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WO1999009141A1 - Cellules totipotentes porcines et procede de culture a long terme - Google Patents

Cellules totipotentes porcines et procede de culture a long terme Download PDF

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Publication number
WO1999009141A1
WO1999009141A1 PCT/US1998/016782 US9816782W WO9909141A1 WO 1999009141 A1 WO1999009141 A1 WO 1999009141A1 US 9816782 W US9816782 W US 9816782W WO 9909141 A1 WO9909141 A1 WO 9909141A1
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cells
porcine
cell
totipotent
pgcs
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PCT/US1998/016782
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English (en)
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Gottfried Brem
Manfred Baetscher
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Biotransplant, Inc.
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Application filed by Biotransplant, Inc. filed Critical Biotransplant, Inc.
Priority to AU88279/98A priority Critical patent/AU8827998A/en
Publication of WO1999009141A1 publication Critical patent/WO1999009141A1/fr

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    • 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
    • C12N5/0608—Germ cells
    • C12N5/0611—Primordial germ cells, e.g. embryonic germ cells [EG]
    • 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
    • C12N2501/00—Active agents used in cell culture processes, e.g. differentation
    • C12N2501/10—Growth factors
    • C12N2501/115—Basic fibroblast growth factor (bFGF, FGF-2)
    • 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
    • C12N2501/00—Active agents used in cell culture processes, e.g. differentation
    • C12N2501/10—Growth factors
    • C12N2501/125—Stem cell factor [SCF], c-kit ligand [KL]
    • 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
    • C12N2501/00—Active agents used in cell culture processes, e.g. differentation
    • C12N2501/20—Cytokines; Chemokines
    • C12N2501/23—Interleukins [IL]
    • C12N2501/235—Leukemia inhibitory factor [LIF]
    • 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
    • C12N2501/00—Active agents used in cell culture processes, e.g. differentation
    • C12N2501/30—Hormones
    • C12N2501/38—Hormones with nuclear receptors
    • C12N2501/385—Hormones with nuclear receptors of the family of the retinoic acid recptor, e.g. RAR, RXR; Peroxisome proliferator-activated receptor [PPAR]
    • 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
    • C12N2502/00—Coculture with; Conditioned medium produced by
    • C12N2502/13—Coculture with; Conditioned medium produced by connective tissue cells; generic mesenchyme cells, e.g. so-called "embryonic fibroblasts"
    • 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
    • C12N2502/00—Coculture with; Conditioned medium produced by
    • C12N2502/99—Coculture with; Conditioned medium produced by genetically modified cells

Definitions

  • This invention relates to totipotent porcine cells and to the recovery, proliferation and use thereof.
  • the invention further relates to the use of a porcine stem cell factor (pSCF) , which may also be termed porcine "steel” factor, which is preferably membrane-bound pSCF on transfected murine STO feeder cells, for establishing pluripotent or totipotent porcine cell lines, especially for the culture of porcine primordial germ cells (PGCs) .
  • porcine stem cell factor pSCF
  • porcine "steel” factor which is preferably membrane-bound pSCF on transfected murine STO feeder cells
  • PGCs are precursor cells of the germ line in the developing embryo.
  • PGCs In swine (porcine) embryos PGCs migrate from the base of the allantois through the hindgut epithelium and dorsal mesentery to colonize the gonadal strom . During the migration to the genital ridge the PGCs increase in number in pigs to approximately 1 x 10 6 by day 50.
  • Porcine PGCs can be distinguished from somatic cells by their morphology: large nuclei, high nuclei-cytoplasm-ratio, occasional blebbing and by clearly visible pseudopodia.
  • Totipotent cell lines have been obtained from primordial germ cells (PGCs) in mice. Such pluripotent or totipotent cell lines are important in the field of transgenic animals.
  • PPCs primordial germ cells
  • ES cells embryonic stem cells
  • ES cells can be injected into a mouse embryo near the embryonic location which will give rise to germ cells in the resulting adult mouse, and result in functional germ cells originating from the injected ES cells. Therefore, such adult mouse can produce offspring that have the traits of the injected ES cells. If the ES cells have been altered genetically prior to their injection into the embryo such offspring of the resulting adult mice can form a chimeric line of mice with the genetically altered trait.
  • an ES cell line maintained in culture in a mouse can be utilized for a variety of gene introduction methods (for example, the retrovirus vector method, the electroporation method and the calcium phosphate method) and then injected into embryos as part of a process to produce chimeras with desired altered genetic traits.
  • gene introduction methods for example, the retrovirus vector method, the electroporation method and the calcium phosphate method
  • embryos as part of a process to produce chimeras with desired altered genetic traits.
  • tissue protein changes and remove certain native antigens so that an organ or tissue from the chimeric animal could be transferred to another species without rejection by the other species.
  • mice primordial germ cells isolated during their migratory phase and cultured on feeders layers (e.g., fetal fibroblast cells ("STO cells"), Kawase et al . Experimental Medicine, Vol. 10, No. 13, 1575 to 1580 (1992)) with leukaemia inhibitory factor (LIF) and mouse stem cell factor (MSCF) provide mice PGCs that result in cell lines for long- term culture.
  • mice PGCs can also be cultured in similar media to which basic fibroblast growth factor (bFGF) has been added, thereby converting PGCs to cells that resemble undifferentiated embryonic stem cells (ESs) (Matsui et al., Cell 1992 70:5:841-847; Resnick et al .
  • bFGF basic fibroblast growth factor
  • mice Such (embryonic germ cell derived lines (“EGs") derived from PGCs can be utilized to contribute to the germ-line of chimeric mice.
  • EGs embryonic germ cell derived lines
  • Early culture mice PGCs cultured in the presence of LIF and MSCF, can be observed as burst colonies of cells with a flattened and polarized morphology that are characteristic of motile cells.
  • mice ESs or EGs derived from PGCs e . g. , long-term cultures
  • PGCs e . g. , long-term cultures
  • ESs or EGs long term cultures or germ cells from differentiated PGCs
  • These totipotent germ cell lines can be maintained in culture (by recycling to fresh media) and used to inject embryos, or alternatively can be frozen, thawed and then used.
  • mice PGCs, ESs or EGs have hypothesized that results with mice embryos could lead to similar results with other species. They hypothesized that it might be possible to use PGCs from other species along with such mice feeder cells which produce MSCF and LIF (such as transfected murine STO cells) for the establishment of totipotent cell-lines in domestic animals.
