The rotator cuff is a grouping of tendons that keep the ball of your upper-arm bone in your shoulder socket – and, as many people will know from first-hand experience, it can get torn away from the bone. Surgery is sometimes required, although the weakened tendons will frequently just tear again after the operation. Now, however, scientists from the University of Connecticut have developed a method of regenerating rotator cuff tendons, using a nanostructured polymer mesh seeded with stem cells.

In lab rat studies, torn rotator cuff tendons were first surgically reattached to the bone (as they would be ordinarily), but then some of them were also wrapped in the stem-cell-seeded "nano-mesh." After a healing period of several weeks, the mesh-wrapped tendons were found to have made a better attachment to the bone than those that weren't wrapped.

Additionally, the wrapped tendons were stronger overall, and had a cell structure more like that of undamaged tissue, making them less prone to subsequent failure. By the time that the tendons had fully regenerated, the mesh simply biodegraded and was absorbed by the body.

While doctors do already sometimes inject stem cells directly into rotator cuff tears, the cells often don't stay at the surgery site long enough to do much good. The nano-mesh, on the other hand, gives them a place to "roost," so that they remain in place. They then send out signals that direct other cells to grow into tendon tissue.

It is now hoped that the technology could be used not just on torn rotator cuffs, but also on injured tendons in other locations such as the knee.

The research was led by Dr. Cato Laurencin, and is described in a paper published in the journal PLOS ONE.