According to the procedure developed by Peterson, surgeons harvest a tiny snippet of healthy cartilage arthroscopically. This biopsy sample-about the size of a thumbnail clipping, according to Ross Tubo of Genzyme Tissue Repair, a subsidiary of Genzyme-is then sent to a cell culture laboratory. This bit of tissue, a mere 100 to 200 milligrams, is roughly 99 percent cartilage and 1 percent chondrocytes, the cells that actually make cartilage. So the sample must be digested to separate the cells from the matrix before the cells can be cultured.
After some three or four weeks, there are enough cells for an implant-roughly 30 million cells per milliliter of fluid. They are sent back in vials to the orthopedic surgeon, who performs traditional methods of knee surgery to insert the cells (researchers are also working on ways to deliver the cells by arthroscope).
Genzyme Tissue Repair began to market the cell-culturing service, which they call Carticel, in 1995. Since that time, more than 1,000 patients have been treated with a joint-restoring medicine that in a sense is of their own making. The procedure is not cheap: Genzyme estimates that the average cost is about $26,000. But the company has mounted a vigorous effort to get insurance companies and health maintenance organizations to reimburse the operation.
Sometimes the transplanted cells work too well. The most frequent side effect appears to be what is known as tissue hypertrophy-an excessive growth of cartilage. In one follow-up study, 43 percent of the patients had some degree of excess tissue growth in the implanted joint. On the other hand, early data suggest that the technique is in many cases quite successful for the optimal patient population-those between 15 and 50 years of age.
And the treatment appears to be durable. In a recent presentation to the American Academy of Orthopedic Surgeons, Lars Peterson reported that in a group of 38 patients who received a cartilage-cell transplant more than five years ago, 31 patients were judged to have had a good-to-excellent result two years after the procedure, and of those, 30 continued to show good-to-excellent results five years after.
Peterson has already applied the basic technique to patients with ankle and shoulder injuries in Sweden, and perhaps it’s only a matter of time before the phrase “autologous cultured chondrocytes” will trip mellifluously off the tongue of ESPN anchormen as they describe the cellular rescue of one more superstar fetlock. “I don’t know of any professional athlete that has used the procedure,” says Tubo, “but it certainly would be applicable to a career-threatening injury where you have a pothole in the middle of your cartilage.”