Neonatal Systemic AAV-Mediated Gene Delivery of GDF11 Inhibits Skeletal Muscle Growth.

Growth and differentiation factor 11 (GDF11; BMP11) is a circulating cytokine in the transforming growth factor beta (TGF-ß) superfamily. Treatment with recombinant GDF11 (rGDF11) protein has previously been shown to reverse skeletal muscle dysfunction in aged mice. However, the actions of GDF11 in skeletal muscle are still not fully understood. Because GDF11 activates the TGF-ß-SMAD2/3 pathway, we hypothesized that GDF11 overexpression would inhibit skeletal muscle growth. To test this hypothesis, we generated recombinant adeno-associated virus serotype 9 (AAV9) vectors harboring the gene for either human GDF11 (AAV9-GDF11) or human IgG1 Fc-fused GDF11 propeptide (AAV9-GDF11Pro-Fc-1) to study the effects of GDF11 overexpression or blockade on skeletal muscle growth and function in vivo. After intravenous administration of AAV9-GDF11 into neonatal C57BL/6J mice, we observed sustained limb muscle growth inhibition along with reductions in forelimb grip strength and treadmill running endurance at 16 weeks. Conversely, treatment with AAV9-GDF11Pro-Fc-1 led to increased limb muscle mass and forelimb grip strength after 28 weeks, although a difference in the total body mass/muscle mass ratio was not observed between treatment and control groups. In sum, our results suggest GDF11 overexpression has an inhibitory effect on skeletal muscle growth.