A New Tissue Scaffold Helps Cartilage and Bone Grow

A new tissue scaffold that can stimulate bone and cartilage growth when transplanted into the knees or other joints could offer a potential new treatment for sports injuries and other cartilage damage, such as arthritis.

Researchers at MIT (Cambridge, MA, USA) and Cambridge University (United Kingdom) developed the triple coprecipitated collagen, glycosaminoglycan, and calcium phosphate (CGCaP) nanocomposites scaffold, which has two layers, one that mimics bone and one that mimics cartilage. To mimic the structure of bone, the researchers began with collagen (from a bovine tendon source) and glycosaminoglycan mixture; to mineralize the resulting collagen scaffold, the researchers than added the sources of calcium and phosphate. By varying the composition of the CGCaP suspension--thus enabling the production of scaffolds whose architecture was composed of pores of a mean size of 50-1,000 μm and controlling the cross-linking density--the researchers were able to produce a scaffold with a gradual transition between the bone and cartilage layers. When implanted into a joint, the scaffold stimulates mesenchymal stem cells in the bone marrow to produce new bone and cartilage. The technology is currently limited to small defects, using scaffolds roughly eight mm in diameter. The technology has been licensed to Orthomimetics (Cambridge, United Kingdom), which has recently started clinical trials of the scaffold in Europe. The new scaffold was described in a series of articles published in the March 2009 issues of the Journal of Biomedical Materials Research.

"We tried to design it so it's similar to the transition in the body. That's one of the unique things about it," said codeveloper Lorna Gibson, Ph.D., a professor of materials science and engineering at MIT. "If someone had a damaged region in the cartilage, you could remove the cartilage and the bone below it and put our scaffold in the hole."

There are currently several different ways to treat cartilage injuries, including stimulating bone marrow to release stem cells by drilling a hole through the cartilage into the bone; transplanting cartilage and the underlying bone from another, less highly loaded part of the joint; or removing cartilage cells from the body, stimulating them to grow in the laboratory, and reimplanting them.

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