Xu Chaolei, Zhang Hao, Yang Chen, Wang Ying, Wang Kejia, Wang Rui, Zhang Wei, Li Chao, Tian Chenyang, Han Chao, Li Mengyang, Liu Xu, Wang Yunwei, Li Yan, Zhang Jian, Li Yu, Luo Liang, Shang Yage, Zhang Lixia, Chen Yuxi, Shen Kuo, Hu Dahai
Department of Burns and Cutaneous Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China.
Department of Plastic Surgery, Burns and Cosmetology, The First Affiliated Hospital of Xi'an Medical University, Xi'an 710032, China.
Burns Trauma. 2024 May 18;12:tkad064. doi: 10.1093/burnst/tkad064. eCollection 2024.
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.
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 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.
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. experiments also revealed that ADSC exosomes could alleviate bleomycin-induced skin fibrosis and downregulate the expression of Smad2.
We found that ADSC exosomes could alleviate hypertrophic scars via the suppression of Smad2 by the specific delivery of miR-125b-5p.
肥厚性瘢痕是烧伤和创伤后最严重且未得到满足的挑战，常导致疼痛、瘙痒甚至功能丧失。然而，理想的瘢痕预防和治疗需求难以满足。我们旨在探究脂肪来源干细胞（ADSC）外泌体在肥厚性瘢痕形成中的作用及机制。
从ADSCs的培养上清液中分离出ADSC外泌体，并通过纳米颗粒跟踪分析、透射电子显微镜和蛋白质印迹法进行鉴定。采用BALB/c小鼠伤口模型检测ADSC外泌体对伤口愈合和瘢痕形成的影响。我们从肥厚性瘢痕组织中分离出肌成纤维细胞，检测肌成纤维细胞的细胞活力、增殖和迁移情况。此外，还检测了胶原蛋白形成及纤维化相关分子。为进一步揭示ADSC外泌体对肌成纤维细胞纤维化的作用机制，我们检测了肥厚性瘢痕组织和正常皮肤中Smad2的表达以及ADSC外泌体对Smad2的调控机制。对雄性BALB/c小鼠注射博来霉素建立纤维化模型，同时给予ADSC外泌体以观察其保护作用。通过苏木精-伊红染色和Masson染色及相关检测观察小鼠的组织损伤情况。
在本研究中，我们发现ADSC外泌体不仅能加速伤口愈合、提高愈合质量，还能预防瘢痕形成。ADSC外泌体抑制了α-平滑肌肌动蛋白、胶原蛋白I（COL1）和COL3等纤维化相关分子的表达，并抑制了肌成纤维细胞的转分化。此外，我们证实Smad2在肥厚性瘢痕组织和肥厚性成纤维细胞中均高表达，而ADSC外泌体下调了肥厚性成纤维细胞中Smad2的表达。进一步的调控机制分析显示，微小RNA-125b-5p（miR-125b-5p）在ADSC外泌体中高表达，并与Smad2的3'非翻译区结合，从而抑制其表达。实验还表明，ADSC外泌体可减轻博来霉素诱导的皮肤纤维化，并下调Smad2的表达。
我们发现ADSC外泌体可通过特异性递送miR-125b-5p抑制Smad2来减轻肥厚性瘢痕。
