Fig. 4.

Postnatal aortic valve endothelial and interstitial subpopulations. Postnatal aortic valves contain localized subpopulations of valve endothelial cells (VECs), valve interstitial cells (VICs) and immune cells that exhibit distinct transcriptional profiles. These populations are present in regions of the valve exposed to unique combinations of mechanical forces. The typical VEC subpopulation (gray) can be found on both sides of the valve leaflet, while a VEC subpopulation expressing Prox1 (yellow), a lymphatic marker influenced by oscillatory shear stress, is found solely on the side away from laminar flow. A coaptation VEC population (orange) is found where the leaflets meet. A collagen-expressing subpopulation of VICs (pink) is found in the fibrosa layer and a GAG-expressing subpopulation of VICs (green) is in the hinge and tip of the leaflet. Similarly, macrophages are present in the hinge and tip regions of the valve leaflet, which are subject to high mechanical stress. GAG, glycosaminoglycan.