There are five known functions of intraglomerular mesangial cells: structural support of glomerular capillaries, regulation of the glomerular filtration rate, mesangial matrix formation, phagocytosis, and monitoring of capillary lumen glucose concentration[citation needed].

The initiation of contraction of mesangial cells is similar to that of smooth muscle.

Intraglomerular mesangial cells synthesize and secrete the extracellular matrix.

Intraglomerular mesangial cells phagocytize glomerular basal lamina components and immunoglobulins.

They are an unusual example of phagocytic cells derived from smooth muscle and not monocytes.