Abstract

The initial phases of atherosclerosis involve the transition of normal vascular smooth muscle cells (VSMCs) to a synthetic, dedifferentiated phenotype, which can migrate and proliferate. This could potentially obstruct blood flow, which, when destined to the cardiomyocytes, can lead to myocardial infarction. Studies have demonstrated that cardiomyocytes, undergoing apoptosis, release a phospholipid molecule called cardiolipin (CL) into the systemic circulation. The objective of this project was to investigate the impact of cardiolipin on VSMCs, specifically addressing cellular dedifferentiation, migration, proliferation, and whether these modifications are mitochondria-mediated. The effect of CL on aortic contractility was also examined. Using adult mice aortas, we quantified a number of differentiation and dedifferentiation markers (αsmooth actin, calponin1, calpain I, and MMP14), following 48 hours of organ culture with physiological concentrations of CL (1µM and 10 µM) through immunoblotting. These CL concentrations were also used to investigate VSMC migration and proliferation over six days using cell culture, and to study blood vessel contraction following 48 hours of organ culture. Additionally, the acute effects of cardiolipin on VSMC mitochondria were examined through the use of high-resolution respirometry and selected substrate-inhibitor-uncoupler titration protocols. We found that calponin1 protein expression has significantly decreased by CL, while the other proteins remained unaffected. VSMC migration was ceased when treated with CL, while proliferation and contraction seemed unaffected. Mitochondrial respiration was significantly decreased for complex I and III. In conclusion, our results demonstrate that CL significantly reduces VSMC migration, calponin levels, and mitochondrial respiration, which could potentially act as an anti-atherosclerotic factor.