26 after the start of differentiation induction.
- culture in serum retinal maturation medium is from day 24 to day 26 after the start of differentiation induction.
- culture in serum retinal maturation medium is from day 7 to day 10 after the start of differentiation induction
- culture in serum retinal maturation medium is from day 10 to day 13 after the start of differentiation induction.
- These culture days are merely examples, and can be changed within a range of 1 to 3 days based on the above days.
- the above-mentioned basic medium can be used as the “retinal maturation medium”, but the basic medium in this step is preferably D-MEM / F-12.
- a serum substitute may be added to the serum-free retinal maturation medium, and the aforementioned serum substitute can be used, but N2 supplement is preferred.
- the serum concentration in the serum retinal maturation medium is preferably about 0.1 to 1%, more preferably about 0.5 to 1%.
- Retinoic acid or the like is added to the serum retinal maturation medium as a neuronal differentiation inducing factor.
- the culture temperature of suspension culture, the CO 2 concentration, and other culture conditions are the same as in step (a).
- the O 2 concentration is preferably the atmospheric oxygen concentration (about 20%) because it tends to differentiate into photoreceptor cells and pigment epithelium at a high oxygen concentration (40%).
- Step (b) Confirmation that differentiation was induced from retinal progenitor cells to retinal ganglion cells by step (b) is the expression of Brn3b, Math5, Sncg, Islet1, Tuj1, etc., which are markers specifically expressed in retinal ganglion cells, Preferably, it can be performed by confirming the expression of Brn3b.
- the expression of the marker can be confirmed by immunostaining the marker protein or measuring the expression level of the marker gene by RT-PCR method.
- the cell mass containing retinal ganglion cells forms an ocular vesicle-like tissue, but the cell mass is directly subjected to adhesion culture without being excised. Can do.
- the medium used in step (c) is referred to as “neural maintenance medium”.
- the time of transition to adhesion culture is 26 to 30 days, preferably 26 to 28 days after the start of differentiation induction in the case of human pluripotent stem cells, and differentiation induction in the case of mouse pluripotent stem cells. It is the 12th to 14th day after the start, but this is just an example, and the 1st to 3rd may be mixed.
- the transition time to this adhesion culture is important, and if it is before or after the above time, the ratio of retinal ganglion cells in which axons are extended decreases.
- the culture is performed from day 26 to day 40 after the start of differentiation induction, and in the case of mouse pluripotent stem cells, it is performed from day 12 to day 20 after the start of differentiation induction.
- the number of culture days and the end of the culture are merely examples, and can be changed as appropriate.
- the container used for adhesion culture may be coated with gelatin, laminin, collagen, poly-D-lysine, polyornithine, fibronectin or vitronectin so that the cells can adhere, spread and proliferate.
- the above-mentioned basic medium can be used as the “neural maintenance medium”, but the basic medium in this step is preferably D-MEM / F-12.
- the “neural maintenance medium” is a serum medium, and the serum concentration in the medium is preferably about 1 to 10%, more preferably about 5 to 10%. The serum concentration may be increased stepwise within this range, or may be constant.
- a neurotrophic factor that promotes axonal elongation can be added to the “neural maintenance medium”. Examples of the neurotrophic factor include BDNF, Neurotrophin-3, and -4, and BDNF is preferable. Moreover, you may contain other growth factors (for example, FGF etc.) and an additive (N2 supplement). However, it is preferable that the nerve maintenance medium does not contain retinoic acid because the addition of retinoic acid is inhibited after a certain period of time even if axons are elongated.
- the adhesion of the cell mass tends to be inhibited when the amount of the medium exceeds the height of the cell mass.
- the amount of the medium is preferably the same height as the cell mass adhered to the incubator.
- Other culture conditions are those used in normal cell culture, for example, the culture temperature is about 30-40 ° C., preferably about 37 ° C., and the CO 2 concentration is about 1-10%, preferably about 5%. It is.
- step (c) retinal ganglion cells with axons extended can be confirmed with an optical microscope or a stereomicroscope.
- the expression of Brn3b, Math5, Sncg, Islet1, Tuj1, etc. which are markers of retinal ganglion cells, preferably the expression of Brn3b may be confirmed. Since Brn3b and Math5, which are most specific to retinal ganglion cells, are found on the outermost layer of the embryoid body, the retinal ganglion cells can be purely removed by separating the outermost layer.
- Retinal ganglion cells with elongated axons prepared by the method of the present invention are used as regenerative medical materials for treating ocular diseases that damage retinal ganglion cells, such as cell preparations or cell sheets. Can be used.
- eye diseases that damage retinal ganglion cells include, for example, glaucoma disease, congenital optic nerve atrophy, hypooptic nerve formation, ischemic disorder, retinal disease, etc., specifically, glaucoma (glaucoma Optic stenosis, glaucomatous optic atrophy), autosomal dominant optic atrophy, label hereditary optic neuropathy (Label disease), idiopathic optic neuritis, optic neurogenesis associated with aniridia, optic neuromyelitis (demyelination), multiple Sclerosis (demyelination), ischemic optic neuropathy, central retinal artery occlusion, branch retinal artery occlusion, central retinal vein occlusion, branch retinal vein occlusion, trauma or drug optic neuropathy, diabetic optic neuropathy, Examples include, but are not limited to, retinopathy of prematurity and retinal detachment.
- the cell preparation of the present invention only needs to contain a culture of retinal ganglion cells prepared by the above method, and can also contain a substance for promoting or assisting contact with the affected area, if necessary.
- a substance for promoting or assisting contact with the affected area examples include extracellular matrix such as Matrigel TM , collagen, fibronectin, vitronectin, laminin, cadherin, integrin, selectin, cell adhesion peptide represented by RGD peptide.
- the cell preparation of the present invention can be administered by, for example, a method of formulating it into a dosage form such as an injection or infusion and locally administering it into the retina.
- a cell sheet can be prepared by overlaying retinal ganglion cells prepared by the method of the present invention.
- the retinal ganglion cell produced by the method of the present invention has a cell layer formed by retinal ganglion cells in which axons are elongated, not simply cell clusters in which retinal ganglion cells are gathered, and cell-cell interaction. Therefore, the retinal ganglion cell culture can be directly transplanted to the affected area.
- a cell sheet in the adhesion culture in the step (c), can be efficiently produced by using an incubator provided with a coating layer that facilitates peeling and collection of cells on the culture surface.
- a cell sheet is formed on the surface of the coating layer by seeding cells on the coating layer provided in the incubator and culturing. Thereafter, based on the properties of the coating layer (temperature responsiveness, enzyme degradability), the culture surface and the cell sheet can be separated from each other, and the cell sheet can be easily peeled and collected from the incubator.
- Such a coating layer examples include those in which the coating layer itself can be decomposed or extinguished, and examples thereof include temperature-reactive polymers (poly-N-isopropylacrylamide (PIPAA) and the like), collagen gels, and the like. it can.
- PIPAA poly-N-isopropylacrylamide
- collagen gels and the like. it can.
- the retinal ganglion cell prepared by the method of the present invention can be used for screening of retinal neuroprotective drug or retinal nerve regenerative drug, for example.
- retinal ganglion cells (normal cell model) prepared by the above method can be used, but retinal ganglion cells (optic nerve disease cell model) that reproduce retinal nerve disease or damage can also be used.
- the normal cell model prepared from iPS cells or ES cells is subjected to stress conditions (for example, pressurization, hypoxia, extension, inflammatory substance). It can be produced by damaging the retinal nerve below.
- retinal ganglion cells prepared under pressurized conditions are cell models for glaucoma
- retinal ganglion cells prepared under hypoxic conditions are cell models for ischemic optic neuropathy
- retinal ganglion cells prepared under extended conditions are trauma. It can be used as a cell model.
- iPS cells disease-specific iPS cells
- the retinal ganglion cell can be induced to differentiate by the method of the present invention.
- hereditary optic nerve diseases include, for example, optic nerve dysplasia associated with congenital aniridia due to Pax6 gene mutation (Pax6 nonsense mutation), autosomal dominant optic nerve atrophy due to OPA1 gene mutation (c.2708delTTAG high frequency mutation), Label hereditary optic neuropathy (Label disease) due to mitochondrial gene mutation (G117788A high frequency mutation) is included.
- a test substance can be brought into contact with these cell models, and the protective or regenerative effect of the test substance on retinal ganglion cells can be evaluated.
- Whether the test substance has a protective or regenerative action on retinal ganglion cells can be determined by, for example, bringing the retinal ganglion cells into contact with the test substance and promoting the survival of cells after a certain period of time, axonal elongation, or It can be performed by analysis of inhibition, changes in axonal flow / electrophysiological reaction (action potential and action current), and expression of molecular markers (eg apoptosis-related genes).
- action potential and action current changes in axonal flow / electrophysiological reaction
- molecular markers eg apoptosis-related genes
- the cells after adding a test substance to a medium containing retinal ganglion cells, the cells may be cultured in the presence of the test substance for a certain period of time.
- the contact can also be performed under stress conditions (for example, pressurization, hypoxia, flame-inducing substance). It is also possible to conduct a determination test for inhibition of neurite outgrowth of retinal ganglion cells by a chemical substance or the like by the same method as the above screening method.
- test substance that is the target of the screening method of the present invention is not particularly limited.
- a mixture containing a plurality of compounds such as extracts of animal and plant tissues or microbial cultures, and preparations purified from them; naturally occurring molecules (eg, amino acids, peptides, oligopeptides, polypeptides, proteins, Nucleic acids, lipids, steroids, glycoproteins, proteoglycans, etc.); or synthetic analogs or derivatives of naturally occurring molecules (eg, peptidomimetics); and non-naturally occurring molecules (eg, combinatorial chemistry techniques) Low molecular organic compounds); and mixtures thereof.
- naturally occurring molecules eg, amino acids, peptides, oligopeptides, polypeptides, proteins, Nucleic acids, lipids, steroids, glycoproteins, proteoglycans, etc.
- synthetic analogs or derivatives of naturally occurring molecules eg, peptidomimetics
- non-naturally occurring molecules eg, combinatorial
- test substance a single test substance may be tested independently, or a mixture of several candidate test substances (including a library) may be tested.
- candidate test substances including a library
- the library containing a plurality of test substances include a synthetic compound library and a peptide library.
- Hereditary optic neuropathy autosomal dominant optic nerve atrophy, Label disease, optic nerve dysplasia associated with aniridia, etc.
- Hereditary optic neuropathy is an intractable optic neuropathy whose pathogenesis and disease-related molecules are unknown.
- iPS cells disease-specific iPS cells
- the pathogenesis of the disease By comparing the process of inducing differentiation with the process of inducing differentiation from iPS cells established from healthy individuals into retinal ganglion cells by the method of the present invention, the pathogenesis of the disease, analysis of disease-related molecules, the cause of the disease Can elucidate the pathology.
