EP0517909A1 - Modified hepatocytes and uses therefor - Google Patents
Modified hepatocytes and uses thereforInfo
- Publication number
- EP0517909A1 EP0517909A1 EP92904304A EP92904304A EP0517909A1 EP 0517909 A1 EP0517909 A1 EP 0517909A1 EP 92904304 A EP92904304 A EP 92904304A EP 92904304 A EP92904304 A EP 92904304A EP 0517909 A1 EP0517909 A1 EP 0517909A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- hepatocytes
- genetic material
- transduced
- interest
- cells
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
- C12N15/00—Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
- C12N15/09—Recombinant DNA-technology
- C12N15/63—Introduction of foreign genetic material using vectors; Vectors; Use of hosts therefor; Regulation of expression
- C12N15/79—Vectors or expression systems specially adapted for eukaryotic hosts
- C12N15/85—Vectors or expression systems specially adapted for eukaryotic hosts for animal cells
- C12N15/86—Viral vectors
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07K—PEPTIDES
- C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
- C07K14/435—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from animals; from humans
- C07K14/575—Hormones
- C07K14/635—Parathyroid hormone (parathormone); Parathyroid hormone-related peptides
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07K—PEPTIDES
- C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
- C07K14/435—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from animals; from humans
- C07K14/705—Receptors; Cell surface antigens; Cell surface determinants
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
- C12N5/00—Undifferentiated human, animal or plant cells, e.g. cell lines; Tissues; Cultivation or maintenance thereof; Culture media therefor
- C12N5/06—Animal cells or tissues; Human cells or tissues
- C12N5/0602—Vertebrate cells
- C12N5/067—Hepatocytes
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K38/00—Medicinal preparations containing peptides
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K48/00—Medicinal preparations containing genetic material which is inserted into cells of the living body to treat genetic diseases; Gene therapy
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
- C12N2740/00—Reverse transcribing RNA viruses
- C12N2740/00011—Details
- C12N2740/10011—Retroviridae
- C12N2740/13011—Gammaretrovirus, e.g. murine leukeamia virus
- C12N2740/13041—Use of virus, viral particle or viral elements as a vector
- C12N2740/13043—Use of virus, viral particle or viral elements as a vector viral genome or elements thereof as genetic vector
Definitions
- the liver is of endodermal origin and the largest gland in the human body. It has numerous crucial roles, including bile secretion, participation in carbohydrate, lipid and protein metabolism, fibrinogen production and detoxification of drugs.
- the liver also serves as the main site at which nutrients absorbed from the gastro-intestinal tract and transported via the blood are processed for use by other body cells.
- Hepatocytes which are the main type of parenchymal or distinguishing cell in the liver, carry out the liver functions and, thus, are responsible for synthesizing, degrading and storing a wide variety of substances.
- a system of small channels (canaliculi) and larger ducts connects hepatocytes with the gut lumen. Through this route, hepatocytes secrete bile, an emulsifying agent which helps in absorption of ingested fats.
- Hepatocytes are also the main location at which lipoprotein particles for export are made; enzymes responsible for synthesis of the lipid constituents of lipoproteins occur in hepatocyte membranes.
- the invention described herein relates to genetically engineered or transduced hepatocytes which express genetic material (DNA or RNA) of interest introduced or incorporated into them, as well as to methods of producing, transplanting and using the genetically engineered hepatocytes.
- the genetic material of interest can be incorporated through the use of a vector, such as a recombinant retrovirus, which contains the genetic material of interest, or by other means.
- Hepatocytes of the present invention express the genetic material of interest.
- Such genetic material of interest can be: 1) genetic material present in and expressed at biologically effective levels by normal hepatocytes, but present in or expressed in less than normal quantities in the hepatocytes prior to transfer of genetic material of interest into them by the method of the present invention; 2) genetic material not present in normal hepatocytes; or 3) genetic material present in normal hepatocytes but not expressed at biologically effective levels in such cells, alone or in any combination thereof.
- the genetic material of interest can be incorporated into the celluar genetic material (e.g., into genomic DNA) or can be present extrachromosomally (i.e., expressed episomally).
- the genetic material of interest can be DNA or RNA; the DNA can constitute all or a portion of a gene of interest (i.e., one whose expression in hepatocytes is desired).
- the genetic material incorporated into and expressed by hepatocytes of the present invention can additionally include genetic material (e.g., DNA) encoding a selectable marker, which provides a means by which cells expressing the genetic material of interest are identified and selected for.
- genetic material e.g., DNA
- a selectable marker which provides a means by which cells expressing the genetic material of interest are identified and selected for.
- Hepatocytes containing incorporated genetic material i.e., genetic material of interest and, optionally, genetic material encoding a selectable marker
- transduced hepatocytes are referred to as transduced hepatocytes.
- Genetic material can be introduced into hepatocytes ex vivo or in vivo. That is, it can be introduced, by means of an appropriate vector, into isolated (cultured) hepatocytes, which are subsequently transplanted into the recipient. Alternatively, it can be introduced directly into the recipient in such a manner that it is directed to-and taken up by target cells (hepatosytes), where it is incorporated and expressed. Particularly useful for this purpose are retroviral vectors which have an amphotropic host range and include the genetic material of interest which is to be incorporated into hepatocytes.
- Retroviral vectors have been used to stably transduce hepatocytes with genetic material which included genetic material encoding a polypeptide or protein of interest and genetic material encoding a dominant selectable marker. Genetic material including DNA encoding a polypeptide of interest and DNA encoding a dominant selectable marker has been introduced into cultured hepatocytes. Expression of the genetic material by the hepatocytes into which they have been incorporated has also been demonstrated.
- Transduced hepatocytes of the present invention are used, for example, for the delivery of polypeptides or proteins which are useful in prevention and therapy of an acquired or an inherited defect in hepatocyte (liver) function.
- they can be used to correct an inherited deficiency of the low density lipoprotein receptor (LDLR), which is synthesized in hepatocytes, and to correct an inherited deficiency of ornithine transcarbalyase (OTC), which results in congenital hyperammonemia.
- LDLR low density lipoprotein receptor
- OTC ornithine transcarbalyase
- Hepatocytes of the present invention are useful as a means by which abnormal hepatocyte function can be corrected. That is, hepatocytes can be transduced with genetic material of interest selected to compensate for over or underproduction of a protein or peptide which is synthesized correctly, but in inappropriate amounts in the hepatocytes. Alternatively, they can be transduced with genetic material of interest encoding a protein or polypeptide which is produced in an appropriate quantity, but is functionally defective (e.g., because of an abnormal structure or amino acid makeup).
- Hepatocytes to be modified ex vivo can be obtained from an individual, modified and returned to the individual by transplanting or grafting or, alternatively, can be obtained from a donor (i.e., a source other than the ultimate recipient), modified and applied to a recipient, again by transplanting or grafting.
- a donor i.e., a source other than the ultimate recipient
- an important advantage of the procedure of the present invention is that the genetically engineered hepatocytes can be used to provide a desired therapeutic protein or peptide by a means essentially the same as that by which the protein or peptide is normally produced and, in the case of autologous grafting, with little risk of an immune response and graft rejection.
- Hepatocytes modified according to the present invention produce the polypeptide as it would normally be produced.
- genes can be introduced into hepatocytes using a retroviral vector, they can be on, (subject to) the retroviral vector control; in such a case, the gene of interest is transcribed from a retroviral promoter.
- a promoter is a specific nucleotide sequence recognized by RNA polymerase molecules that start RNA synthesis.
- retroviral vectors having additional promoter elements in addition to the promoter incorporated in the recombinant retrovirus, which are responsible for the transcription of the genetic material of interest, can be used.
- a construct in which there is an additional promoter modulated by an external factor or cue can be used, making it possible to control the level of polypeptide being produced by the modified hepatocytes by activating that external factor or cue.
- heat shock proteins are proteins encoded by genes in which the promoter is regulated by temperature.
- the promoter of the gene which encodes the metal-containing protein metallothionine is responsive to cadmium (Cd ++) ions. Incorporation of this promoter or another promoter influenced by external cues also makes it possible to regulate the production of the polypeptide by the engineered hepatocytes .
- Figure 1 is a schematic representation of a wild type murine leukemia virus (retroviral) genome.
- Figure 2 is a schematic representation of retroviral vectors, each having a recombinant genome, which are useful in the present invention.
- Figure 2a is pLJ;
- Figure 2b is pEm;
- Figure 2c is pip.
- FIG 3 is a schematic representation of vectors which express human-LDLR. Each has a different transcriptional element which drives expression of LDLR: LTR-LDLR, viral long term repeat sequences (LTR); BA-LDLR, promoter from chicken beta-actin gene (BA); H4-LDLR, promoter from human histone H4 gene (H4); TK-LDLR, promoter from thymidine kinase gene of herpes simplex virus (TK).
- LTR-LDLR viral long term repeat sequences
- BA-LDLR promoter from chicken beta-actin gene (BA)
- H4-LDLR promoter from human histone H4 gene (H4)
- TK-LDLR promoter from thymidine kinase gene of herpes simplex virus
- Figure 4 is a three-day exposure of a Southern blot in which the effect of extracellular matrix and the time of infection on-integration of provirus in rat hepatocyte cultures are shown.
- Figure 5 represents (panels A-F) cytochemical localization of beta-galactosidase activity in transduced cultures of rat hepatocytes and NIH3T3 cell and (panels G-K) liver-specific cytochemical and immunocytochemical stains of rat hepatocyte cultures.
- Figure 6 presents results of a Southern analysis of transduced rabbit hepatocytes.
- Figure 7 presents results of a Northern analysis of transduced rabbit hepatocytes.
- Figure 8 is a graphic representation of human parathyroid hormone (PTH) production by transduced rat hepatocytes and of rat albumin production by control hepatocytes.
- PTH human parathyroid hormone
- Figure 9 is a schematic representation of retroviral vector used and shows in vitro characterization of transduced WHHL hepatocytes.
- Panel A Retroviral vector. The strategy used to clone this vector is described in 'Methods'. Vector sequences involved in the production of appropriate probes are expanded in the area below the vector. The RNA probe complementary to viral sequences in the recombinant transcript is noted; a 172 bp transcript should be protected to digestion with RNase. The 5' and 3' PCR oligonucleotides are derived from human LDL receptor cDNA sequences, and flanking viral sequences, respectively, as shown; a 495 bp fragment is amplified with these oligonucleotides.
