FIG. 5.

High levels of human VEGF₁₆₅ induce mature capillaries rather than angiomas. (A) Myoblast engraftment was tracked by X-gal staining (blue) 4 weeks after implantation of control cells (Ctrl CD8) or mV and hV clones expressing low and high VEGF levels. In the presence of angiomas (white asterisks) induced by high levels of mouse VEGF very few myoblasts survived after 4 weeks, whereas in all other conditions consistent and stable engraftment was observed around the implantation needle tracks. (B) Vascular structures induced in the areas of engraftment 4 weeks after implantation were immunostained with antibodies against CD31 (endothelium, in red), NG2 (pericytes, in green), and SMA (smooth muscle cells, in cyan) in frozen sections of implanted limb muscles. Low levels of both mouse and human VEGF induced normal pericyte-covered capillaries and the aberrant angioma-like vascular structures caused by high mouse VEGF levels (white asterisk) were covered by a thick layer of SMA⁺ cells but no pericytes. However, even higher levels of human VEGF (clone hV_high2) gave rise only to mature capillaries, covered with normal pericytes positive for NG2 and negative for SMA. Size bar=500 μm in (A) and 50 μm in (B). Color images available online at www.liebertpub.com/hgtb