JP5842289B2 - Efficient method for inducing endothelial cells - Google Patents

Description

  The present invention relates to a method for efficiently producing endothelial cells from pluripotent stem cells.

In order to apply pluripotent stem cells including human induced pluripotent stem (iPS) cells (Patent Documents 1 and 2) to regenerative medicine and disease models, it is extremely important to develop an efficient differentiation induction method. The same applies to differentiation induction into cardiovascular cells, and a number of documents have been reported so far. For example, in mouse pluripotent stem cells, a method for inducing systematic differentiation of cardiovascular cells using vascular endothelial growth factor (VEGF) receptor-2-positive mesoderm cells as a common progenitor cell (Non-patent Documents 1 and 2), a direct myocardial guidance method using two-dimensional monolayer high-density culture (Non-patent Document 3), and a myocardial guidance method (Non-patent Document 4) with improved guidance efficiency and yield based on it. . As for endothelial cells among cardiovascular cells, it has been reported that VEGF plays an important role in its differentiation, and that 8-bromo cyclic adenosine monophosphate (cAMP) enhances the differentiation-inducing effect (non-) Patent Documents 5 and 6). Recently, it has been reported that endothelial cells were successfully induced from human iPS cells with high efficiency (Non-patent Document 7).
However, the yield of endothelial cells induced to differentiate from one human iPS cell is still low, and there is a need for further improvement in order to enable medical applications.

USP 5,843,780 WO 2007/069666

Yamashita J. et al., Nature, 408: 92-96, 2000 Narazaki G. et al., Circulation, 118: 498-506, 2008 Laflamme MA et al., Nat Biotechnol. 2007 Sep; 25 (9): 1015-24 Uosaki H. et al., PLoS One, e23657. 2011 Yurugi-Kobayashi T. et al., Arterioscler Thromb Vasc Biol ,, 26: 1977-1984, 2006 Yamamizu K. et al., Blood, 114: 3707-3716, 2009 White MP et al., Stem Cells. 2013 Jan; 31 (1): 92-103

  An object of the present invention is to provide an efficient method for producing endothelial cells. More specifically, to provide a method for efficiently producing endothelial cells by using specific culture conditions or adding a new step in the differentiation induction process from pluripotent stem cells to endothelial cells. It is in.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors can induce differentiation of endothelial cells efficiently and at a high yield when cAMP, VEGF or the like is administered at a specific concentration at a specific time. I found this for the first time. In addition, the present inventors can induce differentiation of endothelial cells efficiently and with high yield by including a step of purifying specific cells in the middle of the differentiation induction step from pluripotent stem cells to endothelial cells. For the first time. The present invention has been completed based on such knowledge.

That is, the present invention provides the following matters.
[1] a) A step of giving differentiation stimulation to pluripotent stem cells to form a cell population containing 20% or more of endothelial progenitor cells from pluripotent stem cells,
b) culturing the cell population in a medium containing cAMP and VEGF so that the ratio of endothelial cell progenitor cells is 40% or more of the total cells; and c) obtaining the cell population obtained in b) with VEGF. Inducing endothelial cells from endothelial cell precursor cells by culturing in a medium containing,
A method for producing endothelial cells from pluripotent stem cells.
[2] The method according to [1], wherein the endothelial progenitor cells are VEGF receptor-2 (KDR) positive cells.
[3] The method according to [1] or [2], wherein in step b), the culture is performed for 1 to 4 days.
[4] The method according to any one of [1] to [3], wherein in step c), the medium containing VEGF does not contain cAMP.
[5] The method according to any one of [1] to [4], wherein in step b), the concentration of cAMP is 0.5 mM to 2 mM.
[6] The method according to any one of [1] to [5], wherein the concentration of VEGF is 50 ng / ml to 200 ng / ml in steps b) and c).
[7] The method according to any one of [1] to [6], wherein in step b), the medium further comprises a p90 ribosomal S6 kinase (RSK) inhibitor.
[8] The method according to any one of [1] to [7], further comprising a step of purifying endothelial progenitor cells during or after step b).
[9] The method according to [8], wherein the step of purifying endothelial progenitor cells is performed 1 to 5 days after the start of the step (b).
[10] The method according to any one of [1] to [9], further comprising a step of culturing the obtained cells in a medium containing bFGF, EGF and fibronectin after step c).
[11] The method according to any one of [1] to [10], wherein step a) includes the following steps i) and ii).
(i) culturing pluripotent stem cells in a medium containing Activin A, and
(ii) culturing the cells obtained in step (i) in a medium containing BMP and bFGF,
[12] A step of coating cells by adding an extracellular matrix to pluripotent stem cells before step (i), and an extracellular matrix on the cells obtained in step (i) before step (ii) The method according to [11], comprising a step of coating a cell by adding
[13] The method according to any one of [1] to [12], wherein the pluripotent stem cell is an iPS cell.
[14] The method according to any one of [1] to [13], wherein the pluripotent stem cell is derived from a human.

  The method of the present invention makes it possible to produce endothelial cells from pluripotent stem cells efficiently and with high yield. Endothelial cells obtained by the method of the present invention can be used as a cell model for diseases caused by treatment of diseases requiring endothelial cell transplantation or abnormalities in endothelial cells.

FIG. 1 shows the time series transition of VE-Cadherin (VECad) and CD31 double positive endothelial cells. (a) Time series of VECad and CD31 double positive endothelial cells every 2 days. The upper group is a control group to which cAMP and VEGF are not administered, and the lower stage is a group to which cAMP and VEGF are administered. (b) Transition over time of VECad and CD31 double positive endothelial cell rate in flow cytometry in control group and cAMP and VEGF administration group. (c) Time course of the number of VECad and CD31 double positive endothelial cells (VECad and CD31 double positive endothelial cell ratio × total number of cells) in the control group and the cAMP and VEGF administration groups. (d) Transition of the total cell number over time in the control group and the cAMP and VEGF administration group. FIG. 2 shows the time series transition of KDR positive cells. (a) Time series transition of KDR and VECad positive cells every 2 days. The upper group is a control group to which cAMP and VEGF are not administered, and the lower stage is a group to which cAMP and VEGF are administered. (b) Transition of KDR positive cell rate over time in flow cytometry in control group and cAMP and VEGF administration group. (c) Transition of the number of KDR positive cells (KDR positive cell rate × total number of cells) over time in the control group and the cAMP and VEGF administration groups. (d) Transition of the total cell number over time in the control group and the cAMP and VEGF administration group. FIG. 3 shows the results of evaluating the administration period of Matrigel and Activin A and the concentration of Activin A in the induction of endothelial cell differentiation. FIG. 4 shows the results of evaluating a suitable time for additionally administering Matrigel in the induction of endothelial cell differentiation. FIG. 5 shows the results of evaluation of cAMP concentration, administration time, and administration period in the induction of endothelial cell differentiation. FIG. 6 shows the results of evaluating the concentration of VEGF in the induction of endothelial cell differentiation. FIG. 7 shows the results of endothelial cell induction efficiency and yield when cAMP and VEGF are added. (A): differentiation induction 4 to 7 days (d4-d7) When cAMP 1.0 mM and VEGF 100 ng / ml are administered, when VEGF alone is administered, and when addition is not performed 9 The comparison of the number of VECad positive cells per 1 cm ² of the culture area in the total number of cells on the day (d9) is shown. (B): Comparison of the number of VECad positive cells under the same conditions. (C): shows results of flow cytometry in which the rate of VECad positive cells was maximized when cAMP 1.0 mM and VEGF 100 ng / ml were administered on differentiation induction days 4 to 7 (d4-d7). FIG. 8 shows the number of collected endothelial cells when the purification method is used. (a): VEGF receptor-2 (KDR) positive cells were purified by FACS on the 6th day of differentiation induction (d6) and cultured, and VECad positive cells were changed to FACS on the 9th day of differentiation induction (d9). Comparison of the number of recovered VECad and CD31 double positive cells from 1iPS cells seeded on day 9 (d9) when purified in the following manner. (b): shows the positive rate of VECad and CD31 of the cell population collected on day 9 (d9) when differentiation was induced on the 6th day (d6) and culture was continued with KDR. (c): When VEGF receptor-2 (KDR) positive cells were purified and cultured on FACS on the 6th day of differentiation induction (d6), and when VECad positive cells were changed to FACS on the 9th day of differentiation induction (d9) 14 shows a comparison of the number of VECad and CD31 double positive cells recovered from 1iPS cells seeded on day 14 (d14). FIG. 9 shows the KDR positive rate before purification (X axis) and the purity of VECad and CD31 double positive cells on differentiation induction day 9 (Y axis) when purification is performed at different timings based on Table 3. The relationship is shown. FIG. 10 shows the enhancement effect of endothelial induction upon administration of cAMP by SL0101-1. (A): cAMP 1.0 mM, VEGF 100 ng / ml, and differentiation induction 4-7 days (d4-d7) under conditions using RPMI medium containing 10% Serum from differentiation induction day 4 (d4) The comparison of the VECad and CD31 double positive cell rate in the total cell number in the 9th day of differentiation (d9) at the time of administering SL0101-1 20 micromol, cAMP 1.0mM, and VEGF 100ng / ml is shown. (B): shows a comparison of the number of VECad and CD31 double positive cells per 1 cm ² of culture area under the same conditions.

