Muscle Stem Cell Migration and Activity
In 2011, Otto, et al, discovered that the satellite cells in muscle tissue move in a particular way, with the researchers suggesting that this could improve the delivery mechanisms developed for future stem cell treatments of muscle damage. Muscle stem cells have two distinct phases of movement, first under the basal lamina, and secondly on the myofiber surface where they speed up. The mechanism behind the movements is a dynamic blebbing or amoeboid-based process which is influenced by both nitric oxide and noncanonical Wnt (Wingless int) signalling pathways. Scientists can then, theoretically, use these mechanisms to facilitate faster and fuller migration of stem cells to aid muscle regeneration.
Free-Radicals, Stem Cells, and Muscle Repair
Researchers at Regenerative Medicine in Italy have also been looking at the activity of muscle stem cells following trauma and have found an interesting association between reactive oxygen species (ROS) formation and the success of muscle repair (Vezzoli, et al, 2011). In a model of acute muscle injury the regeneration of the tissue was accompanied by active ROS production, initially by the mitochondria, and then by non-mitochondrial sources. This leads to the recruitment of leukocytes and stem cells to the area which can then express antioxidant enzymes such as super-oxide dismutase-1 (SOD-1) and free thiols to overcome oxidative damage.
HMGB1 is a weak thiol present in healthy muscle tissue but increasingly expressed in damaged muscles in parallel with the antioxidant moieties. Vezzoli, et al, suggest that it is the reduced environment (due to the early antioxidant response) which allows HMGB1 to remain active and aid muscle regeneration. Oxidation in their laboratory models adversely affected the muscle stem cells’ migration in response to HMGB1 and reduced their ability to differentiate into myofibers, thus reducing the degree of possible muscle regeneration. It is possible then that this research would allow clinicians to create specific antioxidant environments conducive to muscle regeneration with stem cell treatments.
Stem Cells for Facial Paralysis
Further research was carried out by Koning (et al, 2011) into the potential for muscle tissue engineering, this time specifically to treat facial paralysis. Facial paralysis can adversely affect patients physically, psychologically, and socially and the success achieved with autologous muscle transplants is limited. Patients rarely regain a good degree of reanimation following muscle transplants and subtlety of movement is extremely restricted making regenerative medicine look particularly attractive for such a condition. In this study, carried out in the Netherlands, Koning, et al, found that in vitro muscle stem cells responded to hypoxic, ischaemic muscle damage becoming activated, proliferating, and differentiating into myotubes which then matured to muscle fibers. Significantly, the stem cells did this whilst maintaining a reserve of quiescent stem cells, thus allowing for further regeneration at a later date. The success of their experiments in the laboratory have not, as yet, been recreated in human patients.
Continue –> Repairing and Regrowing Muscles with Stem Cells