  • swine Relative to other domestic animals, swine (or pigs) are easy to feed and maintain. Also, they have no reproductive season, can produce a fairly large number of fetuses, and provide offspring after only a relatively short gestation period.
  • porcine pluripotent or totipotent PGC lines as an alternative to embryonic stem cells (ESCs) would be useful for studies of cell differentiation and gene regulation during embryonic development. Such lines would be important for the generation of transgenic pigs especially for their use in gene farming or xenotransplantation .
  • Fig. 1 illustrates the number of PGCs (relative to the number of PGCs present on the first day) in non-passaged initial cultures on days 1, 3 and 5 days when cultured on STO feeder cells (producing MSCF) in three out of four different culture media.
  • the three plot lines represent three out of the four different culture conditions used: (1) ES medium (control) that is supplemented with 15% FCS (ES) , (2) ES medium supplemented with growth factors LIF (ES+LIF), (3) ES medium supplemented with LIF plus bFGF (ES+LIF+bFGF) and (3) conditioned medium prepared from carcinoma cell line 5637.
  • Fig. 2 illustrates the number of PGCs (relative to the number of PGCs present on the first day) in non-passaged initial cultures on days 1, 3 and 5 days when cultured on ST08 feeder cells (producing a form of membrane-bound pSCF) in three out of four different culture media.
  • the three plot lines represent three out of the four different culture conditions used: (1) ES medium (control) that is supplemented with 15% FCS (ES) , (2) ES medium supplemented with growth factors LIF (ES+LIF) , (3) ES medium supplemented with LIF plus bFGF (ES+JIF+bFGF) and (3) conditioned medium prepared from carcinoma cell line 5637.
  • Figure 3 illustrates the full-length sequence for pSCF (SEQ ID NO: 2) based on native cDNA (SEQ ID NO:l) as reported in Biology of Reproduction 50: 95-102 (1994) .
  • Figure 4 illustrates the polynucleotide sequence (SEQ ID NO:5) of a soluble form of pSCF from U.S. Patent 5,589,582.
  • Figure 5 shows a comparison of proliferation results for pig bone marrow cells cultured in the presence of STO cells as compared to STO cells transfected with the polynucleotide sequence that is set forth in Figure 6.
  • the proliferation results for pig bone marrow cells cultured in the presence of the transfected cells are significantly better than results with regular STO cells.
  • Figure 6 illustrates the polynucleotide sequence (SEQ ID NO: 8) of an active membrane-bound form of pSCF from which exon 6 has been been removed and replaced with a tri- nucleotide that encodes the amino acid "Gly” (SEQ ID NO: 9), which is part of plasmid pPSCF.
  • Figure 7A-7C illustrate the proliferation of porcine PGCs isolated from 27 day old fetuses.
  • PGCs are cultured in ES medium supplemented with LIF on ST08 cells.
  • PGCs are identified by alkaline phosphatase activity 1 day after isolation from embryos and plating onto ST08 feeder cells in ESC medium supplemented with LIF. PGCs exist as single cells .
  • Figure 7B shows three days after isolation that PGCs form small colonies.
  • Figure 7C shows five days after isolation that PGCs are found in larger colonies.
  • Figures 7A-7C are photographs formed at a magnification of 50x.
  • Figure 8 shows data from a comparison of STO and ST08 cells when they are used as feeder cells.
  • PGCs were cultured in ESC medium without added growth factors on STO cells (open circles) or ST08 cells (closed circles) , with LIF on STO cells (open triangles) or (ST08 cells (closed triangles) , or with LIF plus bFGF on STO cells (open squares) or ST08 (closed squares) . Data are shown as the mean ⁇ s.e.m.
  • Figures 9A and 9B are photographs of PGC cultures after 8 days of culturing on ST08 feeder cells in the presence of LIF. PGCs are stained to identified by AP activity.
  • Figure 9A shows that some colonies have become multilayered .
  • Figure 9B shows that some colonies grow as a monolayer on ST08 cells and contain only a small number of strongly stained cells together with AP negative cells.
  • Figure 10 shows the primary culture of PGCs in simple media to form single cells essentially as a monolayer.
  • Figure 11 shows a culture for the second passage of PGCs cultured in simple media to form single cells essentially as a monolayer.
  • Figure 12 shows a culture for the third passage of PGCs cultured in simple media.
  • Figure 13 shows a colony of porcine PGCs in primary culture which are seeded on ST08 feeder cells and cultivated in ES-cell media.
  • Figure 14 shows PGC-derived colonies after the fifth passage which are cultivated in ES-cell media. The cells were passaged every two weeks .
  • Figure 15 shows PGC-derived colonies obtained from frozen/thawed PGCs which have been cultured on ST08 feeder cells after their fifth passage. The cells were passaged every two weeks.
  • Figure 16 shows PGC-derived colonies obtained from frozen/thawed PGCs after their fifth passage. The cells were passaged every two weeks.
  • Figure 17 shows AP staining of porcine PGCs after their third passage. The cells were passaged every two weeks.
  • Figure 18 shows AP staining of porcine PGCs after their fourth passage. The cells were passaged every two weeks.
  • Figure 19 shows AP staining of porcine PGCs after their fifth passage. The cells were passaged every two weeks.
  • Figure 20 shows porcine PGCs after four weeks of culturing which have been stained for SSEA-1 as analyzed by a Confocal Laser Scanning Microscope.
  • Figure 21 shows porcine PGCs after four weeks of culturing which have been stained for SSEA-1 as analyzed by a Confocal Laser Scanning Microscope .
  • Figure 22 shows SSEA-1 positive porcine PGCs after ten weeks in culture and the fifth passage. The cells were passaged every two weeks and the culture is stained for SSEA-1 and analyzed by a Confocal Laser Scanning Microscope.
  • Figure 23 shows SSEA-1 positive porcine primordial germ cells after having been frozen and thawed and after their fifth passage. The cells were passaged every two weeks.
  • porcine totipotent cells In accordance with one aspect of the present invention, there is provided porcine totipotent cells.
  • porcine primordial germ cells In accordance with a further aspect of the present invention there is provided porcine primordial germ cells.
  • the invention provides porcine embryonic germ cells.
  • porcine embryonic stem cells In yet a further aspect, there is provided porcine embryonic stem cells.
  • porcine totipotent cells of the invention may be recovered from the genital ridge and then cultured in the presence of porcine stem cell factor to thereby maintain, preserve and proliferate totipotent porcine cells.
  • porcine stem cell factor may be a soluble form (as described in U.S. Patent 5,589,582) or may be a membrane- bound form of porcine stem cell factor as hereinafter described.
