Dataset Information

Revascularization patterns of nerve allografts in a rat sciatic nerve defect model.

ABSTRACT:

Introduction

The specific patterns of revascularization of allograft nerves after the addition of vascularization remain unknown. The aim of this study was to determine the revascularization patterns of optimized processed allografts (OPA) after surgically induced angiogenesis to the wound bed in a rat sciatic nerve model.

Materials and methods

In 51 Lewis rats, sciatic nerve gaps were repaired with (i) autografts, (ii) OPA and (iii) OPA wrapped in a pedicled superficial inferior epigastric artery fascia flap (SIEF) to provide vascularization to the wound bed. At 2, 12, and 16 weeks, the vascular volume and vascular surface area in nerve samples were measured using micro CT and photography. Cross-sectional images were obtained and the number of vessels was quantified in the proximal, mid, and distal sections of the nerve samples.

Results

At 2 weeks, the vascular volume of SIEF nerves was comparable to control (P?=?0.1). The vascular surface area in SIEF nerves was superior to other groups (P<0.05). At 12 weeks, vascularity in SIEF nerves was significantly higher than allografts (P<0.05) and superior compared to all other groups (P<0.0001) at 16 weeks. SIEF nerves had a significantly increased number of vessels compared to allografts alone in the proximal (P<0.05) and mid-section of the graft (P<0.05).

Conclusions

Addition of surgical angiogenesis to the wound bed greatly improves revascularization. It was demonstrated that revascularization occurs primarily from proximal to distal (proximal inosculation) and not from both ends as previously believed and confirms the theory of centripetal revascularization.

SUBMITTER: Saffari TM

PROVIDER: S-EPMC7770618 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Revascularization patterns of nerve allografts in a rat sciatic nerve defect model.

Saffari Tiam M TM Mathot Femke F Friedrich Patricia F PF Bishop Allen T AT Shin Alexander Y AY

Journal of plastic, reconstructive & aesthetic surgery : JPRAS 20191211 3

<h4>Introduction</h4>The specific patterns of revascularization of allograft nerves after the addition of vascularization remain unknown. The aim of this study was to determine the revascularization patterns of optimized processed allografts (OPA) after surgically induced angiogenesis to the wound bed in a rat sciatic nerve model.<h4>Materials and methods</h4>In 51 Lewis rats, sciatic nerve gaps were repaired with (i) autografts, (ii) OPA and (iii) OPA wrapped in a pedicled superficial inferior ...[more]

PMID: 31928962

Similar Datasets

Project description:BACKGROUND:Current methods to repair ablation-type peripheral nerve injuries (PNIs) using peripheral nerve allografts (PNAs) often result in poor functional recovery due to immunological rejection as well as to slow and inaccurate outgrowth of regenerating axonal sprouts. In contrast, ablation-type PNIs repaired by PNAs, using a multistep protocol in which one step employs the membrane fusogen polyethylene glycol (PEG), permanently restore sciatic-mediated behaviors within weeks. Axons and cells within PEG-fused PNAs remain viable, even though outbred host and donor tissues are neither immunosuppressed nor tissue matched. PEG-fused PNAs exhibit significantly reduced T cell and macrophage infiltration, expression of major histocompatibility complex I/II and consistently low apoptosis. In this study, we analyzed the coding transcriptome of PEG-fused PNAs to examine possible mechanisms underlying immunosuppression. METHODS:Ablation-type sciatic PNIs in adult Sprague-Dawley rats were repaired using PNAs and a PEG-fusion protocol combined with neurorrhaphy. Electrophysiological and behavioral tests confirmed successful PEG-fusion of PNAs. RNA sequencing analyzed differential expression profiles of protein-coding genes between PEG-fused PNAs and negative control PNAs (not treated with PEG) at 14 days PO, along with unoperated control nerves. Sequencing results were validated by quantitative reverse transcription PCR (RT-qPCR), and in some cases, immunohistochemistry. RESULTS:PEG-fused PNAs display significant downregulation of many gene transcripts associated with innate and adaptive allorejection responses. Schwann cell-associated transcripts are often upregulated, and cellular processes such as extracellular matrix remodeling and cell/tissue development are particularly enriched. Transcripts encoding several potentially immunosuppressive proteins (e.g., thrombospondins 1 and 2) also are upregulated in PEG-fused PNAs. CONCLUSIONS:This study is the first to characterize the coding transcriptome of PEG-fused PNAs and to identify possible links between alterations of the extracellular matrix and suppression of the allorejection response. The results establish an initial molecular basis to understand mechanisms underlying PEG-mediated immunosuppression.

