Knee-d new cartilage? Look nose further
Patients with knee injuries have been treated using cartilage grown from their own noses, Swiss doctors announced this week.
Cartilage is the slippery "anatomical Teflon" secreted by specialised cells called chondrocytes. It coats the ends of bones and enables them to slide smoothly over one another in joints.
But more than 2 million people, usually through injury, are diagnosed with cartilage-related joint conditions every year, and the problem is often long-lived. This is because articular cartilage of the type found in joints has a very poor ability to self-repair.
At present, treatment options for cartligage damage are very limited, ranging from trying to stimulate injured cartilage to regrow by injecting growth-factor and platelet-rich plasma, to grafting pieces of cartilage from other joints or even completely replacing a joint with a prosthesis.
Now, for the first time in humans, doctors in Switzerland have taken the unusual step of looking to a person's nose for a potential solution.
This is because,, except for some small bones at the bridge, the bulk of the nose is built from nasal cartilage. This is similar to articular cartilage but with one important exception: it seems to have an enhanced potential for regeneration and growth.
With this in mind, Basel University's Ivan Martin and his colleagues recruited ten patients with cartilage injuries to their knees.
A team of plastic surgeons retrieved from each of the patients a small biopsy of cartilage measuring just a few millimetres across from the nasal septum. This was treated with enzymes to release the cartilage-producing chondrocytes which were then incubated in a culture vessel containing a suitable growth medium for fourteen days to increase their numbers.
At this point, 50 million of the cells were then transferred to a supporting matrix material and then incubated for a further fourteen days to enable them to bed down and mature. The result was a tissue "patch" about 2 millimetres thick and 30 by 40 millimetres in width and length.
Under local anaesthetic, and using standard knee operating techniques, the patches were implanted into the damaged knee joint, "butter side down" so that the new cells were in contact with the underlying bone at the injury site. The patients were then followed up for two years.
The results, published this week in the Lancet medical journal, show a significant improvement in function among all of the patients, who ranged in age from 15 to 55.
Studying the implanted nose cartilage also showed that it appeared to have remodelled itself to become more like articular cartilage and had increased the production of spongy molecules called glycosaminoglycans, which are highly abundant in normal cartilage.
The team acknowledge that their study does have its limitations though. For a start, there is no control group, so how the patients might have fared without the intervention isn't known. And it looked at only ten patients.
It is a promising start though, as Ivan Martin is keen to emphasise. "Our findings confirm the safety and feasibility of cartilage grafts engineered from nasal cells to repair damaged knee cartilage. But use of this procedure in everyday clinical practice is still a long way off as it requires rigorous assessment of efficacy in larger groups of patients and the development of manufacturing strategies to ensure cost effectiveness. Moreover, in order to extend the potential use of this technique to older people or those with degenerative cartilage pathologies like osteoarthritis, a lot more fundamental and pre-clinical research work needs to be done."