In Vitro and In Vivo Release of Vascular Endothelial Growth Factor from Gelatin Microparticles and Biodegradable Composite Scaffolds
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This work evaluated gelatin microparticles and biodegradable composite scaffolds for the controlled release of vascular endothelial growth factor (VEGF) in vitro and in vivo.
Gelatin crosslinking, VEGF dose, and buffer type were investigated for their effects on VEGF release. Release was also evaluated from microparticles confined within porous polymer scaffolds (composites). In vitro and in vivo studies were conducted using radiolabeled VEGF.
The effect of VEGF dose on its fractional release from gelatin microparticles in vitro was minimal, but the addition of collagenase to the buffer resulted in a higher cumulative release of VEGF. Gelatin crosslinking extent was a significant factor on release from both microparticles alone and composite scaffolds in vitro and in vivo. VEGF bioactivity from composite scaffolds in vitro was maintained above 90% of the expected bioactivity over 14 days.
VEGF release kinetics were dependent on the extent of gelatin crosslinking and were characteristic of the specific growth factor due to the effects of growth factor size, charge, and conformation on its complexation with gelatin. These studies demonstrate the utility of gelatin microparticles and their composite scaffolds as delivery vehicles for the controlled release of VEGF for tissue engineering applications.
KEY WORDSbone tissue engineering controlled drug delivery gelatin microparticles porous polymer scaffold vascular endothelial growth factor
basic fibroblast growth factor
bone morphogenetic protein-2
collagenase-containing phosphate buffered saline
gel permeation chromatography
human umbilical vein endothelial cells
insulin-like growth factor-1
phosphate buffered saline
scanning electron microscopy
transforming growth factor-β1
vascular endothelial growth factor
volume of interest
The authors would like to acknowledge support of this work by a grant from the National Institutes of Health (R01-DE15164) (AGM) and by a National Science Foundation Graduate Research Fellowship (ZSP).
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