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.