- Panel B Southern blot analysis. Total cellular DNA was isolated and analyzed (10 /tg/lane) for proviral sequences as described in "Methods”. DNA from mock-infected hepatocytes plus 1.25 pg of LTR-LDLR plasmid, lane "Plasmid”; DNA from mock-infected hepatocytes, lane "Mock”; DNA from hepatocytes infected with LTR-LDLR virus, lane 'Infected'.
- RNA blot analysis was performed on total cellular RNA as described in "Methods”. Samples were derived from HepG2 (5 ⁇ g), and hepatocytes infected with the LTR-LDLR virus (5, 1 and 0.2 ⁇ g) . HepG2 cells were grown in medium containing lipoprotein deficient serum prior to harvest for RNA.
- Figure 10 shows the effect of hepatocyte transplantation on cholesterol metabolism in WHHL rabbits.
- Donor hepatocytes were transplanted into WHHL rabbits as described in "Methods”.
- Total serum cholesterol presented as the % pretreatment level, was measured as a function of time following transplantation which occurred on Day 0. Data are plotted for each animal.
- Panel A WHHL hepatocytes were transplanted into two animals.
- Panel B NZW hepatocytes were transplanted into three animals.
- Panel C Mock-infected WHHL hepatqcytes were transplanted into six WHHL recipients.
- Panel D LTR-LDLR infected WHHL hepatocytes were transplanted into seven recipients.
- Figure 11 shows results of analysis of liver tissue for proviral DNA sequences by PCR.
- Hepatocyte DNA was isolated from hepatocytes a nd liver tissues and analyzed for proviral sequences using the polymerase chain reaction.
- Hepatocyte DNA was from mock-infected (200 ng) and LTR-LDLR infected hepatocytes (200, 20, 2 and 0.2 ng). Liver DNA from each tissue was isolated on separate occasions with identical results; representative assays are presented. Samples were from control WHHL rabbits (mock) and livers harvested from transplant recipients 10 minutes, 24 hours, and 19 days following the transplant.
- Figure 12 shows results of RNase protection assays.
- RNA samples were hybridized with two 32 labeled RNA probes (3Z-env and
- 4Z-rLDLR 4Z-rLDLR
- Lane A tRNA (100 ⁇ g) plus virus produced (100 ng);
- Lane B WHHL (100 ng) plus virus producer (100 ng);
- Lane C WHHL control (100 ⁇ g);
- Lane D WHHL control 250 ⁇ g
- RNA size standards measured in bp and noted along the left border. Locations of the full length and protected RNA probes, 3Z-env and 4Z-rLDLR, are noted on the right border. Radioactivity in individual bands were measured with a Betagen Scanner (Betagen Co.). The ratio of radioactivity in the virus specific band to that in the endogenous band is noted below each lane as %.
- Figure 13 shows results of in situ hybridization of liver from transplant recipients.
- Cryostat sections of liver were hybridized with the virus specific RNA probe as described in 'Methods'. These tissues were derived from a
- Panels A and B Bright field (A) and dark field (B) views of an area demonstrating periportal distribution of transplanted cells.
- P.V. indicates portal vessels and a probable biliary ductule. Cells which are clearly positive in the dark field are indicated by arrows in the bright field (magnification - 70 X).
- Panels C and D Higher power magnification (X 250) of transplanted hepatocytes visualized on a bright field (C) and a dark field (D).
- Figure 14 is a schematic diagram of the retroviral vector MFG.
- Figure 15 is a schematic diagram of the retroviral vector ⁇ -SGC.
- Figures 16(a) and 16(b) represents a schematic diagram of the construction of the MFG vector of the invention.
- the present invention is based on development of an effective method of introducing genetic material of interest into hepatocytes and of a method of transplanting hepatocytes containing the genetic material of interest.
- an appropriate vector such as a retroviral vector, which includes the genetic material of interest or other means, it is possible to introduce such genetic material into hepatocytes, where it is expressed.
- DNA of interest can be efficiently and stably introduced into mature cultured hepatocytes, which subsequently express the DNA (produce the encoded polypeptide), and that the transduced hepatocytes can be grafted or transplanted.
- such a vector can be used to introduce genetic material of interest into hepatocytes in vivo, thus avoiding the need to transplant or graft transduced hepatocytes.
- hepatocytes to be transduced ex vivo and grafted or transplanted into a recipient, using the method of the present invention; of vectors useful in introducing genetic material of interest into hepatocytes, either ex vivo or in vivo; and of the method of the present invention by which hepatocytes are transduced.
- cultured mature hepatocytes are transduced and subsequently grafted or transplanted into a recipient.
- hepatocytes are obtained, either from the recipient (i.e., the individual who is to receive the transduced hepatocytes) or from a donor, using known techniques. In general, this includes removing all or a portion of a liver, from which hepatocytes are removed by in situ perfusion of a collagenase solution. For example, in the case of isolation of hepatocytes from an intact liver, a catheter is inserted into a vein which either leaves or enters the liver, collagenase solution is perfused through and hepatocytes are released.
- hepatocytes are plated and maintained under conditions (e.g., on appropriate medium, at correct temperature, etc.) suitable for transfection.
- Hepatocytes can also be prepared using a modification of the procedure developed by Barry and Friend, described below and in Example 1, with the perfusion mixture described by Leffert. Leffert, H.L. et al., Methods in Enzymolog ⁇ . 58:536-544 (1979), the teachings of which are incorporated herein by reference.
- hepatocyte cultures for studying the molecular aspects of processes such as gene regulation has historically been the lack of efficient gene transfer techniques. Conventional methods of transfection are inefficient and toxic to the cells. Tur-Kaspa, R. Molecular and Cellular Biology. 6:716-318 (1986). As described below, recombinant retroviruses have been used to overcome these problems. As a result, it is now possible to efficiently and stably transduce primary cultures of hepatocytes by replication-defective retroviruses. Such replication-defective retroviruses have been used to introduce genetic material of interest into cultured hepatocytes. Transduction is efficient and produces hepatocytes which express the genetic material of interest (i.e., produce the encoded protein or polypeptide) and which retain the ability to be transplanted.
- the genetic material of interest i.e., produce the encoded protein or polypeptide
- Retroviruses are RNA viruses; that is, the viral genome is RNA.
- This genomic RNA is, however, reverse transcribed into a DNA intermediate which is integrated very efficiently into the chromosomal DNA of infected cells.
- This integrated DNA intermediate is referred to as a provirus.
- the retroviral genome and the proviral DNA have three genes: the gag, the pol and the env. which are flanked by two long terminal repeat (LTR) sequences.
- the gag gene encodes the internal structural (nucleocapsid) proteins; the pol gene encodes the RNA-directed DNA polymerase (reverse transcriptase); and the env gene encodes viral envelope glycoproteins.
- Adjacent to the 5' LTR are sequences necessary for reverse transcription of the genome (the tRNA primer binding site) and for efficient encapsidation of viral RNA into particles (the Psi site).
- Mulligan, R.C. Experimental Manipulation of Gene Expression. M. Inouye (ed), 155-173 (1983); Mann, R., et al., Cell. 23:153-159 (1983); Cone, R.D. and R.C. Mulligan, Proceedings of the National Academy of Sciences. U.S.A.. 81:6349-6353 (1984).
- the Psi 2 cell line described by Mulligan and coworkers was created by transfecting NIH 3T3 fibroblasts with pMOV-Psi which is an ecotropic Moloney murine leukemia virus (Mo-MuLV) clone.
- pMOV-Psi expresses all the viral gene products but lacks the Psi sequence, which is necessary for encapsidation of the viral genome.
- pMOV-Psi expresses an ecotropic viral envelope glycoprotein which recognizes a recer>tor present only on mouse (and closely related rodent) cells.
- Psi am line Another cell line is the Psi am line, which are Psi-2-like packaging cell lines.
- Psi-am cell lines contain a modified pMOV-Psi-genome, in which the ecotropic envelope glycoprotein has been replaced with envelope sequences derived from the amphotropic virus 4070A. Hartley, J.W. and W.P. Rowe, Journal of Virology. 19 :19-25 (1976).
- the retrovirus used to make the Psi am cell line has an amphotropic host range and can be used to infect human cells.
- the Psi-am cell line is capable of packaging recombinant retroviral genomes into infectious retroviral particles. Cone, R. and R. Mulligan, Proceedings of the National Academy of Sciences. USA. 81 :6349-6353 (1984).
- the retroviral genome has been modified by Cone and Mulligan for use as a vector capable of introducing new genes into cells. As shown in Figure 2, the gag, the pol and the env genes have all been removed and a DNA segment encoding the neo gene has been inserted in their place. The neo gene serves as a dominant selectable marker.
- the retroviral sequence which remains part of the recombinant genome includes the LTRs, the tRNA binding site and the Psi packaging site. Cepko, C. Cell. 37:1053-1062 (1984).
- This vector is capable of expressing both the gene of interest and a dominant selectable marker, such as the neo gene.
- the gene of interest is cloned in direct orientation into a BamHI /Smal /Sail cloning site just distal to the 5' LTR, while the Neo gene is placed distal to an internal promoter (from SV40) which is farther 3' than is the cloning site (is located 3' of the cloning site).
- Transcription from pLJ is initiated at two sites: 1) the 5' LTR, which is responsible for expression of the gene of interest and 2) the internal SV40 promoter, which is responsible for expression of the neo gene.
- the structure of pLJ is represented in Figure 2a.
- Vector pLJ is represented in Figure 2a.
- the genetic material of interest is inserted just following the 5' LTR. Expression of this genetic material is transcribed from the LTR and expression of the neo gene is transcribed from an internal SV40 promoter.
- the 5' flanking sequence, 5' LTR and 400 bp of contiguous sequence (up to the BamHI site) is from pZIP.
- the 3' flanking sequence and LTR are also from pZIP; however, the Clal site 150 bp upstream from the 3' LTR has been ligated with synthetic BamHI linkers and forms the other half of the BamHI cloning site present in the vector.
- the Hindlll/EcoRI fragment of pBR322 forms the plasmid backbone.
- Moloney Murine Leukemia virus An analogous vector has been constructed from sequences derived from the myeloproliferative sarcoma virus. The structure of pEM is represented in
- pIp This vector is capable of expressing a single gene driven from an internal promoter.
- the structure of pip is represented in Figure 2c.
- the construction of these vectors is summarized below.
