Once a stem cell reaches the treatment site, it will differentiate or specialize into whatever specific cell is needed to repair specific tissue – like cartilage in an arthritic knee or connective tissue in a torn tendon; this is called Transdifferentiation. A number of experiments have reported that certain adult stem cell types can differentiate into cell types seen in organs or tissues other than those expected from the cells’ predicted lineage (i.e., brain stem cells that differentiate into blood cells or blood-forming cells that differentiate into cardiac muscle cells, and so forth). This enables the damaged or degenerative tissues to be repaired at the cellular level without surgery. Once the stem cells specialize, these new cells will continue to divide. Infusing damaged, painful tissue with new healthy cells can lead to regeneration – potentially reducing pain and improving function over a course of months.
This is the basis of stem cell therapy.
References Kamei G, Kobayashi T, Ohkawa S, et al. Articular cartilage repair with magnetic mesenchymal stem cells. Am J Sports Med 2013 Apr 19.