Osteoarthritis is a leading cause of disability all around the world. It affects nearly one in six people in the United States, where more than $125 billion goes toward treatments to reduce pain or delay additional treatment. There is no cure; osteoarthritis is not preventable, and we are not sure what causes it to develop.

But change is on the horizon.

The microJoint, a three-dimensional model that replicates a human joint on a small scale, is under development in Pittsburgh . Once completed, it could have the potential to revolutionize the treatment of conditions related to joint complications, such as osteoarthritis. A radically new way of thinking — and a culture that encourages risk-taking — were key to its development.

Leading the charge on this groundbreaking project is principal investigator Rocky Tuan, PhD, director of the Center for Cellular and Molecular Engineering in the Department of Orthopaedic Surgery at the University of Pittsburgh and a fellow of the National Academy of Inventors. He is also vice chancellor and president of the Chinese University of Hong Kong. He and his collaborators at Stanford University and Tulane University were recently awarded $1.75 million from the National Institutes of Health for their work, which has already shown incredible promise.

The microJoint is composed of human tissues, constructed in the laboratory and grown as microscale structures – usually referred to as tissue chips – and generated using three key components: adult mesenchymal stem cells as the cell source, biological factors to facilitate growth, and a light-polymerized gel that acts as a scaffold.

Engineered cartilage serves as the centerpiece of the model, sitting in a small cylindrical chamber within a microbioreactor built by Dr. Tuan’s team using 3D printing. The cartilage is connected to a series of similar chambers that house the key elements of the microJoint — including the synovium, macrophages, and an infrapatellar fat pad — by a precisely calibrated set of microtubes containing synovial fluid and other tissue fluids. The model may not look much like a human joint, but physical appearances aside, it is nearly identical.

“The only difference between the cartilage we’ve grown and the cartilage in your body is that ours was constructed from scratch as a tissue chip,” said Dr. Tuan. “It’s truly identical to human cartilage, meaning we’ll be able to use it to better understand joint diseases and test experimental treatments.”

Dr. Tuan and his team believe the microJoint could usher in the development of a new wave of effective, permanent treatments, in some cases even replacing options like opioid prescriptions and joint replacements.

The microJoint could revolutionize the testing process, shortening the path to discovery in research

The journey from concept to clinical application is a long, expensive one. Years of research, funding, and promising results often hit brick walls in the clinical trial period, and people developing new ideas can invest significant sums only to reach a dead end. But thanks to the microJoint’s innovative design, many roadblocks may be avoidable.

Normally, researchers trying to understand an injury and its possible treatment would need to study a system all together. After all, most biological processes work as complete systems, not on their own – each step of the process affects what is downstream, eventually shaping the outcome. This approach shows us the big picture, but sometimes being able to separate systemic processes into individual steps can allow researchers to fine-tune their approach and discover details that may be obscured when the system is studied in toto. The design of the microJoint isolates major components of the human joint, allowing researchers to study the reactions of these individual components to various stimuli.

“Let’s say you were in a car crash, and the trauma to your kneecap injures the underlying infrapatellar fat pad,” said Dr. Tuan. “Not only can we mimic this injury with the microJoint, we can see how the synovium alone reacts to the injury; we can see how macrophages respond — we can even analyze what they secrete. Then we can examine what this does to the entire system. It allows for a level of understanding that was not possible before this model existed.”

To put it simply, medicine’s brightest minds can get back to the drawing board faster, with more powerful insights into the problem they are trying to solve.

A calling for excellence and innovation foundational to microJoint success

“I believe that in all areas of medicine, the key requirement for excellence is quite simple,” said Dr. Tuan. “Innovation comes from people who are motivated to change the way medicine is being practiced today to make it better tomorrow. We must always be looking for improvements with the mindset of being unsatisfied with the satisfactory. That’s something that’s woven into the culture at both the University of Pittsburgh; it’s not something that can be claimed by many other organizations.”

This mindset has proven to be critical as Dr. Tuan’s team continues to work toward turning the idea of regenerative medicine into a reality. The freedom to come up with and execute these ideas that will radically change medicine is one of the reasons Dr. Tuan continues to work with his colleagues in Pittsburgh.