Researchers have found that motor neurons can be grown from pluripotent stem cells. Introduction of these motor neurons in sciatic nerve injury patients can reduce muscular dystrophy and increase the chances of post-surgical recovery.
Peripheral injury to motor nerves can result in partial paralysis, leading to muscular dystrophy. The initial treatment for such an injury is surgical repair or transplant of the injured motor nerve. However, a surgery is only done after an observation period of 6 months or more, when the motor neurons are expected to regenerate. During this time, the temporary denervation (absence of motor nerves) can have a significant functional effect, leading to partial paralysis and disabilities.
Stem cells can help prevent prolonged denervation and aid in the regeneration of motor neurons. Research has shown that induced pluripotent stem cells (iPSCs) can be derived from adult somatic cells (skin fibroblasts). Different specialized cell types, like motor neurons, can be derived from these iPSCs. In a study published in the JAMA Facial Plastic Surgery journal, researchers describe the effect of transplanting motor neurons grown from iPSCs in mice with sciatic nerve injury.
In this study, researchers transplanted iPSC-derived motor neurons to thirty-two mice with induced sciatic nerve injuries. These animals were kept under observation over a period of 10 weeks, and the growth of the motor neurons was monitored carefully. Up to 4 weeks, there was a consistent growth of human neurites (a part of neuron) in the mice. Six weeks after the transplant, the researchers observed the development of neuromuscular junctions. This was an exciting observation, given that neuromuscular junctions can promote the retention of muscle mass and help in the restoration of motor function. Ten weeks from the date of transplant, the muscle mass was weighed to observe muscle atrophy. It was found that iPSC-derived motor neurons can reduce the muscle atrophy, retaining significant muscle mass. However, there was no reaction to electric stimuli, indicating an absence of motor function.
The study describes the use of iPSC-derived motor neurons in the treatment of facial nerve injury. Such a cellular transplant can maintain facial tone and minimize nerve and muscle atrophy in patients, increasing the success rate of the nerve transplant surgery. The absence of muscular response to electrical stimuli is a major limitation, since retention of muscle mass alone is not a satisfactory result. The researchers hypothesize that the transplanted human cells may not have reached complete maturity in the bodies of mice and the results may vary in human trials. Use of pluripotent cells derived from the patient may also increase the chances of developing mature and fully functional motor neurons. Further clinical studies on the subject can develop this technique as a treatment strategy for patients with severe nerve injuries.
Written By: Anuja Kulkami, Biomedical Engineer