The fibrotic effect of hypoxic cardiomyocyte-derived exosomes on G U I + cells and its mechanism / 中国药理学通报

ABSTRACT

; Aim To investigate whether the Glil + cells fibrosis is mediated by damaged cardiomyocyte-derived exosomes and explore the possible mechanism. Methods Glil + cells were isolated from mouse heart and identified by flow cytometry. Neonatal rat cardiomyocytes were subjected to normoxic and hypoxic treatment, respectively. Normoxic/hypoxic exosomes were obtained and detected by flow cytometry, nanosight tracficking analysis (NTA), transmission electron microscopy (TEM) and Western blot. Key exosomal miRNA content was determined by RT-qPCR. Then G l i l + cells were co-cultured with normoxic /hypoxic exosomes or transfected with miRNA mimic to confirm the expression level of fibrosis-related proteins. Flow cytometry was used to detect the proportion of G l i l + cells positively expressing both DDR-2 and a-SMA protein. Results G l i l + cells biomarkers, including CD29,CD105 and G l i l, were identified, but CD31, CD34 and CD45 were undetectable. NTA showed that the diameters of exosomes were about 100 nm and exosomal markers CD63, HSP-70, Alix and Flotillin-1 were detectable by Western blot. Further study found that cardiomyocytes produced more exosomal miR-223 (P < 0. 01) under hypoxia treatment. Hypoxic exosomes and miR-223 mimic obviously increased the expression of a-SMA (P < 0. 01, P < 0. 05), DRR-2 (P <0. 01, P < 0. 01) and collagen I (P < 0. 05, P < 0. 01) in G l i l + cells. Conclusions Hypoxic cardiomyocyte-derived exosomes may promote G l i l + cell fibrosis, which may be related to the high expression of miR-223 in exosomes.