Project description:Over the past decade, silk fibroin (SF) has been emergently used in peripheral nerve tissue engineering. Current approaches aiming at producing SF-based nerve guidance conduits (SF-NGCs) used dissolved silk based on either aqueous solutions or organic solvents. In this study, we describe a novel procedure to produce SF-NGCs: A braided tubular structure of raw Bombyx mori silk is subsequently processed with the ternary solvent CaCl2/H2O/ethanol, formic acid, and methanol to improve its mechanical and topographical characteristics. Topographically, the combination of the treatments results in a fusion of the outer single silk fibers to a closed layer with a thickness ranging from about 40 to 75 μm. In contrast to the outer wall, the inner lumen (not treated with processing solvents) still represents the braided structure of single fibers. Mechanical stability, elasticity, and kink characteristics were evaluated with a custom-made test system. The modification procedure described here drastically improved the elastic properties of our tubular raw scaffold, favoring its use as a NGC. A cell migration assay with NIH/3T3-fibroblasts revealed the impermeability of the SF-NGC wall for possible invading and scar-forming cells. Moreover, the potential of the SF-NGC to serve as a substratum for Schwann cells has been demonstrated by cytotoxicity tests and live-dead stainings of Schwann cells grown on the inner surface of the SF-NGC. In vivo, the SF-NGC was tested in a rat sciatic nerve injury model. In short-term in vivo studies, it was proved that SF-NGCs are not triggering host inflammatory reactions. After 12 weeks, we could demonstrate morphological and functional reinnervation of the distal targets. Filled with collagen, a higher number of axons could be found in the distal to the graft (1678±303), compared with the empty SF-NGC (1274±146). The novel SF-NGC presented here shows promising results for the treatment of peripheral nerve injuries. The modification of braided structures to adapt their mechanical and topographical characteristics may support the translation of SF-based scaffolds into the clinical setting. However, further improvements and the use of extracellular matrix molecules and Schwann cells are suggested to enable silk tube based conduits to bridge long-distance nerve gaps.

Project description:Purpose: Current methods to repair ablation-type peripheral nerve injuries (PNIs) using peripheral nerve allografts (PNAs) often result in poor functional recovery due to immunological rejection as well as slow and inaccurate outgrowth of regenerating axon sprouts. In contrast, ablation-type PNIs repaired by PNAs using a multistep protocol, in which one step uses the membrane fusogen polyethylene glycol (PEG), permanently restore sciatic-mediated behaviors within weeks. Axons and cells within the PNA remain viable, even though outbred host and donor tissues are neither immunosuppressed nor tissue matched. PEG-fused PNAs exhibit significantly reduced T cell and macrophage infiltration, apoptosis, and expression of major histocompatibility complex I/II. In this study, we analyzed the coding transcriptome of PEG-fused PNAs to determine possible mechanisms underlying immunosuppression. Methods: Ablation-type sciatic PNIs in adult Sprague Dawley rats were repaired using PNAs and a PEG-fusion protocol combined with neurorrhaphy. Electrophysiological and behavioral recovery tests confirmed successful PEG-fusion of PNAs. RNA sequencing analyzed differential expression profiles of protein-coding genes between PEG-fused PNAs and NC PNAs (not treated with PEG) at 14d PO, along with Unoperated nerves. Sequencing results were validated by Quantitative Reverse Transcription PCR (RT-qPCR). Results: PEG-fused PNAs display significant downregulation of a great many gene transcripts associated with innate and adaptive allorejection responses. Many Schwann cell-associated transcripts are upregulated, and many cellular processes such as extracellular matrix remodeling, cell and tissue development are particularly enriched. Transcripts encoding several potentially immunosuppressive proteins (e.g. Thrombospondins 1 and 2) are upregulated in PEG-fused PNAs. Conclusions: This study is the first to characterize the coding transcriptome of PEG-fused PNAs, and identifies possible links between alterations of the extracellular matrix and suppression of the allorejection response. The results establish a molecular-basis to understand mechanisms underlying PEG-mediated immunosuppression.

Dataset Information

Revascularization patterns of nerve allografts in a rat sciatic nerve defect model.

Introduction

Materials and methods

Results

Conclusions

Publications

Revascularization patterns of nerve allografts in a rat sciatic nerve defect model.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets