Improving the Retention Rate of Fat Grafts in Recipient Areas via Botulinum Toxin A Treatment

Background Improving the retention rate of transplanted fat is, currently, of great concern. Partial immobilization, angiogenesis, and adipose tissue-derived stem cells, all proven to be influenced by botulinum toxin A (BTX-A), are significant in fat graft retention. Objectives The authors sought to determine the impact of BTX-A on fat grafts. Methods Our study included 12 Sprague Dawley rats and each rat’s hind limbs were randomly designated as the BTX-A side and control side. We injected 0.2 mL of BTX-A-treated fat into the quadriceps femoris and subcutaneous space of the BTX-A sides. This was also done for the control sides but with untreated fat. We performed electroneuromyography of recipient muscles at 1 week post-operation. The rats were euthanized at 12 weeks post-operation and we observed the fat retention rate, the fat’s histologic characteristics, and the density of vessels and mature adipocytes. Results The amplitudes of electroneuromyography were smaller for the BTX-A sides than the control sides. For intramuscularly injected fat, the BTX-A sides had better retention rates and histologic characteristics and a higher density of vessels and mature adipocytes than the control sides. For subcutaneously injected fat, the BTX-A sides had better histologic characteristics and a higher density of vessels and mature adipocytes than the control sides, but the retention rates were not significantly different between the 2 sides. Conclusions Injecting BTX-A-treated fat grafts can immobilize the surrounding muscles. BTX-A can improve the density of vessels and mature adipocytes, histologic characteristics of fat grafts, and retention rate of fat grafts transplanted into muscles.