The laboratory of Marni D. Boppart at the Beckman Inst. for Advanced Science and Technology in Urbana, Illinois has published a very interesting study that shows that injections of mesenchymal stem cells (MSCs) into mice after they have exercised increases the number of new blood vessels formed in skeletal muscle.
Early last year, Boppart’s laboratory showed that exercise in mice induces a population of mesenchymal stem cells located near blood vessels (pericytes) to migrate into muscles and form new muscle fibers. A particular adhesion molecule known as integrin α7 is responsible for the movement of MSCs into the muscle. Boppart and his colleagues showed that engineering mice that made extra α7 integrin had muscles that were filled with more stem cells making new muscle than their normal litter mates after exercise.
More recently, Boppart and his colleagues have injected cultured MSCs into the muscles of mice after the mice had exercised by running downhill. The mice injected with MSCs had more blood vessels in their muscles than mice than received no such injections. The blood vessels in the MSC-injected mice were also larger. Further work showed that the MSCs produced a veritable smorgasbord of angiogenic factors, which are molecules that induce the formation of blood vessels.
Thus MSCs, in response to exercise, can increase muscle mass as a result of exercise and increase the density and diameter of blood vessels.
Dr. Centeno at the Regenexx blog site wonders if stem-cell doping will be the next trick athletes will use to increase their muscle size and strength. Such a trick would be completely undetectable with contemporary technology, and it seems as though this might be a genuine possibility.