- Example 1 Preparation of retinal ganglion cells from human iPS cells
- Method 1 Differentiation induction from human iPS cells to retinal progenitor cells
- Human iPS cells used human skin-derived iPS cells 409B2 provided by RIKEN BioResource Center (BRC) (Okita et al. (2011) A more efficient method to generate integration-free human iPS cells, Nat. Methods).
- Induction of differentiation from human iPS cells to retinal progenitor cells can be found in the literature (Nakano T et al., Self-formation of optic cups and storable stratified neural retina from human ESCs. Cell Stem Cell 10, 771-785 (2012)) was basically carried out as follows according to the SFEBq (Serum-free Floating Culture of Embryoid Body-like aggregates with quick reaggregation) method.
- MMC mitomycin
- retinal differentiation medium RDM [G-MEM medium with 20% KSR, 0.1 mM 2-mercaptoethanol, 0.1 mM non-essential amino acid additive, 1 mM sodium pyruvate, 20 ⁇ M Y-27632 (ROCK inhibitor), 3 ⁇ M IWR-1e (Wnt signal inhibitor), 100 U / ml penicillin, 100 ⁇ g / ml streptomycin added] 10,000 suspended in 100 ⁇ l, seeded 9000 per well in a non-adhesive 96 well plate, 37 ° C., was initiated suspension culture in 5% CO 2 (hereinafter, to count the number of culture days the suspension culture starting point as the start of differentiation induction day 0).
- RNA to cDNA After reverse transcription of RNA to cDNA using 2-STEP real-time PCR kit (Takara Bio), real-time PCR (95 ° C: 15 seconds, 60 ° C) using the following primer set with StepOnePlus real-time PCR system (Life Technologies) 30 cycles for 40 seconds), and the expression levels of Brn3b gene, Rx gene, and Pax6 gene were measured.
- FIG. 2 shows an immunostained image of the embryoid body 24 days after initiation of differentiation induction with an anti-Rx antibody. On the 24th day after the initiation of differentiation induction, the presence of the retinal progenitor eye follicle was confirmed.
- FIG. 3 shows a stereomicroscopic image of the embryoid body 40 days after the initiation of differentiation induction (13 days after the start of adhesion culture).
- the axon extension has already been confirmed the day after the start of adhesion culture, and on the 40th day after the start of differentiation induction (13 days after the start of adhesion culture), about 1 cm of axon radiates from the periphery of the embryoid body attached to the plate. It was confirmed that it was elongated.
- the rate of induction of retinal ganglion cells with elongated axons was determined by the ratio of the number of embryoid bodies in which axon elongation was confirmed to the number of adhered embryoid bodies, which was 80 to 90%. Met.
- FIG. 4 shows an immunostained image of an embryoid body with an anti-Brn3b antibody on the 40th day after initiation of differentiation induction (13th day after initiation of adhesion culture). The presence of retinal ganglion cells (Brn3b positive cells) was confirmed on the 40th day after the initiation of differentiation induction.
- FIG. 5 shows changes over time in the expression level of the marker (Brn3b, Rx, Pax6) gene.
- Rx and Pax6 genes which are marker genes of retinal progenitor cells, are expressed from the early stage after the initiation of differentiation induction, and the expression level of Brn3b, a marker gene of retinal ganglion cells, is on and after 18 days after the initiation of differentiation induction From the start of differentiation induction, the maximum value was shown on the 40th day (13 days after the start of adhesion culture).
- Example 2 Production of retinal ganglion cells from mouse ES cells
- Method (1) Induction of differentiation from mouse ES cells to retinal progenitor cells
- GFP-expressing LB10 Mouse Embryonic Stem Cell GSC-5003 was used. Differentiation induction from mouse ES cells to retinal progenitor cells is described in the literature (Eiraku M, Sasai Y. Mouse embryonic stem cell culture for generation of three-dimensional retinal and cortical tissues. Nat Protoc. 2011 7 (1): 69-79. .) And carried out as follows.
- MEF-supporting cells treated with mitomycin are seeded in a petri dish, the mouse ES cells are seeded on the MEF-supporting cells, and a medium for mouse ES cell culture (15% KSR, 0.05 mM 2-mercaptoethanol in Knockout DMEM medium). , 0.1 mM non-essential amino acid supplement, 0.01 v / v% GlutaMax, 0.001 v / v% LIF (Wako) added).
- the culture medium was changed every day, and the cells were passaged every 3 days.
- the mouse ES cells on the third day after the final passage were detached and collected by trypsin treatment, transferred to a 10 cm dish coated with gelatin, and left for 30 minutes.
- 5,000 susceptibility to 100 ⁇ l of retinal differentiation medium [1.5% KSR, 0.1 mM 2-mercaptoethanol, 0.1 mM non-essential amino acid additive, 1 mM sodium pyruvate added to G-MEM medium] 4500 cells were seeded per well in a 96-well plate that had been subjected to adhesion treatment, and suspension culture was started at 37 ° C and 5% CO 2 (hereinafter, the number of days of culture was counted with this suspension culture start time as day 0 of differentiation induction. To do). On the first day after the initiation of differentiation induction, Matrigel was added to a final concentration of 2.0%, and suspension culture was performed in the same medium until the seventh day.
- Adhesion culture is performed using a nerve maintenance medium [GlutaMAX-containing D-MEM / F12, N2 supplement (Life Technologies), 5% FBS, 100 ng / ml BDNF], up to day 20 (7 days after the start of adhesion culture) went. The amount of medium during the adhesion culture was maintained to be as high as the cells.
- RNA to cDNA After reverse transcription of RNA to cDNA using 2-STEP real-time PCR kit (Takara Bio), real-time PCR (95 ° C: 15 seconds, 60 ° C) using the following primer set with StepOnePlus real-time PCR system (Life Technologies) 30 cycles for 40 seconds), and the expression levels of Brn3b gene, Rx gene, and Pax6 gene were measured.
- FIG. 6 shows a stereomicroscopic image of the embryoid body on the 18th day after the initiation of differentiation induction (5th day after the start of adhesion culture). As in the case of human iPS cells, it was confirmed that about 1 cm of axons were radially extended from the periphery of the embryoid body adhered to the plate.
- FIG. 7 shows an immunostained image of an embryoid body with an anti-Brn3b antibody on the 18th day after the initiation of differentiation induction (5th day after the start of adhesion culture).
- the presence of retinal ganglion cells was confirmed.
- FIG. 8 shows the time course of the marker (Brn3b, Rx, Pax6) gene.
- Rx and Pax6 genes which are marker genes of retinal progenitor cells, are expressed from the initial stage after the initiation of differentiation induction, and the expression level of Brn3b, a marker gene of retinal ganglion cells, is 20 days after the initiation of differentiation induction. Rose.
- Example 3 Sustained release test of neurosuppressive factor for retinal ganglion cells
- suspension culture was terminated and a 6-well plate coated with poly-D-lysine and laminin was used. Embryoid bodies were transferred and adhered, and adhesion culture was started using nerve maintenance medium (GlutaMAX-containing D-MEM / F12, N2 supplement (Life Technologies), 1% FBS) supplemented with BDNF (final concentration 100 ng / ml) did.
- nerve maintenance medium GlutaMAX-containing D-MEM / F12, N2 supplement (Life Technologies), 1% FBS
- BDNF final concentration 100 ng / ml
- Medgel SP P15 (Medgel) was immersed in 30 ⁇ l of 100 ⁇ g / ⁇ l Sema3A and left at 4 ° C. for 60 minutes. After the medgel was placed on the Kimwipe to remove the excess solution, it was placed about 5 mm away from the embryoid body. Thereafter, 10 ⁇ l of 100 ⁇ g / ⁇ l Sema3A was added from the top of the medgel every 3 days. Nine days after the start of the sustained release test, the sample was observed with a stereomicroscope. The results are shown in FIG. It was confirmed that axon elongation on the semaphorin 3A (SemaA) side was significantly inhibited. Therefore, the retinal ganglion cell produced by the method of the present invention can be used for evaluating the kinetics of the retinal ganglion cell with respect to the nerve inhibitory factor using the change of the axon as an index.
- Tables 1 and 2 below collectively show the primers used for gene expression analysis by real-time RT-PCR and the antibodies used for immunostaining tests in Examples 4 to 8 and 13 below.
- RNA was extracted from cells using RNeasy Mini Kit (Qiagen). The expression level of mRNA in each RNA sample was measured using StepONE Sequence Detection System (Applied Biosystems). Reverse transcription polymerase chain reaction (RT-PCR) was performed using One Step SYBR TM PrimeScript TM PLUS RT-PCR Kit (Takara Bio). Real-time PCR is performed using the primers (Table 1), and the expression levels of Rx, Pax6, Chx10, Six3, Brn3b, Crx, Syntaxin, Calbidin, PKC ⁇ , Math5, and Mitf are expressed as transcription factors related to retinal formation. Measured over time.
- the PCR conditions were maintained at 42 ° C. for 5 minutes, then 95 ° C. for 10 seconds, followed by 40 cycles of 95 ° C. for 5 seconds and 60 ° C. for 31 seconds.
- the expression level of mRNA was evaluated by the Ct (Threshold cycle) value.
- the Ct value was first corrected with the expression level of HPRT1, and expressed as a relative amount with the expression level of mRNA on day 0 of differentiation induction (at the start of suspension culture) being 1.
- the sample was incubated with 0.1% Triton X-100 for 15 minutes at room temperature and washed three times for 5 minutes each with PBS.
- the first antibody (Table 2) was reacted at 4 ° C. for 16 hours.
- the second antibody reaction was performed by incubating with the corresponding species-specific Alexa Fluor-488-conjugated antibody (1: 500, Invitrogen) at room temperature for 1 hour in the dark.
- the preparation is ProLong
- the cells were stained with Gold Antifade Reagent with DAPI (Invitrogen) and observed with an IX71 inverted research microscope (Olympus) or BZ-9000E (Keyence).
- Rx is the time when the embryoid body (EB) matures and forms, the upregulation starts clearly on the 6th day after the start of differentiation induction (Day 6), and the eye follicle (OV) begins to grow It peaked on the 18th day (Day 18). Thereafter, up-regulation of Pax6, which is a downstream gene of Rx, continued (FIG. 10A).
- Math5 is known to be expressed in post-mitotic retinal progenitor cells under direct control by Pax6 and to control retinal ganglion cell (RGC) formation. It has been reported that the Math5 mutation in mice lacks retinal ganglion cells, and in humans it shows optic nerve formation (optic nerve aplasia).
- Brn3b known as the most reliable RGC marker, is one of the POU-domain families of transcription factors and is regulated by Math5. Brn3b is supposed to determine the fate of RGC cells by functioning as a suppressor of differentiation into non-RGC cell types. In the differentiation process, Llet-homeodomain factor Islet1 is a co-regulator. is working.
