Calcified atherosclerotic plaque - where exactly is the calcium and what does it contain?

Objective To understand the morphology and mineral content in calcified atherosclerotic plaques. Background Recent findings suggest that plaque calcification is biologically organized and regulated. Knowledge of morphology, location and mineral content of calcification in a plaque, could provide valuable insights into developing therapeutic interventions for calcific atherosclerotic disease. Methods We studied various patterns of calcification in atherosclerotic plaques using light and electron microscopy and analyzed their mineral composition by spectroscopic techniques. Results Early luminal deposits in the intima are globular, measuring ~1.5 μm and are basically calcium phosphate while deeper deposits in the media are lamellar and sheet like with sharp spicular edges and composed of calcium colocalized with cholesterol. Sulfur and Silicon are also present in these deposits. Calcification around lipid, as seen using transmission electron microscopy, starts as an encrustation around individual lipid vesicles which progresses and eventually replaces the lipid droplets entirely. Conclusion The mineral composition and the morphological appearance of the calcium seems to vary depending upon its location.