  • the totipotent porcine cells are preferably maintained and caused to proliferate in the form of PGCs or EGs.
  • a totipotent porcine cell line obtained from culturing porcine PGCs that can be successfully cultured long-term and can survive cryopreservation while retaining totipotency.
  • such totipotent cell line is a germ cell line or a long-term culture PGC cell line.
  • such totipotent cell line is obtained from genetically altered embryonic cells having a trait that can be assayed for to ascertain when a chimeric animal is derived from such totipotent cells.
  • a further object is to provide a method for recovering and/or maintaining totipotent porcine cells (whatever the source, e . g. , from PGCs, stem cells, germ cells or manufactured totipotent cells) and causing such totipotent cells to proliferate. In a preferred aspect such method provide for long-term culturing of such totipotent cells without a loss of totipotency.
  • Another object of the present invention is to provide a method for culturing PGCs, or totipotent cell lines obtained from PGCs, in the presence of porcine stem cell factor, which is preferably membrane-bound pSCF, to obtain or maintain a totipotent cell line from such PGCs.
  • porcine stem cell factor which is preferably membrane-bound pSCF
  • such method provides a process for maintaining a line of porcine PGCs in an undifferentiated state by culturing such PGCs for a culture cycle, obtaining seed cells from the culture colonies and repeating the cycle on fresh culture media.
  • such PGC culture process can be interrupted by a cryopreservation step, followed by thawing of the totipotent cells and continuing with a new culture cycle on fresh culture media.
  • Such culture media may also include basic stem cell media or other growth factors.
  • the media may also include LIF, MSCF or bFGF .
  • LIF low-density protein
  • MSCF low-density protein
  • bFGF bFGF
  • mouse stem cell culture media may suffice to maintain such cultures. Examples of mouse stem cell culture media are set forth in U.S. Patent 5,453,357.
  • a still further object of the present invention is to produce a chimeric embryo which is made by using such a totipotent cell line to inject the embryo and to produce a chimeric animal derived from the chimeric embryo .
  • an object of the present invention is to provide a totipotent porcine cell line into which has been introduced at least one extraneous gene, or which has a native gene deleted, knocked out or modified and to produce therefrom a chimeric embryo which is made using the totipotent cell line to provide an animal with a chimeric germ line which is derived from the chimeric embryo and which will result in chimeric animal offspring with the genetically modified trait that is derived from the genetically modified porcine totipotent cells.
  • porcine totipotent cells which are unmodifed cells or have been modified by the introduction of at least one extraneous gene, the deletion or deactivation of a native gene, or the modification of a native gene
  • the PGCs of mammals appear as cells with high alkali phosphatase activity (ALP activity) in the mesodermic cell layer and endodermic cell layer at the base of the allantoic sac outside the embryo.
  • ALP activity alkali phosphatase activity
  • Passive migration of the developing germ cells results from two factors: dynamic morphological formation of the embryo and dynamic cell movement of the PGCs as they migrate.
  • PGCs move to the reproductive strom (conceptacle, genital ridge) which is derived from the mesenchymal cells of the mesentery from the epidermis of the hind gut .
  • ALP activation is an indicator.
  • Literature is sketchy and unclear with regard to the porcine PGCs migratory path cell counts as correlated with the age of the fetus at various stages of development .
  • PGCs are first observed near the backbone at a fetal age of about 17 days (J.L. Black & B.H. Erikson. Anat . Rec 161, 45-46, 1968), and the genital ridge has been confirmed at a fetal age of about 23 to 24 days.
  • the sex of the embryo can be determined at a porcine fetal age of about 26 days.
  • Alkaline phosphatase staining can be carried out as described by Matsui et al . , Nature 1991 353 (6346) : 750-752. After staining, AP positive cells can be counted using an inverted microscope. Such procedures for identifying PGCs use the mouse monoclonal antibody SSEA-1. In general, PGCs cultures are washed twice with PBS containing 2% calf serum, 0.1% sodium azide and then incubated with the SSEA-1 antibody (1:100 dilution) on ice for about 30 minutes.
  • embryonic ectoderm is used herein.
  • Embryonic ectoderm and “epiblast” can be used interchangeably to refer to the same cell type.
  • a “primordial germ cell” or PGC as referred to herein means cells (such as obtained from an embryo) which are characterized by their morphology as having large nucleus, high nuclei-cytoplasm-ratio, occasional blebbing and by clearly visible pseudopodia.
  • a “totipotent cell line” or “embryonic stem cell line” or “primordial germ cell line” as used herein means a cell line which can be maintained in long-term culture via passaging (for example more than 40 days) without losing its totipotent capability, in that cells from the cell line can give rise to many differentiated cell types in an embryo or adult, including the germ cells (sperm and eggs) . This cell type may also referred to as an "ES cell", an “EG cell” or a “PG cell (PGC) " herein.
  • FGF fibroblast growth factor
  • FGF-1 acidic fibroblast growth factor
  • FGF-2 basic fibroblast growth factor
  • FGF-3 int-2
  • FGF-4 hst/K-FGF
  • FGF-5 FGF-6
  • FGF-7 fibroblast growth factor
  • Each of the suitable factors can be utilized directly in the methods taught herein to aid in the production or maintenance of porcine PGCs or a porcine totipotent cell line derived from PGCs.
  • Each FGF can be screened in the methods described herein to determine if the FGF is suitable to enhance the growth of or allow continued proliferation of such totipotent cells.
  • pSCF Porcine Stem Factor
  • mSCF mouse stem factor
  • mSCF porcine mast cell growth factor
  • porcine c-kit ligand porcine c-kit ligand in the art.
  • Each of the native SFs has a transmembrane polypeptide, a cytoplasmic domain and an extracellular domain. Soluble pSCF or mSCF refer to a fragment cleaved from the extracellular domain at a specific proteolytic cleavage site.
  • Membrane associated SF refers to both normal SF before it has been cleaved or the SF which has been altered so that proteolytic cleavage cannot take place.
  • the PSCF may be either a soluble form as described in U.S. Patent 5,589,582, or its equivalents, or may be a membrane-bound form, preferably bound on to the surface of a cell .
  • Feeder cells which produce membrane-bound and/or soluble PSCF may be referred to above and hereinafter as "ST05" or “ST08" and feeder cells which produce MSCF may be referred to as STO cells (the STO cell line is a thioguanine/oubain resistant sub-line of SIM mouse fibroblasts, Wax and Axelrad, Virology 50:339 (1972); STO cells are described in U.S. Patent 5,453,357) .