- Chx10 is involved in the proliferation of retinal progenitor cells and is initially expressed in all retinal progenitor cells, but is later known to be limited to retinal bipolar cells.
- Chx10 expression was revealed on the 18th day (Day 18) from the start of differentiation induction, and at least the 34th day when the retinal ganglion cells and axons were elongated after the initiation of embryoid body adhesion culture It continued until (Day34).
- Crx is also known to be restricted in the immature and mature cells of the photoreceptor series, but Crx is also expressed on the 18th day (Day 18) from the start of differentiation induction following Chx10 expression. ( Figure 10A).
- Amacrine cells begin to differentiate immediately after RGC differentiation.
- Syntaxin known as an amacrine cell marker
- Calbindin a horizontal cell marker that grows at a late stage of retinogenesis
- PKC ⁇ a bipolar cell marker
- Mitf a microphthalmia-related transcription factor and the main regulator of melanocyte and retinal pigment epithelial cell (RPE) growth, was hardly expressed in this analysis. This indicates that the method of the present invention induces human iPS cells to differentiate into the retinal nervous system but does not induce differentiation into the retinal pigment epithelial cell (RPE) system.
- RPE retinal pigment epithelial cell
- Example 5 Structural analysis of retinal ganglion cells induced to differentiate from human iPS cells (1) Optical microscope findings (Method) The sample was fixed in 100 mM phosphate buffer containing 4% paraformaldehyde at 4 ° C. for 3 hours, washed with water, dehydrated in an alcohol / xylene grade series, and embedded in paraffin. Each block was continuously cut to a thickness of 3 ⁇ m. Deparaffinized sections were HE stained with hemoxillin and eosin.
- Islet1 which is a marker for RGC and amacrine cells, is positive in the marginal part of the clamp and further toward the inside, indicating that amacrine cells are also growing.
- Brn3b-positive cells were clearly localized to the outermost edge of the clamp on the dish surface. This indicates that long radial axons originate from the peripheral part of the clamp and that the marginal part is the retinal ganglion cell region (RGCR) (FIG. 12B).
- RGCR retinal ganglion cell region
- RGCs which are considered to be RGCR
- the adherent-cultured structural complex was divided into three parts (retinal ganglion cell region (RGCR), optic vesicle region (OVR), embryoid body). It was mechanically divided into the main body (MBEB) (FIG. 13A). Brn3b showed almost 4 times higher expression level in RGCR than MBEB (FIG. 13B). Furthermore, the expression of Crx, a photoreceptor marker, was generally suppressed in RGCR (FIG. 13B). These results clearly demonstrate that RGCR is highly specific to the ganglion cell lineage.
- Islet1 a marker of retinal ganglion cells and amacrine cells, was also upregulated in both RGCR and OVR (FIG. 13B). Taken together, these results indicate that Islet1-positive / Brn3b-negative cells differentiate into amacrine cells, whereas Brn3b and its coactor Islet1 are involved in RGC growth in RGCR. In addition, isolated RGCR was confirmed to survive about 10 days after separation from OVR, suggesting that RGC can be mechanically purified after abundant axon growth.
- Example 7 Confirmation of Neurofilaments of Axons To confirm that apparent axons emanating from the retinal ganglion cell region (RGCR) constitute typical axons, Tau and neurofilament (NF) Were immunostained (FIG. 14B).
- RGCR retinal ganglion cell region
- NF neurofilament
- neurofilament light chain NNL
- neurofilament medium chain NMM
- neurofilament heavy chain NFH
- actin MAP
- actin actin play an important role in axonal growth
- MAP Tau MAP Tau Contributes to the polymerization, stabilization and organization of microtubules, and is known to promote axon growth and efficient axon transport. Stained against Tau and proved axonal transport.
- Neurofilaments are neuronal intermediate filaments, particularly abundant in the central nervous system (CNS) axons, where there are four subunits: neurofilament light chain (NFL), neurofilament medium chain. It is known to occur as a heteropolymer consisting of (NFM), neurofilament heavy chain (NFH), and ⁇ -internexin. Neurofilaments play an important role in the maintenance of radial axon growth and axon caliber, and have the potential of transmission action, both NFL and NFM appear in the early stages of retinal formation, but NFH The synthesis of is known to be delayed.
- NFM neurofilament light chain
- NFH neurofilament heavy chain
- Example 8 Functional analysis of axons (1) Observation of axon flow (method) RGC and its axons are known to be rich in mitochondria and to maintain homeostasis by axonal transport, like other neurons. NTRK1 is a receptor for nerve growth factor, a member of the neurotrophic tyrosine kinase receptor family, and is known to be expressed when RGC, particularly its cells are damaged.
- NTRK1 and mitochondria as tracers, a plasmid vector composed of GFP-NTRK1 and CMV promoter and a plasmid vector composed of mcherry-mitochondrion and CMV promoter were electroporated, respectively, to human iPS cells. From 34 days after initiation of differentiation induction (D34), it was directly introduced into the RGC cell body, and anterograde fast axonal transport was measured.
- NTRK1 expression vector (RG213091; origin), pPAmCherry-Mito Vector (Takara Bio), and pcDNA TM 6.2 / C-EmGFP Vector (Invitrogen) were electroporated into cultured cells.
- NEPA21 NEPAGENE
- Culture colonies are injected with a fast green stained DNA solution using a sharp glass pipette, placed between the electrodes, and a voltage pulse (pouring pulse: voltage 100 V, width 2.5 ms, interval 50 ms, 2 times; Transfer pulse: Voltage 20V, width 50 ms, interval 50 ms, 5 times) was electroporated.
- Axonal transport showed two characteristic flows (slow and fast), both of which had an antegrade and retrograde component. In some axons, antegrade axonal flow was observed approximately 7-10 hours after introduction. NTRK1 and mitochondria were expressed in axons and cell bodies. Their presence in axons is indicative of antegrade fast axon transport (left of FIG. 15).
- Chamber contains extracellular solution (120 mM NaCl, 3 mM KCl, 2.5 mM CaCl 2 , 1 mM MgCl 2 , 10 mM glucose, 25 mM NaHCO 3 , equilibrated with 95/5% O 2 / CO 2 , pH 7. 4) was continuously perfused at 1.5 mL / min.
- Whole cell patch clamp recordings were made from retinal ganglion cells located around the outer periphery of the cultured colonies. Recording was performed with an Axopatch 200B amplifier (Molecular Devices) using pCLAMP 9.2 software (Molecular Devices). Section preparations were visualized using an upright microscope (BX50WI; Olympus) equipped with DIC optics and a 60 ⁇ water immersion objective.
- Voltage or current traces were low pass filtered (Bessel, corner frequency 10 kHz) and sampled at 20-50 kHz using a Digidata 1322A interface (Molecular Devices). Voltage-dependent Na + current was measured by leakage and electrostatic current subtraction (P / -5 protocol), and the average of three trial results was determined. In some studies, 1 ⁇ M tetratoxin (TTX) was added to the extracellular solution to block voltage-dependent Na + channels.
- TTX tetratoxin
- Current and voltage data were acquired using pCLAMP 9.2 software and stored in a custom-made personal computer (Physio-Tech). Analysis was performed with Clampfit 9.2 (Molecular Devices) and OriginPro 8J (OriginLab). Images of LY injected cells were captured using a high-precision color camera (HCC-600; Flovel) and stored using INFO.TV Plus software (Infocity). The brightness and contrast of the image were adjusted and complemented by pasting into a portion of another image obtained from a section preparation with different depths using Photoshop CS6 software (Adobe Systems). All data are shown as mean ⁇ SD.
- TTX tetrodotoxin
- Example 9 Preparation of cell model of glaucoma and confirmation of its effectiveness (1) Preparation of cell model of glaucoma
- differentiation induction from human iPS cells to retinal ganglion cells was performed, and suspension culture was performed.
- the completed embryoid body is transferred to a 24-well plate and adherent culture is performed using nerve maintenance medium [GlutaMAX-containing D-MEM / F12, N2 supplement (Life Technologies), 1% FBS].
- Retinal ganglion cell (RGC) colonies with extended axons were transferred to a pressure culture apparatus in the eyes (33 days from the start of differentiation induction).
- Apoptosis immunostaining TUNEL was performed using ApopTag plus fluorescein in situ apoptosis detection kit (Merck Milliboa) according to the attached protocol.
- axons disappeared and a marked increase in apoptotic cells was observed by the TUNEL method (FIG. 17A).
- RT-PCR analysis showed increased expression of the apoptosis promoting gene (Bax gene, Caspase asp3 gene) (Fig. 17B).
- the medium was replaced with a medium supplemented with 100 ng / ml neurotrophic factor [Brain-derived neurotrophic factor (hereinafter referred to as BDNF), Ciliary neurotrophic factor (hereinafter referred to as CNTF)], and retinal ganglion cells with axons extended ( RGC) colonies were transferred to a pressure culture apparatus. After culturing at 60 mmHg under pressure for 12 hours, colonies are recovered, RNA is extracted from the cells using RNeasy Mini Kit (Qiagen), and Bax, Caspase 3 or Caspase 8 genes are analyzed by RT-PCR in the same manner as (1). Then, the expression level of the Bcl2 gene was measured.
- BDNF Brain-derived neurotrophic factor
- CNTF Ciliary neurotrophic factor
- RGC retinal ganglion cells with axons extended
- Example 10 Preparation of a cell model of congenital aniridia and optic nerve dysplasia and confirmation of its effectiveness
- Preparation of a cell model of congenital aniridia and optic nerve dysgenesis Two cases in which mutations in the Pax6 gene were observed ( For cases 1 and 2), iPS cells with optic nerve dysplasia associated with congenital anterior iris were prepared from the conjunctival tissue obtained during surgery. Each mutation was Exon 5, 3 'splicing defect c.774 + 1G> T, and case 2 was Q277X, both of which were nonsense mutations.
- iPS cells were prepared in the usual manner by introducing four factors (Yamanaka et al.) of OCT3 / 4, SOX2, KLF4, and C-MYC. This disease iPS cell was used to induce differentiation into retinal ganglion cells in the same manner as in Example 1, and the embryoid body after suspension culture was transferred to a 24-well plate and a nerve maintenance medium [GlutaMAX-containing D- Adhesion culture was performed using MEM / F12, N2 supplement (Life Technologies), 1% FBS].
- the retinal ganglion cell (RGC) colony was observed under a microscope in the same manner as in Example 1, and the retinal ganglion cell formation gene (Brn3b gene and The expression level of (Math5 gene) was measured by RT-PCR.