  The present invention is described in detail below.

<Pluripotent stem cells>
The pluripotent stem cell that can be used in the present invention is a stem cell that has pluripotency that can be differentiated into all cells existing in a living body and also has a proliferative ability. Examples include, but are not limited to, embryonic stem (ES) cells, embryonic stem (ntES) cells derived from cloned embryos obtained by nuclear transfer, sperm stem cells (“GS cells”), embryonic germ cells (“EG cells”), Induced pluripotent stem (iPS) cells and the like are included. Preferred pluripotent stem cells are ES cells, ntES cells, and iPS cells.

(A) Embryonic stem cells
ES cells are stem cells established from the inner cell mass of early embryos of mammals such as humans and mice (for example, blastocysts) and having the pluripotency and the ability to proliferate by self-replication.

  ES cells are embryonic stem cells derived from the inner cell mass of the blastocyst, the embryo after the morula, in the 8-cell stage of a fertilized egg, and have the ability to differentiate into any cell that constitutes an adult, so-called differentiation. And ability to proliferate by self-replication. ES cells were discovered in mice in 1981 (MJ Evans and MH Kaufman (1981), Nature 292: 154-156), and then ES cell lines were also established in primates such as humans and monkeys (JA Thomson et al. al. (1998), Science 282: 1145-1147, JA Thomson et al. (1995), Proc. Natl. Acad. Sci. USA, 92: 7844-7848, JA Thomson et al. (1996), Biol. Reprod ., 55: 254-259 and JA Thomson and VS Marshall (1998), Curr. Top. Dev. Biol., 38: 133-165).

  ES cells can be established by removing an inner cell mass from a blastocyst of a fertilized egg of a subject animal and culturing the inner cell mass on a fibroblast feeder. Cells are maintained by subculture using a medium supplemented with substances such as leukemia inhibitory factor (LIF) and basic fibroblast growth factor (bFGF). be able to. For methods of establishing and maintaining human and monkey ES cells, see, for example, H. Suemori et al. (2006), Biochem. Biophys. Res. Commun., 345: 926-932, M. Ueno et al. (2006). Natl. Acad. Sci. USA, 103: 9554-9559, H. Suemori et al. (2001), Dev. Dyn., 222: 273-279 and H. Kawasaki et al. (2002), Proc. Natl. Acad. Sci. USA, 99: 1580-1585.

As a medium for ES cell production, for example, DMEM / F-12 medium supplemented with 0.1 mM 2-mercaptoethanol, 0.1 mM non-essential amino acid, 2 mM L-glutamic acid, 20% KSR and 4 ng / ml bFGF, 37 Human ES cells can be maintained at 5 ° C. in a humidified atmosphere of 5% CO ₂ . ES cells also need to be passaged every 3-4 days, where passage is for example 0.25% trypsin and 0.1 mg / ml collagenase IV in PBS containing 1 mM CaCl ₂ and 20% KSR. Can be used.

  In general, ES cells can be selected using the expression of gene markers such as alkaline phosphatase, Oct-3 / 4, Nanog as an index. In particular, in the selection of human ES cells, the expression of gene markers such as OCT-3 / 4, NANOG, etc. can be detected by Real-Time PCR, or the cell surface antigens SSEA-3, SSEA-4, TRA-1 -60, TRA-1-81 can be detected by immunostaining (Klimanskaya I, et al. (2006), Nature. 444: 481-485).

  Human ES cell lines such as KhES-1, KhES-2 and KhES-3 are available from the Institute of Regenerative Medicine (Kyoto, Japan), Kyoto University.

(B) Sperm stem cells Sperm stem cells are testis-derived pluripotent stem cells that are the origin of spermatogenesis. Like ES cells, these cells can be induced to differentiate into various types of cells, and have characteristics such as the ability to create chimeric mice when transplanted into mouse blastocysts (M. Kanatsu-Shinohara et al. ( 2003) Biol. Reprod., 69: 612-616; K. Shinohara et al. (2004), Cell, 119: 1001-1012). Sperm stem cells are capable of self-replication in media containing glial cell line-derived neurotrophic factor (GDNF) and repeated passage under the same culture conditions as ES cells (Takebayashi Masanori et al. (2008), Experimental Medicine, Vol. 26, No. 5 (extra), pages 41-46, Yodosha (Tokyo, Japan)).

(C) Embryonic germ cells Embryonic germ cells are cells that are established from embryonic primordial germ cells and have the same pluripotency as ES cells, such as LIF, bFGF, stem cell factor, etc. It can be established by culturing primordial germ cells in the presence of these substances (Y. Matsui et al. (1992), Cell, 70: 841-847; JL Resnick et al. (1992), Nature, 359: 550 -551).

(D) Induced pluripotent stem cellsInduced pluripotent stem (iPS) cells are cells that introduce a specific nuclear reprogramming substance into somatic cells in the form of DNA or protein, or the endogenous nuclear reprogramming substance by drugs. It is an artificial stem cell derived from a somatic cell that has almost the same characteristics as ES cells, such as pluripotency of differentiation and proliferation ability by self-replication, which can be produced by increasing the expression of sex mRNA and protein ( K. Takahashi and S. Yamanaka (2006) Cell, 126: 663-676, K. Takahashi et al. (2007) Cell, 131: 861-872, J. Yu et al. (2007) Science, 318: 1917- 1920, M. Nakagawa et al. (2008) Nat. Biotechnol., 26: 101-106, International Publication WO 2007/069666 and International Publication WO 2010/068955). The nuclear reprogramming substance is not particularly limited as long as it is a gene specifically expressed in ES cells, a gene that plays an important role in maintaining undifferentiation of ES cells, or a gene product thereof. For example, Oct3 / 4 , Klf4, Klf1, Klf2, Klf5, Sox2, Sox1, Sox3, Sox15, Sox17, Sox18, c-Myc, L-Myc, N-Myc, TERT, SV40 Large T antigen, HPV16 E6, HPV16 E7, Bmil, Lin28, Examples are Lin28b, Nanog, Esrrb or Esrrg. These reprogramming substances may be used in combination when iPS cells are established. For example, a combination including at least one, two, or three of the above-described initialization substances, preferably a combination including four.

