Premenopausal Purified Exosome Products from Women Protect against Male Dominant Cardiomyopathies Myocarditis and DCM

Introduction An estimated 3.1 cases of myocarditis were diagnosed in 2017 worldwide. Patients with myocarditis are at risk of sudden death from acute heart failure and may progress to dilated cardiomyopathy (DCM) and chronic heart failure, often requiring a heart transplant. Currently, no disease-specific therapies exist to reduce myocarditis or prevent progression to DCM. Hypothesis Exosomes extracellular vesicles released from stem cells or other cells like platelets are thought to be able to confer cardioprotection. Because more men develop myocarditis (3.5:1 men to women) and DCM we hypothesized that purified exosome product (PEP) from premenopausal women (pmPEP) could improve and/or prevent myocarditis and prevent progression to dilated cardiomyopathy (DCM) using a preclinical mouse model of myocarditis/DCM. Methods We administered PEP (from men and women of all ages), pmPEP (premenopausal women) or control ip to male BALB/c mice at day -1, 0 and +1 and injected virus on day 0 and harvested mice at day 10 post infection (pi) during peak myocarditis or day 35pi during DCM. Next we treated male BALB/c mice with PEP, pmPEP, or control ip on day 7, 8 and 9 pi (a clinically relevant timepoint) and harvested on day 10pi during acute myocarditis or day 35pi during DCM. Results pmPEP, but not PEP, significantly decreased acute myocarditis based on histology (ANOVA p=0.0009) and globally decreased immune cells (CD45 p=0.008, F4/80 p=0.009, CD11b p=0.04, etc.) but had no effect on viral replication in the heart. We found that pmPEP reduced myocardial inflammation by increasing complement receptor (CR)1 (p=0.004)- a master regulator of inflammation. Both PEP and pmPEP treatment given during myocarditis- a clinically relevant timepoint- significantly reduced myocardial inflammation compared to control (ANOVA PEP p=0.005, pmPEP p=0.005). Both PEP and pmPEP globally downregulated inflammation during myocarditis (PEP CD45 p=0.03, pmPEP CD45 p=0.04, and other immune markers); however, pmPEP was more effective than PEP at reducing inflammation. Likewise, PEP and pmPEP given during myocarditis also decreased cardiac inflammation and fibrosis at day 35pi during DCM (PEP p=0.02, pmPEP p=0.04). Interestingly, PEP administration during myocarditis decreased dilatation assessed using echocardiography, while pmPEP decreased cardiac remodeling genes during DCM. Conclusion These findings suggest that PEP regenerative medicine therapies could successfully reduce myocardial inflammation associated with acute onset myocarditis and reduce DCM. Premenopausal PEP therapies from women may be more effective at reducing cardiomyopathy in men.