To identify the function of human umbilical cord derived exosomes (hucMSCs-exo) in hepatic ischemia reperfusion injury (HIRI) and the underlying mechanisms.

HucMSCs were isolated from human umbilical cord using tissue block adhering wall method and hucMSCs-exo were isolated from conditioned medium of hucMSCs through ultracentrifugation. Then, we evaluated the function of hucMSCs-exo both in vivo and in vitro using C57BL/6 mice 70﹪ HIRI model and L02 hypoxia/reoxygenation model. 72 mice were randomly divided into the sham, IRI, PBS and exo groups (n =18 at each group) . Blood and liver samples were collected at hour 6, 12 and 24 (6 mice at each time point) post IRI respectively to test enzyme activities, biochemical and histological changes. Western Blot assay was used for apoptotic proteins detection. Levels of serum AST and ALT were observed. Liver tissues were collected for HE staining and CASPASE-3 immunohistochemistry assay. Data between each group were compared by ANOVA.

After isolation and identification of hucMSCs and hucMSCs-exo, we found that hucMSCs-exo decreased the level of apoptotic proteins cleaved-CASPASE-3 and cleaved-PARP of L02 after hypoxia/reoxygenation injury. In vivo, the levels of serum liver enzymes showed a remarkable decrease in AST in 12 h (2895.0±998.6 U/L vs 971.8±797.8 U/L, t = 4.010, P = 0.004) and in ALT (2074.0±750.3 U/L vs 555.3±493.8 U/L, t = 4.379, P = 0.002) and AST (1926.0±377.2 U/L vs 597.2±524.8 U/L, t = 5.231, P = 0.000) in 24 h for IRI group after the administration of hucMSCs-exo. HE staining and immunohistochemistry assay of liver tissue also proved that hucMSCs-exo alleviate 70﹪ HIRI model of C57BL/6 mice.

HucMSCs-exo showed a protective effect on HIRI via down-regulating the level of apoptosis, which could provide a new promising way for treating HIRI for clinical practice, even though the mechanism needs to be further investigated.