Chitosan/pluronic hydrogel containing bFGF/heparin for encapsulation of human dermal fibroblasts

In order to act as a cell reservoir, a hydrogel has to have a suitable mechanical strength and should also enhance proliferation of cells. We have developed a hydrogel composed of chitosan and Pluronic containing a complex of basic fibroblast growth factor (bFGF) and heparin for cell encapsulation, and its ability as a scaffold for cells was evaluated. The hydrogel was composed of glycidyl methacrylated chitooligosaccharide (COS) and diacrylated Pluronic F127 (Pluronic) in various blend ratios. A mixture of COS and Pluronic was homogeneously mixed with cells, bFGF and heparin; then, the hydrogel precursor was photo-irradiated. With increasing amount of COS, the chemically cross-linked COS/Pluronic hydrogel showed an approx. 2-fold increase of its elastic modulus and a lower mass erosion rate than the hydrogel composed of only Pluronic after 28 days. The amount of bFGF was increased according to the presence of heparin within the hydrogel, but the amount of released bFGF was decreased by increasing the content of COS. The hydrogel containing bFGF with heparin showed higher proliferation of cells compared to the hydrogel without heparin at 20% COS. However, when the blend ratio of COS was 50%, the hydrogel showed less proliferation of cells than those with 20% COS. Therefore, the chemically cross-linked COS/Pluronic hydrogel be useful for a protein-delivery system and tissue-engineering scaffold.