Cardiac Fibroblasts Adopt Osteogenic Fates and Can Be Targeted to Attenuate Pathological Heart Calcification

Mammalian tissues calcify with age and injury. Analogous to bone formation, osteogenic cells are thought to be recruited to the affected tissue and induce mineralization. In the heart, calcification of cardiac muscle leads to conduction system disturbances and is one of the most common pathologies underlying heart blocks. However the cell identity and mechanisms contributing to pathological heart muscle calcification remain unknown. Using lineage tracing, murine models of heart calcification and in vivo transplantation assays, we show that cardiac fibroblasts (CFs) adopt an osteoblast cell-like fate and contribute directly to heart muscle calcification. Small-molecule inhibition of ENPP1, an enzyme that is induced upon injury and regulates bone mineralization, significantly attenuated cardiac calcification. Inhibitors of bone mineralization completely prevented ectopic cardiac calcification and improved post injury heart function. Taken together, these findings highlight the plasticity of fibroblasts in contributing to ectopic calcification and identify pharmacological targets for therapeutic development. [Display omitted] •CFs express osteogenic markers in vitro and in several murine heart calcification models•CFs from calcified hearts can induce ectopic calcification upon transplantation•CFs induce mineralization of the matrix via upregulation of ENPP1•Inhibitors of ENPP1 and mineralization decrease calcification and improve cardiac function Pillai et al. demonstrate that cardiac fibroblasts adopt bone-forming cell fates and induce ectopic calcification. ENPP1, an enzyme that regulates bone mineralization, is induced in cardiac fibroblasts after injury. Administration of ENPP1 inhibitors or inhibitors of bone mineralization significantly decreased pathologic cardiac calcification and augmented cardiac function.