Foam cell

Foam cells form a major part of all known arteriosclerotic damaged, also called " calcified " popularly called blood vessels.

They are formed in the layers intima and media of the vessel walls by fatty deposits.

Foam cells are often already observed in children and adolescents, but there is their origin usually only temporary ( reversible). This gelatinous yellowish fat layers, which are referred to by doctors as fatty streaks may cover from 10 to 50 % of the inner walls of arteries. Studies of these lesions ( lesions) showed that they are composed of both lipid-laden macrophages and lipid-laden smooth muscle cells.

The normally circulating in the blood macrophages reach their preform as monocytes, in the lower vessel layers by penetrating the endothelial cell layer. This process is stimulated by chemotactic factors. Only in the Media ( subendothelium ) is a change in the appearance of monocytes and differentiation into macrophages. There, the macrophages can store lipids and cholesterol esters. This in turn can lead directly to the formation of foam cells.

The observation that the lipid-laden macrophages pass through the endothelial cell layer and can enter the bloodstream again, sparked in medical research is a controversy whether macrophages useful (lipid removal ) or else are harmful and responsible for the development of atherosclerosis, as they exit the endothelial cell layer is violated. Some researchers suggest that the macrophages in the early stage a protective, later to play a more pernicious role.

The mechanism of the formation of foam cells from macrophages and smooth muscle cells is only partially elucidated. There is agreement on the participation of chemically modified ( oxidized ) LDL, which is taken up and stored by the macrophages via scavenger receptors uninhibited and independent of concentration. These scavenger receptors are also found in smooth muscle cells. It can be assumed that mechanisms by which both cell types could prevent overcharging with lipids and cholesterol, are set or impaired except force.