Injectable polysaccharide hybrid hydrogels as scaffolds for burn wound healing

In this study, a type of injectable polysaccharide-based hydrogels were prepared via the Schiff-base crosslinking reaction between the amino groups of carboxymethyl chitosan (CMC) and the aldehyde groups of oxidized dextran (Odex). The gelation time of the CMC/Odex hybrid hydrogels was 25-50 s, depending on the CMC/Odex weight ratio. The hydrogel displayed a storage modulus of ∼1 kPa, and the freeze-dried hydrogel showed an interconnected porous structure. The in vitro degradation test of the hydrogel in PBS showed a fast mass loss in the first 2 days, and then a gradual degradation profile over 4 weeks. The in vitro cytotoxicity and the ability to support cell attachment of the hydrogels were tested by incubation with L929 cells. The results indicated that the hydrogels displayed good cytocompatibility, and the hydrogels with relatively higher CMC content supported the attachment of L929 cells. Moreover, the potential application of the hydrogels in burn wound healing was tested on SD rats with a deep second-degree burn wound. It was found that the group treated with the CMC/Odex hydrogel showed nearly complete wound closure at 21 days after the treatment compared to unsatisfactory wound healing efficiency of the untreated group. Additionally, the histological analysis by H&E and Masson's trichrome staining indicated clearly the regeneration of skin appendages, including hair follicles, sebaceous glands and dermal papillary, suggesting that the treatment with the hydrogel promoted the wound healing and skin regeneration. Overall, the injectable polysaccharide hybrid hydrogels may serve as suitable scaffolds for promoting burn wound healing and skin regeneration.