Hair follicle stem cells repair nerve damage

 

Tissues differentiated from hair follicle stem cells have helped mice with severe sciatic nerve damage walk again, US and Japanese scientists reported on Monday.

These results suggest that hair follicle stem cells can promote nervous axon growth and functional recovery after nerve injury, thus offering an opportunity for the clinical treatment of peripheral nerve diseases, said the researchers.

The team, including researchers from the Massachusetts Institute of Technology, the Kitasato University of Japan, and the University of California, San Diego, reported this achievement in the latest issue of the journal the Proceedings of the National Academy of Sciences.

Embryonic stem cells, known to be capable of differentiating into almost all tissue cells, have aroused ethical debates in many countries. Scientists also found that problems such as immunologic incompatibility are linked with embryonic stem cells.

Therefore, more recent studies have focused on adult stem cells for future clinical applications. And hair follicles afford a highly promising source of relatively abundant and accessible, active, pluripotent adult stem cells, said the researchers.

In earlier studies, the team led by Robert Hoffman, a professor at the University of California, San Diego, has induced hair follicle stem cells to differentiate into blood vessel cells and neurons. The researchers said these studies suggested the potential of hair follicle stem cells to form diverse cell types.

Now the researchers have successfully coaxed the hair follicle stem cells to evolve into the Shwann cells, a variety of glia cells that wrap around axons in the peripheral nervous system.

When injected into disabled mice with injured sciatic nerve, these Shwann cells produced myelin sheaths that surround nerve axons, and then the mice were able to walk normally, the researchers reported.

"Therefore, by differentiating into Schwann cells, the hair follicle stem cells may stimulate the host axons to extend and, thus, to fill the transection gap," they said in the paper.

Hair follicle stem cells may be more promising in therapies, according to the researchers. In the future, patients with injured nervous system could be cured with their own hair follicle.

"Cell-replacement therapies show particular promise in the nervous system, where transplanted embryonic or bone-marrow stem cells have been shown to promote functional recovery in animal models of, for example, spinal cord or peripheral nerve injury," their paper said.

"Although the therapeutic potential of such transplants is clear, a number of problems remain. In particular, use of fetal tissue raise ethical issues," the paper noted. "Moreover, the use of heterologous human tissue requires immunosuppression, which is particularly problematic in individuals with long-term, neuron-specific problems."

"In this regard, the fact that hair follicle stem cells are generated from an autologous and accessible adult tissue source, skin, and that they can readily generate neuron-specific cell types provides a potential solution to these problems," the researchers concluded.