For people with knee joint injuries, the most promising source of new cartilage might be right up their noses. For the first time, doctors in Switzerland have grafted cartilage from the nose into the knees of patients with severe injuries to this connective tissue, the tearing of which can lead to pain and even osteoarthritis. Doctors now have limited means of repairing cartilage: They can graft or inject knee cartilage cells from a cadaver or a healthy part of the person’s own joint. Or they can create tiny breaks in the underlying bone in the hopes of releasing progenitor cells that can restore the cartilage. But over the last decade, researchers have realized that cartilage cells from the nose are adept at forming new tissue that can hold up to the mechanical stress of the knee joint. And extracting those cells is much less invasive and damaging than digging around in someone’s knee. In a study published online today in The Lancet, researchers cut a flat chunk about the diameter of a pencil eraser out of the septum dividing participants’ nostrils, then broke down the tissue with enzymes and grew the cells on a porous membrane. When transplanted into knee joints, the grafts took on key characteristics of knee cartilage, as measured by their concentrations of key structural molecules like the protein collagen and sugar molecules called glycosaminoglycans. The patients also experienced less pain and better daily function—improvements comparable to that of the alternative methods, the authors note. They concede that those effects could be due in part to the placebo effect or improvements independent of the procedure, but they say the results are promising enough to warrant a phase II trial in 108 patients at four different clinical centers, which is underway now.
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