Mesenchymal Stem Cell Mediated Chondrogenesis on Chitosan-Calcium Phosphate Scaffolds: Effect of Collagen Coating

Osteoarthritis, a degenerative disease, is one of the leading disabilities in United States. The emerging field of cartilage tissue engineering shows promising results in regenerating healthy hyaline cartilage which can alleviate pain and restore the functions of normal tissue. The current research is related to a biphasic approach to cartilage tissue engineering, in which one layer supports to form subchondral bone (osteogenesis) and another supports cartilage formation (chondrogenesis). High density human bone marrow mesenchymal stem cells were seeded on top of chitosan calcium phosphate (CHI-CaP) scaffolds. To attain maximum cell-scaffold adhesion, CHI-CaP scaffolds were coated with 0.05% of type I collagen from a rat tail. Macroscopically, a white cartilaginous layer was observed on coated and uncoated scaffolds, but the area of tissue covered on coated scaffolds was significantly higher than that of the uncoated scaffolds. Collagen coating made the scaffolds more hydrophilic and increased cell-scaffold adhesion. Coating did not alter the physical characteristics of scaffold. On collagen coated scaffolds, the directions of preferential fiber alignment in the superficial and deep zones of the engineered tissue were significantly different, a pattern that is similar to that of native articular cartilage. Immunostaining for type II collagen was more intense in the tissue grown on collagen coated CHI-CaP than the uncoated scaffolds after culturing for 28 days in defined chondrogenic medium. This study demonstrates that collagen coating substantially improved hbMSCs adhesion and facilitated formation of a continuous cartilage layer on the surface of CHI-CaP scaffolds.