Local transplantation of syngeneic adipose stromal vascular fraction ameliorates damaged anal sphincter function in a rat model of vaginal distension

Abstract

Background: The adipose stromal vascular fraction contains abundant mesenchymal stem cells and is utilized for cell therapy of male stress urinary incontinence. The purpose of this paper was to explore the effect of local transplantation of the stromal vascular fraction on improvement of damaged anal sphincter function.

Methods: A rat model of vaginal distension was used as a model of damaged anal sphincter function. The adipose stromal vascular fraction was separated from the inguinal fat of syngeneic green fluorescent protein transgenic rats and delivered into the internal anal sphincter of vaginal distension rats. The maximum resting pressure was evaluated during insertion and withdrawal of the catheter at 4 or 10 days after vaginal distension treatment to estimate anal sphincter function. Green fluorescent protein-transfected human-adipose-derived mesenchymal stem cells were transplanted into the internal anal sphincter of nude rats. Hematoxylin-eosin and Masson trichrome staining were performed to evaluate tissue damage and collagen synthesis. Transplanted cells were identified using a green fluorescent protein antibody and a human-specific antibody. Activation of the transplanted human-ADSC was evaluated by quantitative RT-PCR RESULTS: The mean maximum resting pressure (during catheter withdrawal) of vaginal distension rats was significantly lower than that of control rats, and stromal vascular fraction injection normalized it 4 days after treatment (control: 5.66 ± 0.98, vaginal distension: 4.04 ± 1.28, vaginal distension + stromal vascular fraction: 5.92 ± 1.28 [mmHg, control versus vaginal distension: P = .039; vaginal distension versus vaginal distension + stromal vascular fraction: P = .007]). Histological examination showed that vaginal distension disrupted the internal anal sphincter, and the transplanted syngeneic stromal vascular fraction survived for 10 days. Transplanted xenogeneic human-adipose-derived mesenchymal stem cells survived in the internal anal sphincter of nude rats for 4 and 10 days. Genes related to extracellular remodeling were up-regulated in the transplanted human-adipose-derived mesenchymal stem cells CONCLUSION: Syngeneic and heterotopic transplanted adipose-derived mesenchymal stem cells engrafted in the internal anal sphincter and ameliorated damaged anal sphincter function in a rat model of vaginal distension.