- Example 11 Effect of neurotrophic factor or neurosuppressive factor on axon elongation
- differentiation from human iPS cells (normal) to retinal ganglion cells was induced, and the embryoid-like culture was terminated.
- the body was transferred to a 24-well plate and adherent culture was performed using nerve maintenance medium [GlutaMAX-containing D-MEM / F12, N2 supplement (Life Technologies), 1% FBS].
- the medium On the 4th day from the start of adhesion culture (31st day from the start of differentiation induction), the medium was replaced with a medium supplemented with 100 ng / ml neurotrophic factor (BDNF, CNTF) or neurosuppressive factor (Sema3A) in the above nerve maintenance medium. After culturing for days, the retinal ganglion cell (RGC) colony was observed with a microscope in the same manner as in Example 1, and the expression level of Brn3b gene was measured by RT-PCR.
- BDNF braintrophic factor
- CNTF neurotrophic factor
- Sema3A neurosuppressive factor
- BDNF and CNTF When BDNF and CNTF were administered, the axons were elongated better than the control (no administration) (FIG. 21A). In addition, BDNF and CNTF administration significantly increased the expression of Brn3b gene, which is a retinal ganglion cell-specific marker, compared to control (no administration) (FIG. 21B).
- the retinal ganglion cells prepared by the method of the present invention have an action of protecting or regenerating retinal ganglion cells using the axon elongation and retinal ganglion cell-specific marker (Brn3b gene) as an index. It can be used for screening of certain drugs and kinetic evaluation of retinal ganglion cells for neurosuppressive factors.
- Example 12 Confirmation of engraftment and function in mice transplanted with retinal ganglion cells (Method) Retinal ganglion cells (RGC) induced to differentiate from GFP mouse-derived ES cells in the same manner as in Example 2 were transplanted into the eye (vitreous cavity) of B6 mice or Wister rats.
- RRC retinal ganglion cells
- one eye right eye was incised 24 to 36 hours ago, the conjunctiva was incised, the optic nerve behind the eyeball was exposed, and the optic nerve disorder model was created by crushing with tweezers.
- CyclosporinA intramuscular injection 20 mg / kg / day was administered from 1 day before transplantation to 1 week after transplantation, and no immunosuppression treatment was performed in mice.
- colonies to be transplanted were selected at a time when axons began to grow 1 to 3 days after transfer of embryoid bodies subjected to suspension culture to adhesion culture.
- the right eye and its surroundings were disinfected with isodine solution, the conjunctiva was incised, and the sclera at the site considered to be ciliary body was incised with a 25G needle.
- tweezers insert a colony from the sclera wound into the vitreous, suture the sclera with 10-0 nylon thread, suture the conjunctiva with 9-0 silk thread, apply antibiotic ointment, and surgery Ended.
- the animals were euthanized by deep anesthesia, the right eyeball was removed and fixed with 4% paraformaldehyde.
- the eyeball was incised 360 degrees with the ciliary body, the anterior eye and the lens were removed, and the retina of the cup-shaped posterior eye was observed with a fluorescent stereomicroscope. From the specimen in which GFP was observed, a frozen section was prepared and observed with a fluorescence microscope.
- FIG. 24A shows a stereoscopic microscope image of an embryoid body 30 days after the initiation of differentiation induction (3 days after the start of adhesion culture). In the differentiation induction from human ES cells, it was confirmed that axons were radially extended from around the embryoid body.
- the expression levels of transcription factors (Rx, Pax6, Chx10, Brn3b) involved in retinal differentiation on the 24th and 34th days after initiation of differentiation induction (7th day after initiation of adhesion culture) were the same as in Example 1. Measurement was performed by real-time PCR under conditions (see Table 1 for primers). As a result, expression of all transcription factors was observed on the 24th day after induction of differentiation, but the expression level of Brn3b, which is a marker gene specific for RGC, was significantly increased after transfer to adherent cultured cells (FIG. 24B).
- Example 14 Production and analysis of retinal ganglion cells from mouse iPS cells As in Example 2 except that mouse iPS cells (obtained from RIKEN BioResource Center (BRC)) were used instead of mouse ES cells. (However, adhesion culture starts on the 14th day, seeds 4000 per well in a 96-well plate, and Matrigel added on the first day after the induction of differentiation is changed to a final concentration of 1.0%) to differentiate into retinal ganglion cells Guidance was performed.
- FIG. 25A shows a stereoscopic microscope image of an embryoid body on the 22nd day after the initiation of differentiation induction (8th day after the start of adhesion culture).
- Axons of the retinal ganglion cells (RGC) induced to differentiate from the mouse iPS cells and the retinal ganglion cells (RGC) induced to differentiate from the mouse ES cells of Example 2 were analyzed as follows. (Axon transport observation) Axon transport over time is observed by injecting Alexa-Fluo-555-conjugated cholera toxin (Life Technologies) into the central part of the retinal ganglion cell (RGC) optic vesicle differentiated from mouse iPS cells or ES cells. It was. Observation was performed with an IX71 inverted microscope (Olympus). Time lapse analysis was performed using DeltaVision ELITE (Corns Technology) immediately after cholera toxin injection.
- Example 15 Observation of axonal flow of retinal ganglion cells induced to differentiate from human iPS cells Axis of retinal ganglion cells (RGC) obtained from retinal ganglion cells induced to differentiate from human iPS cells in the same manner as in Example 1. Rope transport observation was performed in the same manner as in Example 14. Cholera toxin injected into the central part of the follicle was transported to the peripheral region of the axon by antegrade axonal transport (FIG. 28).
- RRC retinal ganglion cells
- Example 16 Observation and electrophysiological recording of axonal flow of retinal ganglion cells induced to differentiate from human ES cells
- Rope transport observation was performed in the same manner as in Example 14.
- Cholera toxin injected into the central part of the follicle was transported to the peripheral region of the axon by antegrade axonal transport (FIG. 29).
- Electrophysiological recording was performed in the same manner as in Example 8 (2).
- RGCs induced to differentiate from human ES cells also had a long axon process extending to the filter paper side and a dendritic process (FIGS. 30A and B).
- Electrophysiological analysis of cells with axon processes showed a continuous action potential in response to current injection through a recording pipette in current clamp mode (FIG. 30C). Moreover, the cell which generate
- TTX tetrodotoxin
- Example 17 Comparative examination of production conditions of retinal ganglion cells Various conditions in production of retinal ganglion cells (RGC) from human iPS cells of Example 1 were changed, and differentiation induction and axonal elongation were observed.
- the conditions are the date of transition to adhesion culture (18th, 27th, 35th day), the amount of culture medium for adhesion culture (250 ⁇ l, 400 ⁇ l), the optic vesicle from embryoid body (EB) during adhesion culture (EB) OV) excision (with or without), addition of neurotrophic factor (BDNF) to nerve maintenance medium (+,-), addition of retinoic acid (RA) to nerve maintenance medium (+,-), during suspension culture
- the oxygen concentration high oxygen concentration (40%), normal (indoor) oxygen concentration was examined.
- Example 1 Conditions different from Example 1 [Adhesion days: 18th and 35th days, medium volume: 400 ⁇ l, excision of optic ovary (OV): yes, BDNF: no addition (-), RA: addition (+), oxygen concentration : Higher oxygen concentration (40%)] than the culture conditions of Example 1 [Adhesion date: 27th day, medium volume: 250 ⁇ l, excision of eye follicle (OV): none, BDNF: addition (+), RA: Addition (-), oxygen concentration: normal (indoor) oxygen concentration], but differentiation into RGC and axon elongation were good.
- the present invention can be used in the field of producing regenerative medical materials for the treatment of eye diseases such as glaucoma that damage retinal ganglion cells.