For the nucleotide sequences of mouse and human cDNA of each nuclear reprogramming substance and amino acid sequence information of the protein encoded by the cDNA, refer to NCBI accession numbers described in WO 2007/069666, and L-Myc, Lin28 , Lin28b, Esrrb, Esrrg and Glis1 mouse and human cDNA sequences and amino acid sequence information can be obtained by referring to the following NCBI accession numbers, respectively. A person skilled in the art can prepare a desired nuclear reprogramming substance by a conventional method based on the cDNA sequence or amino acid sequence information.
Gene name mouse human
L-Myc NM_008506 NM_001033081
Lin28 NM_145833 NM_024674
Lin28b NM_001031772 NM_001004317
Esrrb NM_011934 NM_004452
Esrrg NM_011935 NM_001438
Glis1 NM_147221 NM_147193

  These nuclear reprogramming substances may be introduced into somatic cells in the form of proteins, for example, by lipofection, binding to cell membrane permeable peptides, microinjection, or in the form of DNA, for example, It can be introduced into somatic cells by techniques such as viruses, plasmids, artificial chromosomes, vectors, lipofection, liposomes, and microinjection. Examples of viral vectors include retroviral vectors and lentiviral vectors (above, Cell, 126, pp.663-676, 2006; Cell, 131, pp.861-872, 2007; Science, 318, pp.1917-1920, 2007 ), Adenovirus vectors (Science, 322, 945-949, 2008), adeno-associated virus vectors, Sendai virus vectors (Proc Jpn Acad Ser B Phys Biol Sci. 85, 348-62, 2009) and the like. Examples of artificial chromosome vectors include human artificial chromosomes (HAC), yeast artificial chromosomes (YAC), and bacterial artificial chromosomes (BAC, PAC). As a plasmid, a plasmid for mammalian cells can be used (Science, 322: 949-953, 2008). The vector can contain regulatory sequences such as a promoter, an enhancer, a ribosome binding sequence, a terminator, and a polyadenylation site so that a nuclear reprogramming substance can be expressed. Examples of the promoter used include EF1α promoter, CAG promoter, SRα promoter, SV40 promoter, LTR promoter, CMV (cytomegalovirus) promoter, RSV (rous sarcoma virus) promoter, MoMuLV (Moloney murine leukemia virus) LTR, HSV- A TK (herpes simplex virus thymidine kinase) promoter or the like is used. Among them, EF1α promoter, CAG promoter, MoMuLV LTR, CMV promoter, SRα promoter and the like can be mentioned. Furthermore, if necessary, drug resistance genes (for example, kanamycin resistance gene, ampicillin resistance gene, puromycin resistance gene, etc.), thymidine kinase gene, diphtheria toxin gene and other selectable marker sequences, green fluorescent protein (GFP), β-glucuronidase ( GUS), reporter gene sequences such as FLAG, and the like. In addition, after introduction into a somatic cell, the above vector contains a LoxP sequence before and after the gene or promoter encoding the nuclear reprogramming substance and the gene encoding the nuclear reprogramming substance that binds to it. You may have. In another preferred embodiment, there is a method for completely removing a transgene from a chromosome by incorporating a transgene into a chromosome using a transposon and then allowing a transferase to act on the cell using a plasmid vector or an adenovirus vector. Can be used. Preferred transposons include, for example, piggyBac, a transposon derived from lepidopterous insects (Kaji, K. et al., (2009), Nature, 458: 771-775, Woltjen et al., (2009), Nature, 458: 766-770, WO 2010/012077). In addition, the vector replicates without chromosomal integration and is present episomally, so that the origin and replication of lymphotrophic herpes virus, BK virus, and bovine papillomavirus The arrangement | sequence which concerns on may be included. Examples include EBNA-1 and oriP or Large T and SV40ori sequences (WO 2009/115295, WO 2009/157201 and WO 2009/149233). Moreover, in order to simultaneously introduce a plurality of nuclear reprogramming substances, an expression vector for polycistronic expression may be used. For polycistronic expression, the gene-encoding sequence may be linked by an IRES or foot-and-mouth disease virus (FMDV) 2A coding region (Science, 322: 949-953, 2008 and WO 2009/092042 2009/152529).

  In order to increase the induction efficiency of iPS cells during nuclear reprogramming, in addition to the above factors, for example, histone deacetylase (HDAC) inhibitors [for example, valproic acid (VPA) (Nat. Biotechnol., 26 (7 ): 795-797 (2008)), small molecule inhibitors such as trichostatin A, sodium butyrate, MC 1293, M344, siRNA and shRNA against HDAC (eg, HDAC1 siRNA Smartpool® (Millipore), HuSH 29mer shRNA Nucleic acid expression inhibitors such as Constructs against HDAC1 (OriGene) etc.], DNA methyltransferase inhibitors (eg 5'-azacytidine) (Nat. Biotechnol., 26 (7): 795-797 (2008)), G9a Histone methyltransferase inhibitors [eg, small molecule inhibitors such as BIX-01294 (Cell Stem Cell, 2: 525-528 (2008)), siRNA and shRNA against G9a (eg, G9a siRNA (human) (Santa Cruz Biotechnology) Etc.), L-channel calcium agonist (eg Bayk8644) (Cell Stem Cell, 3, 568 -574 (2008)), p53 inhibitors (eg siRNA and shRNA against p53) (Cell Stem Cell, 3, 475-479 (2008)), Wnt Signaling activator (eg soluble Wnt3a) (Cell Stem Cell, 3, 132- 135 (2008)), growth factors such as LIF or bFGF, ALK5 inhibitors (eg SB431542) (Nat. Methods, 6: 805-8 (2009)), mitogen-activated protein kinase signaling inhibitors, glycogen synthase kinase- 3 inhibitors (PloS Biology, 6 (10), 2237-2247 (2008)), miRNAs such as miR-291-3p, miR-294, miR-295 (RL Judson et al., Nat. Biotech., 27: 459-461 (2009)), etc. can be used.

  Examples of drugs in the method for increasing the expression of endogenous protein of the nuclear reprogramming substance by drugs include 6-bromoindirubin-3'-oxime, indirubin-5-nitro-3'-oxime, valproic acid, 2- (3- (6-methylpyridin-2-yl) -lH-pyrazol-4-yl) -1,5-naphthyridine, 1- (4-methylphenyl) -2- (4,5,6,7-tetrahydro-2-imino- Examples include 3 (2H) -benzothiazolyl) ethanone HBr (pifithrin-alpha), prostaglandin J2, prostaglandin E2, and the like (WO 2010/068955).

Examples of the culture medium for iPS cell induction include (1) DMEM, DMEM / F12 or DME medium containing 10 to 15% FBS (these media include LIF, penicillin / streptomycin, puromycin, L-glutamine). , (2) ES cell culture medium containing bFGF or SCF, for example, mouse ES cell culture medium (for example, TX-WES medium, thrombos. X) or primate ES cell culture medium (eg primate (
Human and monkey) ES cell culture medium (Reprocell, Kyoto, Japan), mTeSR-1), and the like.

