Divergent effects of myostatin inhibition on cardiac and skeletal muscles in a mouse model of pressure overload

The transforming growth factor-b (TGF-b) superfamily member, myostatin, is a negative regulator of muscle growth and may contribute to adverse cardiac remodeling. Whether suppressing myostatin could benefit pressure-overloaded heart remains unclear. We investigated the effects of pharmacological inhibition of myostatin on cardiac fibrosis and hypertrophy in a mouse model of pressure overload induced by transverse aortic constriction (TAC). Two weeks after the surgery, TAC and sham mice were randomly divided into groups receiving mRK35, a monoclonal anti-myostatin antibody, or vehicle (PBS) for 8 wk. Significant progressive cardiac hypertrophy was observed in TAC mice, as reflected by the increased wall thickness, ventricular weight, and cross-sectional area of cardiomyocytes. In the groups treated with mRK35, compared with sham mice, cardiac fibrosis was increased in TAC mice, accompanied with elevated mRNA expression of fibrotic genes. However, among the TAC mice, mRK35 did not reduce cardiac hypertrophy or fibrosis. Body weight, lean mass, and wet weights of tibialis anterior and gastrocnemius muscle bundle were increased by mRK35. When compared with the TAC-PBS group, the TAC mice treated with mRK35 demonstrated greater forelimb grip strength and a larger mean size of gastrocnemius fibers. Our data suggest that mRK35 does not attenuate cardiac hypertrophy and fibrosis in a TAC mouse model but has positive effects on muscle mass and muscle strength. Anti-myostatin treatment may have therapeutic value against muscle wasting in cardiac vascular disease. NEW & NOTEWORTHY Recent research has highlighted the importance of inhibiting TGF-b signaling in mitigating cardiac dysfunction and remodeling. As myostatin belongs to the TGF-b family, we evaluated the impact of myostatin inhibition using mRK35 in TAC-operated mice. Our data demonstrate that mRK35 significantly increased body weight, muscle mass, and muscle strength but did not attenuate cardiac hypertrophy or fibrosis. Pharmacological inhibition of myostatin may provide therapeutic benefits for the management of muscle wasting in cardiovascular diseases.