Abstract
We investigated the ability of autologous adipose-derived cells injected into cryoinjured rabbit urethras to improve urinary continence and explored the possible mechanisms by which it occurred. Adipose tissue was harvested from the perivesical region of nine 10-week-old female New Zealand White rabbits and cultured for 7 days. Immediately after harvesting the tissue, we injured the internal urethral orifice by spraying liquid nitrogen for 20 s. The cultured cells expressed the mesenchymal cell marker STRO1, but not muscle cell markers myoglobin or smooth muscle actin (SMA). Just before implantation, the adipose-derived cells were labeled with the PKH26 fluorescent cell linker. Autologous 2.0×10(6) adipose-derived cells (five rabbits) or a cell-free control solution (four rabbits) was injected around the cryoinjured urethras at 7 days after injury. Fourteen days later, the leak point pressure (LPP) was measured, and the urethras were harvested for immunohistochemical analyses. At 14 days after implantation, LPP of the cell-implanted group was significantly higher compared with the cell-free control group (p<0.05). In immunohistochemical examination, the reconstructed skeletal and smooth muscle areas in the cell-implanted regions were significantly more developed than those in controls (p<0.01). Implanted PKH26-labeled adipose-derived cells were immunohistochemically positive for myoglobin, SMA, and Pax7 antibodies, which are markers for skeletal muscles, smooth muscles, and myoblast progenitor cells, respectively. In addition, these implanted cells were positive for the nerve cell markers, tubulin β3, S100, and the vascular endothelial cell marker, von Willebrand factor. Furthermore, some of the implanted cells were positive for the transforming growth factor β1, nerve growth factor, and vascular endothelial growth factor. In conclusion, implantation of autologous adipose-derived cells into the cryoinjured rabbit urethras promoted the recovery of urethral function by myogenic differentiation, neuroregeneration, and neoangiogenesis of the implanted cells and/or the surrounding tissues as well as by bulking effects. Thus, treatment of human radical prostatectomy-related stress urinary incontinence by adipose-derived cell implantation could have significant therapeutic effects.