Discoidin domain receptor-1: A novel molecular switch regulating fibrocalcific response in vascular smooth muscle cells

Background: Extracellular vesicle (EV)-derived microcalcifications formed in collagen-poor fibrous caps contribute to plaque rupture. Collagen accumulation and calcification are major determinants of plaque stability, although the mechanisms linking fibrotic and calcific responses are unknown. The collagen receptor discoidin domain receptor-1 (DDR-1) regulates plaque calcification in vivo; however, its role in the release of calcifying EVs remains unclear. We hypothesize that DDR-1 regulates the processes of fibrosis and EV-induced calcification in atherosclerotic plaques. Methods and results: Smooth muscle cells (SMC) from the carotid arteries of wild type and DDR-1 knockout (DDR-1-/-) mice (n=5 per group) were cultured in control or calcifying media. At days 14 and 21, cells were harvested and EVs isolated for analysis. Compared to wild type cells, DDR-1-/- SMCs exhibited a 3.5-fold increase in EV release (p