As an example of a culture method, for example, a somatic cell and a nuclear reprogramming substance (DNA or protein) are contacted in DMEM or DMEM / F12 medium containing 10% FBS in the presence of 5% CO ₂ at 37 ° C. Cultivate for ~ 7 days, then re-spread cells onto feeder cells (e.g., mitomycin C-treated STO cells, SNL cells, etc.), and bFGF-containing primate ES cells approximately 10 days after contact between somatic cells and nuclear reprogramming substance The cells can be cultured in a culture medium and ES cell-like colonies can be generated about 30 to about 45 days or more after the contact. Further, in order to increase the induction efficiency of iPS cells, the cells may be cultured under conditions of an oxygen concentration as low as 5-10%.

  Alternatively, as an alternative culture method, 10% FBS-containing DMEM medium (including LIF, penicillin / streptomycin, puromycin, L-glutamine, etc.) on feeder cells (eg, mitomycin C-treated STO cells, SNL cells, etc.) Non-essential amino acids, β-mercaptoethanol, etc. can be included as appropriate.) And ES-like colonies can be formed after about 25 to about 30 days or more.

During the culture, the medium is replaced with a fresh medium once a day from the second day after the start of the culture. The number of somatic cells used for nuclear reprogramming is not limited, but ranges from about 5 × 10 ³ to about 5 × 10 ⁶ cells per 100 cm ^{2 of} culture dish.

  When a gene containing a drug resistance gene is used as the marker gene, marker gene-expressing cells can be selected by culturing in a medium (selective medium) containing the corresponding drug. In addition, when the marker gene is a fluorescent protein gene, the marker gene-expressing cells can be obtained by observing with a fluorescence microscope, by adding a luminescent substrate in the case of a luminescent enzyme gene, Can be detected.

  As used herein, a “somatic cell” may be any cell other than a germ cell derived from a mammal (eg, human, mouse, monkey, pig, rat, etc.), for example, keratinized epithelial cell (Eg, keratinized epidermal cells), mucosal epithelial cells (eg, epithelial cells of the tongue surface), exocrine glandular epithelial cells (eg, mammary cells), hormone-secreting cells (eg, adrenal medullary cells), cells for metabolism and storage (Eg, hepatocytes), luminal epithelial cells that make up the interface (eg, type I alveolar cells), luminal epithelial cells (eg, vascular endothelial cells) in the inner chain, and ciliated cells that have transport ability (Eg, airway epithelial cells), extracellular matrix secreting cells (eg, fibroblasts), contractile cells (eg, smooth muscle cells), blood and immune system cells (eg, T lymphocytes), sensory cells (Eg, sputum cells), autonomic nervous system neurons (eg, cholinergic neurons) Sensory organs and peripheral neuron support cells (eg, companion cells), central nervous system neurons and glial cells (eg, astrocytes), pigment cells (eg, retinal pigment epithelial cells), and their progenitors ( Tissue precursor cells) and the like. There is no particular limitation on the degree of cell differentiation and the age of the animal from which the cells are collected, and this can be applied to both undifferentiated progenitor cells (including somatic stem cells) and terminally differentiated mature cells. It can be used as the source of somatic cells in the invention. Examples of undifferentiated progenitor cells include tissue stem cells (somatic stem cells) such as neural stem cells, hematopoietic stem cells, mesenchymal stem cells, and dental pulp stem cells.

  In the present invention, the mammal individual from which somatic cells are collected is not particularly limited, but is preferably a human.

(E) Cloned embryo-derived ES cells obtained by nuclear transfer
The nt ES cell is a cloned embryo-derived ES cell produced by a nuclear transfer technique and has almost the same characteristics as an ES cell derived from a fertilized egg (T. Wakayama et al. (2001), Science, 292). : 740-743; S. Wakayama et al. (2005), Biol. Reprod., 72: 932-936; J. Byrne et al. (2007), Nature, 450: 497-502). That is, an ES cell established from an inner cell mass of a clonal embryo-derived blastocyst obtained by replacing the nucleus of an unfertilized egg with the nucleus of a somatic cell is an nt ES (nuclear transfer ES) cell. For the production of nt ES cells, a combination of nuclear transfer technology (JB Cibelli et al. (1998), Nat. Biotechnol., 16: 642-646) and ES cell production technology (above) is used ( Wakayama Seika et al. (2008), Experimental Medicine, Vol. 26, No. 5 (extra number), 47-52). In nuclear transfer, reprogramming can be performed by injecting a somatic cell nucleus into an enucleated unfertilized egg of a mammal and culturing it for several hours.

(F) Fusion stem cell A stem cell that has the same pluripotency as a fused ES cell by fusing a somatic cell and an egg or ES cell, and also has a gene unique to the somatic cell (Tada M et al. al. Curr Biol. 11: 1553-8, 2001; Cowan CA et al. Science. 2005 Aug 26; 309 (5739): 1369-73).

Method for inducing differentiation into endothelial cells A method for producing endothelial cells from the pluripotent stem cells of the present invention comprises:
a) A step of giving differentiation stimulation to pluripotent stem cells to form a cell population containing 20% or more of endothelial progenitor cells from pluripotent stem cells,
b) culturing the cell population in a medium containing cAMP and VEGF so that the ratio of endothelial cell progenitor cells is 40% or more of the total cells, and c) obtaining the cell population obtained in b) with VEGF Culturing in a medium containing the method to induce endothelial cells from endothelial cell precursor cells.

In the present invention, “endothelial cell” means a cell expressing at least one of PE-CAM (CD31), VE-cadherin (VECad) and von Willebrand factor (vWF). Among these, cells expressing VE-cadherin (VECad) are preferable, and cells expressing both PE-CAM (CD31) and VE-cadherin (VECad) are more preferable.
Endothelial cells include vascular endothelial cells and corneal endothelial cells.

  Here, the PE-CAM is exemplified by NCBI accession number NM_000442 in the case of humans, and NM_001032378 in the case of mice. VE-cadherin is exemplified by NCBI accession number NM_001795 for humans and NM_009868 for mice. As for vWF, NCBI accession number NM_000552 is exemplified for humans, and NM_011708 is exemplified for mice. The expression of these molecules can be confirmed by a method using an antibody that specifically recognizes these molecules.

  The endothelial cells obtained in the method of the present invention may be a cell population containing other cell types or a purified population. When the cell population includes other cell types, the cell population preferably contains 50% or more, more preferably 80% or more of the endothelial cells of the total number of cells.

The culture method in each step can be performed according to a normal cell culture method.
It may be induced by suspension culture or may be induced by adhesion culture using a coated culture dish.

  Here, the suspension culture means that an embryoid body is formed by culturing cells in a non-adherent state on a culture dish, and is not particularly limited, but is artificial for the purpose of improving adhesion to cells. Culture dishes that have not been treated (eg, coated with an extracellular matrix) or artificially suppressed adhesion (eg, coated with polyhydroxyethyl methacrylic acid (poly-HEMA)) Can be done using.

  In the adhesion culture, a culture dish coated with an extracellular matrix can be used. In the present invention, the extracellular matrix is a supramolecular structure existing outside the cell and may be naturally derived or an artificial product (recombinant). Examples thereof include substances such as collagen, proteoglycan, fibronectin, hyaluronic acid, tenascin, entactin, elastin, fibrillin and laminin, or fragments thereof. These extracellular substrates may be used in combination, and may be prepared from cells such as Matrigel (trademark: Becton Dickinson).

