Human Stem Cell-Derived Muscle Cells Improve Vaginal Function in a Rat Model

Objectives: A common site of prolapse recurrence after surgery is in the anterior vagina. Up to 30 % of women who suffer from recurrence of prolapse after surgery are faced with reoperation. Therefore, there is a need for non-surgical therapies that can restore vaginal tissue function. Stem-cell-derived therapy is a promising option for tissue regeneration. Human iPSC-derived progenitors of smooth muscle cells (pSMCs) have limited proliferation and differentiation, which minimizes the risk of in vivo tumor formation while restoring smooth muscle cell deficiencies. We hypothesize that human pSMCs can restore vaginal function and improve vaginal extracellular matrix in the surgically injured vagina. In this study, we test this in a chronic vaginal-injury rat model.

Methods: Female immune-compromised RNU rats were divided into 5 groups: intact controls (n=12), VSHAM (vaginal surgery + saline injection, n=33), and cell-injection group (vaginal surgery + cell injection using three patient pSMCs lines A, B, and C, n=14/cell line). The surgery to create the rat model involved ovariectomy, dissection of the bladder and urethra away from the anterior vagina, and vagina injury. The rats were allowed to recover for 5 weeks after surgery. Cell and saline injections were then performed. The vagina, urethra, bladder dome and trigone were harvested 10 weeks after surgery (5 weeks after injection). Organ bath myography was performed on the vagina to evaluate the contractile function of vagina, and smooth muscle thickness was examined by tissue immunohistochemistry. Collagen I, collagen III, and elastin mRNA and protein expressions in tissues were assessed by RT-PCR and ELISA.

Results: When compared to the VSHAM group, cell-injection groups showed significantly increased vaginal smooth muscle contractions induced by carbachol (groups A and C, P< 0.04) and by KCl (group C, P< 0.04), and significantly higher collagen I protein expression in the vagina (groups A and B, P< 0.03). Elastin mRNA and protein expressions in the vagina did not correlate with injection group. In the urethra, mRNA expressions of collagen I, collagen III, and elastin were all significantly higher in the cell-injection groups compared to the VSHAM group (p < 0.001). Collagen I protein expression of the urethra was also higher in the cell-injection group compared to the VSHAM group. Elastin protein expression in the urethra did not correlate with injection group.

Conclusions: Human iPSC-derived pSMCs improved contractile function of the surgically injured vagina. Additionally, pSMC injection modulated collagen I, collagen III and elastin mRNA and protein expressions in the vagina and urethra. These findings suggest that pSMCs may be a possible therapy for prevention of vaginal prolapse recurrence after surgical intervention.