- the 5' section of the vector, including the 5' flanking sequences, 5' LTR, and 1400 bp of contiguous sequence (up to the Xho site in the gag region) is 'derived from wild type Moloney Leukemia virus sequence. Shinnick et al., Nature, 293:543 (1981). The difference between the two is that a SacII linker is cloned into an HaeIII restriction site immediately adjacent to the ATG of the gag gene.
- the 3' section of the vector including the 3' flanking sequences, 3' LTR and 3' contiguous sequence (up to the Clal site in the env coding region) is from pZIP.
- the Clal site has been linked to BamHI and 2) a small sequence in the 3' LTR spanning the enhancer (from PvuII to XbaI) has been deleted.
- Bridging the 5' and 3' sections of the vector is one of several promoters; each one is contained on a Xhol/BamHI fragment, and each is capable of high level constitutive expression in most tissues. These promoters include beta-actin from. chicken (Choudory, P.V.
- the vector backbone is the HindIII/EcoRI fragment from pBR322.
- the gene of interest is cloned into the BamHI site in direct orientation, just downstream from the internal promoter.
- Vectors without a selectable marker can also be used to transduce endothelial cells with genetic material of interest.
- Such vectors are basically simplifications of the vectors previously described, in which there is such a marker.
- Vector pEM is represented in Figure 2b; as represented, the main components of the vector are the 5' and 3' LTR, and the genetic material of interest, inserted between the two LTRs.
- retroviruses suitable for introducing genetic material of interest into cultured hepatocytes and expressing biologically significant amounts of the encoded protein or polypeptide are also represented in Figure 3, with specific reference to the human LDLR gene. These vectors, which included the human LDLR gene, have been used to efficiently transduce hepatocytes, which then expressed levels of LDLR equal to normal endogenous levels. These vectors will be illustrated with reference to the LDLR gene, but any nucleotide sequence of interest can be incorporated into the retroviruses and introduced into hepatocytes.
- each vector differs in the transcriptional elements used to drive expression of the gene. These are described in detail in Example IV. Briefly, in the vector LTR-LDLR, transcription should begin at the 5' LTR with the result that a single full length viral transcript, in this case, one which expresses LDLR, is produced. In the remaining vectors, expression of LDLR should be driven by transcripts initiated from transcriptional control sequences located internal to the proviral transcriptional unit.
- BA-LDLR contains the promoter from chicken beta-actin gene
- H4-LDLR contains the promoter from the human histone H4 gene
- TK-LDLR contains the promoter from the thymidine kinase gene from herpes simplex virus.
- Each of the three vectors also contains a deletion of viral transcriptional enhancer sequences located in the 3' LTR, in order to reduce the amount of viral transcription which occurs after reverse transcription and integration of the recombinant provirus.
- Human LDLR coding sequences for all four vectors were derived from a full length human LDLR cDNA insert.
- each vector may be useful for example, as a means of decreasing the number of transplanted cells required for production of useful quantities of the encoded protein.
- each vector can include specialized transcriptional control sequences which are internal to the proviral transcriptional unit. This makes it possible to provide variation in the level of transcription of the nucleotide sequence of interest.
- transcriptional elements from genes expressed at high levels in liver cells (e.g., alpha-fetoprotein, albumin).
- RNAs generated by the vectors e.g., by generating more translatable RNAs
- selected 5' and 3' nontranslated sequences from a well-characterized gene e.g., RU-5 region of a human retrovirus
- the authentic 5' and 3' nontranslated sequences of the nucleotide sequence of interest can also be included in the retroviral vectors used.
- LDLR lipid-binding protein
- sequences from the nucleotide sequence of interest (or gene) which confer trans criptionally-mediated end-product repression.
- sequences called the steroid responsive e l e m e n t s
- vectors particularly recombinant retroviral vectors
- retroviral vectors to transduce hepatocyte cells in vivo.
- one strategy for targeting the LDLR gene to hepatocytes can be based on the presence of the asialoglycoprotein (ASGP) receptor on hepatocytes.
- ASGP asialoglycoprotein
- This receptor which is specifically expressed in hepatocytes, is involved in the uptake and catabolism of glycoproteins that have had their terminal sialic acids removed, thereby exposing penultimate galactose residues.
- Glycoprotein-receptor complexes are internalized by receptor mediated endocytosis.
- Asialoglycopeptideprotein conjugates and asialoglycopeptide-coated vesicles have been used to specifically deliver a variety of bioactive agents to the liver in vivo. Aitie, A.D. et al., Proceedings of the National Academy of Sciences. USA. 27:5923-5927 (1980); Fiumw, L. et-al., FEBS Letter, 103:47-51 (1979);
- one approach to targeting delivery of genes to hepatocytes can be based on the modification of existing retroviruses to make them ligands for the ASGP receptors.
- the envelope proteins from murine leukemia viruses are complex glycoproteins that have a high content of sialic acid. Internalization of virus occurs through the specific interaction of the viral envelope with a cell surface receptor, followed by receptor-mediated endocytosis of the virus/receptor complex.
- Hepatocyte-specific transduction may be possible if modified virions that are specifically internalized by the ASGP receptor are developed and used. For example, it is possible to use viruses whose envelope protein is devoid of sialic acid, thereby rendering them ligands for the ASGP receptor. One approach is to enzymatically remove the terminal sialic acids from intact virions with neuraminidase. Alternatively, it is possible to construct viral producer lines with genetically modified envelope genes that code for glycoproteins with terminal galactose residues. It is possible to construct chimeric envelope genes that encode fusion proteins in which the carboxy terminal sequences are derived from the 3' portion of the envelope gene and the amino terminal sequences are derived from genes of known ligands for ASGP receptor. In addition, it is possible to use lectin-resistan ⁇ e selection systems to isolate mutants of the viral producer lines that are incapable of adding terminal sialic acids to
- N-linked chains N-linked chains. Viruses produced from these lines should bind to the ASGP receptor.
- Wu coupled pSV2CAT plasmid to a ligand of the ASGP receptor called asialoorosomucoid (ASOR) and demonstrated in HEP G2 cells uptake of the conjugates via the ASGP receptor and expression of CAT activity. After administration of this conjugate to rats, specific, but transient, expression of CAT was demonstrated in liver homogenates. It is possible that this method can be modified to produce a method by which recombinant retroviral vectors or episomal vectors can be introduced into hepatocytes in vivo. The efficiency and specificity of this delivery system can be assessed, for example, by transferring an expression vector that stably expresses a product which can be detected in situ by direct analysis of the product (e.g., beta-galactosidase).
- ASOR asialoorosomucoid
- Genetic material of interest has been incorporated into cultured hepatocytes and expressed in the resulting genetically engineered hepatocytes, as described below and in the examples.
- Genetic material which can be incorporated into hepatocytes according to the method described can be: 1) genetic material (DNA or RNA) which is present in and expressed at biologically effective levels (levels sufficient to produce the normal physiological effects of the polypeptide it encodes) in normal hepatocytes, but present in or expressed in less than normal quantities in the hepatocytes prior to stable transfer of genetic material of interest into them by the method of the present invention; 2) genetic material not present in normal hepatocytes; or 3) genetic material present in normal hepatocytes but not expressed at biologically effective levels in such cells, alone or in any combination thereof.
- Hepatocytes in which genetic material (DNA or RNA) is present in or expressed in less than normal quartitites are referred to herein as genetically deficient hepatocytes.
- the genetic material incorporated into and expressed by hepatocytes can also, optionally, include genetic material encoding a selectable marker, thus making it possible to identify and select cells which contain and express the genetic material of interest.
- DNA or RNA introduced into cultured hepatocytes of the present invention includes the genetic material (DNA or RNA) of interest and, optionally, genetic material encoding a selectable marker; such DNA or RNA is referred to as incorporated genetic material (or incorporated DNA, incorporated RNA) .
- Hepatocytes containing incorporated genetic material are referred to as transduced hepatocytes; they express the DNA or RNA of interest and produce the encoded protein or polypeptide.
- Exogenous DNA encoding a polypeptide or protein of interest and, optionally, a selectable marker is incorporated in vitro into hepatocytes as described below and in Examples I-III.
- a selectable marker e.g., neo, which encodes neomycin resistance
- Hepatocytes isolated as described previously are plated at subconfluent density on matrix substrata and maintained in hormonally defined media, such as that described by Enat, et al., the teachings of which are incorporated herein by reference. Enat, R., et al., Proceedings of the National Academy of
- Cells are subsequently infected with an amphotropic retrovirus which contains DNA of interest (e.g., DNA encoding a polypeptide whose expression in hepatocytes is desired) and optionally, DNA encoding a selectable marker to be incorporated into the hepatocytes.
- DNA of interest e.g., DNA encoding a polypeptide whose expression in hepatocytes is desired
- the hepatocytes are infected with the recombinant retrovirus (and thus transduced with the DNA of interest) by exposing them to virus which has a recombinant genome. This results in infection of the cells by the recombinant retrovirus. It is possible to optimize the conditions for infection of the hepatocytes by using a high titer amphotropic virus.
- a cell line which produces recombinant amphotropic retrovirus having a recombinant genome is used to infect hepatocytes.
- the recombinant genome can include a variety of components, but in general is comprised of two LTRs and, in place of the gag, the pol and the env sequences, a second, promoter sequence; in some cases, it also includes a gene encoding a selectable marker (e.g., neo).
- Viral stocks to be used in introducing genetic material of interest into hepatocytes, are harvested, as described above, supplemented with Polybrene (Aldrich) and added to the culture of hepatocytes. If the titer of the virus is high (e.g., approximately 10 6 cfu per ml.), then virtually all hepatocytes will be infected and no selection of transduced hepatocytes is required. If the titer is very low, then it is necessary to use a retroviral vector that has a selectable marker, such as neo or his.
- a selectable marker such as neo or his.
- a selectable marker is used, after exposure to the virus, the cells are grown to confluence and split into selective media (e.g., media containing G418 if the selectable marker is neo, media containing histidinol and no histidine if the selectable marker is his).
- the neo gene is a bacterial rrene derived from the transposon Tn5, which encodes neomycin resistance in bacteria and resistance to the antibiotic G418 in mammalian cells.
- This neo gene acts as a dominant selectable marker; its presence in a mammalian cell converts the cell into one which will grow in the presence of G418. (If it is not present, the cell dies in the presence of G418.) As a result, the presence of this gene in a mammalian cell can be determined by culturing cells in media which contains G418.
