Moreira Teixeira, L.S. Chitosan-based hydrogels as extracellular matrix for cartilage tissue engineering: in vitro biological evaluation

Moreira Teixeira, L.S., Jin, R., Dijkstra, P.J., Feijen, J., Blitterswijk, C.A. van & Karperien, H.B.J

Tissue Engineering Part A, 14, 711

Cartilage reconstruction demands for biocompatible materials with controlled biodegradation. Hydrogels, based on natural polymers, fulfil these properties. Recently we have developed an injectable chitosan-based hydrogel and have studied its biocompatibility in vitro.
Chitosan was made water soluble by the covalent attachment of glycolic acid with a graft ratio of 43. Phloretic acid was covalently attached to the chitosan (graft ratio 10) and was used as the crosslinking moiety. The hydrogels were prepared by enzymatic crosslinking of the phenol moieties using hydrogen peroxide and horseradish peroxidase. To evaluate biocompatibility, the polymer was mixed with 510 6 mL bovine primary chondrocytes and gelation was induced. Gelation occurred within 1 minute, under mild conditions, and resulted in efficient encapsulation of the cells. The reaction was not associated with cytotoxicity. The gels were cultured for 21 days in standard chondrocyte culture medium and cell viability was evaluated using a live-dead assay at 1,7,14 and 21 days. There was no evidence for toxicity over time. Next, we assessed the cell morphology using SEM-analysis. Results show the presence of round chondrocyte-like cells and the production of extracellular matrix. Biodegradation of the constructs was assessed by weight loss quantification, up to 28 days in culture. Hydrogels with encapsulated chondrocytes degrade slower than control.
In conclusion, our data show efficient encapsulation of primary chondrocytes in a chitosan-based hydrogel. The gelation reaction was fast and not harmful for the cells. Cells retained a chondrocytelike morphology and produced extracellular matrix upto 21 days in culture. This novel chitosan-based biodegradable matrix may have
application in cartilage reconstruction.