Chemistry: molecular biology and microbiology – Animal cell – per se ; composition thereof; process of...
Patent
1995-12-29
2000-11-14
Crouch, Deborah
Chemistry: molecular biology and microbiology
Animal cell, per se ; composition thereof; process of...
435350, 435351, 435352, 435353, 435354, 435355, 435363, 435366, 435368, 435372, C12N 1585, C12N 1586
Patent
active
061468886
DESCRIPTION:
BRIEF SUMMARY
SUMMARY OF THE INVENTION
This invention relates to methods of isolating and/or enriching and/or selectively propagating animal stem cells, genetically modified animal cells and animals for use in said method, transgenic animals providing a source of such cells and selectable marker constructs for producing genetically modified cells and transgenic animals.
Stem cells are progenitor cells which have the capacity both to self-renew and to differentiate into mature somatic tissues.
Embryonic stem cells are the archetypal stem cell, being capable of differentiating to form the whole gamut of cell types found in the adult animal. Such stem cells are described as pluripotential as they are capable of differentiating into many cell types. Other types of stem cells, for example bone marrow stem cells and epidermal stem cells, persist in the adult animal. These stem cells have a more restricted capacity for differentiation.
In general, when required for research purposes or for medical use, stem cells have to be isolated from tissue samples by various fractionation procedures, but even after careful segregation of cell types, these stem cell preparations consist of mixed cell types and while enriched for stem cells, include high proportions of differentiated cells which are not categorised as stem cells.
Furthermore, most stem cells cannot be grown readily in culture and when attempts are made to culture stem cells, the cells being cultured (which ordinarily contain a mixed population of cell types) grow at different rates and stem cells rapidly become overgrown by non-stem cell types. An exception is that embryonic stem cells from two specific strains of mice (129 and Black 6) can be cultured in vitro. Thus established lines of embryonic stem cells can be obtained by culturing early (31/2 day) embryonic cells from murine strain 129 and Black 6, or hybrids thereof.
There has developed a pressing need to isolate and maintain in vitro embryonic stem cells from other murine strains and more especially from other species including other laboratory animals (e.g. rats, rabbits and guinea pigs), domesticated animals (e.g. sheep, goats, horses, cattle, pigs, birds, fish, etc.) and primates. Similarly, numerous medical applications for other pluripotential cells such as haematopoictic stem cells also demand their isolation and culture in vitro.
However hitherto the problems associated with producing cultures of stem cells including the problem of producing cell populations of a satisfactorily low degree of heterogeneity and the problem of overgrowth in culture of non-pluripotent cells have not been solved. A particular problem associated with the continuing presence of certain differentiated cell types is that these can cause elimination of stem cells from the culture by inducing their differentiation or programmed cell death.
We have now developed a technique by which the aforementioned problems can be overcome.
According to one aspect of the invention there is provided a method of isolating and/or enriching and/or selectively propagating animal stem cells, which comprises maintaining a source of said cells under culture conditions conducive to cell survival, characterised in that the source of cells includes cells containing a selectable marker which is capable of differential expression in (a) stem cells and (b) cells other than the desired stem cells, whereby differential expression of said selectable marker results in preferential isolation and/or survival and/or division of the desired stem cells. In the context of this invention, the term "animal cell" is intended to embrace all animal cells, especially of mammalian species, including human cells.
Examples of stem cells include both unipotential and pluripotential stem cells, embryonic stem cells, gonadal stem cells, somatic stem/progenitor cells, haematopoietic stem cells, epidermal stem cells and neuronal stem cells.
In carrying out the method of the invention, the source of cells may include pluripotential cells having a positive selectable marker and expression
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Mountford Peter Scott
Smith Austin Gerard
Crouch Deborah
The University of Edinburgh
Wilson Michael C.
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