Development of a constant pressure perfused ex vivo model of the equine larynx

PLoS One. 2021 May 20;16(5):e0251530. doi: 10.1371/journal.pone.0251530. eCollection 2021.

Abstract

Distal axonopathy is seen in a broad range of species including equine patients. In horses, this degenerative disorder of the recurrent laryngeal nerve is described as recurrent laryngeal neuropathy (RLN). The dysfunctional innervation of the cricoarytenoideus dorsalis muscle (CAD) leads to a loss of performance in affected horses. In general, ex vivo models of the larynx are rare and for equine patients, just one short report is available. To allow for testing new therapy approaches in an isolated organ model, we examined equine larynges in a constant pressure perfused setup. In order to check the vitality and functionality of the isolated larynx, the vessels´ reaction to norepinephrine (NE) and sodium nitroprusside (NP) as vasoactive agents was tested. Additionally, the contractility of the CAD was checked via electrical stimulation. To determine the extent of hypoxic alterations, lactate dehydrogenase (LDH) and lactate were measured and an immunofluorescent analysis of hypoxia-inducible factor (HIF-1α), a key transcription factor in hypoxia, was performed. For this, a hypoxia-induced cell culture for HIF-1α was developed. The application of NE led to an expected vasoconstriction while NP caused the expected vasodilation. During a perfusion period of 352 ±20.78 min, LDH values were in the reference range and lactate values slightly exceeded the reference range at the end of the perfusion. HIF-1α nuclear translocation could reliably be detected in the hypoxia-induced cell cultures, but not in sections of the perfused CAD. With the approach presented here, a solid basis for perfusing equine larynges was established and may serve as a tool for further investigations of equine larynx disorders as well as a transferrable model for other species.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Horse Diseases / pathology*
  • Horses* / physiology
  • Hypoxia / pathology
  • Hypoxia / veterinary
  • Hypoxia-Inducible Factor 1, alpha Subunit / analysis
  • Laryngeal Diseases / pathology
  • Laryngeal Diseases / veterinary*
  • Laryngeal Muscles / pathology
  • Laryngeal Nerves / pathology
  • Larynx / pathology*
  • Perfusion

Substances

  • Hypoxia-Inducible Factor 1, alpha Subunit

Grants and funding

SO received a stipend through Med-El Company, Austria. Project-No: 2511-0712 (https://www.medel.com/de). The specific roles of these authors are articulated in the ‘author contributions’ section.The authors also received financial support from Leipzig University for Open Access Publishing. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.