Controlled Release of VEGF From a Nanofibers Scaffold

Objectives: Electrospinning is a method used to produce nano-scale fibers from dissolved polymers. The aim of this study was to develop an electrospun fiber scaffold with controlled release of human VEGF (hVEGF).
Methods: Core-shell fibers were fabricated by electrospinning process. Shell solutions were composed of polycaprolactone and 0.25-3 wt.% poly ethylene glycol (PEG) dissolved in a mixture of chloroform and dimethyl formamide. The core solution was composed of poly-ethylene oxide (PEO) with various concentrations of hVEGF. Scanning electron microscopy (SEM) was used to evaluate the morphology of the shell, pore size and pore density. The releasing pattern of hVEGF was monitored by ELISA. In vitro biological activity of hVEGF was determined by proliferation and trans-well migration assays.
Results: Core-shell fibers of 6-8µm diameter were fabricated. According to SEM, positive correlation was found between PEG concentrations and pore size within the shell. Mean pore size was 503.497± 64nm in 3% PEG scaffold and 205±60nm in 1 % PEG scaffold. Pore density was negatively correlated with PEG concentration: of 7.3 pores/µm2 vs. 3.8 pores/µm2 in 1% and 3% PEG, respectively. Moreover, changes in PEG concentrations influenced the kinetics of hVEGF release: scaffolds with 3% PEG released 23% of the loaded hVEGF within 4 hours, while mats with 1% PEG released approximately 38% of hVEGF in 18 hours. The biological activity of released hVEGF was also demonstrated: released hVEGF enhanced endothelial cells proliferation (by 1.25 folds) and increased the migration of endothelial cells towards the scaffold by 80 folds compared to the negative control (scaffold without hVEGF).
Conclusions: PEG concentration in the shell solution, influenced scaffold's porosity and hVEGF release kinetics. In vitro, hVEGF that was released from the scaffold increased endothelial cells proliferation and migration. Future studies will be performed to investigate the in vivo angiogenic potential of this scaffold.