Experimental study on the effect and mechanism of adipose stem cell‐derived exosomes combined with botulinum toxin A on skin trauma in rats.

Background: Adipose stem cell‐derived exosomes (ADSC‐EXO) and botulinum toxin type A (BTX‐A) individually showed a therapeutic effect on skin wound repair. Aims: This study investigated their synergistic effect on promoting skin wound healing in vitro and in vivo and the underlying molecular events. Methods: ADSCs were isolated from Sprague–Dawley (SD) rats to obtain ADSC‐EXO by ultrafiltration and ultracentrifugation and were confirmed using nanoparticle tracking analysis and transmission electron microscopy. Human skin fibroblasts (HSF) were cultured and treated with or without ADSC‐EXO, BTX‐A, or their combination. Changes in cell phenotypes and protein expression were analyzed using different in vitro assays, and a rat skin wound model was used to assess their in vivo effects. Results: The isolated ADSC‐EXO from primarily cultured ADSCs had a circular vesicle shape with a 30–180 nm diameter. Treatment of HSF with ADSC‐EXO and/or BTX‐A significantly accelerated HSF migration in vitro and skin wound healing in a rat model. Moreover, ADSC‐EXO plus BTX‐A treatment dramatically induced VEGFA expression but reduced COL III and COL I levels in vivo. ADSC‐EXO and/or BTX‐A treatment significantly upregulated TGF‐β3 expression on Day 16 after surgery but downregulated TGF‐β1 expression, suggesting that ADSC‐EXO plus BTX‐A promoted skin wound healing and reduced inflammatory cell infiltration. Conclusions: The ADSC‐EXO plus BTX‐A treatment demonstrated a synergistic effect on skin wound healing through upregulation of VEGF expression and the TGF‐β3/TGF‐β1 and COL III/COL I ratio. [ABSTRACT FROM AUTHOR]