Cartilage Repair: Is it possible? An update from the Orthopedic Research Society symposium

Every year, the top orthopaedic researchers gather for a four-day conference to share their latest findings and hear from experts in the field, at the annual meeting of the Orthopaedic Research Society (ORS).

As a part of this year’s meeting, Dr. Kevin R. Stone was honored to join Dr. Gordana Vunjak-Novakovic as an invited speaker in a special translational research symposium session entitled “Cartilage Repair: Is it possible?” The session, which was moderated by Dr. George Dodge and attended by over 1,000 members of the ORS, provided the audience with two views on how to solve this problem.

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In his talk, “A Physician-Scientist’s Perspective: 25 years of clinical effort.” Dr. Stone highlighted the various techniques that have been created to repair cartilage and showed examples of patients who had undergone articular cartilage paste grafting with up to 20 years of clinical follow-up.  

Dr. Stone explained the logic of combining marrow cells, with bone marrow and articular cartilage cells and matrix all in one paste to fill cartilage defects, and then applying CPM motion to stimulate cartilage repair.

He went on to highlight the need to address all the issues that are hurting the joint, including meniscus and ligament injuries, showing data from a 2-12 year study which reported 79% success at an average estimated survival of 9.9 years in patients with osteoarthritis who underwent meniscus transplantation. Dr. Stone concluded that, based on his research and clinical experience, cartilage repair is indeed possible. He added the caveat that while the repair tissue might not be perfect, it can provide patients with pain relief and allow them to be active again.

Finally, he offered the audience a glimpse of what he believes is the future of clinical treatments. In order to overcome limitations of current techniques such as supply, defect size constraint, and recovery time, Dr. Stone explained preliminary research that he has done to load tissues with stem cells prior to surgical implantation. Dr. Stone’s hope is that by loading these tissues with the patient’s own cells, he can create a stronger, faster healing, more durable repair tissue.

Following Dr. Stone’s talk, Dr. Vunjak-Novakovic explained nearly 20 years of her work in tissue engineering in her talk, “Cracking the cartilage conundrum: A bioengineer’s view.” Dr. Vunjak-Novakovic explained that, similar to Dr. Stone, the basis of her research involves taking cells from a patient in order to build a repair tissue. Where her approach differs however, is that she then places the cells into a custom-built scaffold. The combined cell and scaffold structure is then placed in a sealed, highly-controlled system called a bioreactor. Once inside the bioreactor, the cells are given all of the nutrients that they need to grow and flourish inside the scaffold, and over a period of several weeks, they grow into a tissue that can be implanted back into the patient.

Dr. Vunjak-Novakovic noted that the first clinical application of this approach was the Carticel technique. In this technique, articular cartilage cells were harvested from a healthy portion of the patient’s knee, grown in cell culture at a specialized lab, and then implanted back into the patient’s cartilage defect several weeks later.

This technique differs from more modern approaches, which now use scaffolds to assist the incorporation of the new cells into the defect. Most impressive were experiments based on the observation that cartilage grows naturally on the surface of intact bone. In a series of experiments, Dr. Vunjak-Novakovic and her colleagues found that by introducing human bone marrow stem cells (mesenchymal stem cells or hMSCs) to bone scaffolds and cartilage defects with a boney base layer in a controlled bioreactor environment, they could regrow functional cartilage tissue. Dr. Vunjak-Novakovic concluded by stating that the future success of tissue engineering will depend on the combination of research efforts and clinical translation to ensure that the engineered tissues will be able to survive after being implanted into the patient.

While the two speakers presented different approaches to solve the same problem, both agreed that cartilage repair is indeed possible, and that while great efforts have been made to date, there is still much work to do before these approaches are perfect.

It is our wish that this session will inspire clinicians and researchers alike to keep the needs of the patients and the clinical reality of injured joints in the front of their minds when developing and refining cartilage repair techniques.