  In the present invention, the medium used for inducing endothelial cells can be prepared using a medium used for culturing animal cells as a basal medium. As the basal medium, for example, IMDM medium, Medium 199 medium, Eagle's Minimum Essential Medium (EMEM) medium, αMEM medium, Dulbecco's modified Eagle's Medium (DMEM) medium, Ham's F12 medium, RPMI 1640 medium, Fischer's medium, StemPro34 (invitrogen) , Mouse Embryonic fibroblast conditioned medium (MEF-CM), and mixed media thereof. In the present invention, RPMI 1640 medium is preferably used. The medium may contain serum or may be serum-free. If necessary, the medium can be, for example, albumin, transferrin, Knockout Serum Replacement (KSR) (serum substitute for FBS during ES cell culture), N2 supplement (Invitrogen), B27 supplement (Invitrogen), fatty acid, insulin, collagen It may contain one or more serum replacements such as precursors, trace elements, 2-mercaptoethanol (2ME), thiol glycerol, lipids, amino acids, L-glutamine, Glutamax (Invitrogen), non-essential amino acids, vitamins, It may also contain one or more substances such as growth factors, small molecule compounds, antibiotics, antioxidants, pyruvate, buffers, inorganic salts.

  The medium may further contain a ROCK inhibitor. In particular, when this step includes a step of dispersing human pluripotent stem cells into single cells, it is preferable that the medium contains a ROCK inhibitor. The ROCK inhibitor is not particularly limited as long as it can suppress the function of Rho kinase (ROCK). For example, Y-27632 can be used in the present invention.

The culture temperature is not limited to the following, but is about 30 to 40 ° C., preferably about 37 ° C., and the culture is performed in an atmosphere of CO ₂ -containing air. The CO ₂ concentration is about 2-5%, preferably 5%.

First, step a) will be described.
In step a), differentiation stimulation is applied to the pluripotent stem cells to form a cell population containing 20% or more of endothelial cell progenitor cells from the pluripotent stem cells. Here, the ratio of the endothelial progenitor cells is not particularly limited as long as it is 20% or more of the total number of cells, but is usually about 20 to 40%.

“Endothelial cell progenitor cells” are a group of cells that can constitute the mesoderm, and the body cavity and the mesothelium, muscle, skeleton, skin dermis, connective tissue, heart and blood vessels (including vascular endothelium) that line it during development ), Blood (including blood cells), lymphatic vessels and spleens, kidneys and ureters, and cells having the ability to produce gonads (testis, uterus, gonadal epithelium). For example, endothelium by expression of markers such as T (synonymous with Brachyury), VEGF receptor-2 (KDR) (Hypertension. 2002 Jun; 39 (6): 1095-100.), FOXF1, FLK1, BMP4, MOX1 and SDF1 The presence of cell precursor cells can be confirmed. Preferably, the endothelial progenitor cells are cells that express KDR.
The expression of a marker such as KDR can be confirmed using, for example, an antibody that specifically recognizes the marker. However, in the method of the present invention, it is sufficient that a certain number of endothelial progenitor cells exist before the start of step b), and the step of confirming the expression level of the marker is unnecessary.

The method for giving differentiation stimulation to pluripotent stem cells is not particularly limited, and examples thereof include a method of adding a differentiation-inducing factor to endothelial cells. Examples of such factors include Activin A, BMP, bFGF, Wnt. Examples include proteins such as (in particular, Wnt3a) and Wnt activators (CHIR, Bio, etc.).
On the other hand, by forming Embrioid body (embryoid body), it is possible to differentiate into endothelial progenitor cells without adding exogenous factors. An aspect in which differentiation stimulation is provided by subjecting sex stem cells to suspension culture as described above is also included in step a).

More specifically, as a method for inducing differentiation from pluripotent stem cells to endothelial progenitor cells, for example, a method including the following steps (i) and (ii) is exemplified.
(i) culturing pluripotent stem cells in a medium containing Activin A,
(ii) culturing the cells obtained in step (i) in a medium containing BMP and bFGF,

The concentration of Activin A in the medium of the step (i) is, for example, 50 ng / ml to 200 ng / ml.
The concentration of BMP in the medium of step (ii) is, for example, 1 ng / ml to 100 ng / ml.
The concentration of bFGF in the medium of the step (ii) is, for example, 1 ng / ml to 100 ng / ml.

The culture time in the step (i) is, for example, culture for 5 days or less, and preferably 12 hours to 3 days.
The culture time in the step (ii) is, for example, 10 days or less, and preferably 2 to 5 days.

Preferably, the method includes a step of coating cells by adding an extracellular matrix to pluripotent stem cells before step (i), and further, cells obtained in step (i) before step (ii) More preferably, the method includes a step of coating cells by adding an extracellular matrix.
The concentration of the extracellular matrix in the step is, for example, in the range of 1/100 dilution to 1/10 dilution.

Next, step b) will be described.
In step b), the cell population obtained in step a) is cultured in a medium containing cAMP and VEGF so that the proportion of endothelial cell progenitor cells is 40% or more of the total cells.
The proportion of endothelial cell progenitor cells may be 40 to 100% of all cells, but is usually 40 to 80%, more preferably 50 to 95%. For example, the ratio of KDR positive cells may be in the above range.
In step b), by culturing the cell population obtained in step a) in a medium containing cAMP and VEGF, the proportion of endothelial cell progenitor cells is preferably 1.5 times higher than the end of step a), More preferably, it becomes twice or more.

  The culture period in step b) may be a period in which the ratio of endothelial cell progenitor cells is 40% or more of the total cells, and is, for example, 1 to 10 days, preferably 1 to 5 days.

The concentration of cAMP in the medium of step (b) is preferably 0.5 mM to 2 mM. CAMP may be a derivative such as 8-bromo cAMP.
The concentration of VEGF in the medium of step (b) is preferably 50 ng / ml to 200 ng / ml.
As the medium components other than cAMP and VEGF, general medium components as described above can be used.

  In step b), the medium may further contain a p90 ribosomal S6 kinase (RSK) inhibitor. Examples of p90 ribosomal S6 kinase (RSK) inhibitors include SL 0101-1. The concentration of the p90 ribosomal S6 kinase (RSK) inhibitor in the medium of step (b) is preferably 1 μM to 100 μM.

Step c), which will be described later, may be performed directly after step b), but preferably, step c) is performed after performing a step of purifying endothelial progenitor cells after or during step b). Thereby, purer endothelial cells can be produced.
The step of purifying the endothelial progenitor cells may be performed by isolating the endothelial progenitor cells from the cell population containing the endothelial progenitor cells, or may be performed other than the endothelial cell progenitor cells from the cell population containing the endothelial cell progenitor cells. You may carry out by removing a cell.
These steps can be performed, for example, by using an antibody against the above-mentioned marker for endothelial cell progenitor cells.

In step c), the cell population obtained in step b) or the purified endothelial cell progenitor cells are cultured in a medium containing VEGF to induce endothelial cells from the endothelial cell progenitor cells.
The medium containing VEGF used in step c) may contain cAMP, but it is preferable that cAMP is not contained because the induction efficiency of endothelial cells may be reduced when culturing is carried out for a long time with cAMP added. .
The concentration of VEGF in the medium of step (c) is preferably 50 ng / ml to 200 ng / ml.
The culture time in the step (c) is, for example, 10 days or less, preferably 1 to 5 days, and particularly preferably 2 days.

  Furthermore, the method of the present invention may include the step (d) of culturing the cells obtained in the step (c) in a medium containing bFGF, EGF and fibronectin. Thereby, the induction efficiency of endothelial cells can be further improved.

