Stem Cells that Promote Nerve Regeneration

A study by Johns Hopkins researchers W. P. Andrew Lee and Gerald Brandacher have used stem cells from fat to promote nerve regeneration in rats that have suffered paralyzing leg injuries and in other rodents that have received hind-leg transplants.

These findings have shown that mesenchymal stem cells (MSCs) can stimulate nerve regeneration, and deepen our understanding of how MSCs improve nerve regeneration after injury and limb transplant, while potentially minimizing the need for lifelong immunosuppression after reconstructive surgery to replace a lost limb.

Medical student John Pang said, “Mesenchymal stem cells may be a promising add-on therapy to help damaged nerves regenerate. We obviously need to learn much more, but we are encouraged by what we learned from these experiments.”

MSCs have the ability to readily differentiate into bone, cartilage, and fat cells, but in the laboratory, scientists have been able to extend the possible cell fates that MSCs can form, including nerve and blood vessel cells.

Another advantage of MSCs is their ability to escape recognition by the immune system. MSCs secrete a variety of molecules that suppress the immune response against them. According to Pang it is this very property of MSCs that researchers hope to use in order to regenerate nerves without requiring patients to take immunosuppressive drugs.

Harvesting MSCs from fat is relatively easy, but they can also be isolated from bone marrow. Although, bone marrow aspirations can cause more pain in some pain than liposuction.

In this experiment, researchers used three different groups of rodents. In one group, the rats had their femoral nerves cut and repaired. In the second group, the rats received a hind-leg transplant, and in the third group, the rats received a different type of transplant. Some of these rats had MSCs directly injected into the sciatic nerve, and others had the MSCs intravenously administered. After 16 weeks, the researchers say the rats with severed and repaired nerves with MSCs showed significant improvements in nerve regrowth and nerve function. Those with transplants from similar rats appeared to also show benefits.

Sciatic nerve

Those rats who transplants came from dissimilar rodent types – a situation similar to those patients who receive transplants from cadavers – rejected their new limbs.  Thus MSCs might be a adjuvant treatment for patients with nerve damage.