If you’re over 60, a baseball pitcher, or an orchestra conductor, you have an increased risk of tearing your rotator cuff. Unfortunately for you, while repairing a rotator cuff is possible through surgery, failure rates have been reported to be as high as 94 percent. The main reason for this is that repairing a torn rotator cuff often involves reconnecting the tendons to the ball of the humerus in your upper arm. This presents a challenge, as tendons are compliant and stringy like rope, while bone is hard and porous like cement. Many rotator cuff repairs bring pain relief, but often times, further investigation will show that a tear has reopened or a new one has formed.
Researchers from Washington University in St. Louis (WUSTL) want to improve the success rate of rotator cuff repair surgery by changing the way that tendons in the rotator cuff are reattached to bone. While typical surgery involves suturing the tendon to the humerus, this new approach involves a patch made of mesenchymal stem cells, nanoscopic fibers, and hydroxyapatite to closely mimic the natural gradient from tendon to bone. The idea is that the patch will promote the maturation of the mesenchymal stem cells into osteoblasts (to form bone) at one end, and fibroblasts (to form cells found in tendons) on the other end.
The concept has been demonstrated in vitro and will soon be tested on rats.
Here’s the description of the biomimetic patch from WUSTL:
The WUSTL scaffold consists of a mat of nanoscopic fibers electrospun in Xia’s lab that mimics the structure of the collagen fibers in a tendon. The mat is then coated with a continuous gradient of hydroxyapatite, a mineral containing calcium and phosphorus that gives strength to bone, so that it is stiff and bone-like toward one end and compliant and tendon-like toward the other.
Finally the scaffold is seeded with adult mesenchymal stem cells, a type of stem cell that can mature into osteoblasts (bone-forming cells) or fibroblasts (cells common in tendon).
The idea is that as the fibers disintegrate over the course of a few months, the mineral gradient will promote the graduated differentiation of the stem cells. Stem cells toward the bone end will be coaxed by the presence of mineral to differentiate into osteoclasts while the stem cells at the tendon end, surrounded by aligned, unmineralized fibers, will form fibroblasts.
Article from Washington University: Biomimetic patch to be tested on tricky tendon-to-bone repairs