  • the ST05 and ST08 feeder cells are STO cells that have been transfected with a membrane -bound portion (or portions) which encode an active PSCF polypeptide.
  • PSCF full-length sequence for PSCF (SEQ ID NO: 2) based on native cDNA (SEQ ID NO:l) and ( Figure 3 attached hereto) is reported in Biology of Reproduction 50: 95-102 (1994) , and active forms can be produced by transfecting cells with active fragments of the cDNA sequence which may have the polynucleotides encoding the leader sequence amino acids (-25 to -1) removed. Soluble forms preferably omit the polynucleotide transmembrane portion. Additionally, an active form of PSCF can be produced and utilized to transfect STO cells by removing exon 6 from the full length cDNA and substituting a polynucleotide segment that encodes one or more amino acids.
  • the STO cells may be transfected with a portion of the cDNA encoding the PSCF gene.
  • the soluble form of PSCF may be produced by STO cells or the like transfected with the polynucleotide encoding the soluble PSCF polypeptide.
  • ST08 cells are produced by transfecting STO cells with a polynucleotide sequence corresponding to the full-length cDNA in which: (1) the first 70 polynucleotides are removed, (2) exon 6 is excised (polynucleotides 591 to 654) from the full polynucleotide sequence, (3) the excised exon 6 segment is replaced by a three-nucleotide segment encoding the amino acid "Gly" , and (4) the fifteen-nucleotide C-terminal tail (polynucleotides 938-952) is removed and replaced by the six-polynucleotide segment 5' -TCTAGA-3 ' .
  • PSCF polynucleotides may be utilized.
  • a polynucleotide sequence for an active soluble form of PSCF is reported in U.S. Patent 5,589,582.
  • PGCs can be extracted from swine fetuses during about 17 to 39 days post fertilization of the embryo. Preferably, 27 day old fetuses are utilized and PGC suspensions are prepared by trypsin (or EDTA) treatment of genital ridges from the porcine embryos (crossbred) and then seeded on feeder cells (for example in 4-well dishes) .
  • the feeder cells are mitotically inactivated and may be STO cells that express MSCF or STO transfected cells ( e . g. , ST05 or ST08 cells) which express PSCF.
  • cell culture media that may be utilized in addition to such feeder cells or to supplement such feeder cells can be ES medium (Robertson, 1987; Terato- carcinomas and Embryonic Stem Cells, IRL Press) supplemented with 15% FCS; the ES medium supplemented with growth factors such as LIF or LIF plus bFGF. Further a conditioned media prepared from 5637 carcinoma call lines may be utilized for initial culturing of PGCs . Seeded PGC Cultures may be maintained at around 37°C in 5% C0 2 in air.
  • PGCs can be identified by alkaline phosphatase (AP) activity at 1 , 3 and 5 days (for example, or at other intervals) using the general procedures set forth above and can also be counted to determine the rate of proliferation.
  • the cultured PGCs are trypsinized, rinsed with fresh medium (such as PBS or ES media) and re-passaged every 5 to 10 days (preferably every 6 or 7 days) , but significantly older live cultures obtained from PGCs which have stopped proliferating may be transferred to media containing LIF and PSCF (preferably PSCF is provided by feeder cells) and begin to proliferate.
  • an un- supplemented gelatin plate may be used. While the first passage of cells resulting from PGCs may be cultured on all of the above media, the best results are obtained with media comprising PSCF and LIF (optionally including bFGF) .
  • PSCs are cultured in the presence of PSCF (such as PSCF produced by ST08 cells or their equivalent as described above) and LIF (optionally including bFGF) in order to provide long-term cultures of undifferentiated PGCs or undifferentiated totipotent cells resulting from PGCs.
  • PSCF such as PSCF produced by ST08 cells or their equivalent as described above
  • LIF optionally including bFGF
  • porcine totipotent cells maintain their totipotency after more than 6 passages and even after having been maintained via passages for more than 90 days. Such is significant since totipotency is frequently lost in long-term cultured porcine totipotent cells, in particular cell lines older than 40 days.
  • cryopreserved porcine totipotent cells that have been cultured in accordance with the present invention may be thawed and reused in that they retain their totipotency and can be passaged again while maintaining their totipotency.
  • the trypsin solution can contain EDTA at about 0.5 percent and the amount of trypsin in the solution is preferably from about 0.1 to about 0.5 percent, and more preferably is about 0.25 percent.
  • Further rinses with other tissue preparation media utilizing procedures know in the mouse art may be performed, such as with buffered fetal calf serum, and the cells may be recovered from such procedures via centrifugation or precipitation/settling.
  • a membrane-bound form of porcine stem cell factor is obtained by utilizing the STO cell line, which is a thioguanine/oubain resistant sub-line of SIM mouse fibroblasts, Virology 50:339 (1972); STO cells as described in U.S. Patent 5,453,357).
  • the STO cells are transfected with a membrane-bound portion which encodes an active PSCF polypeptide.
  • RNA is isolated from pig bone marrow stromal cells, RT-PCR is performed utilizing 1 ⁇ g total RNA in 6 ⁇ l H 2 0 which is incubated at 65°C for 3 minutes, then chilled on ice. Then added is 4 ⁇ l 5xRT buffer, 2 ⁇ l 0.1 M Dithiothreitol (DTT) , 1 ⁇ l RNasin (Promega, Madison, WI) , 2 ⁇ l 30 ⁇ M oligo dT l6 , 2 ⁇ l dNTPs (10 mM each dATP, dTTP, dGTP, dCTP) , 2 ⁇ l 1 mg/ml BSA, 1 ⁇ l reverse transcriptase (Gibco Life Technologies, Baltimore, MD) and the reaction mixture is incubated at room temperature for 10 min., 42°C for 60 min.
  • DTT Dithiothreitol
  • 1 ⁇ l RNasin Promega, Madison, WI
  • the cDNA product is subjected to PCR using the oligonucleotides 5'MSFHindIII (5'GGT CAA GCT TCG CTG CCT TTC CTT ATG AAG AAG, SEQ ID NO: 3) and 3'MSFXbaI (5'TCC ATC TAG AAC CAC CCA ATG TAC GAA AGC AAC, SEQ ID. NO: 4) .
  • SEQ ID NO: 1 contains a Hindlll site and includes nucleotides 1-24 of SEQ ID NO: 3 (SEQ ID. NO:5 in this application) of U.S. patent 5,589,582).
  • SEQ ID. NO: 4 contains an Xbal site and the reverse complement of nucleotides 915 through 935 of L07786.
