title: The curious ability of polyethylene glycol fusion technologies to restore lost behaviors after nerve severance.
abstract: Traumatic injuries to PNS and CNS axons are not uncommon. Restoration of lost behaviors following severance of mammalian peripheral nerve axons (PNAs) relies on regeneration by slow outgrowths and is typically poor or nonexistent when after ablation or injuries close to the soma. Behavioral recovery after severing spinal tract axons (STAs) is poor because STAs do not naturally regenerate. Current techniques to enhance PNA and/or STA regeneration have had limited success and do not prevent the onset of Wallerian degeneration of severed distal segments. This Review describes the use of a recently developed polyethylene glycol (PEG) fusion technology combining concepts from biochemical engineering, cell biology, and clinical microsurgery. Within minutes after microsuturing carefully trimmed cut ends and applying a well-specified sequence of solutions, PEG-fused axons exhibit morphological continuity (assessed by intra-axonal dye diffusion) and electrophysiological continuity (assessed by conduction of action potentials) across the lesion site. Wallerian degeneration of PEG-fused PNAs is greatly reduced as measured by counts of sensory and/or motor axons and maintenance of axonal diameters and neuromuscular synapses. After PEG-fusion repair, cut-severed, crush-severed, or ablated PNAs or crush-severed STAs rapidly (within days to weeks), more completely, and permanently restore PNA- or STA-mediated behaviors compared with nontreated or conventionally treated animals. PEG-fusion success is enhanced or decreased by applying antioxidants or oxidants, trimming cut ends or stretching axons, and exposure to Ca(2+) -free or Ca(2+) -containing solutions, respectively. PEG-fusion technology employs surgical techniques and chemicals already used by clinicians and has the potential to produce a paradigm shift in the treatment of traumatic injuries to PNAs and STAs.
authors.affiliation: Department of Neuroscience, University of Texas at Austin, Austin, Texas.
authors.forename: G D
authors.initials: GD
authors.lastname: Bittner
authors.affiliation: Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana.
authors.forename: D R
authors.initials: DR
authors.lastname: Sengelaub
authors.affiliation: Department of Orthopedic Surgery, Wellspan Health, York, Pennsylvania.
authors.forename: R C
authors.initials: RC
authors.lastname: Trevino
authors.affiliation: Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan.
authors.forename: J D
authors.initials: JD
authors.lastname: Peduzzi
authors.affiliation: Department of Neuroscience, University of Texas at Austin, Austin, Texas.
authors.forename: M
authors.initials: M
authors.lastname: Mikesh
authors.affiliation: Department of Neuroscience, University of Texas at Austin, Austin, Texas.
authors.forename: C L
authors.initials: CL
authors.lastname: Ghergherehchi
authors.affiliation: Department of Psychology, University of Texas at Austin, Austin, Texas.
authors.forename: T
authors.initials: T
authors.lastname: Schallert
authors.affiliation: Department of Plastic Surgery, Vanderbilt School of Medicine, Nashville, Tennessee.
authors.forename: W P
authors.initials: WP
authors.lastname: Thayer
mesh_terms: D000818:Animals; D006801:Humans; D001523:Mental Disorders / Q000209:etiology / Q000628:therapy*; D009416:Nerve Regeneration / Q000187:drug effects; D059348:Peripheral Nerve Injuries / Q000150:complications* / Q000628:therapy; D011092:Polyethylene Glycols / Q000627:therapeutic use*; D020127:Recovery of Function / Q000187:drug effects* / Q000502:physiology; D012997:Solvents / Q000627:therapeutic use*
chemical_list: D012997:Solvents; D011092:Polyethylene Glycols
keywords: Wallerian degeneration; axonal regeneration; axotomy; nerve repair; polyethylene glycol