title: A simple technique for augmentation of axonal ingrowth into chondroitinase-treated acellular nerve grafts using nerve growth factor.
abstract: OBJECTIVE
  Improvement in axonal regeneration may lead to the development of longer nerve grafts and improved outcomes for patients with peripheral nerve injury. Although the use of acellular nerve grafts has been well documented (Groves et al, Exp Neurol. 2005;195:278-292; Krekoski et al, J Neurosci. 2001;21:6206-6213; Massey et al, Exp Neurol. 2008;209:426-445; Neubauer et al, Exp Neurol. 2007;207:163-170; Zuo et al, Exp Neurol. 2002;176:221-228), less is known about the ability of neurotrophic factors to enhance axonal regeneration. This study evaluates axonal ingrowth augmentation using acellular, chondroitinase-treated nerve grafts doped with nerve growth factor (NGF).
  
  
  METHODS
  Acellular chondroitinase-treated murine nerve grafts were placed in experimental (NGF-treated grafts) and control (carrier-only grafts) rats. Five days after implantation, axonal regeneration was assessed by immunocytochemistry along with digital image analysis.
  
  
  RESULTS
  Higher axon count was observed throughout the length of the nerve in the NGF group (P < 0.0001), peaking at 3 mm from proximal repair (P = 0.02). Although the NGF group displayed a higher axon count per slice, the mean diameter of individual NGF axons was smaller (P < 0.0001), potentially consistent with induction of sensory axons (Rich et al, J Neurocytol. 1987;16:261-268; Sofroniew et al, Annu Rev Neurosci. 2001;24:1217-1128; Yip et al, J Neurosci. 1984;4:2986-2992).
  
  
  CONCLUSIONS
  The simple technique of doping acellular, chondroitinase-treated nerve grafts with NGF can augment axonal ingrowth and possibly preferentially induce sensory axons.
authors.affiliation: Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA.
authors.forename: Fernando
authors.initials: F
authors.lastname: Ovalle
authors.forename: Ashit
authors.initials: A
authors.lastname: Patel
authors.forename: Alonda
authors.initials: A
authors.lastname: Pollins
authors.forename: Jorge
authors.initials: J
authors.lastname: de la Torre
authors.forename: Luis
authors.initials: L
authors.lastname: Vasconez
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Hunt
authors.forename: R Pat
authors.initials: RP
authors.lastname: Bucy
authors.forename: R Bruce
authors.initials: RB
authors.lastname: Shack
authors.forename: Wesley P
authors.initials: WP
authors.lastname: Thayer
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology*; D019765:Chondroitin ABC Lyase / Q000008:administration & dosage*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D048091:Guided Tissue Regeneration / Q000379:methods*; D008297:Male; D020932:Nerve Growth Factor / Q000008:administration & dosage*; D009416:Nerve Regeneration; D059348:Peripheral Nerve Injuries / Q000601:surgery; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000293:injuries / Q000502:physiology / Q000637:transplantation*; D023822:Tissue Engineering / Q000379:methods*
chemical_list: D020932:Nerve Growth Factor; D019765:Chondroitin ABC Lyase