Sustained release of vascular endothelial growth factor from mineralized poly(lactide-co-glycolide) scaffolds for tissue engineering

Abstract

Strategies to engineer bone tissue have focused on either: (1) the use of scaffolds for osteogenic cell transplantation or as conductive substrates for guided bone regeneration; or (2) release of inductive bioactive factors from these scaffold materials. This study describes an approach to add an inductive component to an osteoconductive scaffold for bone tissue engineering. We report the release of bioactive vascular endothelial growth factor (VEGF) from a mineralized, porous, degradable polymer scaffold. Three dimensional, porous scaffolds of the copolymer 85 : 15 poly(lactide-co-glycolide) were fabricated by including the growth factor into a gas foaming/particulate leaching process. The scaffold was then mineralized via incubation in a simulated body fluid. Growth of a bone-like mineral film on the inner pore surfaces of the porous scaffold is confirmed by mass increase measurements and quantification of phosphate content within scaffolds. Release of 125I-labeled VEGF was tracked over a 15 day period to determine release kinetics from the mineralized scaffolds. Sustained release from the mineralized scaffolds was achieved, and growth of the mineral film had only a minor effect on the release kinetics from the scaffolds. The VEGF released from the mineralized and non-mineralized scaffolds was over 70% active for up to 12 days following mineralization treatment, and the growth of mineral had little effect on total scaffold porosity.