Italian scientists from Milan have used skin-derived stem cells in combination with a previously developed collagen tube to successfully bridge the gaps in injured nerves in a rat model, On the strength of that animal model system, the Italian group successfully used this procedure to heal the damaged peripheral nerves in the upper arms of a patient whose only other option was limb amputation.
“Peripheral nerve repair with satisfactory functional remains a great surgical challenge, especially for severe nerve injuries resulting in extended nerve defects,” said the corresponding author of this study Dr, Yvan Torrente of the Department of Pathophysiology and Transplantation at the University of Milan. “However, we hypothesized that the combination of autologous (self donated) stem cells placed in collagen tubes to bridge gaps in the damaged nerves would restore the continuity of injured nerves and save from amputation the upper arms of a patient with poly-injury to motor and sensory nerves.”
Although autologous nerve grafting has been the “gold standard” for reconstructive surgeries, these researchers recognized the disadvantages of such a procedure. Graft availability is the first drawback of autologous nerve grafting. Secondly, the condition of the donor site or “donor site morbidity.” If the donor site is in bad shape, taking a nerve from that site will probably make the donor site worse and provide a nerve that does not work as well. Finally, neuropathic pain is also an issue.
Autologous skin-derived stem cells have several advantages over autologous nerve grafts. First, the skin provides an accessible source of stem cells that are rapidly expandable in culture. Secondly, these skin-derived cells are capable of survival and integration within host tissues.
The NeuraGen nerve guide is a tiny collagen tube that connects the two damaged ends of a nerve together to mediate and expedite nerve healing. NeuraGen tubes guide the transplanted stem cells to the gaps in the damaged nerves. Torrente and his co-workers developed and tested the NeuraGen tubes in rats, and the US Food and Drug Administration (FDA) has approved NeuraGen for use in human patients. See this figure from the NeuraGen web site:
Torrente and others successfully used skin-derived stem cells and NeuraGen tubes to heal the severed sciatic nerves in rats. Therefore, once the FDA approved NeuraGen tubes, Torrente tried NeuraGen tubes in human patients with severe peripheral nerve damage.
A three-year follow-up on one particular patient showed that injured median and ulnar nerves showed extensive healing as ascertained by magnetic resonance imaging. Functional tests, such as pinch gauge tests, static two-point discrimination and monofilament touch tests established the functional recovery of these peripheral nerves in the patient.
“Our three-year follow-up has witnesses nerve regeneration with suitable functional recovery in the patient and the salvage of upper arms from amputation,” said researchers from Torrente’s group. “This finding opens an alternative avenue for patients who are at-risk of amputation after the injury to important nerves.”