Pericyte

A pericyte, also known as Rouget cell, adventitial cell or mural cell, is a connective tissue cell that occurs about small blood vessels.

Function
As a relatively undifferentiated cell (oligopotent), it serves to support these vessels, but it can differentiate into a fibroblast, smooth muscle cell, or macrophage as well if required. In order to migrate into the interstitium, the pericyte has to break the barrier, formed by the basement membrane, which can be accomplished by fusion with the membrane. Pericytes are important in blood-brain barrier stability as well as angiogenesis. Their expression of smooth muscle actin (SMA) and vimentin (or desmin in some cases where they are more likely to become smooth muscle cells), and their adherence to the endovascular cells makes them very strong candidates for blood flow regulators in the microvasculature, and indeed they have been implicated in blood flow regulation at the capillary level. After ischemia, an irreversible constriction of pericytes may prevent brain blood flow being restored.

Hemangiopericytoma
Hemangiopericytoma is a malignant vascular tumor.

Diabetic retinopathy
Pericytes express the enzyme aldose reductase, which is implicated in the development of diabetic retinopathy Excess glucose is shunted down the polyol pathway and sorbitol accumulates. This osmotically active metabolite damages the pericytes in the retinal vessels resulting in the symptoms characterizing diabetic retinopathy.

Alzheimer's Disease
The proliferation of pericytes on blood vessels in the brain may play a role in the pathology in Alzheimer's disease and have been found in excess in the nervous tissue of affected individuals.

Research
Researchers have taken pericytes from the pancreas and then reinjected them into an injured muscle. The cells immediately began regenerating muscle tissue.

Pericytes play a major role in the scar-tissue formation of spinal cord lesions.