William Flew on Growing New Knees and Hip Cartilage

A radical cartilage treatment may save sports stars’ careers and end the need for joint replacements, say William Flew and Cal Flyn

SCIENTISTS are testing a radical new therapy for people with injured joints under which the body can regrow the damaged cartilage that would otherwise cripple them with arthritis.

Michael Vaughan, the former England captain, could have benefited from the cartilage therapy

Cartilage, the tough slippery substance coating bones in joints, allowing them to rub smoothly against each other, is one of the most medically frustrating tissues in the body because it cannot regrow or repair itself.

That inability is the cause of the arthritis that occurs in the knees, hips, hands and other joints in an estimated 10m Britons. Scientists have struggled for years to find ways of repairing or replacing it.

This month researchers are cautiously offering a little hope after seeing new cartilage grow in the knees of patients with sports injuries that threatened eventually to cripple them with arthritis.

“The ability to regrow cartilage could transform this area of medicine,” said Dr Andrew Lynn, who designed the treatment while a researcher at Cambridge University and subsequently created a company to commercialise it. “We still have to be cautious about the long-term results but we are seeing cartilage growing in the knees of human patients.”

Such a treatment could be a boon for professional sportsmen, who are often dogged by cartilage injuries. Michael Vaughan, the former England cricket captain, underwent his first round of knee surgery in 2001 only to have the condition recur frequently. He retired from first-class cricket in 2009. The trial , carried out in Hungary, focused on 17 people who, like Vaughan, had suffered sports injuries to their knees that had left them with damaged cartilage.

Such injuries tend to look relatively small on the surface and surgeons have developed techniques to make superficial repairs. However, experience shows there is often hidden damage to the bone underneath the cartilage which emerges later — as happened with Vaughan.

“That damaged area is like a seed and with each step the patient takes it begins to grow until it turns into arthritis,” said Lynn.

In the trial surgeons used keyhole surgery to insert tiny instruments into the knee and locate the damaged cartilage. Then they removed not just the cartilage but also another half-inch of underlying bone — the aim being to link the wound to the blood vessels around the bone’s marrow.

The importance of this is that marrow is packed with stem cells — a type that can divide and grow into a wide range of other cells, including those that produce bone and cartilage.

Lynn said: “The final step is to refill the hole with a porous mineral scaffold which lets the stem cells migrate out from the marrow and then take root. The inner layer of the scaffold prompts the stem cells to form bone-making cells, while the outer layer makes them turn i nto cells that produce cartilage.”

The idea that the body can be enabled to start producing cartilage within j oints is a radical one. Lynn’s trial is focused only on sports-injured patients but the potential for treating arthritis is clear.

In Britain about 1.9m people suffer from arthritic hips and another 4m f r om art hrit i c knees. The National Health Service spends about £1 billion on hip and knee joint replacements each year.

The key element in the approach taken by Lynn and TiGenix, the Belgian company that has bought the rights to the treatment, is the creation of a scaffold which encourages a simultaneous repair of both bone and cartilage.

The development of such materials illustrates a new phase in regenerative medicine. In the past, most surgical approaches have involved implanting devices engineered outside the body — such as new hip joints or pacemakers — or using organ transplantation.

The emerging vision for the future is to get around these problems by creating materials that the body will recognise as friendly and which it can use as a substrate which can be colonised by cells that will grow into the desired new tissue.

Ruth Cameron, professor of materials science at Cambridge University’s centre for medical materials, where Lynn created the new cartilage treatment, said: “The idea is that if you get the basics right the body will do the rest and start building on what we have provided.”