Scaffolds to grow cartilage
doi:10.1038/nindia.2011.138 Published online 26 September 2011
Researchers have shown that blending silk protein with chitosan could yield novel scaffolds for growing cartilage tissue. This development may provide a way of replacing worn-out cartilage tissue caused by various bone diseases.
Normal cartilage is composed of chondrocyte cells that synthesize sulphated glycosaminoglycan and collagen, the load-bearers. Repairing damaged cartilage by inserting an artificial joint neither provides complete recovery nor safety since it can undergo rapid degradation after insertion into the body.
To find an effective way, the researchers made scaffolds by blending silk fibroin (SF), a protein isolated from silk cocoons, with the natural polymer chitosan (CS) in varying ratios. They seeded the scaffolds with chondrocytes isolated from the knee of bovine calves and studied their efficacy over two weeks. The researchers also compared the seeded scaffolds with unseeded similar scaffolds.
After two weeks, a large number of cartilage cells were found on the seeded scaffolds. Of all the scaffolds, SF/CS (1:1) showed the most growth of chondrocytes. Furthermore, the researchers found that SF/CS (1:1) scaffold facilitated a higher deposition of sulphated glycosaminoglycan than SF/CS (2:1) and pure SF. Collagen content was also higher in SF/CS (1:1) than SF/CS (2:1) and pure SF. Unseeded scaffolds showed minimal deposition of sulphated glycosaminoglycan and collagen.
"The presence of silk in chitosan-blended silk scaffolds increases the mechanical strength of the blended scaffold over pure chitosan," says lead researcher Subhas C. Kundu. "Being a blend of two natural polymers, the scaffolds will be more biocompatible than those made from synthetic materials," he adds.
The authors of this work are from: Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal, India; Department of Bioengineering, University of California-San Diego, La Jolla; and Department of Biomedical Engineering, Tufts University, Medford, USA.