'Living hip' grown in lab genetically engineered to stop arthritis
Arthritis sufferers have been offered new hope after scientists grew a ‘living hip’ in the lab which not only replaces worn cartilage but stops painful joints returning.
Researchers in the US have used stem cells to grow cartilage in the exact shape of a hip joint while also genetically engineering the tissue to release anti-inflammatory molecules to fend off the return of arthritis.
The idea is to implant the perfectly shaped cartilage around the joint to extend its life before arthritis has caused too much damage to the bone.
Severe loss of cartilage can lead to bone rubbing on bone, altering the shape of the joint and forcing the bones out of their normal position.
The technology is likely to work for all joints, and could offer an alternative treatment for the 160,000 people in Britain who need hip or knee replacements each year, without the need for metal prosthetics.
In the UK around eight million people suffer from osteoarthritis which occurs when cartilage which surrounds the bone joint starts to roughen and thin out, making movement difficult and painful.
The breakthrough also offers new hope for younger patients, who are often told to wait until they are older for surgery, even when in significant pain.
Current prosthetics only last for a maximum of 20 years, and surgery to replace them risks damaging the bone further, and can lead to infections.
“Replacing a failed prosthetic joint is a difficult surgery,” said Dr Farshid Guilak, a professor of orthopedic surgery at Washington University.
“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."
The technique uses a 3-D, biodegradable synthetic scaffold which is moulded into the precise shape of a patient's joint, based on scans, and then covered with stem cells taken from fat beneath the skin.
The scaffold is built using a weaving pattern that allows the stem cells to transform into the structure and shape of normal cartilage.
Because the implant is made from a patient’s own stem cells, there is no risk of rejection.
The scientists have also genetically engineered the cartilage so that it releases anti-inflammatory molecules when the patient takes a drug.
“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," said Dr Guilak, also a professor of developmental biology and of biomedical engineering.
“We can stop giving the drug at any time, which turns off the gene."
That gene therapy is important because when levels of inflammatory molecules rise in a joint, the cartilage is destroyed and pain increases.
Dr Franklin Moutos, vice president of technology development at biotech firm Cytex, which has been working with Washington University on developing the implant, said the living tissue had been shown to withstand the stresses placed on the joints.
“The implants are strong enough to withstand loads up to 10 times a patient's body weight, which is typically what our joints must bear when we exercise,” said Dr Moutos.
The implants are currently being tested in laboratory animals and if all goes well, the team hopes to being human testing within three to five years.
Dr Bradley Estes, vice president of research and development at Cytex, added: “We envision in the future that this population of younger patients may be ideal candidates for this type of biological joint replacement.”
The research was published in the Proceedings of the National Academy of Sciences.
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