Research Highlights

Cartilage to repair worn-out joints

Published online 9 December 2012

Biplab Das

Cartilage worn down by diseases like osteoarthritis limits the body's ability to heal. A research team led by Farshid Guilak from the Duke University in Durham, North Carolina, has developed a new way to generate cartilage-forming cells with the potential to replace damaged cartilage tissue1.

The research team, which includes Nicolas Christoforou from the Khalifa University of Science, Technology and Research, Abu Dhabi, engineered mouse fibroblast cells, known to synthesize collagen, to create induced pluripotent stem cells (iPSCs), a type of stem cell capable of becoming most type of cells. They used the iPSCs to create the cartilage-forming cells.

Before growing the iPSCs in culture, they were genetically modified to make green fluorescent protein (GFP), used as a way to mark cells containing cartilage specific collagen protein.

After two weeks in culture, the iPSCs formed tiny masses of two types of cells — one showing the presence of GFP, and the others devoid of it. The GFP-positive cells had higher levels of type II collagen, a cartilage-specific collagen protein, than GFP-negative cells. The GFP-positive cells also showed significantly higher activity of the gene coding for type II collagen.

The GFP-positive cells also successfully repaired defective cartilage tissues isolated from young pigs.

"This new technique allows us to create nearly limitless amounts of cartilage that is genetically matched to the original donor and could be used for screening pharmacological compounds for treating osteoarthritis," says Guilak.


  1. Diekman, B.O. et al. Cartilage tissue engineering using differentiated and purified induced pluripotent stem cells. Proc. Natl. Acad. Sci. Unit. States. Am. doi:10.1073/pnas.1210422109