Cartilage grown from stem cells that release anti-inflammatory molecules has been grown in a laboratory. The artificial cartilage could be ready for testing in humans in as little as three years, with scientists saying it could fend off the return of arthritis while providing an alternative to hip-replacement surgery.

The most common reason for hip replacements is arthritis. At present, surgeons are reluctant to carry out hip replacements in patients under the age of 50 because the prosthetic joint normally does not last beyond 20 years, meaning a second operation would be required in later life. Removing an old prosthetic can destroy the bone and lead to infection. Carrying out surgery in later life also comes with greater risks.

A team of US scientists programmed stem cells to grow into cartilage on a 3D template via textile manufacturing methods. Furthermore, they used gene therapy techniques so the cartilage releases anti-inflammatory molecules when activated with a drug.

In their study, published in the journal PNAS, the team showed how they created a biodegradable synthetic scaffold that had been moulded to the exact shape of a patient's joint. This was then covered in cartilage made from the patient's own stem cells. The scaffold could then be implanted onto the arthritic hip, resurfacing it with living tissue. This could ease arthritis pain, meaning that the need for a hip replacement could be either put off or eliminated altogether.

Further to this, the anti-inflammatory molecules were shown to be activated by a drug. Typically, when inflammation levels increase, the cartilage is destroyed – resulting in pain. However, by inserting the gene, when levels rise anti-inflammatories can be released, potentially preventing arthritis from returning.

Study author Farshid Guilak, from Washington University, said: "When there is inflammation, we can give a patient a simple drug, which activates the gene we've implanted, to lower inflammation in the joint. We can stop giving the drug at any time, which turns off the gene.

"Replacing a failed prosthetic joint is a difficult surgery. We've developed a way to resurface an arthritic joint using a patient's own stem cells to grow new cartilage, combined with gene therapy to release anti-inflammatory molecules to keep arthritis at bay. Our hope is to prevent, or at least delay, a standard metal and plastic prosthetic joint replacement."

At present, customised implants are being tested in laboratory animals and the team hopes to begin human trials in three to five years. Bradley Estes, from Cytex Therapeutics, said: "We envision in the future that this population of younger patients may be ideal candidates for this type of biological joint replacement."