Effect of PDGF-CC on EC migration and outgrowth of microvessels. (A) WGA precipitation and subsequent immunoblotting of extracts of control and ligand-stimulated HUVECs and HMVECs, revealing detectable expression of PDGF-Rα but not of PDGF-Rβ. By immunoblotting, PDGF-Rα was tyrosine phosphorylated in both cell lines (data not shown). (B and C) In the scrape wound assay (B), PDGF-CC stimulated HMVEC migration with a potency similar to that of VEGF, while PDGF-AA and -BB had an intermediate or no effect, respectively. In the Boyden chamber assay (C), both PDGF-AA and -CC induced HUVEC chemotaxis, while PDGF-BB was inactive. (D) None of the PDGFs affected HMVEC proliferation, while VEGF potently promoted cell proliferation. *P < 0.05. Values are mean ± SEM. RLU, relative luminescence units. (E–G) Micrographs of aortic rings, displaying microvascular sprouts and perivascular cells. Compared to vehicle (E), PDGF-CC enhanced the outgrowth of both microvascular sprouts and fibroblast-like cells (F), while VEGF stimulated microvascular outgrowth (G). (H and I) In the aortic ring assay, PDGF-CC and VEGF induced microvessel outgrowth, while PDGF-AA and -BB were inactive (H). Each PDGF form stimulated myofibroblast outgrowth from the aortic ring, but PDGF-CC was more potent than PDGF-BB and PDGF-AA, whereas VEGF was inactive (I). P < 0.05 (H and I). WB, Western blot.