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Using stem cells to repair torn tendons

Weekend athletes who overexert themselves running or playing basketball may one day reap the benefits of research that shows adult stem cells can make new tendon tissue. Researchers Dan Gazit and colleagues at Hadassah Medical Center in Israel engineered mouse mesenchymal stem cells (MSCs), which reside in the bone marrow and fat tissue, to express a protein called Smad8 and another called BMP2, each involved in the formation of bone and cartilage. When the researchers filled small sponges with these cells and implanted the sponges into torn Achilles tendons of rats, they found that the cells not only survived the implantation process, but were recruited to the site of the injury and able to repair the tendon for at least 7 weeks after implantation. The cells changed their appearance to look more like tendon cells (tenocytes), and significantly increased production of collagen, a protein critical for creating strong yet flexible tendons and ligaments. Tendon tissue was detected using a special type of imaging known as proton DQF MRI, which recognizes differences among collagen-containing tissue such as tendon, bone, skin, and muscle. The authors note that BMP and Smad proteins are involved in other tissues such as nerve and liver, suggesting that this type of delivery technology may be helpful for other degenerative diseases. The study appears in the April issue of the Journal of Clinical Investigation.

In an accompanying commentary, Dwight A. Towler and Richard Gelberman from Washington University School of Medicine in St. Louis, states that "given our limited understanding of how MSCs become tenocytes, the recent progress demonstrated in these studies is quite remarkable and may be potentially useful in cell-based therapeutic approaches to musculoskeletal injuries."

TITLE: Neotendon formation induced by manipulation of the Smad8 signaling pathway in mesenchymal s
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Journal of Clinical Investigation
3-Apr-2006