New gel could lead to cartilage repair

A new scaffold material that contains cartilage cells and encourages their growth could help scientists create living tissue replacements suitable for treating osteoarthritis and sports injuries, a team of researchers says.

TOUGH TISSUE. Round cartilage cells thrive in a laboratory-made peptide gel. Kisiday

The gel, after it’s been seeded with cells in the laboratory, could someday be inserted through a small incision to an area of cartilage damage. The tissue would continue to grow as the scaffold gel breaks down, says Alan Grodzinsky of the Massachusetts Institute of Technology (MIT).

Doctors already repair some cartilage damage by removing cartilage cells from a patient, culturing them in a flat dish, and then implanting the material at the damaged site. This process doesn’t yield truly cartilagelike tissue, says Grodzinsky. A better approach would be to enable cells to grow in three dimensions, as they do in the body, says Grodzinsky’s MIT coworker Shuguang Zhang. That’s where the new degradable gel comes in.

Although many researchers are trying to develop scaffolds for growing cartilage, the MIT peptide scaffolds have an architecture with dimensions that match the size of cells better than the other materials do, says Zhang.

Grodzinsky, Zhang, and their colleagues made the scaffold gel from artificial protein fragments, or peptides, using techniques developed by Zhang (SN: 12/2/00, p. 364). The researchers then seeded these 3-D peptide networks with cartilage cells taken from young cows. After 4 weeks, the cells were still alive and producing molecules found in cartilage such as the tough protein collagen, the team reports in the July 23 Proceedings of the National Academy of Sciences. In further tests, cells in the peptide scaffolds thrived for as long as 53 days, says MIT team member John Kisiday.

What’s more, Kisiday says that the cells grew even more cartilagelike when he “exercised” them. For that purpose, the researchers periodically compressed the material at pressures comparable to those on knee cartilage during walking or running. The group plans to improve the material further by incorporating growth factors in the gel and designing it to degrade at a given rate.

The researchers’ next step is to test their material in laboratory animals, says Kisiday.

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