title: Directed evolution of motor neurons from genetically engineered neural precursors.
abstract: Stem cell-based therapies hold therapeutic promise for degenerative motor neuron diseases, such as amyotrophic lateral sclerosis, and for spinal cord injury. Fetal neural progenitors present less risk of tumor formation than embryonic stem cells but inefficiently differentiate into motor neurons, in line with their low expression of motor neuron-specific transcription factors and poor response to soluble external factors. To overcome this limitation, we genetically engineered fetal rat spinal cord neurospheres to express the transcription factors HB9, Nkx6.1, and Neurogenin2. Enforced expression of the three factors rendered neural precursors responsive to Sonic hedgehog and retinoic acid and directed their differentiation into cholinergic motor neurons that projected axons and formed contacts with cocultured myotubes. When transplanted in the injured adult rat spinal cord, a model of acute motor neuron degeneration, the engineered precursors transiently proliferated, colonized the ventral horn, expressed motor neuron-specific differentiation markers, and projected cholinergic axons in the ventral root. We conclude that genetic engineering can drive the differentiation of fetal neural precursors into motor neurons that efficiently engraft in the spinal cord. The strategy thus holds promise for cell replacement in motor neuron and related diseases. Disclosure of potential conflicts of interest is found at the end of this article.
authors.affiliation: Département Neuroscience, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U622, Unité Rétrovirus et Transfert Génétique, Paris, France. dbohl@pasteur.fr
authors.forename: Delphine
authors.initials: D
authors.lastname: Bohl
authors.forename: Song
authors.initials: S
authors.lastname: Liu
authors.forename: Stéphane
authors.initials: S
authors.lastname: Blanchard
authors.forename: Michaël
authors.initials: M
authors.lastname: Hocquemiller
authors.forename: Georg
authors.initials: G
authors.lastname: Haase
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Heard
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002450:Cell Communication; D002454:Cell Differentiation; D002465:Cell Movement; D002794:Choline / Q000378:metabolism; D018920:Coculture Techniques; D019020:Directed Molecular Evolution; D005818:Genetic Engineering; D006801:Humans; D051379:Mice; D009046:Motor Neurons / Q000166:cytology* / Q000378:metabolism*; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000378:metabolism; D009928:Organ Specificity; D051381:Rats; D013119:Spinal Cord Injuries / Q000473:pathology; D013126:Spinal Nerve Roots / Q000473:pathology; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D015415:Biomarkers; D014157:Transcription Factors; D002794:Choline