The basal medium used in the step (d) is not particularly limited, but is preferably an Endothelial serum free medium medium.
The concentration of bFGF in the medium of the step (d) is, for example, 10 ng / ml to 30 ng / ml.
The concentration of EGF in the medium of the step (d) is, for example, 1 ng / ml to 100 ng / ml.
The concentration of fibronectin in the medium of the step (d) is, for example, 1 μg / ml to 100 μg / ml.

[Example]
The following examples further illustrate the present invention, but the scope of the present invention is not limited by these examples.

Example 1: Conditioning for efficient differentiation into endothelial cells Human iPS cells (201B6 and 836B3) were received from Professor Yamanaka of Kyoto University and reported previously (Uosaki H. et al. PLoS One 2011; 6: e23657) was used for maintenance culture. The details are as follows. Human iPS cells were seeded in a culture dish coated with Matrigel (growth factor reduced, 1:60 dilution, Invitrogen), and conditioned medium from mouse embryonic fibroblasts (MEF) (MEF-CM) And 4 ng / mL human bFGF (hbFGF, WAKO) was added to the culture medium. Conditioned medium basal medium is Knockout DMEM (GIBCO) 471 mL, Knockout serum replacement (KSR) 120 mL, NEAA 6 mL, 200 mM L-Glutamine 3 mL, 55 mM 2-ME (mercaptoethanol (GIBCO), 4 ng / ml hbFGF) It was produced by doing. MEF used was treated with Mitomycin-C (MMC) (WAKO) for 2.5 hours.
Every 4-6 days, detach the cell colonies using CTK solution (0.1% Collagenase IV, 0.25% Trypsin, 20% KSR, and 1 mM CaCl ₂ in Phosphate buffered saline (PBS)), and use a cell strainer to remove small clumps. Subcultured in a state.
Subsequently, in order to find out conditions for efficiently inducing differentiation into endothelial cells, evaluation was performed by changing various conditions based on each step of the protocol shown below (step (1) to step (6)).
Human iPS cells subcultured by the above method were detached from the culture dish by incubating at 37 ° C. for 3-5 minutes using Versene (Invitrogen). After aspirating Versene, it was pipetted with MEF-CM, collected with a single cell, and then centrifuged to count the number of cells.
(1) Next, cells were seeded on a matrigel-coated culture dish at a density of 6,000 -9,000 cells / cm ² and cultured in MEF-CM medium supplemented with bFGF for several days.
(2) Thereafter, the medium was changed to MEF-CM medium supplemented with Matrigel, and further cultured for several hours, and the upper layer of the cells was covered with Matrigel (Matrigel sandwich).
Using the obtained Matrigel-coated cells, differentiation was induced into endothelial cells by the following procedure.
(3) The medium was replaced with RPMI medium (without insulin) supplemented with Activin A (ActA; R & D Systems) and B27 supplement, and cultured for several hours.
(4) After washing, the medium was replaced with RPMI medium (without insulin) supplemented with human bone morphogenetic protein 4 (BMP4; R & D), hbFGF and B27 supplement, and cultured for several days.
(5) After washing, the medium was replaced with RPMI medium (without insulin) supplemented with 8-bromo cAMP (cAMP), vascular endothelial growth factor (VEGF; WAKO) and B27 supplement, and cultured for several days.
(6) After further washing, the medium was replaced with RPMI medium (without insulin) supplemented with vascular endothelial growth factor (VEGF; WAKO) and B27 supplement and cultured for several days.

Step (3) was performed for 18 hours, step (4) was performed for 3 days, step (5) was performed for 3 days, and step (6) was performed for 3 days. It investigated by detecting by a measurement. The results are shown in FIG. In FIG. 1, the start time of the step (3) is set to 0 day. As a control, the case where a medium not containing cAMP and VEGF is used in step (5) is shown.
As a result, VECad and CD31 double positive cells appeared after the start of step (5), and reached 60 to 80% of the total number of cells in step (6). On the other hand, VECad and CD31 double positive cells were hardly detected in the control.

Similarly, the time course of endothelial cell progenitor cells was examined by detecting KDR positive cells by flow cytometry. The results are shown in FIG. In FIG. 2, the start time of the step (3) is set to 0 day. As a control, the case where a medium not containing cAMP and VEGF is used in step (5) is shown.
As a result, KDR positive cells were present at about 20% of the total cells at the start of culture (d0), and increased to about 50% at the end of step (4). Then, it increased to about 90% by culturing of a process (5). On the other hand, in the control, KDR positive cells decreased after the step (5).
From the above, it is possible to efficiently induce endothelial cells by culturing in a medium containing cAMP and VEGF in step (5) to increase KDR positive cells and then culturing in a medium containing VEGF in step (6). I understood.

Example 2: Evaluation for Matrigel Sandwich and Activin A In order to examine the start period of Step (3) from the Matrigel sandwich in Step (2) and the administration period and concentration of Activin A in Step (3), Concentrations of 100 ng / ml, 125 ng / ml and 150 ng / ml, Activin A administration period of 12 hours, 18 hours and 24 hours, and starting time of step (3) from Matrigel sandwich 12 hours and 24 hours later The induction rate of endothelial cells when each combination was used was evaluated. The culture conditions for each step are as follows.
(1) Cells were seeded on a matrigel-coated culture dish at a density of 6,000 -9,000 cells / cm ² and cultured in MEF-CM medium supplemented with 4 ng / mL bFGF for 3 days.
(2) Thereafter, the medium was changed to MEF-CM medium supplemented with Matrigel (diluted 1/60), and further cultured for several hours. The upper layer of the cells was covered with Matrigel, and cultured for 12 hours or 24 hours (Matrigel sandwich).
(3) The medium was replaced with RPMI medium (without insulin) supplemented with various concentrations of Activin A (ActA; R & D Systems) and B27 supplement and cultured for each period.
(4) After washing, the medium was replaced with RPMI medium (without insulin) supplemented with 10 ng / mL human bone morphogenetic protein 4 (BMP4; R & D), 10 ng / mL hbFGF and B27 supplement and cultured for 3 days. .
(5) After washing, the medium is replaced with RPMI medium (without insulin) supplemented with 1.0 mM 8-bromo cAMP (cAMP), 100 ng / ml vascular endothelial growth factor (VEGF; WAKO) and B27 supplement. Cultured for days.
(6) After further washing, the medium was replaced with RPMI medium (without insulin) supplemented with 100 ng / ml vascular endothelial cell growth factor (VEGF; WAKO) and B27 supplement and cultured for 2 days.
As a result, VECad and CD31 double positive cells were obtained in all cases, but the time from the matrigel sandwich to the start of step (3) was 24 hours, the period of step (3) was 18 hours, and The highest induction rate was found when the concentration of Activin A was 125 ng / ml (FIG. 3).

Example 3 Evaluation Step for Additional Matrigel Sandwiches In order to evaluate the time suitable for additional administration of Matrigel in the steps after (3), the re-administration time of Matrigel was set to d2, d1.5, d1. , D3, d4, d6 and d7 (At this time, the start time of the step (3) is defined as d0), the endothelial cell induction rate was evaluated. The culture conditions for the other steps are as follows.
(1) Cells were seeded on a matrigel-coated culture dish at a density of 6,000 -9,000 cells / cm ² and cultured in MEF-CM medium supplemented with 4 ng / mL bFGF for 3 days.
(2) Thereafter, the medium was changed to MEF-CM medium supplemented with Matrigel (1/60 dilution) and further cultured for 1 day, and the upper layer of the cells was covered with Matrigel (Matrigel sandwich).
(3) The medium was replaced with RPMI medium (without insulin) supplemented with 125 ng / mL Activin A (ActA; R & D Systems) and B27 supplement and cultured for 18 hours.
(4) After washing, the medium was replaced with RPMI medium (without insulin) supplemented with 10 ng / mL human bone morphogenetic protein 4 (BMP4; R & D), 10 ng / mL hbFGF and B27 supplement and cultured for 3 days. .
(5) After washing, the medium is replaced with RPMI medium (without insulin) supplemented with 1.0 mM 8-bromo cAMP (cAMP), 100 ng / ml vascular endothelial growth factor (VEGF; WAKO) and B27 supplement. Cultured for days.
(6) After further washing, the medium was replaced with RPMI medium (without insulin) supplemented with 100 ng / ml vascular endothelial cell growth factor (VEGF; WAKO) and B27 supplement and cultured for 2 days.
As a result, VECad and CD31 double positive cells were obtained in all cases, but the highest induction rate was found when additional Matrigel was administered in step (4) (FIG. 4).

