Abstract 12638: Hsp20-Reprogrammed Exosomes Derived From Cardiomyocytes Provide Protection Against Diabetic Cardiomyopathy in Mice
Background: It has been shown that exosomes, a group of nanovesicles naturally released from living cells, have either beneficial or deleterious effects on cell behavior, depending on the contents encased. We recently showed that Hsp20, as a chaperon protein, could be included in cardiomyocyte exosomes which promoted angiogenesis. Whether such exosomes derived from Hsp20-overexpressing myocytes play any protective role in diabetic animals remains unknown.
Methods and Results: Cultured myocytes were infected with Ad-Hsp20 to overexpress Hsp20. Ad-GFP was used as controls. Then supernatants were collected for purification of exosomes by differential centrifugation. While exosomes derived from Hsp20-myocytes (Hsp20-Exo) displayed similar size and molecular markers (CD63 and CD81) to those originated from the control GFP-myocytes (GFP-Exo), the protein contents encased were different. Western-blotting or ELISA assays revealed that Hsp20-Exo contained higher levels of Hsp20, VEGFR2, Survivin, p-Akt, and SOD1 than GFP-Exo. We next tested the effects of such exosomes in vivo using a diabetic mouse model, which was induced by daily peritoneal injection of streptozotocin (STZ, 50μg/g) for 5 days. Three days after the last injection of STZ, blood glucose levels were measured. Mice were considered diabetic (≥15 mmol/L) and used for the study. We then treated such diabetic mice with exosomes via the tail vein injection (5μg/g body weight). One month later, cardiac function was measured by echocardiography, and showed that left ventricular ejection fraction (EF) and fractional shortening (FS) were increased by 33% and 28%, respectively, in Hsp20-Exo-treated mice, compared with GFP-Exo-controls. We also found that Hsp20-Exo led to an increased density of cardiac blood vessels and reduction of myocardial fibrosis to a greater degree than GFP-Exo-samples. Mechanistically, we identified that PKH67-labled exosomes could be detected in mouse hearts at 2 hours after the tail vein injection and confirmed that exosomal Hsp20 was transferred to the in vivo hearts.
Conclusions: This study indicates that the exosome contents can be modified by Hsp20 in cardiomyocytes. Injection of Hsp20-reprogrammed exosomes protects diabetic animals against cardiomyopathy.
Author Disclosures: X. Wang: None. H. Gu: None. W. Huang: None. Y. Wang: None. G. Fan: None.
- © 2014 by American Heart Association, Inc.