title: Implications of poly(N-isopropylacrylamide)-g-poly(ethylene glycol) with codissolved brain-derived neurotrophic factor injectable scaffold on motor function recovery rate following cervical dorsolateral funiculotomy in the rat.
abstract: OBJECTIVE
  In a follow-up study to their prior work, the authors evaluated a novel delivery system for a previously established treatment for spinal cord injury (SCI), based on a poly(N-isopropylacrylamide) (PNIPAAm), lightly cross-linked with a polyethylene glycol (PEG) injectable scaffold. The primary aim of this work was to assess the recovery of both spontaneous and skilled forelimb function following a cervical dorsolateral funiculotomy in the rat. This injury ablates the rubrospinal tract (RST) but spares the dorsal and ventral corticospinal tract and can severely impair reaching and grasping abilities.
  
  
  METHODS
  Animals received an implant of either PNIPAAm-g-PEG or PNIPAAm-g-PEG + brain-derived neurotrophic factor (BDNF). The single-pellet reach-to-grasp task and the staircase-reaching task were used to assess skilled motor function associated with reaching and grasping abilities, and the cylinder task was used to assess spontaneous motor function, both before and after injury.
  
  
  RESULTS
  Because BDNF can stimulate regenerating RST axons, the authors showed that animals receiving an implant of PNIPAAm-g-PEG with codissolved BDNF had an increased recovery rate of fine motor function when compared with a control group (PNIPAAm-g-PEG only) on both a staircase-reaching task at 4 and 8 weeks post-SCI and on a single-pellet reach-to-grasp task at 5 weeks post-SCI. In addition, spontaneous motor function, as measured in the cylinder test, recovered to preinjury values in animals receiving PNIPAAm-g-PEG + BDNF. Fluorescence immunochemistry indicated the presence of both regenerating axons and BDA-labeled fibers growing up to or within the host-graft interface in animals receiving PNIPAAm-g-PEG + BDNF.
  
  
  CONCLUSIONS
  Based on their results, the authors suggest that BDNF delivered by the scaffold promoted the growth of RST axons into the lesion, which may have contributed in part to the increased recovery rate.
authors.affiliation: Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA. lgc25@drexel.edu
authors.forename: Lauren Conova
authors.initials: LC
authors.lastname: Grous
authors.forename: Jennifer
authors.initials: J
authors.lastname: Vernengo
authors.forename: Ying
authors.initials: Y
authors.lastname: Jin
authors.forename: B Timothy
authors.initials: BT
authors.lastname: Himes
authors.forename: Jed S
authors.initials: JS
authors.lastname: Shumsky
authors.forename: Itzhak
authors.initials: I
authors.lastname: Fischer
authors.forename: Anthony
authors.initials: A
authors.lastname: Lowman
mesh_terms: D000178:Acrylamides / Q000008:administration & dosage; D000180:Acrylic Resins; D000818:Animals; D001369:Axons / Q000502:physiology*; D001522:Behavior, Animal / Q000502:physiology*; D019208:Brain-Derived Neurotrophic Factor / Q000008:administration & dosage* / Q000494:pharmacology; D002574:Cervical Vertebrae / Q000293:injuries*; D004195:Disease Models, Animal; D005260:Female; D005552:Forelimb / Q000503:physiopathology; D009048:Motor Skills / Q000502:physiology; D009069:Movement Disorders / Q000209:etiology / Q000628:therapy*; D011092:Polyethylene Glycols / Q000008:administration & dosage; D011108:Polymers / Q000008:administration & dosage; D019736:Prostheses and Implants; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function; D013119:Spinal Cord Injuries / Q000150:complications / Q000628:therapy*
chemical_list: D000178:Acrylamides; D000180:Acrylic Resins; D019208:Brain-Derived Neurotrophic Factor; D011108:Polymers; C052970:poly-N-isopropylacrylamide; D011092:Polyethylene Glycols