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Some ethical issues surrounding stem cell research remain controversial,
and continued and open debate about the use of stem cells is critical. If
these issues can be resolved, the future of science in this area shows tremendous
promise. Among the areas being explored is the question of how to produce
large numbers of stem cells in the laboratory. Stem cells that are "harvested"
exist in small numbers; they then need to be cultured in the laboratory
setting so that large volumes of them can be produced. This seems to be
particularly challenging in the case of stem cells, as compared to mature
cells.
Scientists will be trying to identify the particular molecular signals
that affect stem cells. Molecular signals are chemicals in whose presence
cells act in a certain fashion. Molecular signals released by surrounding
tissues either tell stem cells to remain stem cells or they tell stem
cells to differentiate into their specialized successors. Once we know
what the various molecular signals are, we can manipulate stem cells,
either by maintaining them as stem cells or by encouraging them to differentiate,
depending on how we plan to use them.
A third area of future research concerns the delivery of stem cells to
the tissues in which they are needed. Current practice involves either
the injection of stem cells directly into the targeted tissue, or injection
of the stem cells into the blood stream without any guarantee that they
will actually find their way to the appropriate tissues. "Targeted
delivery" would ensure that the therapeutic stem cells are introduced
to the organs and tissues that need them, where they need them.
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