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Abstract
Description
(1)以下の工程:
(a)多能性幹細胞を浮遊培養して網膜前駆体細胞に分化誘導する工程;
(b)前記工程(a)で得られた網膜前駆体細胞を浮遊培養して網膜神経節細胞に分化誘導する工程;および
(c) 前記工程(b)で得られた網膜神経節細胞を接着培養して軸索を伸長させる工程;
を含む、軸索が伸長した網膜神経節細胞の作製方法。
(2)多能性幹細胞が、人工多能性幹細胞(iPS細胞)または胚性幹細胞(ES細胞)である、(1)に記載の方法。
(3)接着培養を、神経栄養因子を含む培地で行う、(1)または(2)に記載の方法。
(4)接着培養を、細胞と同じ高さの培地中で行う、(1)~(3)のいずれかに記載の方法。
(5)(1)~(4)のいずれかに記載の方法により得られた、軸索が伸長した網膜神経節細胞の培養物。
(6)(5)に記載の網膜神経節細胞の培養物を含む細胞製剤。
(7)(5)に記載の網膜神経節細胞の培養物を含む細胞シート。
(8)(5)に記載の網膜神経節細胞の培養物に被験物質を接触させ、網膜神経節細胞に対する該被験物質の保護または再生効果を評価することを特徴とする、網膜神経保護薬または網膜神経再生薬のスクリーニング方法。
(9)(5)に記載の網膜神経節細胞の培養物の治療上有効量を哺乳動物に投与することを含む、網膜神経節細胞を障害する眼疾患の治療方法。
(10)網膜神経節細胞を障害する眼疾患が、緑内障性疾患、先天性視神経萎縮、視神経低形成、虚血性障害、または網膜疾患から選ばれる、(9)に記載の治療方法。
(11)網膜神経節細胞を障害する眼疾患の治療における使用のための、(5)に記載の網膜神経節細胞の培養物。
(12) 網膜神経節細胞を障害する眼疾患が、緑内障性疾患、先天性視神経萎縮、視神経低形成、虚血性障害、または網膜疾患から選ばれる、(11)に記載の培養物。
(13)網膜神経節細胞を障害する眼疾患の治療用細胞製剤を製造するための、(5)に記載の網膜神経節細胞の培養物の使用。
(14) 網膜神経節細胞を障害する眼疾患が、緑内障性疾患、先天性視神経萎縮、視神経低形成、虚血性障害、または網膜疾患から選ばれる、(13)に記載の使用。
1.軸索が伸長した網膜神経節細胞の作製方法
本発明は、軸索が伸長した網膜神経節細胞の作製方法であって、該方法は、(a)多能性幹細胞を浮遊培養して網膜前駆体細胞に分化誘導する工程、(b)前記工程(a)で得られた網膜前駆体細胞を浮遊培養して網膜神経節細胞に分化誘導する工程、および、(c) 前記工程(b)で得られた網膜神経節細胞を接着培養して軸索を伸長させる工程を含む。
工程(a):
工程(a)では多能性幹細胞を浮遊培養して網膜前駆体細胞に分化誘導する。多能性幹細胞として使用するiPS細胞やES細胞を維持する場合は、MEF(マウス胎児線維)、SNL、SNLP等のフィーダー細胞上で、適当な培地(市販のiPS細胞用培地や、ES細胞用培地等)を用いればよい。
工程(b)では、工程(a)で得られた網膜前駆体細胞をさらに浮遊培養して網膜神経節細胞に分化誘導する。本工程により、網膜前駆体細胞を網膜神経節細胞に成熟させることができる。工程(b)では、前記工程(a)で得られた網膜前駆体細胞を無血清培地(無血清網膜成熟培地)で浮遊培養をした後、血清培地(血清網膜成熟培地)でさらに培養する。本発明において、工程(b)で使用する上記の無血清網膜成熟培地および血清網膜成熟培地を「網膜成熟培地(RMM培地)」という。工程(b)の浮遊培養の培養日数は、使用する多能性幹細胞の種類により異なる。ヒト多能性幹細胞の場合は、無血清網膜成熟培地での培養は、分化誘導開始後18日目~24日目まで、血清網膜成熟培地における培養は、分化誘導開始後24日目~26日目まで行う。マウス多能性幹細胞の場合は、無血清網膜成熟培地での培養は、分化誘導開始後7日目~10日目まで、血清網膜成熟培地における培養は、分化誘導開始後10日目~13日目まで行う。これらの培養日数はあくまで例示であり、上記の日数を基準として1~3日以内の範囲で変更できる。
工程(c)では、工程(b)で得られた網膜神経節細胞を接着培養に移行させ、さらに培養する。本工程により、軸索が伸長した網膜神経節細胞を形成できる。工程(b)から工程(c)に移行する際に、網膜神経節細胞を含む細胞塊は眼胞様組織を形成しているが、切り出しを行うことなく、細胞塊をそのまま接着培養に供することができる。ここで、眼胞様組織を切り出して接着培養させると分化が不良となることから、細胞塊は眼胞様組織を切り出さずに接着培養させることが好ましい。本発明において、工程(c)で使用する培地は「神経維持培地」という。接着培養への移行時期は、ヒト多能性幹細胞の場合は、分化誘導開始後26日目~30日目、好ましくは26日目~28日目、マウス多能性幹細胞の場合は、分化誘導開始後12日目~14日目であるが、これはあくまで例示であって、1日~3日は前後してもよい。この接着培養への移行時期は重要であって、上記の時期より前又は後であると、軸索が伸長した網膜神経節細胞の割合が低下する。培養日数は、ヒト多能性幹細胞の場合、分化誘導開始後26日目~40日目まで行い、マウス多能性幹細胞の場合、分化誘導開始後12日目~20日目まで行う。培養日数および培養終了時もあくまで例示であって、適宜変更できる。
本発明の方法によって作製された軸索が伸長した網膜神経節細胞は、網膜神経節細胞を障害する眼疾患を治療するための再生医療材料、例えば、細胞製剤または細胞シートとして用いることができる。
本発明の方法で作製された網膜神経節細胞は、例えば網膜神経保護薬または網膜神経再生薬のスクリーニングに利用できる。スクリーニングには、上記の方法で作製された網膜神経節細胞(正常細胞モデル)を用いることができるが、網膜神経疾患や損傷を再現した網膜神経節細胞(視神経疾患細胞モデル)を用いることもできる。視神経疾患細胞モデルの作製は、例えば、非遺伝性疾患細胞モデルの場合、iPS細胞またはES細胞より作製した上記の正常細胞モデルをストレス条件(例えば、加圧、低酸素、伸展、起炎物質)下において網膜神経に障害を与えることにより作製できる。例えば、加圧条件下で作製した網膜神経節細胞は緑内障の細胞モデル、低酸素条件で作製した網膜神経節細胞は虚血視神経症の細胞モデル、伸展条件下で作製した網膜神経節細胞は外傷の細胞モデルとして用いることができる。また、遺伝性疾患細胞モデルの場合は、遺伝性視神経疾患の患者から樹立したiPS細胞や正常iPS細胞を人工的に遺伝子改変することによって疾患の再現を行ったiPS細胞(疾患特異的iPS細胞)から本発明の方法で網膜神経節細胞を分化誘導することにより作製できる。ここで、遺伝性視神経疾患としては、例えば、Pax6遺伝子変異(Pax6 ナンセンス変異)による先天性無虹彩症にともなう視神経形成不全、OPA1遺伝子変異(c.2708delTTAG高頻度変異)による常染色体優性視神経萎縮、ミトコンドリア遺伝子変異(G117788A高頻度変異)によるレーベル遺伝性視神経症(レーベル病)等が挙げられる。これらの細胞モデルに被験物質を接触させ、網膜神経節細胞に対する該被験物質の保護または再生効果を評価することに行うことができる。被験物質が網膜神経節細胞に対する保護または再生作用を有するか否かの判定は、例えば、網膜神経節細胞と被験物質を接触させ、一定時間経過後の細胞の生死、軸索の伸長の促進または抑制、軸索流・電気生理反応(活動電位および活動電流)の変化、分子マーカー(アポトーシス関連遺伝子など)の発現の解析によって行うことができる。被験物質と網膜神経節細胞を接触させる方法については特に制限はなく、当業者に公知の任意の方法により行うことができる。例えば、網膜神経節細胞を含む培地に被験物質を添加した後、被験物質の存在下で該細胞を一定時間培養する方法でよい。また、接触は、ストレス条件(例えば、加圧、低酸素、起炎物質)下で行うこともできる。また、上記のスクリーニング方法と同手法にて、化学物質等による網膜神経節細胞の軸索成長阻害の判定試験を行うことも可能である。
遺伝性視神経障害(常染色体優性視神経萎縮やレーベル病、無虹彩症に伴う視神経形成不全等)は、その発症機構、疾患関連分子が不明な難治性視神経疾患である。このような疾患の患者から樹立したiPS細胞や正常iPS細胞を人工的に遺伝子改変することによって疾患の再現を行ったiPS細胞(疾患特異的iPS細胞)から本発明の方法によって網膜神経節細胞に分化誘導する過程と、健常者から樹立したiPS細胞から本発明の方法によって網膜神経節細胞に分化誘導する過程とを比較することにより、当該疾患の発症機構、疾患関連分子の解析、疾患の原因病態の解明などができる。
1.方法
(1) ヒトiPS細胞から網膜前駆体細胞への分化誘導
ヒトiPS細胞は、理化学研究所バイオリソースセンター(BRC)から提供されたヒト皮膚由来iPS細胞409B2株を使用した(Okita et al. (2011) A more efficient method to generate integration-free human iPS cells, Nat. Methods)。ヒトiPS細胞から網膜前駆体細胞への分化誘導は、マトリゲル濃度とFBS濃度を変更する以外は文献(Nakano T et al., Self-formation of optic cups and storable stratified neural retina from human ESCs. Cell Stem Cell 10, 771-785 (2012))に記載のSFEBq(Serum-free Floating culture of Embryoid Body-like aggregates with quick reaggregation)法に基本的に従い、次のようにして行った。
18日目(Day18)に無血清網膜成熟培地RMM[GlutaMAX含有D-MEM/F12、N2サプリメント(Life Technologies)]に交換し、24日目まで同培地にて浮遊培養を続けた。24日目にFBS(終濃度1%)、レチノイン酸(0.5μM)を添加した網膜成熟培地[GlutaMAX含有D-MEM/F12、N2サプリメント(Life Technologies)]に交換し、その後3日間浮遊培養を継続した。なお、本浮遊培養は、大気酸素濃度下で行った。
27日目に、浮遊培養を終了し、ポリ-D-リシンとラミニンをコーティングした24ウェルプレートに眼胞(OV)を胚様体の本体(main body)につけたままの状態で胚様体を移して接着培養を開始した。接着培養は、BDNF(終濃度100ng/ml)を添加した神経維持培地[GlutaMAX含有D-MEM/F12、N2サプリメント(Life Technologies)、1% FBS]を用いて行い、培地中のFBSの濃度を、30日目に5%、35日目に10%と順次高めていき、40日目(接着培養開始後13日目)まで行った。接着培養時の培地量は細胞と同じ程度の高さ(約250μl)になるように維持した。
以上の(1)~(3)の工程を含むヒトiPS細胞からの網膜神経節細胞の作製方法の模式図を図1に示す。
24日目、40日目に、細胞をPFAで固定化した後、3%BSAでブロッキングした(室温60分)。その後、一次抗体[24日目は抗Rx抗体(Thermo Scientific社製)、40日目は抗Brn3b抗体(Santa Cruz社製)]と一晩反応させた後、TBSで洗浄し、二次抗体(Alexa Fluor-555)と反応させた。
