New suitable for tissue reconstruction injectable chitosan/collagen-based hydrogels

The ability of four gel-forming copolymers to act as in situ dermal fillers in plastic and reconstruction surgery was studied. The four hydrogels, which were based on chitosan (CS), included CS/beta-GP (beta-sodium glycerophosphate), CS-HLC (human-like collagen)/beta-GP, CS-AC (animal-derived collagen)/beta-GP and CS-Gelatin/beta-GP. The potential of the hydrogels as tissue engineering scaffolds was explored by an MTT test and an in vitro degradation assay. The interior morphologies of these hydrogels were also characterized before and after degradation. Histocompatibility in vivo was evaluated by hematoxylin and eosin (II&E) staining, immunohistochemical analysis and transmission electron microscopy (TEM). An MTT assay showed that the CS-HLC/beta-GP hydrogel was less cytotoxic and could promote marrow stromal cell (MSC) proliferation better than other hydrogels. Data from an in vitro degradation test showed that the CS-HLC/beta-GP hydrogel had a longer degradation time and led to a lower weight loss than the other hydrogels. Furthermore, the CS-HLC/beta-GP hydrogel rapidly formed a stable gel that maintained its integrity even after 6 weeks in vivo. From TEM, there were found to be a large quantity of macrophages, fibroblasts, fibrocytes, lymphocytes and capillaries in the CS-AC/beta-GP and CS-Gelatin/beta-GP hydrogels, whilst levels in the CS-HLC/beta-GP hydrogel were small. Furthermore, abnormalities of cell morphology were observed in the CS-AC/beta-GP and CS-Gelatin/beta-GP hydrogels whereas cell morphology in the CS-HLC/beta-GP hydrogel was regular. Therefore, the CS-HLC/beta-GP hydrogel, with good cytocompatibility and histocompatibility, is suitable for soft tissue defect filling, such as skin patches, wrinkles, and tissue cavities formed by surgery.