Biomedical Engineering Reference
In-Depth Information
The fundamental importance is in determining whether cultures of human ES
cells that appear to be homogeneous and undifferentiated are, in fact, homogeneous
and undifferentiated. Is it possible that human ES cells in vitro cycle in and out of
partially differentiated states? And if that occurs, how will it affect attempts to direct
their differentiation or maintain the cells in a proliferating state? [
25
] . There is a
need to identify which signal transduction pathways must be activated to induce
human ES cell differentiation along a particular pathway. This includes understand-
ing ligand-receptor interaction and the intracellular components of the signaling
system, as well as identifying the genes that are activated or inactivated during dif-
ferentiation of specific cell types [
26
]. Identifying intermediate stages of human ES
cell differentiation will also be important. As human ES cells differentiate in vitro,
do they form distinct precursor or progenitor cells that can be identified and iso-
lated? Would such precursor or progenitor cells be useful for therapeutic transplan-
tation? [
17
]. Finally, we need to determine what differentiation stages of human
ES-derived cells are optimal for particular practical applications. For example, what
differentiation stages of ES-derived cells would be best for screening drugs or tox-
ins, or for delivering potentially therapeutic drugs?
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