The effect and safety of polylactic acid and adipose-derived stromal vascular fraction cell as an injectable bulking agent in urologic field: a 24-week follow-up study.

The aim of this study is to evaluate whether polylactic acid (PLA) microspheres and adipose-derived stromal vascular fraction (SVF) cells have appropriate properties as an injectable bulking agent in urologic field. Forty male Sprague-Dawley rats (2-week-old) were randomized into two groups. A total of 0.05 mL of PLA microsphere suspension and 0.05 mL of PLA microsphere suspension mixed with PKH26-labeled SVF cells were injected into bladder wall in group I and group II, respectively. At 2, 8, 16, and 24 weeks of PLA microspheres injection, the volumes of implants were measured and bladder tissues including implants were analyzed and compared grossly and histologically between groups. The distant organs were examined histologically to determine migration of PLA microspheres. At 24 weeks of implantation, 65-70% of injected volume was maintained and there was no significant difference between groups. In histological analyses, injected PLA microspheres were localized in muscular layer of bladder without infiltration into adjacent layer. From 8 to 16 weeks of injection, hybrid tissues contained collagen and actin were observed between PLA microspheres and these findings were more clear in group II. PHK26-labeled SVF cells were identified by fluorescence microscopy at all time points. There was no migration of PLA microspheres to other organs and no abnormality in weight gain and hematologic values. These results suggest the possibility of PLA microspheres as a potentially useful bulking agent in urologic field. And further investigation is needed to know synergic effect of SVF cells.