Gelatin-fibrinogen cryogel dermal matrices for wound repair I: preparation, optimisation and in vitro study

Macroporous sponge-like gelatin-fibrinogen (Gl-Fg) scaffolds cross-linked with different concentrations (0.05-0.5%) of glutaraldehyde (GA) were produced using cryogelation technology, which allows for the preparation of highly porous scaffolds without compromising their mechanical properties, and is a more cost-efficient process than freeze-drying. The produced Gl-Fg-GA(X) scaffolds had a uniform interconnected open porous structure with a porosity of up to 90-92% and a pore size distribution of 10-120 microm. All of the obtained cryogels were elastic and mechanically stable, except for the Gl-Fg-GA(0.05) scaffolds. Swelling kinetics and degradation rate, but not the porous structure of the cryogels, were strongly dependent on the degree of cross-linking. A ten-fold increase in the degree of cross-linking resulted in an almost 80-fold decrease in the rate of degradation in a solution of protease. Cryogels were seeded with primary dermal fibroblasts and the densities observed on the surface, plus the expression levels of collagen types I and III observed 5 days post-seeding, were similar to those observed on a control dermal substitute material, Integra. Fibroblast proliferation and migration within the scaffolds were relative to the GA content. Glucose consumption rate was 3-fold higher on Gl-Fg-GA(0.1) than on Gl-Fg-GA(0.5) cryogels 10 days post-seeding. An enhanced cell motility on cryogels with reducing GA crosslinking was obtained after long time culture. Particularly marked cell infiltration was seen in gels using 0.1% GA as a crosslinker. The scaffold started to disintegrate after 42 days of in vitro culturing. The described in vitro studies demonstrated good potential of Gl-Fg-GA(0.1) scaffolds as matrices for wound healing.