- the recombinant retroviral vectors having the neo gene also have a cloning site.
- genetic material of interest can be introduced into the vector, incorporated into hepatocytes and expressed by hepatocytes transduced with the recombinant retrovirus (referred to as hepatocytes containing incorporated genetic material).
- hepatocytes containing incorporated genetic material At the BamHI cloning site, it is possible to insert genetic material of interest.
- hepatocytes have been transduced with the gene encoding beta-galactosidase from E. coli. The efficiency of transduction was assessed, as described in Example III. Expression of the beta-galactosidase gene was also assessed and is detailed in Example III.
- helper-free amphotropic producer is grown in tissue culture to a confluent density in Dulbecco's Modified Eagle's Medium (DME) supplemented with 10% calf serum (CS). Fresh media is added and subsequently the media is harvested. The spent media (or viral stock) is filtered to remove detached producer cells and is used immediately to infect cells or is stored (e.g., at -70oC) for later use.
- DME Dulbecco's Modified Eagle's Medium
- CS calf serum
- hepatocytes Media is removed from a subconfluert plate of hepatocytes (recipient hepatocytes) and quickly replaced with viral stock which contains Polybrene (Aldrich). Subsequently, this is removed and replaced with fresh media.
- the media used is a viral supernatant and the recombinant genome of the infectious virus includes DNA of interest.
- the infection procedure results in hepatocytes which express the DNA encoding a gene product of interest and, optionally, a selectable marker.
- hepatocytes are exposed to media containing infectious virus produced in
- the infectious virus contain a recombinant genome having the genetic material of interest.
- the recombinant genome in one instance includes genetic material encoding a protein or a polypeptide (e.g., the receptor for low density lipoproteins; ornithine transcarbalyase) and, optionally, a gene encoding a dominant selectable marker (e.g., the neo gene which encodes neomycin resistance).
- the hepatocytes are transduced ⁇ that is, the genetic material of interest (for example, DNA encoding a polypeptide or a protein of interest) and, optionally, the neo gene are stably introduced into the hepatocytes.
- the transduced hepatocytes express the encoded protein or polypeptide and, if the neo gene is present, express it, resulting in cells having the selectable trait.
- hepatocytes were prepared using a modification of the method of Berry and Friend with the perfusion mixture of Leffert. Berry, M.N. et al., J. Cell. Biol.. 43:506-520 (1969); Leffert, H.L. et al.. Methods Enzymol , 58:536-644
- the resulting hepatocytes were plated at a density of 3-4 ⁇ 10 4 cells/cm 2 onto Primaria plates substratum in hormonally defined media supplemented with 10% fetal bovine serum. The media was replaced with fresh hormonally defined media, which was subsequently changed periodically.
- Spent media was obtained by harvesting DME media supplemented with 10% calf serum in which a helper-free amphotropic producer of the BAG virus was cultured.
- Conditions for infection of the hepatocytes were optimized through the use of BAG, which is a high titer amphotropic virus encoding E. coli beta gala ⁇ tosidase.
- the spent media was filtered to remove detached producer cells and used as viral stock to infect hepatocytes.
- hepatocytes were infected by removing media from a subconfluent plate of hepatocytes (recipient hepatocytes) and replacing it with viral stock. Hepatocyte cultures were infected in this way for approximately 12 hours. Hepatocytes containing the DNA of interest (i.e., DNA encoding beta-galactosidase) and the neo gene were isolated by culturing on media containing the antibiotic G418. Those into which the recombinant retrovirus .was effectively introduced by infection, referred to as transduced hepatocytes, produce beta-galactosidase and are neomycin resistant. The ability of hepatocytes transduced with the recombinant retrovirus having the beta-galactosidase gene to produce beta-galactosidase has been assessed in vitro. This assessement is described in Example III.
- Rat hepatocytes have also beer transduced with the gene encoding human parathyroid hormone (hPTH) and shown to express the encoded hormone. This is described in Example VI and results are presented in Figure 9.
- hPTH human parathyroid hormone
- transduced hepatocytes secrete a polypeptide (betagalactosidase) which is normally not secreted by hepatocytes.
- a similar approach can be used to introduce any genetic material into hepatocytes in such a manner that the encoded product is made and to assess expression of the incorporated genetic material.
- hepatocytes have been transduced as a result of exposure to media containing infectious virus in which the recombinant genome includes DNA encoding human LDLR. This is described in detail in Example IV. Hepatocytes were infected with four LDLR virus preparations (each including one of the vectors represented in Figure 5) and subsequently analyzed for gene transfer and LDLR expression.
- the same vectors can be used in the method of the present invention, to introduce into cultured hepatocytes any nucleotide sequence or gene of interest.
- other vectors can be used, as can other means of introducing genetic material of interest into cultured hepatocytes.
- a recombinant retrovirus in which the genome includes the genetic material of interest would be targeted to hepatocytes, with the result that after introduction-into an individual's body (e.g., by intravenous injection), the retrovirus is specifically taken up by hepatocytes. Once taken up by hepatocytes, the recombinant retroviral genome will be expressed, resulting in production of the protein or polypeptide encoded by the genetic material of interest.
- the virus used to introduce the genetic material of interest is podified (e.g., through inclusion of sequences, referred to as autonomously replicating sequences or ARS) in such a manner that integration of the provirus into the host chromosomes does not occur. As a result, replication will occur episomally.
- ARS autonomously replicating sequences
- a vector can include genetic material encoding a selectable marker, the presence of which makes it possible to identify and select for cells transduced with the genetic material of interest.
- a selectable marker As described previously and in Example III, the neo gene, which is such a marker, has been used for this purpose. It is also possible to use dominant selectable markers other than the neo gene to introduce genetic material into hepatocytes.
- the His D gene can be used for this purpose.
- the His D gene is a bacterial gene from Salmonella typhimurium and encodes histidinol dehydrogenase, a polypeptide which converts histidinol to histidine.
- Histidine is an essential amino acid; histidinol is an alcohol analogue of histidine and can be converted to histidine under the proper metabolic conditions. if cells are grown in media containing histidinol but lacking histidine, those cells having the His D gene can convert histidinol to histidine. Because hiscidine is essential to their function, those cells which have the His D gene (and thus can make histidine) will survive and those lacking the gene will not.
- a retrovirus vector having the His D gene has been used to infect keratinocytes.
- the keratinocytes containing His D gene were selected by growing these cells in media lacking histidine but containing histidinol.
- keratinocytes having the His D gene formed colonies and grew to confluence; those lacking the gene did not. In fact, such cells occurred at a much higher frequency than those in which the neo gene was included.
- hepatocytes e.g., the neo gene and the His D gene
- a gene encoding the necessary processing enzyme can be introduced along with the gene encoding the polypeptide requiring such processing. This would enable hepatocytes to process the polypeptide hormone.
- telomeres can be used for this purpose.
- DNA viruses can also be used to introduce genetic material of interest, as well as a gene encoding a selectable marker, into hepatocytes according to the method of the present invention.
- Hepatocytes expressing the incorporated genetic material are grown to confluence in tissue culture vessels; removed from the culture vessel; and introduced into the body. This can be done surgically, for example.
- the tissue which is made up of transduced hepatocytes capable of expressing the nucleotide sequence of interest is grafted or transplanted into the body. For example, it can be placed in the abdominal cavity in contact with/grafted onto the liver or in close proximity to the liver.
- the transduced hepatocyte containing tissue can be attached to microcarrier beads, which are introduced (e.g., by injection) into the peritoneal space of the recipient.
- the transduced hepatocytes provide a continuous supply of the hormone, enzyme or drug encoded by the genetic material of interest.
- the amount of the hormone, enzyme or drug supplied in this way can be modified or regulated as needed (e.g., by using external cues or factors which control or affect production, by controlling the size of the graft or the quantity of fibroblasts introduced into the body, or by removing the graft).
- hepatocytes have been implanted into WHHL rabbits, which lack LDL receptor function.
- animal model of familial hypercholesterolemia was used to develop a new therapeutic approach in which a normal LDL receptor gene is introduced into genetically deficient hepatocytes, which are transplanted into recipients.
- Homozygous familial hypercholesterolemia is a life threatening disorder for which no effective medical therapy exists (Goldstein, J.L. and M.S. Brown, in The
- Example V involves isolating hepatocytes from an animal, transducing a functional LDL receptor gene into these cells in vitro, and transplanting the genetically modified cells into another animal of the same type.
- the present invention makes it possible to genetically engineer hepatocytes in such a manner that they produce a gene product (e.g., a polypeptide or a protein) of interest in biologically significant amounts.
- the hepatocytes formed in this way can serve as a continuous drug delivery system to replace present regimens, which require periodic administration (by ingestion, injection, etc.) of the needed substance.
- Incorporation of genetic material of interest into hepatocytes would be particularly valuable in the treatment of inherited disease and the treatment of acquired disease.
- this approach is used to provide genetically modified hepatocytes which contain DNA encoding a protein or polypeptide which an individual's hepatocytes are unable to make correctly.
- Hepatocytes of the present invention can also be used in the treatment of genetic diseases in which a product (e.g., LDL receptor) normally produced by the liver is not produced or is made in insufficient quantities.
- a product e.g., LDL receptor
- hepatocytes transduced with a DNA encoding the missing or inadequately produced substance can be used to produce it in sufficient quantities.
- the transduced hepatocytes would produce LDL receptor and thus provide a means of preventing or treating familial hypercholesterolemia, which is an inherited disease in which the primary genetic defect is an abnormality in the expression or function of the receptor for low density lipoproteins. This leads to elevated levels of serum cholesterol and the premature development of coronary artery disease.
- the transduced hepatocytes could be used to produce sufficient quantities of the LDL receptor to overcome the underlying defect.
- hepatocytes There are also acquired diseases for which treatment can be provided through use of genetically engineered hepatocytes.
- such cells can be used in treating the coagulopathy associated with liver failure.
- hepatocytes having incorporated in them a gene encoding one or more clotting factors would correct the acquired deficiency of these factors which leads to bleeding.
- viral hepatitis particularly hepatitis B or nonA-nonB hepatitis
- a gene encoding an anti-sense gene could be introduced into hepatocytes to inhibit viral replication.
- a vector including a structural hepatitis gene in the reverse or opposite orientation would be introduced into hepatocytes, resulting in production in transduced hepatocytes of an anti-sense gene having the correct orientation.
