New joint built with stem cells

A pioneering study published online first in The Lancet week shows that failing joints can be replaced with a joint grown "naturally", using the host’s own stem cells. The work paves the way for future joints that would last longer than today’s artificial joints.

The work was carried out in the Tissue Engineering and Regenerative Medicine Laboratory of Dr Jeremy Mao, the Edward V. Zegarelli Professor at Columbia University, along with his team at Columbia University Medical Center, and colleagues from the University of Missouri and Clemson University.

"When it comes to replacing joints, whether it is a hip or a knee, orthopaedic surgeons know that the first question from a patient often is, ‘How long will the replacement last?’" Dr Mao says.

About 400,000 people each year receive an artificial joint to replace a knee, or a hip worn down by osteoarthritis, which involves the structural breakdown of cartilage and bone. An estimated 27 million Americans age 25 and older have the disease, according to the National Institutes of Health.

With an average lifespan of 10 to 15 years, any total joint prosthesis can become problematic for the increasing number of people under age 65 who need joint replacement surgery. These patients face the very real possibility that they will outlive the replacement joint and have to endure another grueling and invasive surgery down the road. Artificial joint prostheses, like the joints they are designed to replace, usually just wear out over time.

Joints made out of natural, biological materials may last longer, and more importantly, patients at an advanced age may not have enough bone left to support a metallic joint.

To set about growing a new joint, Dr Mao and his team first laser-scanned the surface contours of a hip joint in an animal model and then used a special bio-printer to create a three-dimensional life-sized scaffold upon which cartilage and bone could be regenerated.

Then, using a unique stem cell homing technique in the animal model, Dr Mao and his colleagues orchestrated the body’s own stem cells – without removing them from the body – to migrate to the scaffold. Growth factor infused in the scaffold helped the stem cells grow into a functioning, native "synovial" joint.

Stress tests of the new joint showed that it performed virtually the same as native articular cartilage. In other words, after four months of growth, the research yielded a fully functioning leg with a new joint that was grown using the animal host’s own stem cells, instead of stem cells that were harvested apart or outside of the host.

In an accompanying commentary also published by The Lancet, Dr Patrick H. Warnke in the faculty of health sciences and medicine at Bond University in Australia said the study by Dr Mao and his team "is a renaissance of employing the host as the bioreactor and recruiting the host’s endogenous cells, including stem/progenitor cells, for tissue regeneration. They have bucked the current trend of utilising ex vivo cultivated stem cell preparations for tissue engineering."

(Source: Columbia University Medical Centre: Lancet)