Cartilage cells have been grown from embryonic stem cells, raising hopes of a new way to treat injuries, UK scientists have revealed.
Cartilage is found in joints, such as knees, as well as the ears and nose
The Imperial College London team converted the stem cells by growing them alongside cartilage cells.
Cartilage is the dense connective tissue which allows the smooth movement of joints.
The research, in Tissue Engineering, could help treat sports injuries, hip replacements and even cosmetic surgery.
Scientists can already treat cartilage damage by growing up healthy cartilage cells by from the patient.
However, there are some concerns over this technique - such as a limited supply of cartilage cells and damage to the site they are taken from. Implants, or prostheses can also be used.
Joint replacement delay
The Imperial team say this new technique could mean stem cells could be taken from the patient, grown in a laboratory, and then transplant them after the surgery.
The research involved growing human embryonic stem cells with chondrocytes or cartilage cells in Petri dishes in the lab in a specialised system that encouraged them to change into cartilage cells.
When this was compared with just growing the human embryonic stem cells alone, the mixed stem cells and cartilage were found to have higher levels of collagen, the protein constituent of cartilage.
The converted cells were then implanted in mice on a "scaffold" for 35 days.
When this scaffold was removed, the cells were found to have formed new cartilage, which the researchers say shows they can be successfully transplanted in living tissue.
The Imperial team say it could take around five years for the necessary research to be carried out to enable this technique to be used in patients.
Dr Archana Vats, an ear, nose and throat surgeon who led the research, said: "The problem we have now is that if cartilage gets damaged, it's very difficult for the tissue to repair itself.
"We can take replacement cells from the patient, but there can be problems accessing cell, damage at the site we take them from - and a limited supply."
She added: "With the UK's increasing ageing population there will be an inevitable increase in problems created by people living longer.
"Although doctors have been able to carry out joint replacements for a number of years, it has not possible to replace the worn out cartilage.
"By replacing the cartilage it may be possible to avoid the need for a joint replacement for some time."
Dr Chris Mason, head of regenerative medicine at University College London, said: "This is very good science.
"But we can grow cartilage cells already.
"With this technique, you would still have to take cells from the patient to get the cells with which you are going to convert the embryonic stem cells.
"And using embryonic stem cells, which would not be from the patient, you would have to take immunosuppressant drugs for the rest of their lives."