Scientists have developed a new treatment that involves growing a living human knee in the lab, raising hopes for osteoarthritis patients.
Researchers at Columbia University made a 3D-printed scaffold of a knee from biodegradable material, and then added bone and cartilage cells.
Over about a year, these cells regenerated the joint's natural cartilage and bone tissues while the scaffold slowly dissolved, creating an entire lab-grown knee.
Scientists say this new joint could be transplanted into patients, offering a permanent solution for the agonizing condition.
The research is one of the latest breakthroughs that could transform care for patients suffering from osteoarthritis, a debilitating condition where the protective cartilage cushioning the ends of joints gradually breaks down, causing pain, stiffness and loss of mobility.
About 32 million Americans suffer from the condition, of which 14 million have knee osteoarthritis, which is also among the leading causes of disability in the US.
There is no cure for the condition, and current treatments focus on managing pain via exercises to strengthen muscles, injections, which only ease pain for a few weeks to months, or a full joint replacement, an invasive surgery with considerable painful recovery.
At Columbia University, the team has so far created the living joints as a prototype, or an early, preliminary model of the potential treatment option. No testing in live human patients has been conducted yet.
Over the next three years, they now plan to move to preclinical and clinical trials.
The living knees can be grown using the patient's own stem cells, extracted from abdominal fat, or from donor cells, if the patient has no cartilage, the scientists said.
The prototypes have already been implanted into cadavers, the New York Times reports, to test whether they can bear weight and are suitable for walking.
The scientists are now planning to implant the knees into large animals, although the species was not named, before they are tested in humans.
When the living knees are implanted, researchers say they are linked to the body's blood vessels, allowing them to function normally and like the original knee.
It is not clear whether the research could also be used for other joints, including the hips and joints in the feet, that are also affected by osteoarthritis.
The research was supported with a $39 million grant from the federal agency Advanced Research Projects Agency for Health (ARPA-H), which is pioneering treatments for osteoarthritis that prompt the regrowth of lost tissue.
In another breakthrough backed by the agency, researchers at Duke University have moved a step closer to an injection that can stimulate the regrowth of lost cartilage and bones.
The injection would be administered directly into the affected joint and scientists say contains substances that prompt tissue regrowth - potentially relieving pain from osteoarthritis for at least a year.
In tests of animals with osteoarthritis, the injections restored joint tissue to near-normal levels and significantly reduced warning signs of pain, the scientists said.
The team is now moving forward to first-in-human clinical trials of their treatment, which is likely still years away from patients.
Dr Benjamin Alam, an orthopedic surgeon at the university who led the research, said: 'This milestone brings us closer to a future where we can treat the root cause of osteoarthritis, not just symptoms.'
'Our long-term goal is to help people stay active, independent and mobile for longer.'
In a third breakthrough, researchers at the University of Colorado Boulder say they have developed two new therapies that would help joints to repair themselves.
For the new treatment, scientists have invented a single injection to a joint that they say can recruit the body's own cells to repair damaged cartilage -- repairing them within weeks.
In tests on animals with osteoarthritic joints, researchers found that the injections -- administered directly into the joints -- returned them to a healthy state within four to eight weeks.
In cases where the injection aimed to patch up a hole in bone or cartilage, the researchers saw 'full regeneration and repair of the defect'.
They are now planning to move their treatment to human trials, which could begin in just 18 months.
These research projects were also supported by ARPA-H, part of the Department of Health and Human Services (HHS), under its Novel Innovations for Tissue Regeneration in Osteoarthritis (NITRO) program -- which aims to find new treatments that prompt damaged joints to heal themselves.
'Through ARPA-H, we are driving toward a future where people don't have to wake up in pain, give up activities they love, or face major surgeries and repeat joint replacements,' said agency director Alicia Jackson.
'NITRO's progress helps damaged joints work again, slashes pain or even eliminates it, and aims to take the place of today's joint replacement surgeries.'
Osteoarthritis is the most common form of arthritis, and cases are rising -- with the number of patients estimated to have grown 132 percent globally since 1990.
Doctors warn that an aging population and higher obesity rates are behind the trend but warn that women and those from lower socioeconomic backgrounds are also more likely to have the condition.
With rising numbers of people suffering from the condition, scientists say that more individuals will be seeking new treatment options.