Scientists say they have made a significant step towards finding a new treatment for osteoarthritis, a disease that can leave people unable to walk.
Arthritis can cause severe pain
Researchers at Bristol University successfully grew new cartilage from a patient's own stem cells.
They hope the technique will allow them to carry out transplants in the future, but experts warn it could take over a decade to perfect the technique.
Osteoarthritis, a form of rheumatic disease, affects 2m people in the UK.
Experts from Bristol University grew a piece of cartilage using stem cells, which are self-renewing and have the ability to grow into blood, bones or organs.
The cells were taken from the bone marrow of people undergoing hip replacement operations because of the disease.
The cells were placed in a solution to help them develop. They were then grown into a scaffold made up of polyglycolic acid, which is the same material used to make dissolvable, surgical stitches.
This means that once the cartilage is transplanted, the scaffold should melt away.
'Really good quality'
The new technique is expected to overcome problems of transplant rejection because the patient's own cells are used to create the cartilage.
Ethical concerns over using human embryos in stem cell research can also be avoided.
Dr Anthony Hollander from Southmead Hospital, where the research has been carried out, told the BBC: "We believe this is the first time really good quality cartilage that's very similar to your own cartilage has been grown in this way."
But experts warned that perfecting the technique for transplants could take more than a decade.
Professor George Nuki, from the British Society for Rheumatology, said: "I think we should be encouraged but not overly excited. At the moment this is a milestone but not really a breakthrough."
There is no single cause of osteoarthritis but several factors can increase the likelihood of getting it, including being over 40, female, overweight or having an existing injury to a joint.
With the disease, the smooth cartilage that takes the strain in a normal joint becomes rough, brittle and weak.
To compensate, the bone beneath it thickens and spreads out, forming knobbly outgrowths.
The membrane surrounding the joint also thickens and the fluid-filled space within it becomes smaller.
As osteoarthritis gets worse, bits of cartilage may break away from the bone, causing the bone ends to rub together and the ligaments to become strained.
This causes a lot of pain and changes the shape of the joint.
Osteoarthritis is most common in the hands, knees, hips and feet but some people also develop it in the back and neck.