Cultivated cartilage could help arthritic knees

A UCD researcher is studying the possibility of growing knee cartilage cells in the lab to replace those lost to arthritis, writes…

A UCD researcher is studying the possibility of growing knee cartilage cells in the lab to replace those lost to arthritis, writes Claire O'Connell

Growing older can take the spring out of your step as knee joints succumb to decades of wear and tear. But a researcher at University College Dublin (UCD) is figuring out how best to grow cartilage-making cells in the lab, with a view to giving people with painful joint conditions a leg up on healing.

In the degenerative condition knee osteoarthritis, which affects around 30 million people worldwide, the natural cushion of cartilage that covers the ends of bones at joints wears down, says Prof Mohamed Al-Rubeai, who is professor of biochemical engineering at UCD and a principal investigator at the centre for synthesis and chemical biology.

"Injuries in the cartilage may arise either through a traumatic mechanical destruction or progressive mechanical degeneration, and this can lead to pain in the joint" he explains. "But the problem with cartilage is that it has a limited ability to heal, and the healing capacity decreases with age."

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The key to making new cartilage is a good supply of "progenitor" cells. These can develop into cells that make the cushion of cartilage that keeps joints supple. But as we age, the number of progenitor cells falls dramatically, meaning we become less capable of producing new cartilage, says Prof Al-Rubeai.

One way of treating osteoarthritis is to transplant fresh cartilage into the ailing joint. The cartilage can come from the patient themselves or from someone else, but there are problems associated with both approaches, he says.

If the cartilage comes from the patient, who already has limited healing capacity, it is less likely to graft onto the damaged area. And if the cartilage comes from a donor, it may be rejected unless the patient takes immunosuppressant drugs.

A process called cell therapy provides a potential way around these problems, states Prof Al-Rubeai. "You remove the patient's own cells by biopsy, you grow them in the lab, then you re-implant them into the defect," he explains.

The patient is receiving their own cells so there's little chance of rejection, but the healing capacity of those cells has been beefed up through careful management in the lab.

The trick is to isolate the all-important progenitor cells and grow them up in substantial numbers outside the body. "These cells have to be able to synthesise the cartilage matrix at any time when you harvest them," says Al-Rubeai.

He has worked out that isolating and growing the progenitors in the lab provides more scope than simply growing mature cartilage cells for transplant. "We know mature cells, which are normally used, don't last more than 16 generations. But so far we have found that these progenitor cells can maintain their ability to form perfect cartilage for 60 generations," he says.

His work, which he started at the University of Birmingham and is continuing in Dublin, also looks at how to create optimal and economically viable conditions for growing cartilage-making cells in vast numbers in the lab.

Prof Al-Rubeai currently uses progenitor cells from cows to work out a regime for optimal growth in the lab, but he believes the technology will transfer easily to human cells. "We don't think there will be a substantial difference in the physical and chemical environment required for the expansion of the human cells," he says.

He is also working with a UK-based company to develop methods of seeding progenitor cells grown in the lab onto biodegradable scaffolds that could be implanted into a patient. "It is at an early stage, but we think that with the proper funding and with the collaboration of clinicians we will be able to take this technology into the clinic," he says.