肝脏是人体中最大和最主要的代谢器官，承担着物质存储、能量代谢、解毒、免疫应答等重要生理功能。肝脏缺血再灌注损伤、脂肪肝、肝纤维化、肝过氧化损伤、肝药物损伤是多发的肝损伤疾病。干细胞具有自我复制和多分化潜能。肝干细胞被分为肝源性干细胞和肝外来源的干细胞。在肝脏损伤治疗中，干细胞可以通过干细胞归巢、转分化、直接分化为肝细胞、旁分泌效应、免疫调节、分泌外泌体等机制修复肝脏损伤。在肝损伤的临床治疗中，干细胞可直接发挥作用，也可通过外泌体间接发挥修复作用。除了对肝损伤的修复作用，干细胞分泌的外泌体也可以作为肝病诊断和预后监测判断的分子生物学标志。干细胞还可评估药物对人体的毒性，用于筛查药物对人体的不良反应。

Liver is the biggest and the most important metabolic organ in human body. Hepatic ischemia⁃ reperfusion injury，fatty liver，cirrhosis，hepatic fibrosis，hepatic peroxidation injury and hepatic drug injury are common liver injury diseases. Stem cells are cells with the potential to self⁃renew and develop into many different cell types. Liver stem cells can be divided into hepatogenic stem cells and extrahepatic stem cells. In the treatment of liver injury，stem cells can repair liver injury through stem cells homing，transdifferentiation and direct differen⁃ tiation，paracrine effect，immune regulation，exosomes and other mechanisms. In the clinical treatment of liver injury，stem cells can play a role directly or indirectly through exosomes indirectly. In addition to repairing liver injury，stem cells⁃derived exosomes can also be used as molecular biomarkers for liver disease diagnosis and prog⁃ nosis monitoring and to assess the toxicity of drugs as well as adverse drug reactions.