  • the resulting PCR product is cleaved with Hindlll and Xbal and cloned in pRcCMV (Invitrogen, Portland, OR) .
  • the resulting plasmid is described as pSCFpRcCMV#2 and contains the full-length porcine cDNA for stem cell factor.
  • fragment 1 a DNA fragment of approximately 250 bp (fragment 1) is isolated.
  • Clal and Xbal are also used to cleave pSCFpRcCMV and a DNA fragment of approximately 6.2 Kb is isolated (fragment 2) .
  • oligonucleotides described as 5'SCFlk (ATCCATCGAT GCCTTCAAGG ATTTGGAGAT GGTGGCACCT AAAACTAGTG AATGTGTGAT TTCTTCAA, SEQ ID NO: 6) and 3 ' SCFlk (TCT GAGGCCTTCC TATTACTCT ACTGCTGTCA TTCCCTTTTT CAGGAGTTAA TGTTGAAGAA ATC, SEQ ID NO : 7) are synthesized.
  • the oligonucleotides (l ⁇ g (10 ⁇ g) of SEQ ID NO: 6 and (1 ⁇ g 10 ⁇ l) of SEQ ID NO: 7 are mixed with 3 ⁇ l 10X Klenow buffer [Sambrook, 1989 #1973] and incubated at 75 °C for 5 min. and then allowed to cool slowly. Afterwards 2 ⁇ l 2.5 mM each dXTP, 1.5 ⁇ l (7.5 unit) DNA polymerase Klenow fragment 3.5 ⁇ l H20 are added. After 30 min at 37°C, the reaction is heated at 70°C for 10 min. The DNA fragment (fragment 3) is cleaved with Clal and Stul. A three-way ligation is then performed with the DNA fragments 1,2 and 3.
  • a resulting plasmid pPSCF is identified to have the correct sequence, shown in Figure 6 (SEQ ID NO: 8 encoding amino acid sequence SEQ ID. NO: 9) .
  • the plasmid does not contain exon 6 and therefore is a form of SCF that is ordinarily expressed preferentially as a membrane bound form.
  • STO cells are electroporated according to the BIORAD (Hercules, CA) instructions for use of the Gene Pulser ® Electroprotocols, using Pvul linerized pPSCF.
  • Cells are selected for growth in G418 (500 ⁇ g/ml) and analyzed for the expression of the modified PSCF, using RT-PCR from RNA isolated from G418 resistant clones.
  • Examples of STO cell lines that are successfully transfected with the polynucleotides of the above plasmid are designated as cell lines ST05, ST08, ST012 and ST018.
  • STO cell (or other STO type cell lines such as ST08) were used as feeder cells.
  • the ST08 cells express the membrane-bound form of porcine SCF.
  • the feeder cells were maintained in Dulbecco's modified Eagle's medium (DNEM; Life Technologies) supplemented with 10% fetal calf serum (FCS, Boehringer Mannheim) 100 ⁇ g/ml streptomycin sulfate and 100 IU/ml penicillin G at 37°C with 5 % C0 2 in air.
  • DNEM Dulbecco's modified Eagle's medium
  • FCS fetal calf serum
  • confluent monolayers of feeder cells were treated with 5 ⁇ g/ml mitomycin C for 2.5 h and seeded onto gelatine-coated 4-well-dishes (Nunc; 1.5 x 10 6 cells per well) for proliferation studies of PGCs in 5 days of culture and 35 mm petri dishs (6 x 10 6 cells per dish) for study of prolonged culture of porcine PGCs and were used within 24 hours.
  • STO control expressing murine membrane SCF
  • ST08, ST012 and ST018 are plated into 96 well flat bottom plates in Iscove's Modified Dulbecco' s Media containing 10% heat- inactivated fetal bovine serum.
  • the plates Prior to the addition of bone marrow cells, the plates are irradiated to prevent further proliferation of the STO, ST05, ST08, ST012, and ST018 cells.
  • Bone marrow cells are added to the wells. After 2 days in culture, 1 microcurie of 3 H-Tdr is added to each well, and the plates are harvested on day 3. Results are counts per minute (cpm) and expressed as a mean value of triplicate plates.
  • Figure 5 shows that each of the transfected STO cell lines supports the proliferation of pig bone marrow cells to a greater extent than the untransfected STO cell line.
  • the proliferative response on the bone marrow cells of the transfected cells is similar to that observed with untransfected STO cells that were cultured in combination with of 100-200 ⁇ g soluble pig SCF (for example, as set forth in U.S. Patent 5,589,582) .
  • ES medium Robottson, 1987; Teratocarcinomas and Embryonic Stem Cells, IRL Press
  • control that is supplemented with 15% FCS
  • ES medium supplemented with the growth factor LIF
  • ES medium supplemented with the growth factors LIF and bFGF
  • a conditioned medium prepared from 5637 carcinoma call lines.
  • Feeder cells which are mitotically inactivated STO and ST08 cells were seeded in 4-well-dishes .
  • PGC suspensions were prepared by trypsin treatment of genital ridges from 27 day old embryos (crossbred) and then seeded on feeder cells.
  • urogenital ridges of the fetuses were collected in PBS supplemented with 10% FCS and washed two times in PBS.
  • the genital ridges were incubated in digestive solution (0.1% trypsin/0.05% EDTA) at 37°C for 5-8 min and dissociated by gentle pipetting.
  • Suspension of PGCs and somatic cells was seeded in aliquot equivalents of one tenth of a genital ridge per well in 4-well-dishes (Nunc) onto feeder cells.
  • the cells were cultured in embryonic stem cell (ESC) medium consisting of DMEM, supplemented with 15% FCS, 2 mM L-glutamine (Gibco, Life Technologies) , 10 4 mM ⁇ -mercaptoethanol (Sigma) , 2 mM non-essential amino acids (Gibco, Life Technologies) 100 ⁇ g/ml streptomycin sulfate and 100 IU/ml penicillin G in 5% C0 2 in air at 37°C.
  • ES medium was supplemented with murine leukemia inhibitory factor (ESGRO, Amrad, 1000 IU/ml) alone or in combination with human basic fibroblast growth factor (Sigma, 10 ng/ml) . The medium was changed every other day. Cultures were maintained at 37°C in 5% C0 2 in air.
