title: Delayed intrathecal delivery of RhoA siRNA to the contused spinal cord inhibits allodynia, preserves white matter, and increases serotonergic fiber growth.
abstract: RhoA is a key regulator of the actin cytoskeleton that is upregulated after spinal cord injury (SCI). We analyzed different methods for siRNA delivery and developed siRNAs targeting RhoA (siRhoA) for SCI treatment. Cy 3.5-labeled siRNA delivered at the time of SCI yielded fluorescence in several cell types in the injury site. Intraspinal injections of chemically stabilized siRhoA into the spinal cord of injured rats reduced RhoA protein levels after 1 week and improved hindlimb walking over 6 weeks. To explore a less invasive route, we tested intrathecal injection of Cy 3.5-labeled siRNA via lumbar puncture 1 day after SCI, which resulted in robust uptake in the T9-T10 injury site. Lumbar injection of siRhoA 1 day after SCI reduced RhoA mRNA and protein levels 3 days after injection. Although siRhoA treatment did not yield significant improvement in locomotion, it decreased tactile hypersensitivity significantly compared to controls. Histological analysis at 8 weeks showed significant improvement in white matter sparing with siRhoA compared to control siRNA. siRhoA treatment also resulted in less accumulation of ED1+macrophages, increased PKC-γ immunoreactivity in the corticospinal tract rostral to the injury site, and increased serotonergic fiber growth 12 mm caudal to the contusion site. The ability of siRhoA to preserve white matter and promote serotonergic axonal regrowth caudal to the injury site is likely to suppress allodynia. This provides justification for considering clinical development of RhoA inhibitors to treat SCI sub-acutely to reduce allodynia, which occurs frequently in SCI patients.
authors: W.M. Keck Center for Collaborative Neuroscience, Rutgers Stem Cell Research Center, Department of Cell Biology & Neuroscience, Rutgers, State University of New Jersey, Piscataway, New Jersey 08854-8082, USA.
authors: Seiji
authors: S
authors: Otsuka
authors: Crista
authors: C
authors: Adamson
authors: Venkatachalam
authors: V
authors: Sankar
authors: Kurt M
authors: KM
authors: Gibbs
authors: Noriko
authors: N
authors: Kane-Goldsmith
authors: Jennie
authors: J
authors: Ayer
authors: Joanne
authors: J
authors: Babiarz
authors: Hagar
authors: H
authors: Kalinski
authors: Hagit
authors: H
authors: Ashush
authors: Evgenia
authors: E
authors: Alpert
authors: Ron
authors: R
authors: Lahav
authors: Elena
authors: E
authors: Feinstein
authors: Martin
authors: M
authors: Grumet
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D015316:Genetic Therapy / Q000379:methods*; D006930:Hyperalgesia / Q000235:genetics / Q000628:therapy*; D007278:Injections, Spinal; D009416:Nerve Regeneration / Q000235:genetics; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000235:genetics / Q000628:therapy*; D015854:Up-Regulation / Q000502:physiology; D020742:rhoA GTP-Binding Protein / Q000008:administration & dosage* / Q000037:antagonists & inhibitors / Q000235:genetics
chemical_list: D034741:RNA, Small Interfering; D012701:Serotonin; D020742:rhoA GTP-Binding Protein