title: Initial observations on using magnesium metal in peripheral nerve repair.
abstract: Biodegradable magnesium metal filaments placed inside biodegradable nerve conduits might provide the physical guidance support needed to improve the rate and extent of regeneration of peripheral nerves across injury gaps. In this study, we examined basic issues of magnesium metal resorption and biocompatibility by repairing sub-critical size gap injuries (6 mm) in one sciatic nerve of 24 adult male Lewis rats. Separated nerve stumps were connected with poly(caprolactone) nerve conduits, with and without magnesium filaments (0.25 mm diameter, 10 mm length), with two different conduit filler substances (saline and keratin hydrogel). At 6 weeks after implantation, magnesium degradation was examined by micro-computed tomography and histological analyses. Magnesium degradation was significantly greater when the conduits were filled with an acidic keratin hydrogel than with saline (p < 0.05). But magnesium filaments in some animals remained intact for 6 weeks. Using histological and immunocytochemical analyses, good biocompatibility of the magnesium implants was observed at 6 weeks, as shown by good development of regenerating nerve mini-fascicles and only mild inflammation in tissues even after complete degradation of the magnesium. Nerve regeneration was not interrupted by complete magnesium degradation. An initial functional evaluation, determination of size recovery of the gastrocnemius muscle, showed a slight improvement due to magnesium with the saline but not the keratin filler, compared with respective control conduits without magnesium. These results suggest that magnesium filament implants have the potential to improve repair of injured peripheral nerve defects in this rodent model.
authors.affiliation: Department of Biomedical Engineering, University of Cincinnati, OH, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Vennemeyer
authors.affiliation: Department of Molecular and Cellular Physiology, University of Cincinnati, OH, USA.
authors.forename: T
authors.initials: T
authors.lastname: Hopkins
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, University of Cincinnati, OH, USA.
authors.forename: M
authors.initials: M
authors.lastname: Hershcovitch
authors.affiliation: Department of Orthopaedic Surgery, University of Cincinnati, OH, USA.
authors.forename: K D
authors.initials: KD
authors.lastname: Little
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Cincinnati, OH, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Hagen
authors.affiliation: Department of Bioengineering, University of Pittsburgh, PA, USA.
authors.forename: D
authors.initials: D
authors.lastname: Minteer
authors.affiliation: Division of Facial Plastic and Reconstructive Surgery, Department of Otolaryngology-Head & Neck Surgery and Dermatology, University of Cincinnati, OH, USA.
authors.forename: D B
authors.initials: DB
authors.lastname: Hom
authors.affiliation: Department of Bioengineering and Department of Plastic Surgery, University of Pittsburgh, PA, USA.
authors.forename: K
authors.initials: K
authors.lastname: Marra
authors.affiliation: Department of Molecular and Cellular Physiology, University of Cincinnati, OH, USA sarah.pixley@uc.edu.
authors.forename: S K
authors.initials: SK
authors.lastname: Pixley
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001672:Biocompatible Materials; D020100:Hydrogels; D007633:Keratins; D008274:Magnesium; D008297:Male; D008422:Materials Testing; D018482:Muscle, Skeletal / Q000294:innervation / Q000473:pathology; D009416:Nerve Regeneration; D059348:Peripheral Nerve Injuries / Q000378:metabolism / Q000473:pathology / Q000601:surgery*; D011091:Polyesters; D051381:Rats; D011917:Rats, Inbred Lew; D012584:Sciatic Nerve / Q000293:injuries / Q000378:metabolism / Q000601:surgery; D055114:X-Ray Microtomography
chemical_list: D001672:Biocompatible Materials; D020100:Hydrogels; D011091:Polyesters; C016240:polycaprolactone; D007633:Keratins; D008274:Magnesium
keywords: Peripheral nerve repair; biodegradable metal; magnesium; micro-computed tomography; nerve regeneration; rat; sciatic nerve