Example 4: Evaluation for cAMP In order to evaluate the cAMP concentration, administration timing and administration period in step (5), the cAMP concentrations were 0.25 mM, 0.5 mM and 1 mM, and d4-d7, d5 -Induction rate of endothelial cells was evaluated by the combination when administered during the period of d8, d3-d7, d4-d8 and d3-d8 (in the case of d3 initiation, step (4) was 2 days, and d5 initiation Step (4) will be 4 days, and if d8 ends, step (6) will be 2 days). The culture conditions for the other steps are as follows.
(1) Cells were seeded on a matrigel-coated culture dish at a density of 6,000 -9,000 cells / cm ² and cultured in MEF-CM medium supplemented with 4 ng / mL bFGF for 3 days.
(2) Thereafter, the medium was changed to MEF-CM medium supplemented with Matrigel (1/60 dilution) and further cultured for 1 day, and the upper layer of the cells was covered with Matrigel (Matrigel sandwich).
(3) The medium was replaced with RPMI medium (without insulin) supplemented with 125 ng / mL Activin A (ActA; R & D Systems) and B27 supplement and cultured for 18 hours.
(4) After washing, the medium was replaced with RPMI medium (without insulin) supplemented with 10 ng / mL human bone morphogenetic protein 4 (BMP4; R & D), 10 ng / mL hbFGF and B27 supplement, and cultured for several days. .
(5) After washing, the medium is replaced with RPMI medium (without insulin) supplemented with 8-bromo cAMP (cAMP), 100 ng / ml vascular endothelial growth factor (VEGF; WAKO) and B27 supplement, and cultured for several days. did.
(6) After further washing, the medium was replaced with RPMI medium (without insulin) supplemented with 100 ng / ml vascular endothelial growth factor (VEGF; WAKO) and B27 supplement and cultured for several days until d9.
As a result, it was found that when cAMP was administered with d4-d7 at a concentration of 1 mM, the endothelial cell induction rate was the highest (FIG. 5). In addition, it was found that cAMP was preferably removed from the medium after a certain period of time because the percentage of endothelial cells slightly decreased when cultured in the presence of cAMP up to d8.

Example 5: Evaluation for VEGF To evaluate the concentration of VEGF in step (5), endothelial cells using 0 ng / ml (-), 100 ng / ml, 200 ng / ml and 400 ng / ml of VEGF concentration. The induction rate of was evaluated. Furthermore, it evaluated also in combination with the presence or absence of cAMP. The culture conditions for each step are as follows.
(1) Cells were seeded on a matrigel-coated culture dish at a density of 6,000 -9,000 cells / cm ² and cultured in MEF-CM medium supplemented with 4 ng / mL bFGF for 3 days.
(2) Thereafter, the medium was changed to MEF-CM medium supplemented with Matrigel (1/60 dilution) and further cultured for 1 day, and the upper layer of the cells was covered with Matrigel (Matrigel sandwich).
(3) The medium was replaced with RPMI medium (without insulin) supplemented with 125 ng / mL Activin A (ActA; R & D Systems) and B27 supplement and cultured for 18 hours.
(4) After washing, the medium was replaced with RPMI medium (without insulin) supplemented with 10 ng / mL human bone morphogenetic protein 4 (BMP4; R & D), 10 ng / mL hbFGF and B27 supplement and cultured for 3 days. .
(5) After washing, replace the medium with RPMI medium (without insulin) supplemented with 0 mM or 1.0 mM 8-bromo cAMP (cAMP), various concentrations of vascular endothelial growth factor (VEGF; WAKO) and B27 supplement. And cultured for 3 days.
(6) After further washing, the medium was replaced with RPMI medium (without insulin) supplemented with 100 ng / ml vascular endothelial cell growth factor (VEGF; WAKO) and B27 supplement and cultured for 2 days.
As a result, it was found that when VEGF was administered at a concentration of 100 ng / ml together with 1 mM cAMP, the endothelial cell induction rate was the highest (FIG. 6, FIG. 7 and Table 1).

Example 6: Efficient induction method for differentiation into endothelial cells Experiments for induction of differentiation into endothelial cells were performed by combining the optimum conditions of the respective parameters, which were revealed in Examples 2 to 5.
That is, the differentiation induction protocol is as follows.
The human iPS cells were detached from the culture dish by incubating the subcultured human iPS cells with Versene (Invitrogen) at 37 ° C. for 3-5 minutes. After aspirating Versene, it was pipetted with MEF-CM, collected with a single cell, and then centrifuged to count the number of cells. MEF-CM supplemented with 4 ng / mL bFGF was seeded as a medium at a density of 6,000 to 9,000 cells / cm ² on a culture dish coated with Matrigel. After culturing for 3 days, the medium was changed to MEF-CM supplemented with Matrigel (1/60 dilution) and cultured for another 1 day, and the upper layer of the cells was covered with Matrigel (Matrigel sandwich).
Using the obtained Matrigel-coated cells, differentiation was induced into endothelial cells by the following procedure.
The (d0-d1) medium was replaced with RPMI medium (without insulin) supplemented with 125 ng / mL Activin A (ActA; R & D Systems) and B27 supplement and cultured for 18 hours.
(D1-d4) After washing, the medium was diluted with RPMI medium (insulin-free) supplemented with 10 ng / mL human bone morphogenetic protein 4 (BMP4; R & D), 10 ng / mL hbFGF, Matrigel (1/60 dilution), and B27 supplement. And then cultured for 3 days.
(D4-d7) After washing, replace the medium with RPMI medium (without insulin) supplemented with 1.0 mM 8-bromo cAMP (cAMP), 100 ng / ml vascular endothelial growth factor (VEGF; WAKO) and B27 supplement. Cultured for 3 days.
(D7-d9) After further washing, the medium was replaced with RPMI medium (without insulin) supplemented with 100 ng / ml vascular endothelial growth factor (VEGF; WAKO) and B27 supplement and cultured for 2 days.
Thereafter, on the ninth day of differentiation induction (D9), vascular endothelial cadherin positive cells (VECad positive cells) were collected as endothelial cells by flow cytometry, and the number of cells was measured.
As a result, the number of VECad positive cells / total number of cells (%) was 56.2 ± 12.5%, and the number of VECad positive cells was 1.66 ± 0.70 × 10 ⁵ .

