A stem cell therapy for osteoarthritis is to be tested on patients in the UK for the first time.
A year-long trial, funded by Arthritis Research UK, will mix stem cells with cartilage cells in the lab and inject them back into damaged knee joints.
The new treatment could be an alternative to joint replacement surgery, experts hope.
Scientists from Keele University will study up to 70 people from the end of this year.
The trial will be run at the Robert Jones and Agnes Hunt Orthopaedic Hospital in Oswestry, Shropshire as part of a five-year research programme.
Three treatments are being tested in a randomised trial of patients with osteoarthritis of the knee.
Using keyhole surgery, a patient's cartilage cells - also known as chondrocytes - and bone marrow stem cells will be removed and grown in a laboratory for three weeks.
They will then be re-implanted separately in some patients, and mixed together in other patients, into the area of damaged or worn cartilage.
Scientists will then test the effectiveness of all three types of cell therapy, based on the quality of the new cartilage formed over a period of 12 months.
Chondrocytes - cartilage cells - have been grown in a lab and re-injected into patients' damaged knees for the last 15 years.
But scientists now want to find out if combining cartilage cells and stem cells in the same process could work better, and specifically if one type of cell stimulates the other.
Osteoarthritis affects an estimated 8m people in the UK.
The condition is caused by wear and tear to the surface of joints, leading to stiffness and pain.
At present there is little effective treatment for osteoarthritis patients, apart from pain-relieving drugs and joint replacement.
The trial will focus on knee joints, but the results could have implications for other joints, say the scientists.
The advantage of stem cell treatment is that it's much less invasive than major joint replacement surgery.
Sally Roberts, professor of orthopaedic research at Keele University and lead scientist on the trial, says it's also a more "biological approach".
"We are using the body's own cells to repair damaged joints. The hope is that it will be permanent and long-term repair," she said.
But, even if successful, the treatment won't be used on everyone with osteoarthritis.
"Surgeons don't want to put implants into young patients in their 30s, so we are targeting these people for the use of this cell therapy if we can produce robust new cartilage cells.
"Stem cells certainly have huge potential - we just need to learn how to harness it properly," she added.
Jane Tadman, spokesperson for Arthritis Research UK, said: "This is just the start of developing this technique, and it could be a few years before such treatment will be in routine use."