title: Axonal fusion via conduit-based delivery of hydrophilic polymers.
abstract: BACKGROUND
  Hydrophilic polymers have been shown to improve physiologic recovery following repair of transected nerves with microsutures. Our study was designed to combine hydrophilic polymer therapy with nerve tubes (NT) to enhance polymer delivery to the site of nerve injury.
  
  
  METHODS
  Using a rat sciatic nerve injury model, a single transection injury was repaired in an end-to-end fashion with NT + polyethylene glycol (PEG) to NT alone. Compound action potentials (CAPs) were recorded before nerve transection and after repair. Behavioral testing was performed for 5 weeks.
  
  
  RESULTS
  PEG therapy restored CAPS in all, but one, animals, while no CAPS were recorded in animals not receiving PEG. Behavioral nerve function was measured using the standardized functional assessment technique and foot fault asymmetry scores (FF). FF scores were improved for the PEG therapy groups on postoperative days 7, 14, and 21. However, after expected eventual axonal outgrowth, the benefit was less noticeable at days 28 and 35. Immunohistochemistry of the distal axon segments showed an increase number of sensory and motor axons in the NT + PEG group as compared to NT alone.
  
  
  CONCLUSIONS
  These data suggest that PEG delivery via a conduit may provide a simple, effective way to fuse severed axons and regain early nerve function. For proximal nerve injuries in large animals, recovery of axonal continuity could dramatically improve outcomes, even if fusion only occurs in a small percentage of axons.
authors.affiliation: Department of Plastic Surgery, Vanderbilt University Medical Center, 1161 21st Avenue South S2221, Medical Center North, Nashville, TN 37232 USA ; Department of General Surgery, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, TN 37232 USA.
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Sexton
authors.affiliation: Vanderbilt University School of Medicine, 215 Light Hall, Nashville, TN 37232 USA.
authors.forename: Charles L
authors.initials: CL
authors.lastname: Rodriguez-Feo
authors.affiliation: Vanderbilt University School of Medicine, 215 Light Hall, Nashville, TN 37232 USA.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Boyer
authors.affiliation: Department of Plastic Surgery, Vanderbilt University Medical Center, 1161 21st Avenue South S2221, Medical Center North, Nashville, TN 37232 USA.
authors.forename: Gabriel A
authors.initials: GA
authors.lastname: Del Corral
authors.affiliation: Department of Plastic Surgery, Vanderbilt University Medical Center, 1161 21st Avenue South S2221, Medical Center North, Nashville, TN 37232 USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Riley
authors.affiliation: Department of Plastic Surgery, Vanderbilt University Medical Center, 1161 21st Avenue South S2221, Medical Center North, Nashville, TN 37232 USA.
authors.forename: Alonda C
authors.initials: AC
authors.lastname: Pollins
authors.affiliation: Department of Plastic Surgery, Vanderbilt University Medical Center, 1161 21st Avenue South S2221, Medical Center North, Nashville, TN 37232 USA.
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Cardwell
authors.affiliation: Department of Plastic Surgery, Vanderbilt University Medical Center, 1161 21st Avenue South S2221, Medical Center North, Nashville, TN 37232 USA.
authors.forename: R Bruce
authors.initials: RB
authors.lastname: Shack
authors.affiliation: Department of Plastic Surgery, Vanderbilt University Medical Center, 1161 21st Avenue South S2221, Medical Center North, Nashville, TN 37232 USA.
authors.forename: Lillian B
authors.initials: LB
authors.lastname: Nanney
authors.affiliation: Department of Plastic Surgery, Vanderbilt University Medical Center, 1161 21st Avenue South S2221, Medical Center North, Nashville, TN 37232 USA.
authors.forename: Wesley P
authors.initials: WP
authors.lastname: Thayer
keywords: Axonal fusion; Hydrophilic polymers; Methylene blue; Nerve fusion; Nerve tube; Polyethylene glycol; Traumatic neuropathy