A potential new source of motor neurons that does not require human eggs or embryos could be an enormous benefit to research into conditions such as amyotrophic lateral sclerosis (ALS) and spinal cord injury and could open the door to eventual treatments. In a recent study led by Dr. William Lowry and colleagues at UCLA, the first electrically active motor neurons, were generated from induced pluripotent stem (iPS) cells. The researchers compared the ability of different human cell lines to generate motor neuron progenitors and fully differentiated motor neurons. When measuring the electrophysical properties of the iPS-derived neurons, it was found that the iPS cells followed a normal developmental progression to mature, electrically active neurons that are molecularly and physiologically indistinguishable from motor neurons derived from human embryonic stem cells. The study demonstrates the feasibility of using iPS-derived motor neurons and their progenitors to replace damaged or dead motor neurons in patients with certain disorders. It also opens the possibility of studying motor neuron-related diseases in the laboratory to uncover their causes. Medically, these iPS-derived neurons have great implications. It is possible that iPS motor neurons, which are usually damaged or destroyed in traumatic injury to the spine, could be used as therapy for those who are paralyzed. Moreover, these neurons can be applied to the study of neurodegenerative diseases such as ALS and spinal muscular atrophy (SMA). Future studies aim to combine the motor neurons with muscle cells to see if they can stimulate a response. If the muscles contract, it will be further proof that fully functional motor neurons have been generated. The data from this study support the possibility that reprogrammed somatic cells might prove to be a viable alternative to the more controversial embryo-derived cells in regenerative medicine.

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