Differentiation of smooth muscle cells from human amniotic mesenchymal cells implanted in the freeze-injured mouse urinary bladder

摘要

Background: The multipotency of human amniotic mesenchymal cells (HAMCs) has been reported, but the role of HAMCs in urinary tract regeneration is unknown. Objective: The aim of the study was to determine if cells derived from HAMCs support the structural and functional reconstruction of freeze-injured mouse bladders. Design, setting, and participants: HAMCs were harvested from an amnion membrane, and cells were cultured for 7 d prior to injection into the freeze-injured bladder walls of nude mice. Intervention: Three days prior to implantation, the posterior bladder walls were freeze injured for 30 s. The cultured HAMC-derived cells (0.5 × 105 cells per 50 μl) were implanted into the injured regions. Control bladders received a cell-free injection. At 1, 2, 4, and 6 wk after the cell implantation, the experimental bladders were extirpated. Measurements: The bladder tissues were examined by immunohistochemistry for α-smooth muscle actin (SMA). The HAMC-derived cells were detected by antihuman nuclei antibody (HuNu). Separately, bladder muscle strips were examined for contractile responses to potassium. Results and limitations: At 1 wk after implantation, the HAMC-derived cells, which were detected by HuNu, differentiated into muscular layers composed of SMA-positive cells. From 2 to 6 wk after implantation, abundant layers of SMA-positive and HuNu-positive cells developed. In control bladders, few SMA-positive cells remained at the injured regions at 1 wk, but by 6 wk, more were present. At 1 wk, the contractile responses to potassium of the cell-implanted bladders were significantly higher than those of the control-injected ones. Control-injected bladders also recovered by 6 wk, but the rate of recovery was slower. Conclusions: Freeze-injured mouse bladders implanted with HAMC-derived cells recovered morphology and function faster than control-injected bladders.