基因修饰的干细胞外泌体水凝胶治疗放射性皮肤损伤的实验研究

Effects of hydrogel loaded with gene⁃modified stem cell exosomes on radioactive skin injury

目的研究肝细胞生长因子修饰的牙髓干细胞外泌体水凝胶对放射性皮肤损伤的促愈合作用。方法利用超速离心法分离提取外泌体,分别通过纳米颗粒跟踪分析法、扫描电镜和Western印迹法对外泌体的粒径、形态和标志蛋白进行分析。采用CCK-8、划痕实验和流式细胞术评估外泌体对辐射损伤皮肤细胞的作用。制备温敏型泊洛沙姆水凝胶,采用CCK-8法测试其生物相容性。建立小鼠放创复合伤模型,应用外泌体水凝胶进行治疗,通过创面愈合情况、创面组织HE染色和Masson染色评价创面愈合效果和治疗效果,通过Tunnel染色检测创面细胞凋亡情况,通过丙二醛含量和过氧化物酶活性检测评估创面氧化应激情况,对其作用机制进行初步分析。结果外泌体直径范围为30~150 nm,扫描电镜下呈圆盘状囊泡,CD9、CD63和TSG101表达阳性。细胞实验结果显示,外泌体能显著促进辐射损伤皮肤角质细胞和成纤维细胞的增殖和迁移,减少细胞凋亡。肝细胞生长因子修饰增强外泌体的作用。泊洛沙姆水凝胶显示出良好的温敏性和生物相容性。动物实验结果显示,外泌体治疗显著加快了小鼠放创复合伤的愈合,并抑制炎性浸润、减轻胶原沉积,肝细胞生长因子修饰外泌体促创面愈合作用最强,其促创面愈合的作用机制可能与促细胞增殖、减少细胞凋亡和氧化应激有关。结论成功制备了一种新型的基因修饰的干细胞外泌体水凝胶,并证明了其在放射性皮肤损伤治疗中的有效性,为临床放射性皮肤损伤治疗提供了一种新的策略。

Objective To evaluate the therapeutic effect of poloxamer hydrogel loaded with exosomes derived from human dental pulp stem cells genetically modified with human hepatocyte growth factor against radiation skin injuries.Methods Human dental pulp stem cells derived exosomes(DPSC-Exo)and hepatocyte growth factor modified DPSC-Exo(HGF-DPSC-Exo)were extracted via ultracentrifugation separation,identified in terms of particle size and morphology,and analyzed separately by means of nanoparticle tracking analysis and scanning electron microscopy(SEM),while exosome marker proteins were determined by Western blot.Then,the effect of exosomes on radiation-damaged skin cells was assessed.The poloxamer hydrogel was prepared and its safety was evaluated with CCK-8.A mouse model of injury combined with radiation injury was established,and the therapeutic effect of hydrogel loaded with exosomes was determined based on wound size,HE and Masson staining.Furthermore,the underlining therapeutic mechanism was explored with Tunnel assay,malondialdehyde content and peroxidase activity.Results The diameter exosomes ranged from 30 to 150 nm and their morphology was a disc-shaped vesicle under SEM.Moreover,CD9,CD63 and TSG101 were expressed.The results of cellular experiments showed that exosomes significantly promoted the proliferation and migration of radiation-damaged skin keratinocytes and fibroblasts,and reduced their apoptosis.HGF modification enhanced the healing effect of exosomes.Poloxamer hydrogel showed good temperature-sensitive properties and biocompatibility.The results of animal experiments showed that exosomes significantly accelerated the healing of radiationcombined injuries in mice,inhibited inflammatory infiltration and mitigated collagen deposition in the wound.Interestingly,the healing effect in the group treated with hydrogel loaded with exosomes was the best.The underlining mechanism was possibly related to promotion of cell proliferation and inhibition of apoptosis and oxidative stress.Conclusion A novel poloxamer hydrogel loaded HGF-DPSC-Exo has been prepared and its therapeutic effect against radiation combined injury has been proved,thus providing a new strategy for the treatment of radiation skin injury in clinic.