Bladder patch repair using mesothelial Cell-Seeded autologous granulation tissue: an experimental study in male...

Currently, bladder reconstruction using gastrointestinal segments is considered as the gold standard for bladder repair or augmentation. However, postoperative complications including bowel dysfunction, metabolic abnormalities, chronic urinary tract infection and stone formation are common. This study aims to evaluate the utility of the compound graft for bladder patch repair by seeding mesothelial cells onto autologous granulation tissue.

22 Fr silastic tubes were implanted subcutaneously in 18 male rabbits. The animals were equally divided into two groups. In the experimental group, nine animals underwent omentum biopsies and mesothelial cells were cultured and expanded in vitro. Two weeks after the implantation, the autologous granulation tissue encapsulating the silastic tubes were harvested. The tissue was cut longitudinally and trimmed to 2 × 2 cm². In the experimental group, mesothelial cells were seeded onto the outer surface of the tissue and cocultured for 7 days to construct a compound graft. In each animal, a full-thickness defect of 2 × 2 cm² in the anterior wall of the bladder was created. The defect was repaired with the constructed compound graft in the experimental group and with the granulation tissue directly in the control group. The bladder was harvested and analyzed grossly and histologically at 1, 2 and 6 months postoperatively. In addition, urodynamics were performed 6 months postoperatively to evaluate the function of the bladder.

In the experimental group, no severe fibrosis and shrinkage were observed postoperatively and the mucosa at the grafts site appeared sleek and normal in color. Histologically, multilayers of urothelium surrounded by increasingly organized smooth muscles were observed. In contrast, severe contracture and fibrosis of the grafts occured in the control group. Gross examination of bladder mucosa revealed ulcer and stone formation at the site of the grafts. Histologically, accumulation of inflammatory cells and fibroblasts, and extensive scarring occurred. Six months after surgery, the urodynamic results showed that the experimental group had a larger bladder capacity (83.33 ± 2.08 ml vs. 76.33 ± 3.22 ml, p = 0.034), a lower maximum intravesical pressure (18.77 ± 1.79 mmHg vs. 24.02 ± 1.22 mmHg, p = 0.014) and a better bladder compliance (5.64 ± 0.8 ml/mmHg vs. 3.87 ± 0.13 ml/mmHg, p = 0.019), compared to the control group.

Mesothelial cell-seeded granulation tissue can be successfully used for bladder patch repair in male rabbits. With further investigations, this technique may be considered for clinical use in human. Keywords · ··.