Going Weak in the Knees over Nanofiber ScaffoldGoing Weak in the Knees over Nanofiber Scaffold

May 11, 2009

2 Min Read
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Researchers in the Cartilage Biology and Orthopedics Branch of the National Institute of Arthritis and Musculoskeletal and Skin Diseases (Baltimore) have developed a nanofiber scaffold to replace damaged or lost cartilage. Headed by Rocky Tuan, the team employs electrospinning, a technique adopted from the textile industry, to weave a scaffold that is structurally similar to the extracellular matrix, a fibrous material that supports the body's connective tissue.Cartilage damage often results in osteoarthritis, a degenerative joint disease that affects approximately half of the population by age 65. Traditional methods for repairing or replacing cartilage involve encouraging cell-rich blood and bone marrow to form clots in the damaged area or transplanting cartilage cells collected from healthy joints. However, both procedures create a scarlike version of cartilage that is more fibrous than the real thing and does not appear to have the same durability. "It's like a pothole filler," remarks Tuan. "It's not the same as resurfacing, but if the stuff hangs in there, it will last a couple of winters and it's fine."Based on a liquid polymer material, Tuan's nanofiber scaffold is generated when the material is subjected to a strong electric field, causing it to form long fibers when it attempts to dissipate the charge. After formation, the fibers are collected in a tangled ball that resembles cotton candy. Then they are seeded with mesenchymal stem cells—adult stem cells derived from bone marrow, fatty tissue, and other sources that can be formed into muscle, bone, fat, and cartilage.Experiments demonstrate that nanoscale structures are more effective at growing cells than millimeter-scale ones. Finer scaffolds are more on the scale of what a cell would normally see, states Farshid Guilak, director of the Orthopaedic Bioengineering Laboratory at Duke University (Durham, NC).Pilot tests on pigs' knees have shown that in six months, the cell-laden scaffolds can grow new tissue with a smooth surface and mechanical properties similar to those of natural cartilage. The new tissue also has molecular markers characteristic of normal cartilage. Using polymer material that has already been approved for medical use, Tuan and his group aim to commence with human trials within the next two years.

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