Spontaneous healing of Articular Cartilage (Sharc)
Helen McCarthy, John Garcia, Sally Roberts, Bernhard Tins, Paul Jermin, Peter Gallacher, Oksana Kehoe, Karina Wright, Caroline Stewart, Jan Herman Kuiper
Funded by Medical Research Council (MRC)
Osteoarthritis is a painful disease of the joint involving cartilage and bone at the joint. Many factors increase the risk of getting osteoarthritis. Very important among these factors is an injury or a defect of the cartilage. More than 250 years ago, a famous surgeon presented a paper at the Royal Society of London explaining that cartilage, once injured, does not heal. Since those days, doctors and scientists have thought that this is indeed the case. Nobody was therefore surprised that having a cartilage injury or defect is so dangerous when it comes to osteoarthritis.
Research from the past 15 years is now throwing doubt on this old certainty. Researchers who took regular MRI scans of volunteers over time noted that sometimes cartilage defects appear and then disappear. These observations suggest that perhaps cartilage can heal spontaneously or naturally. Over the past five years, we have studied this natural healing process in our cartilage cell therapy patients. Cell therapy starts with removing a piece of healthy cartilage, from which we grow the cartilage cells. This leaves a defect of around 10-15mm, which fills with new tissue over time. We studied this new tissue after 12 months on MRI scans and by taking a small biopsy from it (see picture insert). The biopsy was used to analyse the structure of the new tissue and what it is made of.
What we found showed that although the damaged cartilage did repair itself, it did not return to its normal structure, at least not in one year. For instance, collagens (especially type II) and proteoglycans are very important molecules in cartilage, and we found that their organisation was different in the naturally repaired cartilage compared to normal. This information may help to understand how we can encourage better repair tissue to form.
