High cholesterol in the blood can lead to atherosclerosis – a life-threatening condition characterised by the build-up of fatty deposits called plaques on blood vessel walls. In addition to fat, plaques contain an abundance of macrophages – a type of immune cell that originates in the bone marrow – and vascular smooth muscle cells – which reside in blood vessel walls but proliferate and migrate to the growing plaques. Curiously, plaques also contain cells with characteristics of both macrophages and smooth muscle. Intrigued as to the origin of these hybrid cells, researchers labeled the muscle cells (shown here in red and green in the aorta of a mouse) and observed their behaviour during atherosclerosis development. To their surprise the muscle cells transformed into macrophages. Indeed, the majority of plaque macrophages arose not from bone marrow but from muscle. Inhibiting this unexpected conversion may be a novel therapeutic strategy for slowing plaque growth.
Written by Ruth Williams
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