AIM:To investigate the reparative effect of extracellular vesicles(EVs)derived from H9 human embryonic stem cells(H9-hESCs)on endometrial injury.METHODS:EVs were isolated from the culture supernatant of H9-hESCs and characterized.A mouse model of endometrial injury was established,with bilateral uterine divisions into an EVs experimental group and a PBS control group.EVs and PBS were injected respectively.Histological changes in the endometrium were assessed using HE staining,and proliferating cell nuclear antigen(PCNA)expression was analyzed via immunohistochemistry.The impact of EVs on the proliferation of human endometrial stromal cells(hEndoSCs)was eva-luated using EdU staining and Western blot.RESULTS:H9-hESCs-EVs exhibited a membrane-structured nanobody with a particle size of(144.7±2.1)nm and expressed characteristic proteins CD63 and TSG101.Compared to the PBS control group,the EVs group showed increased endometrial tissue morphology,thickness,and gland numbers.The average opti-cal density of PCNA expression significantly increased in the EVs group compared to the PBS group(P<0.05).Results from EdU staining and Western blot demonstrated that H9-hESCs-EVs promoted hEndoSC proliferation,with a positive correlation observed between H9-hESCs-EVs and EVs protein concentration(P<0.05).CONCLUSION:H9-hESCs-EVs enhance the repair of endometrial injury by stimulating the proliferation of endometrial stromal cells.