  • PGCs were identified by alkaline phosphatase (AP) activity at 1, 3 and 5 days and counted. In determining the number in culture, cells were fixed by drying in air and stained with Alkaline Phosphatase Leukocyte Kit (Sigma) according to the manufacturer's instructions. AP- positive cells in 4 well dishes were counted using an inverted microscope. Alkaline phosphatase (AP) activity was used for identification of porcine PGCs after different days of culture. Initially, PGCs were identified in culture as single red AP-positive cells which eventually formed groups of small colonies by aggregation ( Figure 7A) .
  • AP alkaline phosphatase
  • Figures 1 and 2 show the relative number of PGCs on 1, 3, and 5 days in culture utilizing STO feeder cells and ST08 feeder cells, respectively, (Figure 1 data reports results with STO feeder cells with membrane-bound MSCF, and Figure 2 data reports results with ST08 feeder cells with membrane- bound PSCF excluding the polypeptides corresponding to exon 6) .
  • the three plot lines in each Figure represent three of the four different culture media utilized with the respective feeder cells under the same culturing conditions.
  • the plot line corresponding to the ES medium control utilizes just the feeder cells and the ES medium described above.
  • One of the plot lines in Figure 1 shows the relative numbers of PGCs resulting from culturing in the presence of STO feeder cells and the 5637 carcinoma cells medium.
  • the 5637 carcinoma cell medium supports cell proliferation well for first three days, the total number of cells decreases rapidly after day three.
  • the results for the first three days in Figure 1 show that the STO feeder cell support initial growth better than the results in Figure 2 from ST08 for the first 3 days with regard to the 5637 carcinoma cell conditioned medium.
  • the numbers of PGCs resulting from culturing in the presence of the ST08 cells is better for the other three types of media than for the same three types of media in the presence of STO cells.
  • the proliferation of PGCs is significantly better on ST08 feeder cells than on STO feeder cells for each of the four media types except the carcinoma cell 5637 media.
  • porcine membrane bound stem cell factor SCF
  • MSCF mouse membrane bound SCF
  • PSCF porcine SCF
  • the data plotted in Figures 1 and 2 are displayed in Tables 1 and 2 along with some simple statistical analysis.
  • the first two columns in each table are the culture day and culture conditions.
  • the last column is the percent relative standard deviation (% RDS) and the average given at the bottom is the average of the % RDS value on day 3 and 5.
  • Table 1 is presented below to provide the results with STO feeder cells. Day 1 SD and % RDS are zero because the data was normalized to Day 1. Table 1
  • Table 2 is presented below to provide the results with ST08 feeder cells. Day 1 SD and % RDS are zero because the data was normalized to Day 1. The other aspects of the data are the same as reported above for the results in Table 1. Table 2
  • 5637 conditioning medium may contain additional other growth factor (s), which are as of now undefined that also support the initial proliferation of PGCs on the STO feeder cells. Further, adequate growth factors may remain in the tissue or in the seed cells themselves that have an effect upon growth during the first three days.
  • Cultures of totipotent cell lines were maintained for more than 6 passages .and some more than 90 days via passaging every 6 to 7 days in the presence of ST08 feeder cells and preferably also in the presence of least LIF or LIF and bFGF. Cryopreserved cells from such cultures were reconstituted using methods standard in the art and repassaged. Totipotent cells were obtained from such cryopreserved cells.
  • Example 2 The procedures from Example 2 were followed utilizing the ST08 feeder cells and initial culture PGCs were obtained from EDTA-treated day 26 genital ridges isolated from fetuses of Duroc-German Landrace crossbred gilts mated with transgenic boars heterozygous for a gene construct consisting of the human growth hormone (GH) gene driven by the murine whey acidic polypeptide (WAP) promoter.
  • GH human growth hormone
  • WAP murine whey acidic polypeptide
  • the porcine totipotent cell lines having the gene construct were also maintained in long-term culture for at least three months using the passaging and culture conditions as set forth in Examples 2, above.
  • the cells may be passaged about every 3 days to two weeks but were optimally passaged once every six to seven days by trypsin/EDTA treatment .
  • porcine totipotent cells lines having the gene construct as described above also survived cryopreservation in liquid nitrogen and proliferated after thawing . Details of the materials and methods as well as of the individual experiments are as follows:
  • PGC donors Eight sows (Duroc/German Landrace/Pietrain- crossbred) were slaughtered at different stages of pregnancy which varied between 25 and 28 days after natural mating. All of them had been hormonally treated by Pregnant Mare's Serum Gonadotropin (PMSG, 1000 IU) followed by Human Chorionic Gonadotropin (HCG, 750 IU) after 72 hours. The females were mated with transgenic boars heterozygous for a gene construct consisting of the human growth hormone (GH) gene driven by the murine whey acidic protein (WAP) promoter. Also five of the dams had this transgenic marker. 119 fetuses were obtained. They were transported to the lab in cold PBS (without Ca + , Mg ++ ) on ice. Time between slaughtering and beginning of preparation was about 2 hours.
  • PMSG Pregnant Mare's Serum Gonadotropin
  • HCG Human Chorionic Gonadotropin
  • GH human growth hormone
  • WAP murine
  • Recipients For embryo transfer 12 recipient gilts were used (Duroc or German Landrace) . They also were prepared by hormonal stimulation synchronous or 24 hours asynchronous with the donors .
  • fetuses were transferred to fresh PBS (without Ca ++ , Mg ++ ) at room temperature. Each fetus was dissected by dividing the fetus caudal to the forelimb strom and the genital ridges were removed from the fetus. In dependence on the age specific stage of development of the genital ridges gonads including or without their surrounding tissues such as mesonephric were removed. Isolated tissues were washed with PBS and treated with 0.02% EDTA solution for 15 to 20 minutes at room temperature. After incubation the gonads were transferred to culture medium and pricked with a fine cannula (30g) to release the PGCs. After disaggregation and gentle pipetting the suspension was immediately transferred to either gelatin-coated dishes or to ST08 feeder cells which were inactivated by mitomycin C.
  • Embryonic Stem Cell Medium containing 15% fetal calf serum, MEM nonessential amino acids (0.1 mM) , L-glutamine (1 mM) , sodium pyruvate (1 mM) , ⁇ -mercaptoethanol (0.1 mM) and antibiotics.
  • In vitro culturing conditions were 37°C, 5 % C0 2 and saturated air humidity.
  • the culture dishes (Nunc or Falcon) were petri dishes or multidishes (4-6-well-dishes) .
  • Feeder cells Cells were seeded on gelatin-coated dishes until micromanipulation. After injection the cells which were not needed were seeded on murine STO cells (ST08) transfected with the membrane-bound pig stem cell factor.
