Cartilage Grown in Lab Repairs Knees, Study Says

In a remarkable surgical advance that could benefit professional athletes and hundreds of thousands of weekend warriors, Swedish researchers report that they have been able to repair damaged knees using cartilage tissue grown in the laboratory.

Cartilage is the soft tissue that cushions joints, and when it is damaged, the trauma sets off a chain reaction of decay and disintegration that ultimately leads to the loss of the entire knee joint. More than 190,000 Americans have knee joints replaced each year.

There is currently no effective treatment for cartilage damage, but the Swedish scientists report today in the New England Journal of Medicine that they have used the lab-grown tissue to treat 23 people, with “good to excellent” results in 16 and some improvement in virtually all.

In several cases, individuals who could not work because of their knee damage are not only holding down jobs, but are back on the soccer field and the hockey rink as well, said Dr. Lars Peterson of the University of Goteberg.

Peterson said that since the study was completed, the research team has performed the procedure on an additional 65 patients with equally good results and is in the process of teaching surgeons from the United States how to perform it.

“For the first time, this gives us an effective tool with which to treat these patients,” he said.

“If this is indeed effective, it really does open up another door to treating people with knee injuries,” said Dr. Ralph Gambardello of the Kerlan-Jobe Orthopedic Medical Clinic in Los Angeles, where many athletes are treated. “There is no doubt that this is an exciting area of research and that it will have significant implications for clinical practice.”

Gambardello cautioned, however, that the results need to be confirmed in a controlled trial in which the surgery is compared to a sham operation in which an incision is made but the laboratory-grown tissue is not implanted. Such a trial is now being organized in Europe and will begin early next year, Peterson said.

Dr. Myron Spector of Brigham and Women’s Hospital in Boston hopes eventually to conduct a U.S. trial, which will be necessary before the federal Food and Drug Administration can approve the procedure for general use, but he wants to see more data about long-term wear in the joints first. Spector said the new results were “quite compelling . . . but not yet ready for widespread use.”

“I certainly wouldn’t mind (heading) one of the groups that participates in the trial,” said Dr. William Garrett of the Duke University Medical Center. “It looks very good.”

Cartilage lines the inner surfaces of the knee and other joints to minimize friction. It is extremely slippery, with only one-fifth the friction of ice sliding on ice. In healthy joints, cartilage slowly regenerates as it wears out. But it cannot recover from the more severe damage caused by a serious athletic injury. “If we leave a hole in it, a year later there is still a hole,” Garrett said.

Researchers have made many efforts to regenerate cartilage in damaged joints, but without success. That may be because the cartilage does not have its own blood supply or because something destroys it faster than it can regenerate, according to Dr. Henry J. Mankin of Massachusetts General Hospital in Boston.

In one current procedure, a somewhat different form of cartilage can be grown at the site of the injury by drilling holes in the bone, which allows cells called fibroblasts to migrate from the bone and fill in the injury site. But this “pseudocartilage,” said Gambardello, is less durable and much rougher than original cartilage. This procedure does not restore complete motion and the repair is not durable.

Peterson and his colleague, Dr. Anders Lindahl, circumvented this problem by removing a small section of cartilage from a spot on the joint that does not receive wear. They then grew the cells in a laboratory dish using a variety of techniques and growth factors that have recently been developed for growing cells outside the body. Within three weeks, they had 10 to 20 times as many cells as they started with.

The surgeons then cleaned all the dead cartilage cells out of the wound, covered it with a flap of membrane removed from nearby bone to hold the cells in, and injected the cells. The procedure now requires cutting open the knee, but the researchers are developing an arthroscopic procedure to minimize recovery time. Patients receive a special exercise program to help them strengthen their knees.

When Lindahl and Peterson cut into the repaired knees later to examine the cartilage, they found that in most cases it was like the original tissue rather than the rough, fragile cartilage produced by conventional procedures. “That’s very significant,” said Gambardello. “If they can get a better surface to form, then obviously those patients are going to do better.”

Injuries to the knee can occur in either the upper, or thighbone, portion of the joint or the lower portion, the kneecap. The procedure worked best in patients with damage to the thighbone portion: 14 of 16 patients had good to excellent results. In the seven patients with kneecap damage, only two showed “good to excellent” results, although five had improved mobility of the joint.

One of their patients was Henrik Esbjornsson, 24, a professional athlete who plays a form of ice hockey called bandy. Seven years ago, he injured the cartilage on his thighbone, which caused his knee to be very painful and to lock up frequently. Now, he told the Associated Press, “I can use the knee as I could before. It’s completely OK.”

Peterson noted that the lower success rate with damaged kneecaps was not unexpected because kneecaps undergo more stress than the thigh bones. He said his team is revising the kneecap procedure in an attempt to make it more successful.

Clinical trials of the procedure are being supported by BioSurface Technology Inc. of Cambridge, Mass., which is developing new ways to grow the cells. If the procedure is eventually approved by the FDA, BioSurface would take the biopsy specimen from the surgeon, grow the cells in the lab and then return them for implantation.

A New Knee

Swedish researchers have developed the first technique to repair damage to cartilage, the tissue that cushions joints.

A) They remove a small slice of cartilage from a non-weight-bearing area of the knee.

B) The cartilage cells are multiplied in the lab to increase their volume at least tenfold.

C) Surgeons clean all the dead tissue from the wound and cover it with a flap to hold the cells in.

D) The cells are then injected into the cavity, where they grow and fill the gap, ultimately restoring function.

Source: University of Goteberg