NLRP3 downregulation enhances engraftment and functionality of adipose-derived stem cells to alleviate erectile dysfunction in diabetic rats

BACKGROUND: The transplantation of adipose-derived stem cells (ASCs) is a most promising treatment for diabetic erectile dysfunction (DMED). However, the effect of high glucose on the post-transplantation survival of stem cells limits the efficacy of ASCs transplantation. Prolonging the survival time of ASCs in vivo after transplantation is a key issue in the utilization of ASCs for DMED. Herein, we aimed to investigate the therapeutic effect of ASCs by downregulating NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) as well as its mechanism of action in DMED. METHODS: ASCs were obtained by isolating subcutaneous fat from SD rats and were identified using lipogenic and osteogenic differentiation assays, as well as flow cytometric analysis. The shNLRP3 lentivirus with the best downregulating effect was screened, and shNLRP3 lentivirus (LV-shNLRP3) was transfected into ASCs (ASCs(shNLRP3)) to detect apoptosis and the reactive oxygen species (ROS) levels in each group under high glucose conditions. In DMED rats, ASCs(LV-shNLRP3), ASCs(LV-control), or phosphate buffered saline (PBS) were administrated via intra-cavernous injection, and normal rats served as normal controls. One week post-injection, animal imaging was performed to track the ASCs. Four weeks post-injection, erectile function was evaluated by measuring the intra-cavernosal pressure and mean arterial pressure. Corpus cavernosum pyroptosis and endothelial function were examined by western blotting and immunofluorescence. RESULTS: NLRP3-mediated pyroptosis might be a pathogenic mechanism of ED and DMED. ASCs were isolated successfully. Thereafter, the LV-shNLRP3 with the highest transfection efficiency was selected and used to modify ASCs successfully. LV-shNLRP3 could protect ASCs paracrine function under hyperglycemia through anti-apoptosis and anti-ROS deposition mechanisms. Furthermore, ASCs(LV-shNLRP3) showed an advantage in the suppression of pyroptosis compared to ASCs(LV-control). The ASCs(LV-shNLRP3) group had improved cavernous endothelial function and smooth muscle injury, thus reversing erectile function, and was superior to the ASCs(LV-control) group. CONCLUSIONS: NLRP3 Inflammasome-mediated pyroptosis might be involved in DMED formation. Intra-cavernous injection of ASCs(LV-shNLRP3) could suppress cavernosal pyroptosis, contributing to improved erectile function in DMED rats.