miR-125b-5p delivered by adipose-derived stem cell exosomes alleviates hypertrophic scarring by suppressing Smad2

Chaolei Xu; Hao Zhang; Chen Yang; Ying Wang; Kejia Wang; Rui Wang; Wei Zhang; Chao Li; Chenyang Tian; Chao Han; Mengyang Li; Xu Liu; Yunwei Wang; Yan Li; Jian Zhang; Yu Li; Liang Luo; Yage Shang; Lixia Zhang; Yuxi Chen; Kuo Shen; Dahai Hu

doi:10.1093/burnst/tkad064

miR-125b-5p delivered by adipose-derived stem cell exosomes alleviates hypertrophic scarring by suppressing Smad2

Burns Trauma. 2024 May 18:12:tkad064. doi: 10.1093/burnst/tkad064. eCollection 2024.

Authors

Chaolei Xu¹, Hao Zhang¹, Chen Yang², Ying Wang¹, Kejia Wang¹, Rui Wang³, Wei Zhang², Chao Li², Chenyang Tian¹, Chao Han¹, Mengyang Li¹, Xu Liu¹, Yunwei Wang¹, Yan Li¹, Jian Zhang¹, Yu Li¹, Liang Luo¹, Yage Shang¹, Lixia Zhang¹, Yuxi Chen¹, Kuo Shen¹, Dahai Hu¹

Affiliations

¹ Department of Burns and Cutaneous Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China.
² Department of Plastic Surgery, Burns and Cosmetology, The First Affiliated Hospital of Xi'an Medical University, Xi'an 710032, China.
³ Department of Aerospace Medical Training, School of Aerospace Medicine, Fourth Military Medical University, Xi'an 710032, China.

Abstract

Background: Hypertrophic scarring is the most serious and unmet challenge following burn and trauma injury and often leads to pain, itching and even loss of function. However, the demand for ideal scar prevention and treatment is difficult to satisfy. We aimed to discover the effects and mechanisms of adipose-derived stem cell (ADSC) exosomes in hypertrophic scarring.

Methods: ADSC exosomes were isolated from the culture supernatant of ADSCs and identified by nanoparticle tracking analysis, transmission electron microscopy and western blotting. The effect of ADSC exosomes on wound healing and scar formation was detected by the wound model of BALB/c mice. We isolated myofibroblasts from hypertrophic scar tissue and detected the cell viability, proliferation and migration of myofibroblasts. In addition, collagen formation and fibrosis-related molecules were also detected. To further disclose the mechanism of ADSC exosomes on fibrosis in myofibroblasts, we detected the expression of Smad2 in hypertrophic scar tissue and normal skin and the regulatory mechanism of ADSC exosomes on Smad2. Injection of bleomycin was performed in male BALB/c mice to establish an in vivo fibrosis model while ADSC exosomes were administered to observe their protective effect. The tissue injury of mice was observed via hematoxylin and eosin and Masson staining and related testing.

Results: In this study, we found that ADSC exosomes could not only speed up wound healing and improve healing quality but also prevent scar formation. ADSC exosomes inhibited expression of fibrosis-related molecules such as α-smooth muscle actin, collagen I (COL1) and COL3 and inhibited the transdifferentiation of myofibroblasts. In addition, we verified that Smad2 is highly expressed in both hypertrophic scar tissue and hypertrophic fibroblasts, while ADSC exosomes downregulated the expression of Smad2 in hypertrophic fibroblasts. Further regulatory mechanism analysis revealed that microRNA-125b-5p (miR-125b-5p) is highly expressed in ADSC exosomes and binds to the 3' untranslated region of Smad2, thus inhibiting its expression. In vivo experiments also revealed that ADSC exosomes could alleviate bleomycin-induced skin fibrosis and downregulate the expression of Smad2.

Conclusions: We found that ADSC exosomes could alleviate hypertrophic scars via the suppression of Smad2 by the specific delivery of miR-125b-5p.

Keywords: Adipose-derived stem cell, Exosomes; Fibrosis; Hypertrophic scar; MicroRNA; Skin; Smad2; miR-125b-5p.