QS9: Determining the Critical Time of Chronic Schwann Cell Denervation on Functional Recovery and Rna Expression

Alison L. Wong, MD, MSE; Thomas Harris, MBBS; Connor Glass, BS; Nicholas Nicholas von Guionneau, MBBS; Erica Lee, MS; Nicholas Hricz, BS; Harsha Malapati, BS; Ruifa Mi, MD, PhD; Vivek Swarup, PhD; Riki Kawaguchi, PhD; Ahmet Hoke, MD, PhD; Sami Tuffaha, MD

doi:10.1097/01.GOX.0000770036.06431.5c

Plastic and Reconstructive Surgery, Global Open (Jul 2021)

QS9: Determining the Critical Time of Chronic Schwann Cell Denervation on Functional Recovery and Rna Expression

Alison L. Wong, MD, MSE,
Thomas Harris, MBBS,
Connor Glass, BS,
Nicholas Nicholas von Guionneau, MBBS,
Erica Lee, MS,
Nicholas Hricz, BS,
Harsha Malapati, BS,
Ruifa Mi, MD, PhD,
Vivek Swarup, PhD,
Riki Kawaguchi, PhD,
Ahmet Hoke, MD, PhD,
Sami Tuffaha, MD

Affiliations

Alison L. Wong, MD, MSE: 1 Johns Hopkins University, Baltimore, MD, USA,
Thomas Harris, MBBS: 1 Johns Hopkins University, Baltimore, MD, USA,
Connor Glass, BS: 1 Johns Hopkins University, Baltimore, MD, USA,
Nicholas Nicholas von Guionneau, MBBS: 1 Johns Hopkins University, Baltimore, MD, USA,
Erica Lee, MS: 1 Johns Hopkins University, Baltimore, MD, USA,
Nicholas Hricz, BS: 1 Johns Hopkins University, Baltimore, MD, USA,
Harsha Malapati, BS: 1 Johns Hopkins University, Baltimore, MD, USA,
Ruifa Mi, MD, PhD: 1 Johns Hopkins University, Baltimore, MD, USA,
Vivek Swarup, PhD: 2 University of California Irvine, Irvine, CA, USA, 3University of California Los Angeles, Los Angeles, CA, USA.
Riki Kawaguchi, PhD: 2 University of California Irvine, Irvine, CA, USA, 3University of California Los Angeles, Los Angeles, CA, USA.
Ahmet Hoke, MD, PhD: 1 Johns Hopkins University, Baltimore, MD, USA,
Sami Tuffaha, MD: 1 Johns Hopkins University, Baltimore, MD, USA,

DOI: https://doi.org/10.1097/01.GOX.0000770036.06431.5c
Journal volume & issue: Vol. 9, no. 7S
pp. 21 – 21

Abstract

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Purpose: There is poor functional recovery following delayed peripheral nerve repair since both muscle and Schwann cells (SC) undergo denervation atrophy. We investigated the specific temporal effect of nerve/SC denervation on recovery as well as changes in RNA expression in the nerves that may elucidate changes in recovery potential. We hypothesized that functional recovery would be worse after prolonged nerve/SC denervation and that the expression profiles would differ. Methods: Our study was conducted using a forelimb model in adult Lewis rats. Each animal underwent unilateral forelimb denervation of 8, 12, 16, or 24 weeks duration. In the functional recovery arm of the study, the ulnar nerve was denervated proximally or a sham surgery was performed. After the denervation period had elapsed, an in situ nerve transfer of median to ulnar to median nerve was performed. Functional recovery was then measured by stimulated grip strength weekly for 12 weeks. In the RNA expression arm, median and ulnar nerves were denervated. The same time points were used with the addition of a 1-week denervation group. After the denervation period, the median and ulnar nerves were harvested bilaterally. To create a comprehensive RNA-Seq dataset, the median nerve, with an average length of 3 cm, was homogenized and RNA was purified. RNA-sequencing was carried out using TrueSeq RiboZero gold kit. Samples were analyzed through FastQC, aligned to reference genome using STAR and quantified as transcripts per million (TPM) using Salmon. Principle component analysis was performed, followed by differential gene analysis using a linear mixed effects model to control for the control nerves being from the same animals. Results: Functional recovery was statistically significantly different depending on the duration of nerve/SC denervation (P0.05, we identified 1624 genes differentially expressed, of which 327 genes were upregulated and rest (1297 genes) downregulated with denervation. Conclusions: Prolonged nerve/SC denervation of more than 12 weeks resulted in significantly worse functional recovery. RNA sequencing demonstrated that not only were there many genes differentially expressed, but these appear to vary with duration of denervation as well. Further investigation into the specific genes and their changes over time will allow us to know why recovery potential is decreased and targets for interventions to improve recovery.

Published in Plastic and Reconstructive Surgery, Global Open

ISSN: 2169-7574 (Online)
Publisher: Wolters Kluwer
Country of publisher: United States
LCC subjects: Medicine: Surgery
Website: http://www.prsgo.com

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