Figure 5

Cell morphology of differentiated mesenchymal stem cells into endothelial cells. Images taken by inverted microscope after 10 days of stimulation. Control mesenchymal stem cells (MSCs) cultured in growth media retained fibroblastoid morphology (A). MSCs differentiated in high-dose vascular endothelial growth factor (VEGF-A) changed into the cobblestone shape typical of endothelial cells (B); however, low-dose VEGF-A produced less of an effect (C). Combination treatment with low-dose VEGF-A and low-dose angiotensin II (Ang II) also induced cobblestone morphology (D), but Ang II alone had no effect (E). Positive control (human umbilical vein endothelial cells (HUVECs)) demonstrated rigid cobblestone morphology (F). Capillary formation by differentiated MSCs into endothelial cells (ECs) (G, H, I, J, K, L). After 10 days of stimulation, cells were seeded onto ECMatrix gel. Naïve MSCs cultured in control media and incubated on the matrix did not form elliptical structure (G). High-dose VEGF-A was capable of forming characteristic capillary structures associated with EC regeneration (H). MSCs differentiated in low-dose VEGF-A started forming elliptical structures. However, individual cells did not connect with each other (I). Combination treatment with low dose VEGF-A and Ang II resulted in complex mesh-like formation in addition to closed polygonal structure (J). Ang II alone did not induce any mesh-like structure or connections (K). The effect of the combined treatment was more striking compared with HUVEC cells forming capillaries (L). One image representative of three independent experiments performed from three different swine bone marrow samples is shown.