Biomedical Engineering Reference
In-Depth Information
Chapter 1
Pathways to Pluripotency: How Germ
Cells Make Stem Cells
Peter J. Donovan
Abstract
Recent studies have demonstrated that many types of differentiated cells
can be reprogrammed to give rise to pluripotent stem cells. Reprogramming of
differentiated cells is brought about by the forced expression or delivery of defined
factors previously shown to be associated with pluripotent stem cells. But important
questions about the safety, efficiency, and completeness of cellular reprogram-
ming remain. Primordial germ cells (PGCs), specialized embryonic precursors of
the gametes, can also give rise to pluripotent stem cells both
in vivo
and
in vitro
.
Reprogramming of PGCs
in vitro
only requires the addition of exogenous growth
factors. Moreover, genetic studies in both mice and humans have begun to elucidate
the pathways responsible for reprogramming germ cells to the pluripotent state.
Thus, these two situations, one
in vivo
and one
in vitro
, in which a PGC gives rise
to a pluripotent stem cell provide important insights into the molecular mechanisms
regulating the pluripotent state and could fill vital gaps in our knowledge about the
successful reprogramming of other cell types.
Keywords
Primordial germ cells
•
Embryonic germ cells
•
Testicular germ cell
tumors • Pluripotent stem cells
1.1
Introduction
In all vertebrates and many invertebrates only a single lineage, the germ cell lineage,
carries the genome on into the next generation. It does so by the creation of a single
totipotent cell, the zygote, formed by the fusion of two germ cells or gametes, an egg
and a sperm. The totipotent zygote gives rise to a so-called pluripotent groups of cells,
P.J. Donovan (
*
)
Departments of Biological Chemistry and of Developmental and Cell Biology, Sue and Bill
Gross Stem Cell Research Center, University of California, Irvine, CA 92697, USA
e-mail: pdonovan@uci.edu
Search WWH ::
Custom Search