Composite Hydrogels Based on Cross-Linked Chitosan and Low Molecular Weight Hyaluronic Acid for Tissue Engineering

The objectives of the study were as follows: (1) to develop two methods for the preparation of macroporous composite chitosan/hyaluronic acid (Ch/HA) hydrogels based on covalently cross-linked Ch and low molecular weight (Mw) HA (5 and 30 kDa); (2) to investigate some properties (swelling and in vitro degradation) and structures of the hydrogels; (3) to evaluate the hydrogels in vitro as potential biodegradable matrices for tissue engineering. Chitosan was cross-linked with either genipin (Gen) or glutaraldehyde (GA). Method 1 allowed the distribution of HA macromolecules within the hydrogel (bulk modification). In Method 2, hyaluronic acid formed a polyelectrolyte complex with Ch over the hydrogel surface (surface modification). By varying compositions of the Ch/HA hydrogels, highly porous interconnected structures (with mean pore sizes of 50-450 μm) were fabricated and studied using confocal laser scanning microscopy (CLSM). Mouse fibroblasts (L929) were cultured in the hydrogels for 7 days. Cell growth and proliferation within the hydrogel samples were studied via MTT-assay. The entrapment of low molecular weight HA was found to result in an enhancement of cell growth in the Ch/HA hydrogels compared to that in the Ch matrices. The Ch/HA hydrogels after bulk modification promoted better cell adhesion, growth and proliferation than the samples prepared by using Method 2 (surface modification).