The characterisation of articular chondrocyte seeded chitosan hydrogels for cartilage tissue engineering

Abstract

Cartilage is a type of connective tissue which has very little potential for spontaneous natural repair when damaged. The use of tissue engineering for the treatment of articular cartilage has been investigated for a number of years. However, due to its unique biomechanical properties and functional requirements, the neo-tissues produced thus far have proved to be of limited long-term functionality. One avenue being investigated is the use of cell-seeded scaffolds as cartilage templates. Chitosan is a natural, abundant polysaccharide, biocompatible and biodegradable, with the ability to form open, porous and interconnected networks. It has the potential to fulfil many of the requirements of a cartilage tissue engineering scaffold material.

A procedure was developed to form glutaraldehyde cross-linked chitosan hydrogels under relatively mild conditions and seed them with bovine articular chondrocytes. The cylindrical scaffolds formed were subjected to several investigations, including FTIR, microstructure analysis via pycnometry and porosimetry, static compression, biochemical analysis and a number of microscopic techniques, including confocal microscopy, optical microscopy and SEM.

These investigations have shown that the chondrocytes migrate readily into the chitosan hydrogel structure within 1 hour of seeding, attach within 1 day, and maintain a well-defined, rounded morphology for up to 28 days in culture. The GAG and DNA data implies that the chitosan hydrogels were not cytotoxic towards the chondrocytes and the growth rate corresponds to previous studies suggesting chitosan partially inhibits the cell cycle in G1 phase. The microstructure analysis suggests that the main limitation of the hydrogels produced in this work, from a cartilage tissue engineering standpoint, is their relatively low porosity. The compression data shows that these hydrogels behave as visco-elastic polymeric materials. However, the variation in the results suggests that the quality of the hydrogel is of grave importance and specimen selection should be carried out with great care.