Muscle precursor cell autografting in a murine model of urethral sphincter injury

OBJECTIVE: To determine whether muscle precursor cells (MPCs) harvested from limb skeletal muscle can enhance the regeneration process of the striated urethral sphincter after injury. MATERIAL AND METHODS: Striated urethral sphincters of male mice were injured by an injection of a myotoxic substance (notexin). In the experimental group, 2 days after injury, MPCs were enzymatically harvested from striated muscles of the lower limbs and labelled with PKH 26, then immediately re-injected into the injured urethral sphincter of the same animal. In the control group, saline buffer was injected instead of MPCs. Animals were killed 7 days or 1 month after injury and the sphincters removed for histological study (the presence of PKH 26-labelled myofibres, measurement of myofibre diameter and total number of myofibres). RESULTS: MPC autografting accelerated sphincter muscle repair, as shown by a higher myofibre diameter (P = 0.03) and number (P = 0.01) in the experimental group than in the controls at 7 days. One month after their injection MPCs were still detectable in the regenerating sphincters and participated in the formation of new myofibres. CONCLUSION: This study provides the experimental basis for a new therapeutic approach to urethral sphincter insufficiency after surgical or obstetrical injury, based on MPC autografting.