SP23. Photochemical Tissue Bonding With Commercial Amniotic Membranes For Nerve Regeneration
Year: 2023
Type: conference-abstract
Abstract: PURPOSE: In the United States, twenty million people suffer from peripheral nerve injuries caused by trauma and medical disorders [1], resulting in $150 billion dollars spent per year [2]. Despite decades of research into the underlying mechanisms of nerve injury and recovery, outcomes remain suboptimal. Transected nerve fibers regenerate spontaneously to an extent limited by neuroma, scar formation and nerve gap size [3].Photochemical tissue bonding (PTB) is a photomedicine technique using green light and a photoactivated dye to bond tissues through collagen crosslinking. It has demonstrated efficacy in peripheral nerve repairs [4-7]. PTB combined with a human amniotic membrane (PTB/HAM) has shown superior functional and histologic outcomes compared to suture repair (SR) [4, 7-9]. Unlike preclinical work, executed with HAM [10], clinical use will require a commercial amnion source. The purpose of this study was to compare different commercial products vs SR and PTB/HAM, using a rat sciatic nerve (SN) transection injury (NTI) model. METHODS: Materials used in the in vivo model were selected based on mechanical properties from NTI repairs ex vivo. SNs harvested from Lewis rats were transected and repaired using SR or PTB/HAM, and the commercial amniotic membranes AmnioExcel (AE), AmnioExcelPlus (AEP), BioDFense-G3, DryFlex (Integra), and Oasis (swine intestinal submucosa; Smith and Nephew). For each repair type, 10 nerves were used for biomechanical testing (5 nerves for ultimate tensile strength [UTS], and 5 for fatigue testing [FT]). The elastic modulus was determined with MATLAB (Simulink). AE, AEP and Oasis were selected for further in vivo testing. 75 Lewis rats underwent sciatic NTI and were randomized to one of five groups: AE/PTB, AEP/PTB, Oasis/PTB, HAM/PTB, and SR. Functional recovery was assessed by footprint analyses preoperatively and at POD30, 60, 90 and 120. At POD30, 25 rats (5 per group) were euthanized, and their SN and muscle were harvested en bloc, and stained with H&E, Picrosirirus red and Masson’s trichrome, to assess for immune reaction to the wraps and epineurial scar formation. The remaining rats were euthanized at POD120, and for half of them (5 rats/group) the nerve and muscle were harvested en bloc and stained as previously mentioned. For the other half (5 rats/group), the SN was harvested, and processed for histomorphometry. RESULTS: UTS testing showed that nerves repaired with suture withstood the highest load at 0.98 +- 0.27N, followed by AEP (0.51 +- 0.24N), HAM (0.37 +- 0.14N), AE (0.37 +- 0.11N), G3 (0.36 +- 0.1N), Dryflex (0.31 +- 0.25N), and Oasis (0.28 +- 0.17N). Repairs with AEP and G3 were consistently able to withstand above-physiological strain during linear strain testing, while repairs with AEP and AE were the most resistant to repeated strain during FT. Analysis of in vivo testing and histological outcomes will be presented. CONCLUSIONS: Commercial amniotic membranes perform comparably to HAM in UTS and FT. When compared to suture repair, they had greater elasticity but less strength. Besides their favorable mechanical properties, these commercial membranes are expected to have similar outcomes as PTB/HAM and would serve as excellent materials for clinical studies.
Institution: Massachusetts General Hospital
Language: English
Subfield: Cellular and Molecular Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $2,195
OpenAlex ID: W4384948572