Example 7: Comparison between direct purification method and indirect purification method Next, in inducing endothelial cells, the effect of culturing after purifying endothelial progenitor cells was examined.
That is, in the method of inducing differentiation into endothelial cells, a method of directly purifying endothelial cells on the ninth day (d9) after the completion of step (6) (hereinafter also referred to as direct purification method), and a step in the process (5) In order to compare the yield and purity of the collected endothelial cells when a step of purifying VEGF receptor-2 (KDR) positive cells was added on day 6 (d6) (hereinafter also referred to as indirect purification method) The following experiment was conducted.
First, in order to obtain a sample by the direct purification method, the cells were cultured until day 9 (d9) based on the endothelial cell differentiation induction method of Example 1, and VECad and CD31 were doubled using a fluorescence activated cell sorter (FACS). Positive cells were purified and collected. The total number of cells was counted, and the yield and purity of the collected endothelial cells were measured by measuring the ratio of VEcad and CD31 double positive cells by flow cytometry.
On the other hand, in order to obtain a sample by the indirect purification method, the cells were cultured until day 6 (d6) based on the endothelial cell differentiation induction method of Example 6, and KDR positive cells were purified and collected. The recovered KDR-positive cells were transferred to a 1.0-mM cAMP, 100 ng / ml VEGF, 10 μmol / L Rho-binding protein kinase inhibitor (Y-27632; CalBiochem) at a density of 10,000 cells / cm ² on a Matrigel-coated culture dish. And seeded with RPMI medium (without insulin) supplemented with B27 supplement. Thereafter, the cells were cultured in RPMI medium (without insulin) supplemented with 100 ng / ml vascular endothelial growth factor (VEGF; WAKO) and B27 supplement for 2 days (d7-d9), and collected on differentiation day 9. Similarly to the direct purification method, the yield and purity of the collected endothelial cells (VECad, CD31 double positive cells) were measured.
As a result, when VEGF receptor-2 (KDR) positive cells were purified on the sixth day (d6) during the step (5) and the culture was continued, the endothelial cells were directly purified on the ninth day (d9). Were also found to show significantly higher yields (Figure 8a and Table 2).
Furthermore, it was examined whether the cells collected by the direct purification method and the indirect purification method could be recultured and expanded. Differentiation induction by day 9 (d9) was performed in the same manner as described above. Endothelial cells at d9 obtained by direct purification method and indirect purification method (purified with d6) were seeded on dishes coated with 1% gelatin respectively, and bFGF (20 ng / ml), EGF (10 ng / ml) and Human Endothelial-SFM medium (Gibco) supplemented with human plasma fibronectin (10 μg / ml) and purified VECad and CD31 double positive cells on differentiation day 14 (d14). The collected endothelial cells were measured for yield and purity.
As a result, the cells collected by the direct purification method and the indirect purification method on the 9th day (d9) are 2.57 ± 1.41 times by the direct purification method and by the indirect purification method for 5 days up to the 14th day (d14). 2.65 ± 0.64 times. There was no difference in proliferation after re-culture, and cell yield on day 14 (d14) was also directly purified on day 9 (d9) when KDR positive cells were purified on day 6 (d6). It was found to show a higher yield than (Figure 8c and Table 2).

Example 8: Evaluation of purification timing in indirect purification method In the method of Example 6, the purification steps of KDR positive cells were performed on d4, d5, and d6, respectively, and the culture was continued until d9. That is, when purifying to d4, KDR positive cells are purified immediately after culturing in a medium containing BMP and bFGF, then cultured for 3 days in a medium containing cAMP and VEGF, and then a medium containing VEGF. For 3 days. When purifying to d5, after culturing in a medium containing BMP and bFGF, the medium is replaced with a medium containing cAMP and VEGF, and further cultured for 1 day, and then KDR positive cells are purified, and then cAMP and VEGF Was further cultured for 2 days in a medium containing VEGF, and then cultured for 3 days in a medium containing VEGF. When purifying to d6, after culturing in a medium containing BMP and bFGF, the medium is replaced with a medium containing cAMP and VEGF, and further cultured for 2 days, and then KDR positive cells are purified, and then cAMP and VEGF are purified. Was further cultured for 1 day in a medium containing VEGF, and then cultured for 3 days in a medium containing VEGF.
Table 3 and FIG. 9 show the timing of purification, the KDR positive rate immediately before purification, and the percentage of endothelial cells in d9. As a result, at the stage where about 20% of KDR positive cells appeared with d4, stimulation was performed with VEGF and cAMP, and after 1-2 days, when KDR positive cells reached about 50-90%, they were purified and induced into endothelial cells. It has been found that the method of producing endothelial cells can be produced particularly efficiently.

Example 9: Effect of enhancing endothelium induction by cAMP administration by inhibiting p90 ribosomal S6 kinase (RSK)
In order to verify the endothelial cell-inducing effect of RSK, it was examined in a medium containing serum, which is known to be difficult to differentiate into endothelial cells. Up to the fourth day of induction of differentiation into endothelial cells (d1-d4) was performed in the same manner as in Example 6. Subsequently, the medium was changed to RPMI medium supplemented with 10% Serum, and differentiation induction 4 to 7 days (d4-d7), 20 μM SL 0101-, which is a selective inhibitor of 1.0 mM cAMP, 100 ng / ml VEGF and RSK VECad and CD31 double positive cell ratios in the total number of cells on the 9th day of differentiation (d9) when 1 (Tocris Bioscience) was administered and when 1.0 mM cAMP and 100 ng / ml VEGF were administered were measured.
As a result, it was found that when SL 0101-1 was added, the endothelial cell induction rate was significantly higher than when SL 0101-1 was not added (FIG. 10 and Table 4).

  The method of the present invention makes it possible to produce endothelial cells from pluripotent stem cells efficiently and with high yield. The present invention makes it possible to supply a large amount of endothelial cells at a low cost, which is extremely useful for industrial applications, particularly in the field of regenerative medicine. In addition, endothelial cells derived from iPS cells prepared from somatic cells of patients with endothelial cell-related diseases are also useful as disease models, and can be used in elucidation of pathological mechanisms and drug discovery screening.

Claims (7)

a) A step of giving differentiation stimulation to pluripotent stem cells to form a cell population containing 20% or more of endothelial progenitor cells from pluripotent stem cells,
b) culturing the cell population in a medium containing cAMP and VEGF so that the ratio of endothelial cell progenitor cells is 40% or more of the total cells; and c) obtaining the cell population obtained in b) with VEGF. the step of inducing endothelial cells seen including, cultured in medium without cAMP and endothelial precursor cells,
A method for producing endothelial cells from pluripotent stem cells. a) A step of giving differentiation stimulation to pluripotent stem cells to form a cell population containing 20% or more of endothelial progenitor cells from pluripotent stem cells,
b) culturing the cell population in a medium containing cAMP and VEGF so that the ratio of endothelial cell progenitor cells is 40% or more of the total cells; and c) obtaining the cell population obtained in b) with VEGF. Inducing endothelial cells from endothelial cell precursor cells by culturing in a medium containing,
A step of purifying endothelial progenitor cells during or after step b);
A method for producing endothelial cells from pluripotent stem cells. The method according to claim 2 , wherein in step c), the medium containing VEGF does not contain cAMP. The method according to any one of claims 1 to 3 , wherein in step b), the medium further comprises a p90 ribosomal S6 kinase (RSK) inhibitor. The method according to any one of claims 1 to 4 , further comprising a step of culturing the obtained cells in a medium containing bFGF, EGF and fibronectin after step c). The method according to any one of claims 1 to 5 , wherein step a) comprises the following steps i) and ii).
(i) culturing pluripotent stem cells in a medium containing Activin A, and
(ii) culturing the cells obtained in step (i) in a medium containing BMP and bFGF, The step of coating cells by adding extracellular matrix to pluripotent stem cells before step (i), and the addition of extracellular matrix to cells obtained in step (i) before step (ii) The method of claim 6 , further comprising the step of coating the cells.