- Rat hepatocytes were prepared by the procedure of Berry and Friend, using the perfusion mixture of Leffert. Berry, M. N. and D. S. Friend, Journal of Cell Biology. 41:506-520 (1969); Leffert, H. L. et al., Methods in Enzymology, 58: 536-544 (1979). Male Sprague-Dawley rats weighing between 200 and 250 gms were used as the source of hepatocytes. Cells were plated at a density of 4 ⁇ 10 4 cells/cm 2 onto one of several matrix substrata in hormona lly defined media supplemented with 10% fetal bovine serum. Enat, R. et al., Proceedings of the National Academy of Sciences.
- a helper-free amphotropic producer of the BAG virus was provided by Dr. C. Cepko (Harvard).
- the retroviral vector used to make this producer has been described by Cepko and co-workers. Price, J., Proceedings of the National Academy of Sciences. USA. 84: 156-160 (1987).
- the producer was maintained in Dulbecco's modified Eagle's Medium supplemented with 10% calf serum. Unconcentrated viral stocks were prepared and titered as described by Mann. Mann, R.
- Hepatocyte cultures were infected for 12 hours with viral stocks (5 ml of viral stock/ 10 cm plate of hepatocytes) containing 8 ⁇ g/ml of Polybrene (Aldrich). Transduction efficiency was optimized with respect to the time of exposure to virus and the matrix substrate on which the hepatocytes were plated.
- the restriction fragments were resolved by electrophoresis in 1% agarose gels and analyzed according to the method of Southern using standard procedures and a probe that is complementary to sequences unique to the provirus (i.e., the neo gene).
- Maniatis, T. et al. Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y. (1982).
- the blot was probed with the BamHI/Hind III fragment of the neomycin gene that was labelled to high specific activity with 32P-dCTP using the random primer method.
- the intensity of the resulting band on the autoradiograph is proportional to the number of proviral integrants in the population.
- Figure 4 shows the effect of extracellular matrix used and of the time of infection on integration of provirus in hepatocyte cultures.
- Panel A presents a Southern blot of hepatocytes isolated from a single collagenase perfusion which were cultured on 10 cm. plates coated with one of several forms of matrix substrata (type I collagen, laminin, type IV collagen, and tissue culture plastic) and infected on days 1, 2, 3, 4, or 5. Infection was carried out using fresh preparations of viral stocks and plates were analyzed for copy number of integrated provirus 48 hours after the infection was initiated. A three day exposure of a Southern blot is shown. A single band was visualized in each lane; the area of the autoradiograph containing this band is shown. Lanes 1-5 indicate the days that the cells were infected.
- the top four series of bands represent hepatocytes cultured on different forms of matrix: Col I - type I collagen, Lam-laminin, Col IV - type IV collagen, and TCP-tissue culture plastic.
- the bottom series of bands shows an identical analysis of NIH3T3 cellsinfected with the same viral stocks used to infect the hepatocyte cultures.
- proviral integration increased from virtually undetectable on day 1 to maximal on days 2 or 3, and subsequently diminished to low levels by day 5.
- Maximal proviral integration which was essentially independent of matrix, occurred when cultures were infected on day 2 for cells on tissue culture plastic, or day 3 for cells on type I collagen, laminin, or type IV collagen.
- NIH3T3 cells were infected with the same viral stocks used to infect hepatocytes (Fig. 1, panel A). Southern analysis demonstrated little variation in the titer of the viral stocks; the estimated proviral copy number ranged from 0.5 to 0.7 copies/cell. This estimate of copy number was based on a comparison with samples with known quantities of standard plasmid (Fig. 4, panel B) and the assumption that NIH3T3 cells are hypotetraploid.
- the samples with known quantities of standard plasmid were made by mixing varying amounts (2 pg and 10 pg) of the purified BAG plasmid with 7.5 ⁇ g of uninfected NIH3T3 DNA. Analysis showed a single band, which comigrated with the bands shown in panel A.
- the data from panels A and B were derived from a three day exposure of the same Southern blot. It was estimated that 2 pg and 10 pg of plasmid in 7.5 ⁇ g of NIH3T3 DNA correlates to approximately 0.3 and 1.2 copies of provirus/cell, respectively.
- the estimated copy number of proviral integrants in maximally infected hepatocytes (e.g., Figure 4, Lam, lane 3) is approximately 0.2 copies/cell, assuming that the DNA content of NIH3T3 cells is equal to that of hepatocytes. This assumption is probably valid since the majority of hepatocytes in culture are either tetraploid or octaploid. Tomita, Y., Exp. Cell Res.. 135:363-370 (1981).
- Beta-galactosidase Cells infected with the BAG virus constitutively produce high levels of cytoplasmic beta-galactosidase.
- Activity of beta-galactosidase was detected in situ with the substrate 5-bromo-4-chloro-3-indolyl-D-galactosidase, which forms a blue precipitate in infected cells.
- Price, J. et al. Proceedings of the National Academy of Sciences. U.S.A.,84:156-166 (1987).
- results showed that labeled cells are often found in groups of 2, probably representing infection and integration into a dividing cell with labeling of the two daughter cells.
- expression of beta-galactosidase as determined by the intensity of staining, is quite variable, but tends to be consistent within members of a pair of labeled cells (e.g., see panel C).
- the efficiency of transduction as measured cytochemically, exhibited the same dependence on time in culture as was demonstrated by Southern analysis. The fraction of labeled cells increased from less than 1% in cultures infected on day 1 to approximately 25% when infected on day 3; the transduction efficiency dropped dramatically in cultures infected on the next 2 days (days 4 and 5).
- Immunocytochemical analysis of cultured hepatocytes using the monospecific polyclonal antibody to UDP-glucuronosyltransferase shows reaction product distributed in cytoplasmic clumps and at the periphery of the nucleus in greater than 95% of the cells ( Figure 4, panel G); these reactive sites correspond to the endoplasmic reticulum and the nuclear envelope, respectively. No reaction product is seen in experiments performed with preimmune rabbit IgG ( Figure 5, panel 1).
- This well described receptor is specifically expressed in hepatocytes. Immunocytochemical analysis in rat liver localizes this receptor to a domain of the plasma membrane which borders the sinusoids; under light microscopy the receptor is seen at the perimeter of the hepatocyte along its sinusoidal face. Genze, J.E. et al., Journal of Cellular Biology. 22:867-870 (1982); Matsuura, S. et el., Journ al of Cellular Biology. 25:864-875 (1982). The level of asialoglycoprotein receptor decreases in culture; however, it is still demonstrated in virtually all cells of a three-day-old hepatocyte culture.
- This glycolytic enzyme is a well recognized cytochemical marker for hepatocytes. It can be detected in virtually all hepatocytes of liver sections. However, there is marked regional variation in enzyme activity; the greatest activity is found in the periportal region. Sasse, D., "Regulation of Hephtic Metabolism and Intra- and Intercellular Compartmentalization, eds. Thurman, R.G., Kauffman, F. C. and Jungermann, K. (Plenum Press, NYC), pp. 57-86 (1986).
- Glucose-6-phosphatase activity was detected in three-day-old hepatocyte cultures by the lead phosphate enzyme cytochemical procedure. Wachstein, M. and E. Meisel, J. Histochem. Cytochem., 4:592 (1956).
- Novikoff et al. The method of Novikoff et al. was used to visualize the distribution of peroxisomes in hepatocyte cultures.
- Novitoff, A. B. et al. Histochemistry and Cytochemistry. 20:1006-1023 (1972).
- These small cytoplasmic structures are found specifically in hepatocytes (in the context of the liver) and are visualized by cytochemical staining for catalase.
- DeDuve, C. et al. Physiol. Rev.. 46:323-357 (1966).
- Newborn New Zealand white (NZW) rabbits and WHHL rabbits were used as the source of hepatocytes. NZW rabbits have been used as controls in most previous studies of the WHHL rabbit. Newborn WHHL rabbits vere derived from matings between homozygous deficient males and females and were kindly provided by Dr. Knapka (NIH) . Four WHHL rabbits from 2 litters (2 rabbits/litter) were used in these studies (named WHHL 1-4). Newborn NZW rabbits were purchased from Pine Acres Rabbitry (West Brattleboro, Vermont).
- Hepatocytes were prepared using a modification of the procedure of Berry and Friend with the perfusion mixture of Leffert. Berry, M.N. and D.S. Friend, Journal of Cell Biology. 43:506-520 (1969). Leffert, H.L. et al., Methods in Enzymology, 58:536-544 (1979). Collagenase perfusions were performed retrograde as described by Clayton and Darnell for the preparation of adult mouse hepatocytes. Clayton, D.F. and J.E. Darnell, Jr., Molecular-Cell Biology, 1:1552-1561 (1983).
- Hepatocyte cultures were infected for 12 hours with viral stocks (5 ml/10 cm plate) containing Polybrene (8 ⁇ g/ml). Unconcentrated viral stocks were prepared from the producer cells as described above.
- RNA and DNA Analysis High-molecular-weight genomic DNA was isolated and analyzed for integration of proviral sequences. Total cellular RNA was prepared using a guanidine thiocyanate procedure, fractionated in formaldehyde/agarose gells and transferred to nitrocellulose paper. Chirgwin, J.M. et al.. Biochemistry. 18:5294-5299 (1980). Northern and Southern blots were probed with a 1.9 kb LDLR cDNA fragment (Hind III to EcoRI fragment of pTZl) that was labeled to high specific activity with 32 P-dCTP using the random primer method. Feinberg, A. P. and B. Vogelstein, Anal. Biochem., 132: 6- 13 ( 1984 ) .
- LTR-LDLR - viral long terminal repeat sequences LTR-LDLR - viral long terminal repeat sequences (LTR); BA-LDLR . contains a 267 bp segment of the chicken beta-actin gene (BA) extending from -266 to +1.
- BA-LDLR contains a 704 bp segment of the histone H4 gene (H4) extending from -696 to +8.
- TK-LDLR contains a 256 bp segment of the thymidine kinase gene of herpes simplex virus (TK), extending from -200 to +56.
- Plasmid sequences of LTR-LDLR were derived from the 7.2 Kb Bam HI to Cla I fragment of D01 with the following modification: sequences spanning the Nhe I to Xba I sites of the 3' Moloney murine leukemia virus (NO-MLV) LTR (nuc. 7846 to 8113) were replaced with homologous sequences from the LTR of the myeloproliferative sarcoma virus (represented by darkened area).
