Mesenchymal Stem Cells Improve Muscle Function Following Single Stretch Injury: A Preliminary Study

Stem cells have shown promise as a therapeutic intervention by enhancing skeletal muscle regeneration following muscle injury. The purpose of this study was to determine the effect of mouse mesenchymal stem cells (MSCs) on muscle function following a single stretch injury in the calf muscle of C57BL/67 mice. A custom isokinetic device was used to induce a single stretch injury. An intramuscular injection of MSCs or saline was administered three days post-injury. Mechanical testing to measure peak isometric joint torque in vivo was done immediately and at seven or 14 days post-injury. Susceptibility to reinjury was assessed in the soleus muscle using an in situ repeated eccentric contraction (ECC) protocol. In vivo isometric torque of the plantar flexors dropped immediately following stretch injury by 50%. Treatment with MSCs attenuated the torque deficit at seven days, while there were no differences in torque deficit between groups at 14 days. In situ ECC testing of the soleus showed a significant specific force drop following injury, with the MSC group demonstrating a protective effect at seven and 14 days. These results demonstrate transient improvement in isometric torque and reduced susceptibility to reinjury following single stretch injury with intramuscular injection of MSCs.