分化誘導過程におけるマーカー(Brn3b、Rx、Pax6)遺伝子の経時変化を調べた。具体的には、分化誘導開始から経時的(6、12、18、24、30、40日目)に細胞を回収し、PBS(-)にて2回洗浄し、RNeasy Mini Kit (キアゲン)によって細胞からRNAを抽出した。2-STEPリアルタイムPCRキット(タカラバイオ)を用いて、RNAをcDNAに逆転写後、StepOnePlusリアルタイムPCRシステム(ライフテクノロジーズ)により、下記のプライマーセットを用いてリアルタイムPCR(95℃:15秒間、60℃:30秒間、40cycles)を実施し、Brn3b遺伝子、Rx遺伝子、Pax6遺伝子の発現量を測定した。
フォワード:5'-TGACACATGAGCGCTCTCACTTAC-3'(配列番号1)
リバース:5'-ACCAAGTGGCAAATGCACCTA-3'(配列番号2)
ヒトRx遺伝子増幅用プライマーセット
フォワード:5'-CCGTCCCTAAGCGTGCTTTC-3'(配列番号3)
リバース:5'-ACTGGGAGCTTCACTAATTTGCTCA-3'(配列番号4)
ヒトPax6遺伝子増幅用プライマーセット
フォワード:5'-TTTAAAGATCCTGGAGGTGGACATA-3'(配列番号5)
リバース:5'-GCTCAGGTGCTCGGGTTCTA-3'(配列番号6)
mRNAの発現量をHPRT遺伝子の発現量で補正し、分化誘導開始日の発現量を1とした相対発現量の値を算出した。
図2は、分化誘導開始後24日目の胚様体の抗Rx抗体による免疫染色像を示す。分化誘導開始後24日目には、網膜前駆体である眼胞の存在が確認できた。
1.方法
(1) マウスES細胞から網膜前駆体細胞への分化誘導
マウスES細胞は、GFP-expressing LB10 Mouse Embryonic Stem Cell GSC-5003(コスモバイオ)を用いた。マウスES細胞から網膜前駆体細胞への分化誘導は、文献(Eiraku M, Sasai Y. Mouse embryonic stem cell culture for generation of three-dimensional retinal and cortical tissues. Nat Protoc. 2011 7(1):69-79.)に従って次のようにして行った。
7日目に無血清網膜成熟培地[GlutaMAX含有D-MEM/F12、N2サプリメント(Life Technologies)]に交換し、10日目まで同培地にて浮遊培養を続けた。10日目の段階でFBS(終濃度1%)、レチノイン酸(0.5μM)を添加した網膜成熟培地[GlutaMAX含有D-MEM/F12、N2サプリメント(Life Technologies)]に交換し、その後3日間浮遊培養を継続した。
13日目に、浮遊培養を終了し、ポリ-D-リシンとラミニンをコーティングした24ウェルプレートに胚様体を移して接着培養を開始した。接着培養は、神経維持培地[GlutaMAX含有D-MEM/F12、N2サプリメント(Life Technologies)、5% FBS、100ng/ml BDNF]を用いて行い、20日目(接着培養開始後7日目)まで行った。接着培養時の培地量は細胞と同じ程度の高さになるように維持した。
18日目に、細胞をPFAで固定化した後、3%BSAでブロッキングした(室温60分)。その後、一次抗体[抗Brn3b抗体(Santa Cruz社製)]と一晩反応させた後、TBSで洗浄し、二次抗体(Alexa Fluor-555)と反応させた。
分化誘導過程におけるマーカー(Brn3b、Rx、Pax6)遺伝子の経時変化を調べた。具体的には、分化誘導開始から経時的(7、10、14、20日目)に細胞を回収し、PBS(-)にて2回洗浄し、RNeasy Mini Kit (キアゲン)によって細胞からRNAを抽出した。2-STEPリアルタイムPCRキット(タカラバイオ)を用いて、RNAをcDNAに逆転写後、StepOnePlusリアルタイムPCRシステム(ライフテクノロジーズ)により、下記のプライマーセットを用いてリアルタイムPCR(95℃:15秒間、60℃:30秒間、40cycles)を実施し、Brn3b遺伝子、Rx遺伝子、Pax6遺伝子の発現量を測定した。
フォワード:5'-ATCGTCTCCCAGAGTAAGAGC-3'(配列番号7)
リバース:5'-CACGGGATGGTGTTCATGG-3'(配列番号8)
マウスRx遺伝子増幅用プライマーセット
フォワード:5'-CGACGTTCACCACTTACCAA-3'(配列番号9)
リバース:5'-TCGGTTCTGGAACCATACCT-3'(配列番号10)
マウスPax6遺伝子増幅用プライマーセット
フォワード:5'-TACCAGTGTCTACCAGCCAAT-3'(配列番号11)
リバース:5'-TGCACGAGTATGAGGAGGTCT-3'(配列番号12)
mRNAの発現量をHPRT遺伝子の発現量で補正し、分化誘導開始日の発現量を1とした相対発現量の値を算出した。
図6に、分化誘導開始後18日目(接着培養開始後5日目)の胚様体の実体顕微鏡像を示す。ヒトiPS細胞の場合と同様に、プレートに接着した胚様体の周囲から1cm程度の軸索が放射状に伸長していることが確認できた。
実施例1の分化誘導開始後27日目に、浮遊培養を終了し、ポリ-D-リシンとラミニンをコーティングした6ウェルプレートに胚様体を移して接着させ、BDNF(終濃度100ng/ml)を添加した神経維持培地[GlutaMAX含有D-MEM/F12、N2サプリメント(Life Technologies)、1% FBS]を用いて接着培養を開始した。接着培養開始後2日目に神経成長阻害物質セマフォリン3A(SemaA)の除放試験を開始した。まずメドジェル SP P15 (メドジェル)を100μg/μl Sema3A 30μlに浸し、4℃で60分放置した。キムワイプの上にメドジェルを載せて余分な溶液を除去した後、胚様体から5mm程度離れたところに置いた。その後3日置きに100μg/μl Sema3A 10μlをメドジェルの上から添加した。徐放試験開始9日後、実体顕微鏡で観察した。結果を図9に示す。セマフォリン3A(SemaA)側の軸索の伸長が顕著に阻害されることが確認できた。よって、本発明の方法により作製された網膜神経節細胞は、その軸索の変化を指標として、神経抑制因子に対する網膜神経節細胞の動態評価に用いることが可能である。
1.方法
(1)リアルタイムRT-PCR
全RNA をRNeasy Mini Kit (キアゲン)を用いて細胞から抽出した。各RNA 試料中のmRNAの発現量をStepONE Sequence Detection System (アプライドバイオシステムズ社)を用いて測定した。逆転写ポリメラーゼ鎖反応(RT-PCR)をOne Step SYBRTM PrimeScriptTM PLUS RT-PCR Kit (タカラバイオ)を用いて行った。前記プライマー(表1)を用いてリアルタイムPCRを行い、網膜形成に関連する転写因子としてRx、Pax6、Chx10、Six3、Brn3b、Crx、Syntaxin、Calbidin、PKCα、Math5、Mitfの各遺伝子の発現量を経時的に測定した。PCRの条件は、42℃5分保持後、95℃10秒、続いて、95℃5秒、60℃31秒を40サイクルとした。mRNAの発現量は、Ct(Threshold cycle)値によって評価した。Ct値は、まずHPRT1の発現量で補正し、分化誘導開始0日目(浮遊培養開始時点)のmRNAの発現量を1とした相対量で表した。
ヒトiPS細胞から分化誘導開始後24日目の浮遊胚様体(EB)上の眼胞(OV)、および分化誘導開始後34日目の細胞(胚様体(EB)を接着培養に移行し、眼胞(OV)から分化誘導した細胞)クランプの突出部のRx、Pax6、Brn3b、Math5およびCrxの免疫染色を以下のようにして実施した。標品(凍結細胞切片または全細胞)を4% パラホルムアルデヒド(pH 7.0)に室温で20分間固定した。PBSで2回洗浄後、標品を0.1% Triton X-100と室温で15分間インキュベートし、PBSで各5分間3回洗浄した。次に、標品を3% BSAと室温で30分間インキュベートした後、第1抗体(表2)を4℃で16時間反応させた。第2抗体反応を対応する種特異的Alexa Fluor-488-結合抗体(1:500、インビトロジェン)と室温にて1時間暗室でインキュベートすることによって行った。PBSで各5分間4回洗浄した後、標品をProLong Gold Antifade Reagent with DAPI(インビトロジェン)で染色し、IX71 倒立型リサーチ顕微鏡(オリンパス)または BZ-9000E (キーエンス)を用いて観察した。
上記転写因子の発現解析結果を図10に示す。網膜ホメオボックス遺伝子であるRx、およびペアボックス遺伝子であるPax6は、眼形成転写因子群(eye-field transcription factors)に属し、最も初期段階の網膜形成(retinogenesis)に重要であることが知られている。Rxは、胚様体(EB)が成熟して形成される時期である分化誘導開始後6日目(Day6)にアップレギレーションが明確に始まり、眼胞(OV)が成長し始める時期である18日目(Day18)にピークとなった。その後、Rxの下流遺伝子であるPax6のアップレギレーションが続いた(図10A)。
(1)光学顕微鏡所見
(方法)
標品を4%パラホルムアデヒド含有100 mM リン酸緩衝液に4℃で3時間固定し、水にて洗浄し、アルコール/キシレンの等級系列で脱水し、パラフィンに包埋した。各ブロックを連続的に3μmの厚さに切断した。脱パラフィンした切片をヘモキシリン及びエオシンでHE染色した。
分化誘導開始後26~29日にディッシュに接着させた眼胞(OV)は、形状が平たくなり、ディッシュは細胞で満たされ、ディッシュ表面には外側辺縁部分から多くの軸索が放射状に伸びた。クランプ内の細胞は明らかに胚様体の本体(main body)の細胞とは異なっており、小さな細胞で満たされていた。クランプ内の細胞は、鮮明な細胞質と核を有する比較的大きな細胞体(範囲:16.1-23.6μm、平均:21.6μm、n=10)で、紡錘型から丸型の形状を有しており、際立った軸索を伴う場合もあった。これらの所見は、細胞体の大きさが12-25μの範囲にあるin vivoの網膜神経節細胞(RGC)と一致していた。注目すべきは、周辺に位置する幾つかの細胞はニッスル小体(Nissl body)を有しており、それは網膜神経節細胞(RGC)の特徴であると考えられた。軸索はエオシン好性であり、分枝はほとんどなく、in vivoにおける視神経乳頭に向かって成長するRGCの軸索と同じようにまっすぐ放射状に成長していることが確認された(図11A、B)。
(方法)
標品を2% グルタルアルデヒド含有100 mMカコジル酸緩衝液中で2時間、続いて、1% 酸化オスミウム含有100 mMカコジル酸緩衝液中で1時間固定した。それらをアルコール/キシレンの等級系列で脱水し、酸化プロピレンで満たし、エポキシ樹脂に包埋した。代表的領域の超薄切片を酢酸ウラニルおよびクエン酸鉛で染色し、JEM-1200EX (日本電子株式会社製)で観察した。
