FIG. 4.

Immunohistochemical staining of thin sections of CPC construct after 42 days of HUVEC+HOB coculture. In (A), PECAM1 was stained into a brown/red color. Arrows indicate tube-like structures. PECAM1 staining confirmed the endothelial nature of the lumen-forming cells. In (B), the von Willebrand factor (vWF) was stained into a brown/red color. Arrows indicate microcapillary-like structures and lumens. In (C), collagen I was stained into a brown/red color. In (D), osteonectin (ON) was stained into a brown/red color. The pattern of ON staining appeared as clumps without a microcapillary-like structure, because ON is related to osteogenic differentiation and mineralization. Color images available online at www.liebertpub.com/tea