Release kinetics and cellular profiles for bFGF-loaded electrospun fibers: Effect of the conjugation density and molecular weight of heparin

The integration mode and release modulation of growth factors inside the scaffolds represent major challenges for inductive tissue regeneration. The integration of the bioaffinity of heparin with growth factors and the biomimicry of electrospun fibrous network to extracellular matrices is expected to efficiently bind and gradually release growth factors. Functional ketone groups were incorporated into poly(dl-lactide) backbone through copolymerization with functional ε-caprolactone-based monomers. Heparin molecules were conjugated on the fiber surface up to 112.4 ± 3.2 ng/cm2, and recombinant basic fibroblast growth factor (bFGF) was loaded onto heparinized fibers up to 96.3 ± 4.7 ng/mg scaffold. The release profiles of bFGF were modulated by the heparin conjugation densities and the molecular weights of heparin conjugated. Higher release rates were found after incubation bFGF-loaded fibers in cell culture media and with NIH3T3 cells than that in buffer solutions. The gradual release of bFGF stimulated the cell growth and collagen secretion for over 21 d, which were more significant for fibrous mats conjugated with heparin of higher density and molecular weights. It is indicated that a novel strategy to fabricate growth factors-loaded fibrous scaffolds has been developed to manipulate desired signals at effective levels within local tissue microenvironment.