Harvesting Stem Cells

Stem cells used in both research and therapeutic settings can be derived from an embryonic source, umbilical cord blood, a terminated foetus, living donor, or a patient themselves.  The type of stem cell is dependent on the cell’s origin with many adult stem cells being unipotent in comparison to undifferentiated embryonic stem cells which maintain a high degree of plasticity (potency) and capacity for self-renewal.  Harvesting stem cells involves several decisions over the relative merits for each cell type in the particular condition being treated or trial to be conducted.  Sourcing stem cells with a limited potency will mean that a specific site of extraction is needed to ensure correct cell-type growth in culture and implantation.

Arguments persist over the merits of differentiating stem cells prior to implantation in stem cell therapy with some cautious over the potential for undifferentiated stem cells to create unwanted tissue types (in neurosurgery for example).  Other researchers feel that allowing stem cells to differentiate in the living tissues of a patient will allow the body to provide its own guidelines determining cell type.  Several sources of stem cells in the body retain the capacity to differentiate into numerous cell types but are usually confined to a particular tissue-type, such as cartilage, bone, or connective tissue.  Other stem cells, such as those in the liver, retain their capacity for self-renewal and can regenerate a substantial amount of living tissue.
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