Comparison of Collagen and Human Amniotic Membrane Nerve Conduits and Wraps for Peripheral Nerve Repair in Preclinical Models: A Systematic Review of the Literature
Erin M. Wolfe, BS, Sydney A. Mathis, BS, Steven A. Ovadia, MD and Zubin J. Panthaki, MD, University of Miami Miller School of Medicine, Miami, FL
Introduction: Purified collagen and human amniotic membrane (hAM) are FDA-approved biomaterials that can be used as nerve wraps or conduits for repair of peripheral nerve injuries. Both biomaterials have been evaluated for peripheral nerve repair and have been shown to reduce scarring and fibrosis. hAM is also anti-inflammatory and contains stem cells and neurotrophic factors. However, comparative advantages and disadvantages of these biomaterials has not been definitively shown in the literature. Comparative analysis of hAM and collagen nerve wraps may help guide clinical decision making for differing injuries. The purpose of this systematic review is to comprehensively evaluate the literature regarding the roles of amniotic membrane and collagen nerve wraps and conduits on peripheral nerve regeneration in preclinical models.
Materials & Methods: The MEDLINE database was queried using the PubMed search engine on July 7th, 2019 with the following search strategy: ("amniotic membrane" OR "amnion") OR ("collagen conduit" OR "nerve wrap")] AND "nerve." Articles were compiled, and two independent reviewers screened titles and abstracts. All studies contained at least one treatment group with either hAM or collagen nerve wraps or conduits, with no adjunct treatment. The following data points were collected from included articles: nerve type, lesion type/injury model, repair type, treatment (conduit/wrap material), outcomes and timepoints.
Results: 258 articles were initially identified, and 45 studies remained after application of inclusion and exclusion criteria. Of 27 collagen studies total, 23 utilized a conduit and 4 utilized a collagen wrap. Of 18 hAM studies total, 6 utilized a conduit and 12 utilized a wrap. Assessment types included neuromorphometric analysis (88%), electrophysiology (64%), functional motor indices (42%), and qualitative histological analysis (31%). Muscle weights (26%) and functional sensory indices (13%) were also reported. Two (9%) collagen studies involving a conduit and one (25%) involving a wrap demonstrated at least one significant improvement in outcomes compared with a control. While none of the hAM conduit studies showed significant improvements, 9 (75%) of the studies investigating hAM wraps showed at least one significant improvement in outcomes.
Conclusions: Most studies reported positive outcomes, indicating that collagen and hAM nerve wraps both have the potential to enhance peripheral nerve regeneration, especially if used synergistically with adjunctive therapeutic interventions. However, relatively few studies reported significant findings compared to controls, except for studies evaluating hAM wraps. Preclinical models comparing these biomaterials may play an important role in guiding clinical practice regarding their applications in peripheral nerve repair.
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