In adults, stem cells are responsible for the repair of damaged tissues, and the replacement and regeneration of tissues that turn over rapidly, such as the skin, blood or the lining of the intestine. Recent evidence suggests that most, if not all tissues may contain stem cells with the potential to repair damaged tissue.
Harnessing the power of adult stem cells to repair damaged tissue or generate repalcement organs is slowly moving from vision to reality; the use of stem cells to repair damage to eyes, or replace skin that has been subject to severe burns is already a reality. The use of stem cells to restore bone marrow in cancer patients is also in widespread use.
If an adult patient could provide his or her own stem cells, this would avoid both the problem of immune rejection and the ethical objections to the use of embryonic stem cells.
Yet major challenges remain before we can harness the full power of our own stem cells for use in regenerative medicine for many tissues and organs such as the heart and brain. Not least, we need to identify resident stem cells in different organs, understand the molecular switches that activate them, and that control their own regeneration, and ulitmately develop novel drugs that will facilitate the repair and regeneration of damaged or diseased tissue through pharmacological manipulation of our own stem cells.
This ambition is one that will only be attained if stem cell researchers in multiple fields work closely with medicinal chemists, and tissue engineers towards the common goal of deriving effective stem cell-based therapies.