Purified Human Skeletal Muscle-Derived Stem Cells Enhance the Repair and Regeneration in the Damaged Urethra

Background Postoperative damage of the urethral rhabdosphincter and nerve-vascular networks is a major complication of radical prostatectomy and generally causes incontinence and/or erectile dysfunction. The human skeletal muscle-derived stem cells, which have a synchronized reconstitution capacity of muscle-nerve-blood vessel units, were applied to this damage. Methods Cells were enzymatically extracted from the human skeletal muscle, sorted using flow cytometry as CD34+/45− (Sk-34) and CD29+/34−/45− (Sk-DN/29+) fractions, and separately cultured/expanded in appropriate conditions within 2 weeks. Urethral damage was induced by manually removing one third of the wall of the muscle layer in nude rats. A mixture of expanded Sk-34 and Sk-DN/29+ cells was applied on the damaged portion for the cell transplantation (CT) group. The same amount of media was used for the non-CT (NT) group. Urethral pressure profile was evaluated via electrical stimulation to assess functional recovery. Cell engraftments and differentiations were detected using immunohistochemistry and immunoelectron microscopy. Expression of angiogenic cytokines was also analyzed using reverse transcriptase-polymerase chain reaction and protein array. Results At 6 weeks after transplantation, the CT group showed a significantly higher functional recovery than the NT group (70.2% and 39.1%, respectively; P < 0.05). Histological analysis revealed that the transplanted human cells differentiated into skeletal muscle fibers, nerve-related Schwann cells, perineuriums, and vascular pericytes. Active paracrine angiogenic cytokines in the mixed cells were also detected with enhanced vascular formation in vivo. Conclusions The transplantation of Sk-34 and Sk-DN/29+ cells is potentially useful for the reconstitution of postoperative damage of the urethral rhabdosphincter and nerve-vascular networks.