To try and find out how to make damaged cartilage heal in old people, scientists have undertaken a study on fish to see how they do it.
The project, which has just been published in the medical journal Matrix Biology, was undertaken by Dr Doreen Ashurst of the Department of Anatomy, St. George's Hospital Medical School, London, looked at the Dogfish, an elasmobranch with a skeleton made from cartilage, rather than bones.
Ashurst made small cuts in the cartilaginous dorsals of the dogfish and monitored the health and repair of the wounds over a six month period. Although the wounds were inflammed for a couple of weeks and fibrous tissue formed about a month later, it took up to three months for cartilage-like tissue to regrow.
However, when this was scientifically examined it was found that it didn't have all of the properties of true cartilage. Instead it was made-up of large chondrocyte-like cells in a matrix and wasn't as vascularised. It didn't actually integrate back with the damage fin cartilage and merely acted as a sort of glue to bond the split fin back together.
Ashurst says that her study shows that elasmobranchs have no way of repairing damaged cartilage, so unfortunately, for those that suffer from the disorder, sharks and rays may not provide much in the way of inspiration for medical scientists.