  • Experiment (i) The dispersed cells collected from the embryos of the same dam were pooled. Primordial germ cells were injected into host blastocysts on the day of isolation. The following day the cells were seeded on feeder layer.
  • Experiment (v) The cells were maintained in long-term culture. After freezing and thawing they were passaged two times and used for microinjection. When the PGCs had been seeded onto feeder cells the medium was changed every other day. Approximately 4 days later the first proliferating primordial germ cells could be seen. After 7 to 10 days in culture the first embryonic stem cell like colonies could be observed. For further subculture the cells were passaged by trypsin/EDTA treatment at 6- to 10-day intervals.
  • the cultivated PGCs were washed with PBS and incubated in 0.25% trypsin-EDTA-solution for up to 3 minutes at 37°C.
  • the cells were suspended in medium and centrifuged at 600 x g for 5 minutes.
  • the pellet was resuspended in 1 ml freezing solution consisting of 90% fetal calf serum/10% Dimethylsulfoxide (DMSO) and filled in cryotubes (Nunc) .
  • the cryotubes were cooled at -80°C and stored in liquid nitrogen (LN 2 ) after 24 hours.
  • Thawing was performed rapidly in a 37°C-waterbath. Thawed cell-suspension was diluted in 4 ml culture medium and centrifuged at 600 x g for 5 minutes. After resuspending the pellet in 1 ml culture medium the cells were seeded onto freshly inactivated STO-cells (ST08) .
  • AP staining kit Sigma
  • AP-staining was carried out in about 2 weeks intervals during the long-term culture. Thawed PGCs also were tested for AP activity.
  • SSEA-1 Stage specific embryonic antigen- l:
  • porcine primordial germ cells were used at different passages (2, 5 and 11 passages) which were cultivated for 4, 10 and 16 weeks, respectively. Also cryopreserved and thawed cells were tested for SSEA-1- activity. One to three days before staining PGCs and feeder cells were transferred on gelatinized cover slips.
  • the fixed cells are incubated with 10% goat serum in a humidified chamber for 30 min at room temperature to prevent unspecific immunostaining - incubation with the first antibody SSEA-1 (1:3 in PBS) for 90 min at 37°C
  • the embryos were placed in transfer medium (PBS containing 20% heat inactivated lamb serum and gentamicin) covered by liquid paraffin at 39°C in 5% C0 2 .
  • transfer medium PBS containing 20% heat inactivated lamb serum and gentamicin
  • a suspension of non- adherent PGCs, collected from the culture dish by using a mouth-controlled glass micropipette was transferred into a drop of micromanipulation medium.
  • the embryos were held in a conventional holding pipette (130-140 ⁇ m internal diameter) ; the injection pipette had about 30 ⁇ m internal diameter.
  • Five to ten cells phenotypically resembling PGCs were deposited within the blastocyst cavity.
  • recipient gilts were prepared for blastocyst transfer by hormonal stimulation 24 hours asynchronous with the donors. One transfer was carried out in a synchronous recipient. Transfers were performed by endoscopy under general anesthesia. Per recipient 16-20 blastocysts were transferred into the tip of one uterine horn. Five weeks later the recipients were slaughtered to check chimerism.
  • TWEEN 20 supplemented with 1 mg/ml proteinase K at 64 °C for
  • the fetuses resulting from blastocyst injection were dissected. Ten to eleven different tissue samples were collected separately: whole fetus (skin and muscle) , umbilical cord, brain, heart, lungs, gastrointestinal tract, liver, kidney, gonads, fetal placenta, spleen, mesonephron. The samples were incubated at 64 °C overnight in Kawasaki buffer and proteinase K.
  • PCR reactions were carried out in a final volume of 50 ⁇ l using 5 ⁇ l of the diluted lysates as templates. Amplifications were performed in 10 x PCR buffer (166 mM (NH 4 ) 2 S0 4 , 677 mM Tris-HCl, pH 8.8, 0.1 % (v/v) TWEEN 20, 20 mM MgCl 2 ) , 0.2 mM of each dNTP's, 50 pmol of each primer (pWAP 8 and hGh S2.1) and 1 U Taq polymerase.
  • 10 PCR buffer 166 mM (NH 4 ) 2 S0 4 , 677 mM Tris-HCl, pH 8.8, 0.1 % (v/v) TWEEN 20, 20 mM MgCl 2
  • 0.2 mM of each dNTP's 50 pmol of each primer (pWAP 8 and hGh S2.1) and 1 U Taq polymerase.
  • sequences of the primers were 5' -CCA CCC CCA AAG TCT TCC TCC TGT GGG TC- 3' (pWAP8, SEQ ID NO:10) and 5' -ATG CGC ACC CAT TCC CCA AG - 3 ' (hGh S2.1, SEQ ID NO: 11) .
  • primer annealing at 68°C for 40s and primer extension at 72°C for 40s PCR was carried out for 35 cycles each consisting of 40s denaturation at 95°C, 40s annealing at 68°C and 40s polymerization at 72°C in a RoboCyclere (Stratagene) .
  • the PCR products were electrophoresed on a 2% agarose gel (1 x TBE buffer, 120V const.) , stained with ethidium bromide and evaluated using ultraviolet light. The fetus/tissue was judged to be transgenic if a 500 bp fragment was visible.
  • primordial germ cells could clearly be distinguished because of their morphology. There were large roundish cells with typical "blebbing" pseudopodial activity. When the culture conditions employed porcine PGCs seeded onto ST08 the culture showed proliferation about 7-8 days after isolation. In simple media the PGCs remained single cells, which formed nearly a monolayer. They very rarely formed colonies, in most of the cases there were aggregates of single cells up to passage 3-4 ( Figures 10-11) . The cells were passaged once per two weeks.
  • Porcine primordial germ cells/ primordial germ cell- derived cells have been derived from 20 primary pools of genital ridges. Eight lines survived up to 13 passages and still are in culture. Various passages are cryopreserved.
  • primordial germ cells either differentiated into endodermal-like cells or fibroblast-like cells. If differentiation took place the remaining undifferentiated PGCs rapidly decreased in number and were overgrown by the other cells.
  • AP positive cells were found in almost every sample we treated with the staining kit by Sigma. In primary culture AP positive single cells could be detected arranged near by small pieces of gonadal tissues which were still in the culture dishes. Different passages showed positive colonies ( Figures 17-19) .
  • a total of 203 host blastcysts were injected with (a) freshly isolated PGCs, or (b) PGCs cultivated twenty hours or (c) PGCs cultivated for 4 days or (d) PGCs cryopreserved/thawed and cultivated for 4 weeks. Eleven transfers were performed in recipient gilts 24 hours asynchronous with the donors .