分化誘導開始後35日目の試料の電子顕微鏡観察では、軸索を有する網膜神経節細胞(RGC)は比較的大きく(範囲:16.0-24.1μm、平均:20.6μm、n=10)、クランプの辺縁部分で重層化することが確認できた。これらのRGCは、際立った粗面の小胞体(図11C、矢印部分)を含んでいた。軸索小丘(axon hillock)から伸展した軸索(図11C、三角矢印部分)は、多くの神経細管(neurotubules)を有するが粗面小胞体を有さない特徴的な円錐形の細胞体を示し、in vivoの網膜神経節細胞(RGC)と一致していた。軸索の直径は様々であり(範囲:1.7-2.2μm、平均:1.8μm、n=10)、ミエリン化されておらず、網膜神経線維層や篩板(lamina cribrosa)の前方にある視神経における軸索のそれらと一致するという所見が得られた(図11D)。
眼胞(OV)から分化したクランプの辺縁部分にある軸索を伴った細胞が網膜神経節細胞(RGC)であることを確認するために、RGCに関連する典型的なマーカーであるBrn3b、Math5、Islet1、γ-synuclein (Sncg)、及びβ3-tublin (Tuj1)の発現と分布について試験した。ヒトiPS細胞から分化誘導開始後34日目(Day34)において抽出した全RNAのリアルタイムPCR(プライマーは前記表1参照)では、Brn3b、Math5、Islet1、Sncg、及びTuj1の発現量が30倍以上増加した。これらのマーカー群のなかでも、最もRGCに特異的なBrn3bは、分化誘導開始後1日目(Day1)と34日目(Day34)との比較において、ほぼ3000倍増加した(図12A)。
網膜神経節細胞領域(RGCR)から発する見かけ上の軸索が典型的な軸索を構成することを確認するために、Tau及びニューロフィラメント(NF)を免疫染色した(図14B)。すべてのニューロフィラメント成分(ニューロフィラメント軽鎖(NFL)、ニューロフィラメント中鎖(NFM)、ニューロフィラメント重鎖(NFH)の経時的発現(分化誘導開始から34日目(Day 34)および50日目(Day 50))を平行して観察した。微小管、ニューロフィラメント(NF)、微小管-関連タンパク質(MAP)、及びアクチンは軸索の成長において重要な役割を果たしている。また、MAPであるTauは、微小管の重合化、安定化、及び組織化に寄与し、軸索成長及び効率的な軸索輸送を促進することが知られている。本実施例において検出された軸索は明確にTauに対して染色され、軸索輸送を証明できた。
(1)軸索流の観察
(方法)
RGCおよびその軸索は、ミトコンドリアが豊富であること、および、他の神経細胞と同様に、軸索輸送によって恒常性を維持することが知られている。NTRK1は神経成長因子のレセプターであって、神経栄養チロシンキナーゼ受容体ファミリーの一員であり、RGC、特にその細胞が損傷を受けたときに発現することが知られている。
軸索輸送は2つの特徴的な流れ(slow 及びfast)を示し、それらの両方が順行性および逆行性成分を有していた。幾つかの軸索に、導入から約7~10時間後に順行性軸索流が認められた。NTRK1およびミトコンドリアは、軸索および細胞体において発現していた。軸索におけるこれらの存在は、順行性高速軸索輸送を示すものである(図15左)。また、コレラトキシンをマイクロピペットでコロニー辺縁の細胞体が主に分布する領域に注入し、細胞体に取り込ませたところ、順行性軸索輸送(fast slow)がRGCRに明確に観察され、コレラトキシン注入後2時間以内に順行性軸索輸送によって細胞体から軸索の周辺領域まで輸送された(図15右)。
(方法)
本発明の方法によってヒトiPS細胞より分化誘導した網膜神経節細胞(RGC)が活動電位を発生するかどうかを測定した。コロニーを1枚の混合セルロースエステル性フィルターペーパー(0.2 μm ポアサイズ; アドバンテック)上で1週間培養した。コロニーを載せたフィルターペーパーを培地から除去した後、コロニーを強固に固着させるために、フィルターの底に吸引を行った。厚さ200 μmの切片を垂直に組織チョッパーで切断し、少量のシリコングリース(Dow Corning)を付けた1.5 mL容量の記録チャンバーのガラス底に固定した。すべての試験をThermoClamp-1 (Automate Scientific)を用いて生理学的温度(35-37℃)に維持した。チャンバーを細胞外溶液(120 mM NaCl、3 mM KCl、2.5 mM CaCl2、1 mM MgCl2、10 mM グルコース、25 mM NaHCO3を含有。95/5% O2/CO2で平衡化。pH7.4)を連続的に1.5 mL/minにて潅流した。全細胞パッチクランプ記録を培養コロニーの外周囲に位置する網膜神経節細胞から作成した。記録はpCLAMP 9.2 software (Molecular Devices)を用いるAxopatch 200B amplifier (Molecular Devices)で実施した。切片調製物は、DIC optics 及び 60× 水浸対物レンズを備えた正立顕微鏡(BX50WI; オリンパス)を用いて可視化した。電圧または電流トレースはローパスフィルター(ベッセル(Bessel)、コーナー周波数10 kHz)し、Digidata 1322A インターフェース(Molecular Devices)を用いて20-50 kHzでサンプリングした。電圧依存Na+電流を漏出および静電電流減算(P/-5 protocol)で測定し、3回の試行結果の平均を求めた。幾つかの試験では、電圧依存Na+チャネルをブロックするために細胞外溶液に1 μM テトラトキシン(TTX)を添加した。記録ピペット(6-8 MΩ) を細胞内溶液(120 mM グルコン酸カリウム, 6 mM KCl, 2 mM NaCl, 1 mM CaCl2, 1 mM MgCl2, 5 mM EGTA, 10 mM HEPES, 4 mM Na2ATP, 及び 0.5 mM GTP含有;pH 7.2)で満たした。すべての試験において、ルシファーイエロ-CH二リチウム塩(LY; 0.05%)を細胞内溶液に添加して、記録した細胞の形態を可視化した。液間電位差(-11 mV)を補正した。平均直列抵抗(Rs)は29.4±4.77 MΩ(n = 5)であった。Rsは40 %だけ補正した。Rs>35 MΩのデータを分析から除外した。記録中の平均膜静電容量(average membrane capacitance)は7.20 ± 2.84 pF (n = 5)であった。電流および電圧データをpCLAMP 9.2 software を用いて取得し、特注パーソナルコンピユータ(Physio-Tech)に保存した。解析はClampfit 9.2 (Molecular Devices) 及び OriginPro 8J (OriginLab)で行った。LY注入細胞の画像を、高精度カラーカメラ(HCC-600; Flovel)を用いてキャプチャし、INFO.TV Plus software (Infocity)を用いて保存した。画像の明るさ及びコントラストを調節し、Photoshop CS6 software (Adobe Systems)を用いて深さの異なる切片調製物から得られた他の画像の一部にペーストすることによって補完した。すべてのデータをmean ± SDとして示した。
各網膜神経節細胞(RGC)は、フィルターペーパー側に伸びる長い軸索プロセスを有し、樹状プロセスを有していた(図16A)。軸索プロセスを伴う細胞の電気生理学的分析では、電流クランプモード内の記録ピペットを通した電流インジェクションに応答して連続的な活動電位を示した(5細胞中4細胞)(図16B)。残留膜電位および第1活動電位の増幅はそれぞれ-81.8 ± 26.8 mV 及び 56.8 ± 24.6 mVであった (n = 4)。また、活動電位を発生した細胞は、外向き電流(outward current)に続いて、テトロドトキシン(TTX)-感受性、ナトリウム依存性の最大増幅電流(1,248 ± 573 pA (n = 4))を示した(図16C)。
(1)緑内障の細胞モデルの作製
実施例1と同様にしてヒトiPS細胞から網膜神経節細胞への分化誘導を行い、浮遊培養を終了した胚様体を、24ウェルプレートに移して神経維持培地[GlutaMAX含有D-MEM/F12、N2サプリメント(Life Technologies)、1% FBS]を用いて接着培養を行い、接着培養開始から6日目(分化誘導開始から33日目)に、軸索が伸長した網膜神経節細胞(RGC)コロニーを加圧培養装置に移した。60mmHgの加圧条件下で12時間培養後、コロニーを回収し、RNeasy Mini Kit (キアゲン)によって細胞からRNAを抽出し、RNAをcDNAに逆転写後、StepOnePlusリアルタイムPCRシステム(ライフテクノロジーズ)により、下記のプライマーセットを用いてリアルタイムPCR(95℃:15秒間、60℃:30秒間、40cycles)を実施し、アポトーシス関連遺伝子であるBax遺伝子、Caspase 3またはCaspase 8遺伝子、Bcl2遺伝子の発現量を測定した。またアポトーシスの免疫染色(TUNEL)はApopTag plus fluorescein in situ apoptosis detection kit(メルクミリボア)を使用し、添付のプロトコルに従って実施した。
フォワード:5'- CCCGAGAGGTCTTTTTCCGAG -3'(配列番号51)
リバース:5'- CCAGCCCATGATGGTTCTGAT -3'(配列番号52)
Caspase 3遺伝子増幅用プライマーセット
フォワード:5'- CATGGAAGCGAATCAATGGACT -3'(配列番号53)
リバース:5'- CTGTACCAGACCGAGATGTCA -3'(配列番号54)
Caspase 8遺伝子増幅用プライマーセット
フォワード:5'-CTCCCCAAACTTGCTTTATG -3'(配列番号55)
リバース:5'-AAGACCCCAGAGCATTGTTA -3'(配列番号56)
Bcl2遺伝子増幅用プライマーセット
フォワード:5'- GGTGGGGTCATGTGTGTGG -3'(配列番号57)
リバース:5'- CGGTTCAGGTACTCAGTCATCC -3'(配列番号58)
実施例1と同様にしてヒトiPS細胞から網膜神経節細胞への分化誘導を行い、浮遊培養を終了した胚様体を、24ウェルプレートに移して神経維持培地[GlutaMAX含有D-MEM/F12、N2サプリメント(Life Technologies)、1% FBS]を用いて接着培養を行い、接着培養開始から4日目(分化誘導開始から31日目)に、上記神経維持培地に100ng/ml神経栄養因子[Brain-derived neurotrophic factor(以下、BDNFと記載)、Ciliary neurotrophic factor(以下、CNTFと記載)]を添加した培地に交換し、軸索が伸長した網膜神経節細胞(RGC)コロニーを加圧培養装置に移した。60mmHgの加圧条件下12時間培養後、コロニーを回収し、RNeasy Mini Kit (キアゲン)によって細胞からRNAを抽出し、(1)と同様にしてRT-PCRによりBax遺伝子、Caspase 3またはCaspase 8遺伝子、Bcl2遺伝子の発現量を測定した。
(1)先天無虹彩症・視神経形成不全の細胞モデルの作製
