In light of recent public proclamations about the "enormous promise"
of therapies based on human embryo stem cells, people might be surprised to
learn that mouse embryo stem cells have been worked on for 20 years.  There
are many mouse models for human diseases, but there do not appear to be any
scientific papers reporting cures of any of these mouse conditions with
embryo stem (ES) cells.  It should also be of interest that the
distinguishing characteristic of mouse ES cells when they were first
identified was that they caused cancer when injected into mice.  This fact
has not figured in the public discussions of potential therapeutic uses of
human ES cells.  Indeed, until human ES cells were identified and patented
during the last two years there seems to have been few (or no) papers in the
scientific literature (as indexed in Medline) that discussed ES cells as
therapeutic agents in tissue reconstruction.  The abstract of the first
report of mouse ES cells is printed below.
        ____________________________
      Proc Natl Acad Sci U S A 1981 Dec;78(12):7634-8
      Isolation of a pluripotent cell line from early mouse embryos cultured
in medium conditioned by teratocarcinoma stem cells.

Martin GR.

This report describes the establishment directly from normal preimplantation
mouse embryos of a cell line that forms teratocarcinomas when injected into
mice. The pluripotency of these embryonic stem cells was demonstrated
conclusively by the observation that subclonal cultures, derived from
isolated single cells, can differentiate into a wide variety of cell types.
Such embryonic stem cells were isolated from inner cell masses of late
blastocysts cultured in medium conditioned by an established teratocarcinoma
stem cell line. This suggests that such conditioned medium might contain a
growth factor that stimulates the proliferation or inhibits the
differentiation of normal pluripotent embryonic cells, or both. This method
of obtaining embryonic stem cells makes feasible the isolation of
pluripotent cells lines from various types of noninbred embryo, including
those carrying mutant genes. The availability of such cell lines should made
possible new approaches to the study of early mammalian development.


***********************************************
Stuart A. Newman, Ph.D.
Professor of Cell Biology and Anatomy
Basic Science Building
New York Medical College
Valhalla, NY 10595

Tel:  (914) 594-4048
Fax: (914) 594-4653
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