Nanostimulators boost stem cells for muscle repair

In regenerative medicine, an ideal treatment for patients whose muscles are damaged from lack of oxygen would be to invigorate them with an injection of their own stem cells.

In a new study published in the journal ACS Nano, researchers at the University of Illinois at Urbana-Champaign demonstrated that "nanostimulators" – nanoparticles seeded with a molecule the body naturally produces to prompt stem cells to heal wounds – can amp up stem cells' regenerative powers in a targeted limb in mice.

"We wanted to utilize the natural functions of the stem cells and the stimulating factors to address muscle ischemia locally," said study leader Hyunjoon Kong, a Robert W. Schafer Professor of Chemical and Biomolecular Engineering at Illinois.

Muscle ischemia, or damage to muscle from limited oxygen or blood supply, can result from multiple causes, such as injury to a limb or peripheral artery disease.

A molecule naturally produced in the body called tumor necrosis factor alpha can spur the stem cells to secrete more of the desired factors. Other studies have tried incubating the cells with TNF-alpha before injection, but the effects fade quickly, Kong said.

The Illinois team decided to try tethering the TNF-alpha directly to the stem cells, creating nanostimulators – nanoparticles laced with TNF-alpha. The nanoparticles bind to a receptor on the surface of the stem cells, providing localized, targeted and extended delivery of TNF-alpha.