Table 1.

Phenotypes and characteristics of valve cells.

Cell type	Location	Function
Embryonic progenitor endothelial/ mesenchymal cells	Embryonic cardiac cushions	Give rise to VICs through an activated stage or EMT
Progenitor-VIC	Bone marrow, blood, valve leaflet	Provide fibroblast-VICs for valve repair. May be CD34−, CD133−, and/or S100+
Fibroblast-VIC	Valve leaflet	Maintain valve structure and function and prevent angiogenesis
Myofibroblast-VIC	Valve leaflet	SMA-containing VICs with activated cellular repair processes. Respond to valve injury and abnormal hemodynamic or mechanical forces
Osteoblast-VIC	Valve leaflet	Calcification, chondrogenesis and osteogenesis in the leaflet. Secrete ALP, osteocalcin, osteopontin and bone sialoprotein
Valve endothelial Cells	Surfaces of valve leaflet	Blood/valve interface, source of biological factors. Prevents cell adhesion, platelet activation, protects against calcification

VIC, valvular interstitial cells; qVIC, quiescent valvular interstitial cells; VEC, valvular endothelial cells; EMT, endothelial to mesenchymal transformation; ALP, alkaline phosphatase; SMA, smooth muscle α-actin.