- NO-MLV 3' Moloney murine leukemia virus
- the backbone structure of plasmids BA-LDLR, H4-LDLR, and TK-LDLR was derived from DO1, with the exception that sequences containing the viral enhanced elements of the 3' LTR (from the Pvu II site at nucleotide 7933 to the Xba I site at nucleotide 8111) were deleted (indicated by the inverted triangle). This was done to reduce the amount of viral transcription after reverse transcription and integration of the recombinant provirus.
- vectors also contained additional Mo-MLV sequence between the 5' LTR and the internal promoters.
- the additional sequence was derived from wild type Mo-MLV (from nucleotide 146 at the border of U5 to the Xho I site in the gag coding region-at nucleotide 1560) with the exception that a Sac
- Virus producing cell lines for the vector BA-LDLR, H4-LDLR, and TK-LDLR were made by transfecting the particular plasmid DNA with pSV2-Neo into the amphotropic packaging cell line Psi-Crip, as described previously. Cone, R.D. et al., Molecular and Cellular Biology. 1:887-897 (1987); Mulligan, R.C. and P. Berg, Science, 209 :1422-1427 (1980).
- Psi-Crip is a modified type of Psi-am packaging cell line which provides cells with the functions of Psi-am (e.g., gag, pol, and env) in two components. That is, the gag-pol function is provided in the form of one integrated provirus and the env function is produced from a separate provirus. The host range is amphotropic.
- G418 resistant colonies of cells were expanded and tested for production of virus that transmitted the correct proviral structure. This was done by harvesting supernatants from the producer cells, infecting NIH3T3 cells, and analyzing the infected population for integrated provirus by Southern analysis.
- High titer amphotropic producers of the LTR-LDLR vector were obtained using a 2-step procedure. First, high titer ecotropic producers were made by cotransfection of LTR-LDLR with pSV2-Neo into the Psi-2 packaging cell line as described above. Mann', R. et al., Cell, 11:153-159 (1983). Psi-Crip cells were then infected with virus harvested from the Psi-2 producer and subsequently split into 10 cm plates at clonal densities. Individual clones were isolated and analyzed for the production of high titer amphotropic virus as described above. Virus-producing cell lines transmitting the highest number of proviral copies to recipient cells were chosen for this study.
- NIH3T3 cell line designated 7-35, producing amphotropic virus that expresses the gene for human LDL receptor has been deposited (February 3, 1988) under the terms of the Budapest Treaty, with the American Type Culture Collection (Rockville, MD) under accession number CRL 9635.
- LDLR LDLR Transfer and Expression of LDLR in Hepatocytes
- Cells used for the infection studies were hepatocytes isolated from 3 NZW rabbits and 4 WHHL rabbits as described above. Collagenase perfusions routinely produced 40-80 ⁇ 10 6 cells/animal with greater than 90% viability.
- Cells plated at subconfluent densities formed aggregates (5-20 cells/aggregate) that covered approximately 20% of the dish when visualized 6 hours after plating. The primary cultures underwent marked proliferation after 36 hours in culture achieving confluence by day 3 or 4.
- WHHL hepatocytes cultured for 5 days were analyzed in several ways.
- the cells were stained for glucose-6-phosphatase, as described above, to determine the number of hepatocytes in the cultures.
- Glucose-6-phosphatase is a specific marker for hepatocytes in sections of liver and in hepatocyte cultures. More than 95% of the cells had the brown cytoplasmic staining characteristic of hepatocytes. No staining was detectable in pure cultures of fibroblasts or endothelial cells.
- the cultures were analyzed for the presence of endothelial cells and Kupffer cells, since these nonparenchymal cells are abundant in the intact liver and could potentially contaminate the primary cultures.
- Sinusoidal and capillary endothelial cells as well as Kupffer cells express high levels of the receptor for AcLDL and can be identified in mixed cultures by their selective uptake of Dil-AcLDL.
- Analysis of the cultured hepatocytes for Dil-AcLDL uptake revealed that approximately 1 in 50 cells were fluorescent. The uptak0 of Dil-AcLDL by the rare contaminating cells in the hepatocyte cultures was equivalent to that observed in pure secondary cultures of endothelial cells derived from bovine aorta.
- a high titer amphotropic virus (BAG) encoding E. coli beta-galactosidase was used.
- BAG amphotropic virus
- Cells transduced by the BAG virus can be detected by a simple cytochemical reaction that stains the cell's cytoplasm blue.
- Optimal transduction of WHHL hepatocytes was achieved when the cells were plated at subconfluent density and exposed to virus 36 hours after the initial plating. The matrix substrata had little effect on transduction efficiency.
- NZW and WHHL hepatocytes were infected with the four different LDLR virus preparations 2 days after being placed in culture and vere analyzed for gene transfer and LDLR expression on day 5. Integration of the recombinant proviral sequences into the cellular DNA isolated from infected hepatocytes was detected by Southern blot analysis ( Figure 6). DNA from transduced hepatocytes was digested with Kpn I and analyzed by the method of Southern using the LDLR cDNA as a probe. Kpn I has unique recognition sites in the LTR sequences; consequently, each integrated provirus should yield a common restriction fragment irrespective of the site of integration.
- Each virus producing cell line efficiently transmitted proviral sequences without rearrangement in hepatocytes from both NZW and WHHL rabbits.
- the relative copy number of integrated provirus varied from a maximum of 1-2 copies/cell for cultures infected with the H4-LDLR virus to a minimum of 0.1 to 0.2 copies/cell for cultures infected with the LTR-LDLR virus. This efficiency of infection was approximately 50% of that achieved in murine fibroblastic cells infected with the same virus preparations.
- Biochemical activity of the exogenous LDLR was assessed in situ by visualizing the uptake of LDL; transduced cultures of hepatocytes were incubated with Dil-LDL and viewed by fluorescent microscopy. Mock infected NZW rabbits exhibited a uniformly high level of fluorescence in all cells; mock infected WHHL hepatocytes showed very little fluorescence. WHHL hepatocytes infected with the LTR-LDLR virus had the greatest amount of LDL uptake with approximately
- BA-LDLR infected WHHL hepatocytes demonstrated a population of cells with moderate activity; H4-LDLR infected WHHL hepatocytes showed a low level of activity in virtually all cells.
- the activity of LDLR in TK-LDLR infected cells was barely over background.
- the estimate of transduction efficiency based on this in situ assay for LDLR activity agrees with that measured by Southern analysis (e.g., WHHL hepatocytes infected with the LTR-LDLR virus showed fluorescence in approximately 20% of cells while Southern analysis detected a copy number of integrated proviral sequences equal to approximately 0.2) .
- Transduced hepatocytes were also analyzed for degradation of 125 I-LDL in an attempt to quantify the amount of human LDLR expressed. These data are summarized in the Table. Activity of LDLR was greatest in hepatocytes infected with the LTR-LDLR virus : hepatocytes from a NZW rabbit showed an increase in LDLR activity from 170 ng/mg/5hrs in mock infected cells to 274 ng/mg/5hrs in transduced cells, while cells from WHHL rabbits exhibited an increase in activity from 30-40 ng/mg/5hrs in mock infected cells to 155 (WHHL 1) and 84 (WHHL 3) ng/mg/5hrs in transduced cells.
- the level of LDLR activity in LTR-LDLR transduced hepatocytes is approximately 700 ng/mg/5hrs (4 fold greater than the activity of the endogenous receptor in NZW rabbits) when corrected for the actual number of cells that were transduced. Dzierzak, E.A. et al., Nature. 111:35-41 (1987). Hepatocytes infected with viruses that express LDLR from a transcript driven by an internal promoter (i.e., BA-LDLR, H4-LDLR, and TK-LDLR) exhibited little to modest increases in 125 I-LDL degradation.
- an internal promoter i.e., BA-LDLR, H4-LDLR, and TK-LDLR
- LTR-LDLR 274 ⁇ 6 155 4 84 ⁇ 13 1Degradation rates were also measured in the presence of 50 fold excess of unlabeled LDL. under these conditions NZW hepatocytes (aock Infected and transduced) had degradation rates that ranged from 50 to 60 ng/ag/5 hrs while WHHL hepatocytes had degradation rates that ranged from 10 to 20 ng/ag/5 hrs.
- WHHL rabbits used were derived from mating bomozygous LDL receptor deficient rabbits and were obtained from three sources: Dr. Knapka from the National Institutes of Health, Dr. Mahlan from New York University, and from our own breeding colony. Wild type NZW rabbits were purchased from Dutchland Farms (Denver, PA) . All animals were maintained on a Purina laboratory rabbit chow. Individual animals exhibited less than 2% variation in total serum cholesterol for a period up to 2 weeks prior to hepatocyte transplantation.
- Recombinant Retrovirus The retroviral vector used to produce amphotropic virus has been described previously, and is depicted in Figure 9. The vector is derived from a wild type Moloney provirus in which sequences between the Pst I site at n.t. 739 and the Cla I site at n.t. 7674 have been deleted and replaced with Bam HI linkers (for numbering see Van Beveren, C.
- Human LDL receptor coding sequences were derived from a 2.6 kb Hind III fragment of plasmid pTZl (kindly provided by D. Russell, J. Goldstein, and M. Brown). The Hind III sites were converted to Bel I sites with synthetic oligonucleotides and the modified fragment was cloned into the BamHI site of the retroviral vector.
- Rabbit hepatocytes were prepared using the procedure of Berry and Friend, J. Cell Biol. 43:506-520 (1969), with a perfusion mixture of Leffert et al., Methods Enzymol . 59:536-544 (1979). Cells were plated at a density of 6.7 ⁇ 10 4 /cm 2 onto a polycation matrix (Primaria, Falcon, Oxnard, CA) in a hormonally defined medium supplemented with 10% fetal bovine serum; 4 to 6 hours later the medium was replaced with fresh hormonally defined medium (Enat, R. et al., Proc . Natl . Acad. Sci. USA 81: 1411-1415 (1984).
- the media were changed to virus containing media (supplemented with polybrene 8 ⁇ g/ml) that was freshly harvested from the virus producing cells (Wilson, J.M. et al., Proc. Natl. Acad. Sci. USA 85: 4421-4425 (1988)). 12 to 18 hours later, the cells were harvested for transplantation and assayed for gene expression. Cells were detached from the tissue culture plates by incubation in 0.1% trypsin for 10-20 minutes at 37oC.
