title: Subdural engraftment of serotonergic neurons following spinal hemisection restores spinal serotonin, downregulates serotonin transporter, and increases BDNF tissue content in rat.
abstract: Spinal hemisection injury at T13 results in development of permanent mechanical allodynia and thermal hyperalgesia due to interruption and subsequent loss of descending inhibitory modulators such as serotonin (5-HT) and its transporter (5-HT(T)). We hypothesize that lumbar transplantation of non-mitotic cells that tonically secrete 5-HT and brain-derived neurotrophic factor (BDNF) will restore alterations in 5-HT and 5-HT(T) systems within the spinal dorsal horn. We used an immortalized rat neuronal cell line derived from E13 raphe (RN46A-B14) which is shown to secrete 5-HT and BDNF in vitro and in vivo. Three groups (n=35) of 30 day old male Sprague-Dawley rats were spinally hemisected at T13 and 28 days later received either lumbar RN46A-V1 control empty-vector (n=15) or RN46A-B14 (n=15) intrathecal grafts, or no transplant. Twenty-eight days following transplantation, animals were perfused and tissue examined for changes in 5-HT, 5-HT(T), and BDNF at the site of transplantation or at lumbar enlargements (L5). Immunohistochemistry revealed that RN46A-B14, but not RN46A-V1 cells, increased 5-HT tissue staining at L5 in the dorsal white matter as well as in superficial dorsal horn laminae I and II on both ipsilateral and contralateral sides, results confirmed by ELISA. Transplantation of RN46A-B14 cells significantly reduced ipsilateral 5-HT(T), upregulated after injury. Significantly increased levels of BDNF were also observed after RN46A-B14 transplantation but were not localized to particular spinal laminae. These results are consistent with recovery of locomotor function and reductions in chronic pain behaviors observed behaviorally after RN46A-B14 transplantation and supports the pragmatic application of cell-based therapies in correcting damaged circuitry after spinal cord injury.
authors.affiliation: Department of Anatomy and Neurosciences, and Marine Biomedical Institute, University of Texas Medical Branch, Galveston, TX 77555-1043, USA.
authors.forename: B C
authors.initials: BC
authors.lastname: Hains
authors.forename: S D
authors.initials: SD
authors.lastname: Fullwood
authors.forename: M J
authors.initials: MJ
authors.lastname: Eaton
authors.forename: C E
authors.initials: CE
authors.lastname: Hulsebosch
mesh_terms: D000818:Animals; D015153:Blotting, Western; D016380:Brain Tissue Transplantation / Q000379:methods*; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002461:Cell Line, Transformed / Q000378:metabolism / Q000637:transplantation; D015536:Down-Regulation / Q000502:physiology*; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005333:Fetus; D007839:Functional Laterality / Q000502:physiology; D007150:Immunohistochemistry; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D009474:Neurons / Q000378:metabolism / Q000637:transplantation*; D011903:Raphe Nuclei / Q000196:embryology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*; D050486:Serotonin Plasma Membrane Transport Proteins; D013116:Spinal Cord / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery; D013119:Spinal Cord Injuries / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery*; D013355:Subdural Space / Q000601:surgery; D016896:Treatment Outcome; D015854:Up-Regulation / Q000502:physiology
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D050486:Serotonin Plasma Membrane Transport Proteins; C493232:Slc6a4 protein, rat; D012701:Serotonin