title: Transplantation of glial progenitors that overexpress glutamate transporter GLT1 preserves diaphragm function following cervical SCI.
abstract: Approximately half of traumatic spinal cord injury (SCI) cases affect cervical regions, resulting in chronic respiratory compromise. The majority of these injuries affect midcervical levels, the location of phrenic motor neurons (PMNs) that innervate the diaphragm. A valuable opportunity exists following SCI for preventing PMN loss that occurs during secondary degeneration. One of the primary causes of secondary injury is excitotoxicity due to dysregulation of extracellular glutamate homeostasis. Astrocytes express glutamate transporter 1 (GLT1), which is responsible for the majority of CNS glutamate clearance. Given our observations of GLT1 dysfunction post-SCI, we evaluated intraspinal transplantation of Glial-Restricted Precursors (GRPs)--a class of lineage-restricted astrocyte progenitors--into ventral horn following cervical hemicontusion as a novel strategy for reconstituting GLT1 function, preventing excitotoxicity and protecting PMNs in the acutely injured spinal cord. We find that unmodified transplants express low levels of GLT1 in the injured spinal cord. To enhance their therapeutic properties, we engineered GRPs with AAV8 to overexpress GLT1 only in astrocytes using the GFA2 promoter, resulting in significantly increased GLT1 protein expression and functional glutamate uptake following astrocyte differentiation in vitro and after transplantation into C4 hemicontusion. Compared to medium-only control and unmodified GRPs, GLT1-overexpressing transplants reduced lesion size, diaphragm denervation and diaphragm dysfunction. Our findings demonstrate transplantation-based replacement of astrocyte GLT1 is a promising approach for SCI.
authors.affiliation: Department of Neuroscience, Farber Institute for Neurosciences, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Ke
authors.initials: K
authors.lastname: Li
authors.affiliation: Department of Neuroscience, Farber Institute for Neurosciences, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Elham
authors.initials: E
authors.lastname: Javed
authors.affiliation: Department of Neuroscience, Farber Institute for Neurosciences, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Tamara J
authors.initials: TJ
authors.lastname: Hala
authors.affiliation: Department of Neuroscience, Farber Institute for Neurosciences, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Sannie
authors.affiliation: Department of Neuroscience, Farber Institute for Neurosciences, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Regan
authors.affiliation: Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Maragakis
authors.affiliation: Department of Biology, Arcadia University, Glenside, Pennsylvania, USA.
authors.forename: Megan C
authors.initials: MC
authors.lastname: Wright
authors.affiliation: Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Poulsen
authors.affiliation: Department of Neuroscience, Farber Institute for Neurosciences, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Angelo C
authors.initials: AC
authors.lastname: Lepore
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism / Q000637:transplantation*; D064987:Cell- and Tissue-Based Therapy / Q000379:methods*; D000229:Dependovirus / Q000235:genetics; D003964:Diaphragm / Q000378:metabolism* / Q000473:pathology; D004195:Disease Models, Animal; D027342:Excitatory Amino Acid Transporter 2 / Q000235:genetics* / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D017930:Genes, Reporter; D005822:Genetic Vectors / Q000737:chemistry / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D009046:Motor Neurons / Q000378:metabolism / Q000473:pathology; D010791:Phrenic Nerve / Q000293:injuries / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function; D013116:Spinal Cord / Q000378:metabolism* / Q000473:pathology; D013119:Spinal Cord Injuries / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D019076:Transgenes
chemical_list: D027342:Excitatory Amino Acid Transporter 2; C493396:Slc1a2 protein, mouse; D049452:Green Fluorescent Proteins