- Hepatocytes Transplantation Animals were prepared for laparotomy and portal vein infusion of hepatocytes with IV pentobaribital anesthesia. Using sterile surgical technique, the abdomen was opened through a 3 cm midline incision, a loop of jejunum externalized, and a tributary of the superior mesenteric vein was identified and secured with ligatures. A prewarmed 8 suspension of hepatocytes (1-2 ⁇ 10 8 cells in a volume of 10 ml containing 100 units of heparin) was introduced into the mesenteric vein through a 27 gauge butterfly needle over 5 minutes.
- the needle was then removed, hemostasis was achieved by tying the ligature, the loop of jejunum returned to the abdomen, and the abdominal incision closed in two layers.
- the animals received amoxicillin (5 mg/kg body wt, subcutaneously) once daily on the day of surgery and for 5 days after the operation.
- Venous samples were subsequently obtained through a marginal ear vein and analyzed for total cholesterol as described (Trinder, P., Annals Clin. Biochem.. 12: 226-228 (1974)). Selected plasma samples were separated into individual lipoprotein fractions as described (Havel, R.J. et al., J. Clin. Invest. 34:1345-1353 (1955)).
- RNA and DNA hybridization filters were probed with 32P-labeled human LDL receptor cDNA as described (Wilson, J.M. et al., Proc. Natl. Acad. Sci. USA 85:4421-4425 (1988)).
- PCR polymerase chain reaction
- RNA probes were generated from transcription plasmids (Promega Co.) constructed in the following manner. Moloney sequences in the retroviral vector between the synthetic BamHI site at n.t. 7674 and the Nhe I site at n.t. 7846 ( 1 of 8 for numbering) were cloned between the BamHI and XbaI sites of pGEM-3Z (called 3Z-env); transcription from the SP6 promoter produces antisense RNA that is specific for the virus directed transcript.
- This BamHI to NheI fragment was also cloned into pGEM-4Z in order to produce sense RNA (4Z-env) from the same promoter.
- Artisense RNA spanning rabbit LDL receptor coding sequences was used as an internal control in RNase protection experiments.
- a SmaI to XhoI restriction fragment from a rabbit LDL receptor clone (n.t. 2475 to 2572) (Yamamoto, T. et al., Science 232:1230-1237 (1986)) was cloned between the Smal and Sail sites of pGEM-4Z (4Z-rLDLR). This cDNA was provided by D. Russell.
- Transcription vectors were linearized by digestion with appropriate restriction endonucleases (3Z-e ⁇ v, EcoRI, 4Z-env, HindIII; and 4Z-rLDLR, HindIII) and used as templates in transcription reactions according to the recommendations of the manufacturer (Promega Co.).
- Retrovirus Mediated Gene Transfer into Adult WHHL Hepatocytes In previous studies, recombinant retroviruses were used to transduce hepatocytes derived from newborn WHHL rabbits with a human LDL receptor gene (Wilson, J.M. et al., Proc. Natl. Acad. Sci. USA 85:4421-4425 (1988)). A similar approach was used here to infect hepatocytes derived from adult WHHL animals.
- the recombinant virus LTR-LDLR was used in the present studies to infect adult WHHL hepatocytes.
- the proviral form of this virus transcribes a single mRNA that is responsible for expression of LDL receptor and passage of the virus (Wilson, J.M. et al., Proc. Natl. Acad. Sci. USA 85: 4421-4425 (1988)).
- WHHL hepatocytes were maintained in hormonally defined medium for 48 hours and subsequently exposed to the LTR-LDLR virus for 12 to 18 hours, following the infection, hepatocytes were harvested for transplantation, and analyzed for retrovirus transduction and human LDL receptor expression.
- Tecbriques for transplanting rabbit hepatic-tes were initially developed in an allogeneic system in which hepatocytes were isolated from a strain of rabbits that expresses normal levels of LDL receptor (NZW rabbits) and transplanted into the portal vein of WHHL rabbies. Rabbit recipients were analyzed for changes in total serum cholesterol and, in selected cases, changes in specific lipoprotein fractions. Donor hepatocytes were obtained by in situ collagenase perfusion of adult NZW rabbit livers. Previous experience with this technique in rat animal models suggests .that a substantial number of the infused cells seed in the sinusoids of the liver (Patel, A. et al., Molec. Biol. and Med. (1989)).
- Hepatocytes from a single WHHL rabbit were harvested, plated into culture, and mock infected or infected with the LTR-LDLR virus. Following infection, the cells were harvested and transplanted into WHHL recipients via the portal vein ( 1-2 ⁇ 10 8 cells/animal which is approximately 1-4% of the total number of hepato ⁇ ytes found in the liver). This experiment was repated with three donors and seven recipients (Figure 10, Panel D). Animals that received LTR-LDLR infected cells demonstrated significant decreases in serum cholesterol on days 2 through 5 following transplantation (p ⁇ 0.001, Student's t test).
- Tissues were harvested from transplant recipients in order to perform detailed molecular and cellular analyses of gene transfer and expression. Separate animals were euthanized for tissue harvest at 10 minutes, 24 hours and 19 days following transplantation with genetically modified hepatocytes.
- liver tissues were analyzed for proviral DNA sequences using the polymerase chain reaction (Figure 11) because standard hybridization techniques lacked the ne ⁇ essary sensitivity. Proviral DNA sequences were detected in animals transplanted with infected hepatocytes and sacrificed 10 minutes and 24 hours after transplantation; proviral DNA was no longer detected in liver harvested 19 days after transplantation. Similar analysis of DNA from other tissues, such as lung, failed to detect proviral liver DNA suggesting that most of the hepatocytes seed in sinusoids.
- RNA from liver tissue was detected with an antisense probe that is complementary to viral sequences in its 3' untranslated portion ( Figure 9A) .
- Another probe that is specific for endogenous rabbit LDL receptor RNA was incorporated into each assay as an internal control.
- Analysis of RNA from LTF-LDLR transduced murine fibroblasts demonstrated protection of the 3Z-env probe (172 bp, Figure 12, Lane A) but not the 4Z-rLDLR probe, while assays of control WHHL RNA revealed no protection of 3Z-env probe with substantial protection of the 4Z-rLDLR probe (98 bp, Figure 12, Lane C).
- Virus directed RNA was detected in liver tissue harvested 10 minutes and 24 hours after transplantation with genetically modified hepatocytes ( Figure 12) . Quantitative analysis of this experiment indicated that the viral transcript was present at 1-3% of the level of endogenous rLDLR mRNA. No recombinant transcript was detected in liver tissue harvested at 19 days.
- RNA probe complementary to virus specific sequences provided excellent specificity for this in situ detection of human LDL receptor mRNA.
- in situ hybridization was initially performed with the antisense probe on liver that was harvested 24 hours following transplantation of genetically modified hepatocytes. Approximately 1 in 1000 to 1 in 500 cells contained a high density of cytoplasmic grains (10-100 fold over background).
- WHHL hepatocytes c.a. 2% of the total hepatocytes in an adult rabbit liver
- Functional replacement of LDL receptor activity should be approximately 2% of normal in transplant recipients. This prediction is in excellent agreement with quantitative analyses of RNA from liver harvested 10 minutes and 24 hours after transplantation which detected the recombinant transcript at 1-3% of the level of the endogenous transcript. This rather modest amount of genetic correction, however, led to a substantial improvement in hypercholesterolemiato 70% o pretreatment levels.
- receptor negative patients ⁇ 2% of control receptor activity
- receptor defective patients >2% control residual receptor activity
- Metabolic improvements associated with hepatocyte transplantation were not permanent. There are two potential explanations for the apparent deterioration in LDL receptor function in vivo. There could be destruction and actual loss of the genetically modified hepatocytes. Alternatively, the cells may engraft but expression from the recombinant gene may extinguish. In an attempt to differentiate between these possible mechanisms, the integrated provirus was used as a specific and sensitive marker of the genetically modified cells in vivo. Proviral DNA was detected in liver of transplant recipients prior to and during the period of metabolic improvement. The provirus was no longer detected in liver tissue after the total cholesterol returned to baseline. This suggests that cell loss is an important factor in the deterioration of in vivo LDL receptor function.
- Cells were plated at a density of 10 ⁇ 10 6 c e l l s o nto a bacteriologic plate (10 cm) with 160 mg of cytodex beads and inoculated with hormonally defined medium (HDM) with 10% fetal calf serum. After 90 minutes, the media was replaced with fresh HDM.
- the plate was inoculated with viral supernatant from an amphotropic PTH producer (prepared as described in Example II). After 12 hours, the cells were transplanted into an analbuminemic rat (approximately 200 gm intraperitoneally in approximately 5 ml. phosphate buffered saline).
- Serum was subsequently obtained and analyzed at various times (see Figure 8) for human PTH, using the commercially-available Nichols radioimmunoassay procedure. Serum was analyzed for rat albumin using Western blot analysis. Results are presented in Figure 8.
- the MFG vector having the identifying characteristics of ATCC accession No. 68754 is derived from the pEM vector but contains 1038 base pairs of the gag sequence from MMLV to increase the encapsulation of recombinant genomes in the packaging cell lines, and 350 base pairs derived from MOV-9 which contains the splice acceptor sequence and transcriptional start.
- An 18 base pair oligonucleotide containing NcoI and BamHI sites directly follows the MOV-9 sequence and allows for the convenient insertion of genes with compatible sites.
- the MMLV LTR controls transcription and the resulting mRNA contains the authentic 5' untranslated region of the native gag transcript followed directly by the open reading frame of the inserted gene.
- a detailed map of MFG is provided in Figure 14.
- MFG was constructed by ligating the 5' LTR containing XhoI/NdeI fragment of the half-GAG retroviral vector ( half-GAG is described in Bender, et al., J. Virol. 6I:1639-1646) to an XhoI/BamHI H4 histone promoter fragment.
- Retroviral vector pEM was digested with NdeI and BamHI, and the 3' LTR containing fragment was ligated to the half GAG fragment already ligated to the H4 fragment so as to produce an intermediate retrovirus vector containing 2 LTRs in the proper orientation and also containing the H4 fragment within the viral portion of the vector.
- the intermediate vector was then linearized by digestion with NdeI and the NdeI site in the pB322 portion of the vector was filled in by polymerase and destroyed by ligation.
