Restoration of bladder contraction by bone marrow transplantation in rats with underactive bladder.

We attempted to increase bladder contraction by bone marrow cell transplantation in rats with underactive bladder due to bladder outlet obstruction (BOO). Twelve female rats were anesthetized with halothane to create BOO. After 1 month, the urethral obstruction was removed and they were divided into a transplant group and a sham-operated group (n = 6 each). Bone marrow cells (1 × 107 / 0.2 mL) isolated from green fluorescent protein transgenic rats were injected into the bladder wall of the transplant group. Rats from the sham-operated group received injection of culture medium alone. One month after transplantation, isovolumetric cystometry parameters and histological features of bladder were observed as well as intact control rats (n = 6). The amplitude of bladder contractions was larger and the interval between contractions was shorter in the transplant group than the sham-operated group, and there were no differences in these parameters between the transplant group and the control group. Some green fluorescent muscle layers were found in the bladder wall of the transplant group, and these layers were also labeled by anti alpha-smooth muscle actin antibody. These results suggest that transplanted bone marrow cells may improve bladder contractility by differentiating into smooth muscle-like cells.