Fabrication of composite scaffolds impregnated with an optimized fibrin-alginate hydrogel for cartilage tissue engineering

Osteoarthritis (OA) is a painful degenerative joint disease that affects millions of North Americans. OA could be better managed if tissue engineers can develop methods to create long-term mechanically stable engineered articular cartilage tissue substitutes. Many of the tissue engineered cartilage constructs currently available lack the chemical stimuli, cell-friendly environment, and/or mechanical strength needed for use in joint cartilage repair. The goal of my research was to test the efficacy of composite scaffolds comprised of a solid synthetic polymer framework impregnated with a fibrin/alginate hydrogel containing hyaluronic acid (HA) and/or chondroitin sulphate supplements (CS). The suitability of a polylactic-co-glycolic acid (PLGA) and iron(III) oxide material slurry as the synthetic polymer framework was determined. It was found that a solid three-dimensional scaffold with an interconnected porous structure could be fabricated from this material using dispensing-based rapid prototyping. Moreover, films of the PLGA-iron oxide material supported higher cell populations of porcine chondrocytes compared to a previously reported PLGA-hydroxyapatite material film. In addition, an experiment examining the effects of HA and/or CS macromolecule supplementation on chondrocytes cultured in a fibrin-alginate hydrogel was performed. Chondrocytes cultured in fibrin-alginate hydrogels retained their phenotype better than chondrocytes cultured in monolayer as analysis of expression of type I collagen and type II collagen mRNA transcripts. HA or CS supplementation of the hydrogels increased matrix production during the first week of culture. However, the effects of these supplements on matrix accumulation were not additive and were no longer observed after 2 weeks of culture. Supplementation of the hydrogels with HA and/or CS increased the chondrocyte cell population after two weeks of culture, and the effects of these macromolecule on cell numbers were additive. Finally, composite scaffolds were successfully fabricated by impregnating the solid PLGA-iron oxide scaffold with a CS-supplemented fibrin-alginate hydrogel. However, a large amount of cell death that occurred during the cell seeding prevented quantification of cellular DNA or sulphated GAG accumulation in these composite scaffolds. Nevertheless, my research suggests that, with refinement of the cell seeding process, a CS supplemented fibrin-alginate/PLGA-iron oxide composite may be a superior three-dimensional scaffold system for use in articular cartilage tissue engineering applications