Collagenase-resistant implants exhibit a deficiency of endothelial cells but not other cell types.

WT or collagenase-resistant, r/r collagen at equal concentrations was copolymerized with buffer alone or bFGF/VEGF, prior to placement on the chick CAM. The embryos containing the collagen implants were incubated for 66 hours. Immunofluorescent detection of multiple cell types revealed a deficiency only of endothelial cells in collagenase-resistant (B,D,F) compared to WT (A,C,E) implants. Staining is shown for the endothelial cells with anti–von Willebrand factor (A,B), PMN heterophils with antichicken MMP-9 (C,D), or myofibroblasts with antismooth muscle actin (E,F). Bar indicates 50 μm. (G) Total cellularity was similar between collagenase-resistant and WT implants, as indicated by image analysis of total nuclear staining in the upper region of the implants. Data shown in bar graphs are the average of 5 independent samples ± SEM Mann-Whitney U test: n = 5, P > .05.