Tear Your Meniscus? This “Living Bandage” May Help
When Sir Martin John Evans published evidence of the first embryonic stem cell cultures in 1981, the research offered a glimmer of hope in the medical field. Many thought that these unspecialized cells could be a panacea.
The idea is tantalizing: With a little coaxing, these cells have the potential to turn into anything from skin to cartilage. They could even grow into complete organs or body parts. And in recent years, researchers have learned that these cells have another special property: they can spur growth in nearby tissues.
Thirteen years ago, it was this latter property that enticed Anthony Hollander, the head of the Institute of Integrative Biology at the University of Liverpool, to figure out new ways to repair meniscus tears in knees. Now, Hollander and his team have finally completed the first in-human trial of the so-called “living bandage.” And today, he was officially granted a patent (US Pat. No. 9,539,364) for the invention.
The bandage consists of a thin scaffold of collagen—a protein found in connective tissue that can form a porous but tough material. The researchers infuse this layer with a type of stem cells, known as mesenchymal cells, cultured from the bone marrow of each patient. During the repair, the doctor places the bandage between the two sides of the meniscus and then sutures the meniscal-collagen sandwich together. The idea is that the stem cells emit growth factors that promote the healing of the meniscus tissue, helping the two sides knit back together.
The new study, published recently in Stem Cells Translational Medicine, documented the first test of this bandage in five human subjects ages 18 to 45 with meniscus tears. After two years, three of the patients remained symptom free.
Meniscus tears are a common injury, but they are notoriously difficult to repair. This pair of c-shaped cartilage rings in each knee act like shock absorbers, cushioning the knee from impact while walking, running, jumping and lunging. They protect the caps of cartilage that cover the ends of bones that come together in the knee. As we age, however, continued stress causes the menisci to wear, which means tears.
The problem, Hollander explains, is that the meniscus doesn’t heal like a cut on your arm. Tears in the outer edges of the disc heal relatively well. This region, known as the red-red zone, has relatively good blood supply. But that decreases towards the inner edges of the disc, known as the white-white zone. Tears in this region don’t easily repair themselves. The injuries addressed in this study all occur in the region of intermediate vascularity (red-white zone) as well as the white-white zone, meaning these tears are the most difficult to fix.
Until the last several decades, the repair for meniscus tears was the removal of part or all of the meniscus containing the break. But researchers now believe this leaves the joints more susceptible to osteoarthritis—a degenerative condition in the joints. Without the cushion of the meniscus the joint is thought to suffer greater wear and tear as the cartilage of the knee is stressed during basic daily activities like walking and stair climbing. Even so, this procedure remains the most common treatment for meniscus tears.
So are stem cells the solution?