  • Tables 4-6 below show the data of PCR and Southern Blot for Experiments (i) , (iv) and (v-) above. Table 4
  • Porcine totipotent primordial cells from PGCs were injected into embryo blastocysts to demonstrate the ability of such cells to become germ cells in the fetus resulting from the injected embryo and cause such fetuses to have the ability to pass on the traits of the totipotent cells to their offspring.
  • Porcine totipotent cells are obtained from (1) Freshly isolated PGC suspensions (isolated as described in Example 2) which have the construct described in Example 4 or another detectable trait different from the blastocysts to be injected, (2) totipotent cells from long-term cultures as set forth in Examples 2 and 3 which have a detectable trait as described above, and (3) cryopreserved cells which have a detectable trait .
  • the totipotent cells thus obtained were seeded to either gelatin-coated dishes or to mitotically inactivated feeder layers of ST08 cells and cultured briefly in Dulbecco's modified Eagle's medium (DMEM), 10% heat inactivated fetal calf serum in an atmosphere of 5% C0 2 in air at 37°C.
  • DMEM Dulbecco's modified Eagle's medium
  • Five to ten cells phenotypically resembling PGCs large round cells with typical "blebbing" pseudopodial activity
  • Each fetus was dissected and eleven tissues were selected for DNA analysis by PCR to detect the WAP-hGH transgene (or other detectable trait) in skin/muscle, umbilical cord, brain, heart, lungs, gastrointestinal tract, liver, kidney, gonads, fetal placenta and spleen.
  • the PCR data shows that the gonads of the embryos resulting from such injected blastocysts contain germ cells which correspond in genotype to the WAP-hGH transgene or other detectable trait .
  • Porcine totipotent cells from PGCs are injected into enucleated eggs (fertilized or unfertilized ovum from which the nucleus have been removed using standard methods well-known in the art) to demonstrate the ability of such cells to become total individuals homozygous for a desired trait.
  • the fetuses and adults that result from such injected eggs have the desired trait phenotypically and genotypically as well the ability to pass on the trait of the totipotent cells to their offspring in a homozygous manner.
  • Porcine totipotent cells are obtained from (1) Freshly isolated PGC suspensions (isolated as described in Example 2) which have the construct described in Example 5 or another detectable trait different from the blastocysts to be injected,
  • cryopreserved cells which have a detectable trait.
  • porcine totipotent cells from such cultures is/are injected into the enucleated eggs using methods standard in the art and the embryos are then cultured until they are expanded embryos.
  • Each of the resulting embryos is transferred to recipients who have been prepared for such embryo transfer using methods standard in the art by placing the embryos into the tip of the uterine horns by endoscopy.
  • the gilts were slaughtered after 5 weeks of pregnancy and the normally developed fetuses are delivered.
  • Each fetus is dissected and eleven tissues were selected for DNA analysis by PCR to detect the WAP-hGH transgene or other detectable trait: skin/muscle, umbilical cord, brain, heart, lungs, gastrointestinal tract, liver, kidney, gonads, fetal placenta and spleen.
  • the PCR data shows that all of the tissues have the WAP-hGH transgene or other detectable trait.
  • adults resulting from such embryos will have the desired trait of the totipotent cells as well as the ability to pass the trait on to offspring.

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Abstract

L'invention concerne un procédé d'utilisation d'un facteur de cellule souche porcine (PSCF), pouvant être également désigné par facteur 'acier' porcin, qui est de préférence un PSCF lié à membrane sur des cellules nourricières STO murines transfectées, en vue d'établir des lignées cellulaires porcines pluripotentes ou totipotentes, en particulier pour la culture de cellules germinales porcines primordiales (PGC).
PCT/US1998/016782 1997-08-14 1998-08-13 Cellules totipotentes porcines et procede de culture a long terme WO1999009141A1 (fr)

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WO2002010337A3 (fr) * 2000-07-28 2003-04-10 Infigen Inc Methode de clonage de porcs
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Cited By (14)

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Publication number Priority date Publication date Assignee Title
WO2000031237A3 (fr) * 1998-11-24 2000-11-16 Infigen Inc Procede de clonage de porcins
EP1586633A1 (fr) * 1998-11-24 2005-10-19 Infigen, Inc. Méthode de préparation de cellules porcines totipotentes
WO2002000847A3 (fr) * 2000-06-28 2002-07-18 Thromb X N V Lignees cellulaires souches embryonnaires (es) multipotentes, leur procede perfectionne de production, et leur utilisation pour la transmission de la lignee germinale et pour la production d'animaux genetiquement modifies
US8030537B1 (en) 2000-07-27 2011-10-04 Apogene Gmbh & Co. Kg Somatic cloning gene transfer for the production of recombinant proteins, cells and organs
WO2002009507A1 (fr) * 2000-07-27 2002-02-07 Apogene Gmbh & Co. Kg Clonage/transfert de gene somatique pour produire par recombinaison des proteines, des cellules et des organes
WO2002010337A3 (fr) * 2000-07-28 2003-04-10 Infigen Inc Methode de clonage de porcs
EP2138583A1 (fr) 2000-12-22 2009-12-30 Institut National De La Recherche Agronomique Expression position-indépendante et tissus-spécifique d' un transgène dans le lait d'animaux transgéniques
US7795493B2 (en) 2002-08-21 2010-09-14 Revivicor, Inc. Porcine animals lacking any expression of functional alpha 1, 3 galactosyltransferase
US8106251B2 (en) 2002-08-21 2012-01-31 Revivicor, Inc. Tissue products derived from porcine animals lacking any expression of functional alpha 1,3 galactosyltransferase
US10130737B2 (en) 2002-08-21 2018-11-20 Revivicor, Inc. Tissue products derived from animals lacking any expression of functional alpha 1, 3 galactosyltransferase
US10912863B2 (en) 2002-08-21 2021-02-09 Revivicor, Inc. Tissue products derived from animals lacking any expression of functional alpha 1, 3 galactosyltransferase
US11172658B2 (en) 2002-08-21 2021-11-16 Revivicor, Inc. Porcine animals lacking expression of functional alpha 1, 3 galactosyltransferase
US7560538B2 (en) 2003-11-05 2009-07-14 University Of Pittsburgh Porcine isogloboside 3 synthase protein, cDNA, genomic organization, and regulatory region
WO2006016790A1 (fr) * 2004-08-13 2006-02-16 Jong-Won Kim Appareil de traitement de broderie solide

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