Establishment of a functionally active collagen-binding vascular endothelial growth factor fusion protein in situ.

OBJECTIVE Tissue regeneration requires both growth factor and extracellular matrix such as collagen, serving as a scaffold for cell growth. We established FNCBD-VEGF121, consisting of the fibronectin collagen-binding domain (FNCBD) and vascular endothelial growth factor (VEGF) 121, and investigated its properties. METHODS AND RESULTS FNCBD-VEGF121 specifically bound to gelatin and type I, II, III, IV, and V collagen. This collagen-bound FNCBD-VEGF121 captured soluble VEGF receptor 2 (VEGFR-2)/Fc chimeric protein. Cell growth-promoting activity of FNCBD-VEGF121 was almost identical to that of VEGF121. The VEGF fusion protein significantly enhanced the expression of VEGFR-2 (71.6+/-0.8%) on endothelial progenitor cells (EPCs) derived from umbilical cord blood. Expectably, the collagen-bound VEGF fusion protein not only promoted the growth of endothelial cells (ECs) but also induced the expression of VEGFR-2 (63.7+/-0.8%) on non-adherent cells expanded from bone marrow CD34+ cells. Moreover, the VEGF fusion protein enhanced sprout formation of ECs in a matrigel model. In vivo experiments revealed that FNCBD-VEGF121 had local effects but not systemic effect on EPC mobilization. CONCLUSIONS These results suggest that FNCBD-VEGF121 stably maintains an optimally high and local concentration of VEGF with collagen matrix and stimulates both ECs and EPCs in situ, supplying a vascular regeneration niche.