- the vector was subsequently digested with XhoI and the XhoI site was joined to an NdeI linker.
- the vector was subsequently cleaved with BamHI and the large fragment containing both LTRs and the pBR322 sequence) was purified.
- NdeI/XvaI fragment from pMOV9 [containing a splice acceptor site next to the NdeI edge] so as to form a circular vector, MFG as illustrated in Figure 14 .
- a plasmid containing vector MFG has been deposited with the American Type Culture Collection and it has accession number 68,754.
- factor VIII and human tPA have been ligated into MFG so as to be operably joined to the viral promoter.
- These factor VIII and tPA expressing MFG vectors have been deposited with the American Type Culture Collection and given the accession numbers 68726 and 68727 respectively.
- the ⁇ -SGC vector utilizes transcriptional promoter sequences from the ⁇ -globin gene to regulate expression of the tPA gene.
- the 600 base pair fragment containing the promoter element additionally contains the sequences for the transcriptional initiation and 5' untranslated region of the authentic ⁇ -globin mRNA.
- a 360 base pair fragment which includes the transcriptional enhancer from cytomeglovirus precedes the ⁇ -globin promoter and is used to enhance transcription from this element.
- the MMLV enhancer is deleted from the 3' LTR. This deletion is transferred to the 5' LTR upon infection and essentially inactivates the transcriptional activating activity of the element.
- a detailed description of ⁇ SGC is provided in Figure 15.
- a plasmid containing the ⁇ -SGC vector has been deposited with the American Type Culture Collection and it has accession number 68,755.
- factor VIII and human tPA have been ligated into ⁇ -SGC so as to be operably joined to the ⁇ globin pranoter.
- factor VIII and tPA expressing ⁇ -SGC vectors have been deposited with the American Type Culture Collection and given the accession numbers 68728 and 68729. respectively.
- ATCC American Type Culture Collection, Rockville, Md., USA
- ATCC accession no. 68726 ATCC accession no. 68726
- plasmid MFG with the tPA insertion described herein, given ATCC accession no. 68727
- the plasmid ⁇ -SGC described herein
- with the factor VIII insertion given ATTC ascession no. 68728
- plasmid ⁇ -SGC with the tPA insertion described herein, given ATCC accession no. 68729.
Abstract
Hépatocytes mis au point par génie génétique ou transduits génétiquement exprimant une matière génétique à étudier introduite ou incorporée dans lesdits hépatocytes, et procédés de production, de transplantation et d'utilisation des hépatocytes mis au point par génie génétique. La matière génétique à étudier peut être incorporée par l'intermédiaire d'un vecteur tel qu'un rétrovirus recombiné, lequel contient la matière génétique à étudier, ou par d'autres moyens.Hepatocytes developed by genetic engineering or genetically transduced expressing a genetic material to be studied introduced or incorporated into said hepatocytes, and methods of production, transplantation and use of hepatocytes developed by genetic engineering. The genetic material to be studied can be incorporated via a vector such as a recombinant retrovirus, which contains the genetic material to be studied, or by other means.
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US63368890A | 1990-12-26 | 1990-12-26 | |
US633688 | 1990-12-26 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0517909A1 true EP0517909A1 (en) | 1992-12-16 |
EP0517909A4 EP0517909A4 (en) | 1993-05-26 |
Family
ID=24540700
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19920904304 Withdrawn EP0517909A4 (en) | 1990-12-26 | 1991-12-23 | Modified hepatocytes and uses therefor |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0517909A4 (en) |
JP (1) | JPH05505944A (en) |
AU (1) | AU9179591A (en) |
CA (1) | CA2076848A1 (en) |
WO (1) | WO1992012242A1 (en) |
Families Citing this family (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6048729A (en) | 1987-05-01 | 2000-04-11 | Transkaryotic Therapies, Inc. | In vivo protein production and delivery system for gene therapy |
US6054288A (en) * | 1991-11-05 | 2000-04-25 | Transkaryotic Therapies, Inc. | In vivo protein production and delivery system for gene therapy |
NZ245015A (en) | 1991-11-05 | 1995-12-21 | Transkaryotic Therapies Inc | Delivery of human growth hormone through the administration of transfected cell lines encoding human growth hormone, which are physically protected from host immune response; the transfected cells and their production |
US6692737B1 (en) | 1991-11-05 | 2004-02-17 | Transkaryotic Therapies, Inc. | In vivo protein production and delivery system for gene therapy |
US6063630A (en) | 1991-11-05 | 2000-05-16 | Transkaryotic Therapies, Inc. | Targeted introduction of DNA into primary or secondary cells and their use for gene therapy |
US6324404B1 (en) | 1991-12-26 | 2001-11-27 | Sycord Limited Partnership | Cellular telephone system that uses position of a mobile unit to make call management decisions |
US6531124B1 (en) | 1992-07-10 | 2003-03-11 | Transkaryotic Therapies, Inc. | In vivo production and delivery of insulinotropin for gene therapy |
US6670178B1 (en) | 1992-07-10 | 2003-12-30 | Transkaryotic Therapies, Inc. | In Vivo production and delivery of insulinotropin for gene therapy |
US5591625A (en) * | 1993-11-24 | 1997-01-07 | Case Western Reserve University | Transduced mesenchymal stem cells |
EP0784681A1 (en) * | 1994-10-06 | 1997-07-23 | Warner-Lambert Company | Method of using a scavenger receptor in the treatment of atherosclerosis |
US6107027A (en) * | 1994-12-14 | 2000-08-22 | University Of Washington | Ribozymes for treating hepatitis C |
US5980886A (en) * | 1994-12-14 | 1999-11-09 | University Of Washington | Recombinant vectors for reconstitution of liver |
WO1996039490A1 (en) * | 1995-06-06 | 1996-12-12 | The Trustees Of The University Of Pennsylvania | Organ function replacement compositions and methods of making and using the same |
FR2746109B1 (en) | 1996-03-12 | 1998-04-17 | Rhone Poulenc Rorer Sa | ENVIRONMENT FOR THE CONSERVATION OF BIOLOGICAL MATERIAL |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1989007136A2 (en) * | 1988-02-05 | 1989-08-10 | Whitehead Institute For Biomedical Research | Modified hepatocytes and uses therefor |
WO1990006757A1 (en) * | 1988-12-15 | 1990-06-28 | The Regents Of The University Of California | Grafting genetically modified cells to treat diseases of the central nervous system |
-
1991
- 1991-12-23 CA CA002076848A patent/CA2076848A1/en not_active Abandoned
- 1991-12-23 AU AU91795/91A patent/AU9179591A/en not_active Abandoned
- 1991-12-23 JP JP92504389A patent/JPH05505944A/en active Pending
- 1991-12-23 EP EP19920904304 patent/EP0517909A4/en not_active Withdrawn
- 1991-12-23 WO PCT/US1991/009700 patent/WO1992012242A1/en not_active Application Discontinuation
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1989007136A2 (en) * | 1988-02-05 | 1989-08-10 | Whitehead Institute For Biomedical Research | Modified hepatocytes and uses therefor |
WO1990006757A1 (en) * | 1988-12-15 | 1990-06-28 | The Regents Of The University Of California | Grafting genetically modified cells to treat diseases of the central nervous system |
Non-Patent Citations (1)
Title |
---|
See also references of WO9212242A1 * |
Also Published As
Publication number | Publication date |
---|---|
EP0517909A4 (en) | 1993-05-26 |
JPH05505944A (en) | 1993-09-02 |
AU9179591A (en) | 1992-08-17 |
CA2076848A1 (en) | 1992-06-27 |
WO1992012242A1 (en) | 1992-07-23 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US5521076A (en) | Modified hepatocytes and uses therefor | |
Wilson et al. | Temporary amelioration of hyperlipidemia in low density lipoprotein receptor-deficient rabbits transplanted with genetically modified hepatocytes. | |
Wilson et al. | Ex Vivo Gene Therapy of Familial Hypercholesterolemia. Howard Hughes Medical Institute, University of Michigan | |
AU659824B2 (en) | Retroviral vectors useful for gene therapy | |
EP0517909A1 (en) | Modified hepatocytes and uses therefor | |
JPH03505036A (en) | Genetic modification of endothelial cells | |
CA2005199A1 (en) | Genetically engineered endothelial cells and use thereof | |
WO1992015676A1 (en) | Somatic cell gene therapy | |
Miyanohara et al. | Efficient expression of retroviral vector-transduced human low density lipoprotein (LDL) receptor in LDL receptor-deficient rabbit fibroblasts in vitro. | |
US5580776A (en) | Modified hepatocytes and uses therefor | |
US6140111A (en) | Retroviral gene therapy vectors and therapeutic methods based thereon | |
US6110743A (en) | Development and use of human pancreatic cell lines | |
WO1995034669A2 (en) | Retroviral gene therapy vectors and therapeutic methods based thereon | |
NZ300795A (en) | Retroviral Plasmid Vectors (enhancer region of LTR replaced, primer binding site replaced or mutated), packaging/transduced cells, use for gene therapy | |
AU716854B2 (en) | Human pancreatic cell lines: developments and uses | |
EP0781333A1 (en) | Gene therapy for transplantation and inflammatory or thrombotic conditions | |
Dichek et al. | Retroviral vector-mediated in vivo expression of low-density-lipoprotein receptors in the Watanabe heritable hyperlipidemic rabbit | |
Messina et al. | Endothelial Cells: Endothelium as a Target Organ for Somatic Gene Therapy | |
US20030202967A1 (en) | Development and use of human pancreatic cell lines | |
AU709477C (en) | Retroviral gene therapy vectors and therapeutic methods based thereon |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU MC NL SE |
|
17P | Request for examination filed |
Effective date: 19930115 |
|
A4 | Supplementary search report drawn up and despatched |
Effective date: 19930406 |
|
AK | Designated contracting states |
Kind code of ref document: A4 Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU MC NL SE |
|
17Q | First examination report despatched |
Effective date: 19970324 |
|
GRAH | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOS IGRA |
|
RIC1 | Information provided on ipc code assigned before grant |
Ipc: 7A 61K 48/00 B Ipc: 7C 12N 5/10 B Ipc: 7C 12N 15/867 A |
|
RIC1 | Information provided on ipc code assigned before grant |
Ipc: 7A 61K 48/00 B Ipc: 7C 12N 5/10 B Ipc: 7C 12N 15/867 A |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 20030731 |