INTRODUCTION AND OBJECTIVES: Patients with end-stage bladder disease can be treated with cystoplasty using gastrointestinal segment. The presence of such segments in the urinary tract has been associated with significant complications. To overcome these problems, we have developed a novel approach for autoaugmentation cystoplasty using autologous smooth muscle cell (SMC) sheet engineering as scaffoldless tissue engineering in rabbit animal model.

METHODS: Viable SMCs were obtained from sixteen rabbits by partial detresorectomy. Harvested SMCs were labeled with red fluorescent PKH-26 and seeded on temperature responsive culture dishes. After 7-10 days, cultured SMCs generated contiguous cell sheets that were noninvasively harvested with no enzymatic treatment from these dishes, by reducing culture temperature. Using the intact cell sheets, triple layer cell-dense thick tissues were constructed.

Following detrusorectmy for autoaugmentation, transplantation of engineered SMC tissue onto urothelial diverticulum was done. Eight other animals underwent the same procedure except SMC sheets graft (control). At 14, 30, 90, and 180 days after augmentation, animals were sacrificed and their bladders were excised, immunofluorescence and immunohistochmistry studies were performed to evaluate bladder reconstruction (CD34, CD31 and α-actin as well as elastin fibers and collagen). Moreover, cystometric evaluation was also performed before and 6 months after bladder augmentation.

RESULTS: Two weeks after SMC sheets grafting, full thickness bladder wall was seen and PKH-26 labeled SMCs were evident in muscular layer which was in accordance with positively stained cells for α-actin . Moreover, graft borders were completely aligned with the host bladder in the first month.

CD34+ endothelial progenitor cells and CD31+ microvessels were found in all grafts 14 days after grafting. The number of these cells increased continuously and peaked 1 month after grafting. Intensity of collagen and elastin fibers reached to normal values 6 months after grafting. Cystometric study revealed significantly higher bladder capacity and compliance in grafted bladders in comparison with controls, 6 months after surgery.

CONCLUSIONS: Autologus smooth muscle cell sheet grafting showed the potential for reliable bladder reconstruction leading to excellent bladder compliance in animal model.

Our findings would pave the way toward the future tissue engineering of bladder using cell sheet technology in end-stage bladder disease.

Source of Funding: none