Figure 1.

Uncoordinated expression of VEGF and PDGF-BB leads to a mixture of normal and aberrant vasculature. A) Retroviral constructs used to generate myoblast populations expressing mVEGF₁₆₄ (pMFG-V) or hPDGF-BB (pAMFG-P). B–K) At 2 wk after implantation in ear muscles (n=7), control cells expressing only CD8 (B) or PDGF-BB (C) induced no angiogenesis. VEGF myoblasts (D) induced aberrant vessels. A 50:50 mixture of the two populations (E–G) induced robust normal angiogenesis (E) but also aberrant vascular structures (F, arrows; G). Vessels are stained brown after intravascular lectin perfusion and implanted myoblasts expressing β-galactosidase are stained blue (X-gal). Different proportions of coimplanted cells (n=4), with a 50:1 excess of PDGF-BB expression (V₁) or 50:20 of VEGF expression (P₂₀), did not prevent the development of aberrant angiogenesis (I, K) in neighboring large areas of normal vessels (H, J). Scale bars = 25 μm.