Pax6遺伝子の変異が認められた2例(症例1、症例2)について、手術中に得られた結膜組織から先天無虹彩に伴う視神経形成不全の疾患iPS細胞を作製した。それぞれの変異は、症例1はExon 5の 3' splicing defect c.774+1G>T、症例2はQ277Xで、いずれもナンセンス変異であった。iPS細胞は、OCT3/4、SOX2、KLF4、及びC-MYC の4つの因子(Yamanakaら)を導入して、通常通りの方法で作製した。この疾患iPS細胞を用いて、実施例1と同様にして網膜神経節細胞への分化誘導を行い、浮遊培養を終了した胚様体を、24ウェルプレートに移して神経維持培地[GlutaMAX含有D-MEM/F12、N2サプリメント(Life Technologies)、1% FBS]を用いて接着培養を行った。接着培養開始から8日目(分化誘導開始から35日目)に、実施例1と同様にして、網膜神経節細胞(RGC)コロニーの顕微鏡観察を行い、網膜神経節細胞形成遺伝子(Brn3b遺伝子およびMath5遺伝子)の発現量をRT-PCR法にて測定した。
上記症例1の無虹彩症(c.774+1G>T変異)疾患iPS細胞または正常iPS細胞から、実施例1と同様にして網膜神経節細胞への分化誘導を行い、浮遊培養を終了した胚様体を、24ウェルプレートに移して神経維持培地[GlutaMAX含有D-MEM/F12、N2サプリメント(Life Technologies)、1% FBS]を用いて接着培養を行った。接着培養開始から4日目(分化誘導開始から31日目)に、上記神経維持培地に100ng/ml神経栄養因子(BDNF、CNTF)を添加した培地に交換し、10日間培養した後、網膜神経節細胞(RGC)コロニーの実体顕微鏡により軸索伸長を観察した。また、網膜神経節細胞形成の転写因子(Brn3b、Math5、Islet1、Tuj1)および網膜神経線維の構造遺伝子(Tau、NFL)の発現量をRT-PCR法にて測定した。
実施例1と同様にしてヒトiPS細胞(正常)から網膜神経節細胞への分化誘導を行い、浮遊培養を終了した胚様体を、24ウェルプレートに移して神経維持培地[GlutaMAX含有D-MEM/F12、N2サプリメント(Life Technologies)、1% FBS]を用いて接着培養を行った。接着培養開始から4日目(分化誘導開始から31日目)に、上記神経維持培地に100ng/ml神経栄養因子(BDNF、CNTF)または神経抑制因子(Sema3A)を添加した培地に交換し、10日間培養した後、実施例1と同様にして、網膜神経節細胞(RGC)コロニーの顕微鏡観察を行い、Brn3b遺伝子の発現量をRT-PCR法にて測定した。
(方法)
実施例2と同様にしてGFPマウス由来のES細胞から分化誘導した網膜神経節細胞(RGC)を、B6マウスまたはWisterラットの眼内(硝子体腔)に移植した。いずれの動物も、24-36時間前に片眼(右眼)を、結膜を切開し、眼球後方の視神経を露出し、ピンセットで挫滅して、視神経障害モデルを作製した。ラットでは移植1日前から移植後1週間まで、CyclosporinA筋注20mg/kg/dayを行い、マウスでは免疫抑制処置を行わなかった。移植するコロニーは、実施例2に記載の方法に従い、浮遊培養を行った胚様体を接着培養に移行後1~3日で軸索が伸び始めた時期のものを選択した。
蛍光実体顕微鏡で、網膜上にGFP陽性の組織が観察された。凍結切片の蛍光顕微鏡観察では、GFP陽性の網膜神経節細胞(RGC)が網膜内に生着し、さらに網膜内に軸索の伸長が認められた(図23)。
ヒトiPS細胞に代えて、ヒトES細胞(理化学研究所バイオリソースセンター(BRC)より入手)を用いる以外は、実施例1と同様にして網膜神経節細胞への分化誘導を行った。図24Aに分化誘導開始後30日目(接着培養開始後3日目)の胚様体の実体顕微鏡像を示す。ヒトES細胞からの分化誘導においても、胚様体の周囲から軸索が放射状に伸長していることが確認できた。また、分化誘導開始後24日目、34日目(接着培養開始後7日目)における網膜分化に関与する転写因子(Rx、Pax6、Chx10、Brn3b)の発現量を、実施例1と同様の条件にてリアルタイムPCR(プライマーは前記表1参照)によって測定した。その結果、いずれの転写因子も分化誘導後24日目において発現が認められたが、RGCに特異的なマーカー遺伝子であるBrn3bの発現量は接着培養細胞移行後に顕著に増加した(図24B)。
マウスES細胞に代えて、マウスiPS細胞(理化学研究所バイオリソースセンター(BRC)より入手)を用いる以外は、実施例2と同様(ただし、接着培養開始は14日目、96ウェルプレートに1ウェルあたり4000個播種、分化誘導開始後1日目に添加するマトリゲルを終濃度1.0%に変更)にして網膜神経節細胞への分化誘導を行った。図25Aに分化誘導開始後22日目(接着培養開始後8日目)の胚様体の実体顕微鏡像を示す。マウスiPS細胞からの分化誘導においても、胚様体の周囲から軸索が放射状に伸長していることが確認できた。また、分化誘導開始後14日目(接着培養開始時)における網膜分化に関与する転写因子(Rx、Pax6、Chx10、Math5、Brn3a、Brn3b)の発現量を、実施例2と同様の条件にてリアルタイムPCR(プライマーは下記参照)によって測定したところ、いずれの転写因子も発現が認められたが、マウスでは、Brn3bよりもBrn3aの発現量が大きいことが特徴的であった(図25B)。
フォワード:5'-ATCGTCTCCCAGAGTAAGAGC-3'(配列番号7)
リバース:5'-CACGGGATGGTGTTCATGG-3'(配列番号8)
マウスRx遺伝子増幅用プライマーセット
フォワード:5'-CGACGTTCACCACTTACCAA-3'(配列番号9)
リバース:5'-TCGGTTCTGGAACCATACCT-3'(配列番号10)
マウスPax6遺伝子増幅用プライマーセット
フォワード:5'-TACCAGTGTCTACCAGCCAAT-3'(配列番号11)
リバース:5'-TGCACGAGTATGAGGAGGTCT-3'(配列番号12)
マウスChx10遺伝子増幅用プライマーセット
フォワード:5'-CGATTCCGAAGATGTTTCCTCC -3'(配列番号59)
リバース:5'-ATCTGGGTAGTGGGCTTCATT -3'(配列番号60)
マウスMath5遺伝子増幅用プライマーセット
フォワード:5'-ATCACCCCTACCTCCCTTTCC -3'(配列番号61)
リバース:5'-CGAAGAGCCTCTGCCCATA -3'(配列番号62)
マウスBrn3a遺伝子増幅用プライマーセット
フォワード:5'-AGGCCTATTTTGCCGTACAA -3'(配列番号63)
リバース:5'-CGTCTCACACCCTCCTCAGT-3'(配列番号64)
(軸索輸送観察)
軸索輸送を経時観察は、Alexa-Fluo-555結合コレラトキシン(ライフテクノロジーズ)をマウスiPS細胞またはES細胞から分化誘導した網膜神経節細胞(RGC)の眼胞の中央部に注入することによって行った。観察は、IX71倒立型顕微鏡(オリンパス)で行った。低速度撮影による解析(time lapse analysis)はコレラトキシン注入直後からDeltaVision ELITE (コーンズテクノロジー)を用いて行った。マウスES細胞から分化誘導したRGC及びマウスiPS細胞から分化誘導したRGCのいずれにも順行性軸索輸送が観察され、注入されたコレラトキシンは順行性軸索輸送によって軸索の周辺領域まで輸送された(図26)。
電気的生理学記録は、記録中の平均膜静電容量をマウスiPS細胞から分化誘導した RGC(n=3)については11±9.2pF、マウスES細胞から分化誘導したRGC(n=3)については12±5.7pFに変更する以外は、実施例8(2)と同様にして行った。マウスES細胞から分化誘導したRGC及びマウスiPS細胞から分化誘導したRGCはいずれも、フィルターペーパー側に伸びる長い軸索プロセスを有し、樹状プロセスを有していた(図27上)。軸索プロセスを伴う細胞の電気生理学的分析では、電流クランプモード内の記録ピペットを通した電流インジェクションに応答して連続的な活動電位を示した(図27下)。
実施例1と同様にしてヒトiPS細胞から分化誘導した網膜神経節細胞した網膜神経節細胞(RGC)の軸索輸送観察を実施例14と同様にして行った。眼胞の中央部に注入したコレラトキシンは、順行性軸索輸送によって軸索の周辺領域まで輸送された(図28)。
実施例13と同様にしてヒトES細胞から分化誘導した網膜神経節細胞(RGC)の軸索輸送観察を実施例14と同様にして行った。眼胞の中央部に注入したコレラトキシンは、順行性軸索輸送によって軸索の周辺領域まで輸送された(図29)。電気的生理学記録は、実施例8(2)と同様にして行った。ヒトES細胞から分化誘導したRGCもまた、フィルターペーパー側に伸びる長い軸索プロセスを有し、樹状プロセスを有していた(図30A、B)。軸索プロセスを伴う細胞の電気生理学的分析では、電流クランプモード内の記録ピペットを通した電流インジェクションに応答して連続的な活動電位を示した(図30C)。また、活動電位を発生した細胞は、外向き電流(outward current)に続いて、テトロドトキシン(TTX)感受性を示した(図30D)。
実施例1のヒトiPS細胞からの網膜神経節細胞(RGC)の作製における諸条件を変更し、分化誘導と軸索伸長を観察した。条件としては、接着培養への移行日(18日目、27日目、35日目)、接着培養の培地量(250μl、400μl)、接着培養時の胚様体(EB)からの眼胞(OV)の切り出し(有り、無し)、神経維持培地への神経栄養因子(BDNF)の添加(+、-)、神経維持培地へのレチノイン酸(RA)の添加(+、-)、浮遊培養時の酸素濃度(高酸素濃度(40%)、正常(室内)酸素濃度)について検討した。結果を図31-1、31-2に示す。実施例1と異なる条件[接着日:18日目及び35日目、培地量:400μl、眼胞(OV)の切り出し:有り、BDNF:無添加(-)、RA:添加(+)、酸素濃度:高酸素濃度(40%)]よりも、実施例1の培養条件[接着日:27日目、培地量:250μl、眼胞(OV)の切り出し:無し、BDNF:添加(+)、RA:添加(-)、酸素濃度:正常(室内)酸素濃度]が、RGCへの分化、および軸索の伸長が良好であった。
Claims (11)
- 以下の工程:
(a)多能性幹細胞を浮遊培養して網膜前駆体細胞に分化誘導する工程;
(b)前記工程(a)で得られた網膜前駆体細胞を浮遊培養して網膜神経節細胞に分化誘導する工程;および
(c) 前記工程(b)で得られた網膜神経節細胞を接着培養して軸索を伸長させる工程;
を含む、軸索が伸長した網膜神経節細胞の作製方法。 - 多能性幹細胞が、人工多能性幹細胞(iPS細胞)または胚性幹細胞(ES細胞)である、請求項1に記載の方法。
- 接着培養を、神経栄養因子を含む培地で行う、請求項1または2に記載の方法。
- 接着培養を、細胞と同じ高さの培地中で行う、請求項1~3のいずれかに記載の方法。
- 請求項1~4のいずれかに記載の方法により得られた、軸索が伸長した網膜神経節細胞の培養物。
- 請求項5に記載の網膜神経節細胞の培養物を含む細胞製剤。
- 請求項5に記載の網膜神経節細胞の培養物を含む細胞シート。
- 請求項5に記載の網膜神経節細胞の培養物に被験物質を接触させ、網膜神経節細胞に対する該被験物質の保護または再生効果を評価することを特徴とする、網膜神経保護薬または網膜神経再生薬のスクリーニング方法。
- 請求項5に記載の網膜神経節細胞の培養物の治療上有効量を哺乳動物に投与することを含む、網膜神経節細胞を障害する眼疾患の治療方法。
- 網膜神経節細胞を障害する眼疾患の治療における使用のための、請求項5に記載の網膜神経節細胞の培養物。
- 網膜神経節細胞を障害する眼疾患の治療用細胞製剤を製造するための、請求項5に記載の網膜神経節細胞の培養物の使用。
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