CD47 deficiency protects cardiomyocytes against hypoxia/reoxygenation injury by rescuing autophagic clearance.

Abstract

To assess the effect of cluster of differentiation(CD47) downregulation on autophagy in hypoxia/reoxygenation(H/R)‑treated H9c2 cardiomyocytes. H9c2cells were maintained in normoxic conditions (95% air, 5%CO2, 37˚C) without CD47antibodies, Si‑CD47 or chloroquine(CQ) treatment; H9c2cells in the H/R group were subjected to 24h of hypoxia (1%O2, 94%N2, 5%CO2, 37˚C) followed by 12h of reoxygenation (95% air, 5%CO2, 37˚C). All assays were controlled, triplicated and repeated on three separately initiated cultures. The biochemical parameters in the medium supernatant were measured to evaluate the oxidative stress in cardiomyocytes. The AnnexinV‑fluorescein isothiocyanate assay was used to detect the apoptotic rate in the H9c2cells. Transmission electron microscope, immunofluorescent staining and western blot analysis were performed to detect the effect of the CD47 antibody on autophagic flux in H/R‑treated H9c2 cardiomyocytes. The cardiomyocytic oxidative stress and apoptotic rate decreased and autophagic clearance increased after CD47 downregulation. H/R triggered cell autophagy, autophagosome accumulation and apoptosis in H9c2 cell lines. However, these effects can be attenuated by CD47 downregulation. This study demonstrates its clinical implications in ischemia/reperfusion injury treatment.