Stem cells therapy is becoming a common form of therapy in medicine especially for strokes, heart attacks degenerative diseases like arthritis and disc degeneration. In some cases the cells undergo many cell divisions as they become miniature organ structures like beating hearts etc. It is now generally accepted that as normal cells divide their telomeres become shorter and when reach a certain shortening length the cells eventually stop division. This phenomenon of telomere shortening is believed to be the cause of Hayflick limit of cell divisions.
I wonder is some of the failures in using stem cell therapy may be due to telomere shortening.