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Epithelial cells are active participants in vocal fold wound healing: an in vivo animal model of injury.

PloS one (2014-12-17)
Ciara Leydon, Mitsuyoshi Imaizumi, Rebecca S Bartlett, Sarah F Wang, Susan L Thibeault
ABSTRACT

Vocal fold epithelial cells likely play an important, yet currently poorly defined, role in healing following injury, irritation and inflammation. In the present study, we sought to identify a possible role for growth factors, epidermal growth factor (EGF) and transforming growth factor-beta 1 (TGFβ1), in epithelial regeneration during wound healing as a necessary first step for uncovering potential signaling mechanisms of vocal fold wound repair and remodeling. Using a rat model, we created unilateral vocal fold injuries and examined the timeline for epithelial healing and regeneration during early and late stages of wound healing using immunohistochemistry (IHC). We observed time-dependent secretion of the proliferation marker, ki67, growth factors EGF and TGFβ1, as well as activation of the EGF receptor (EGFR), in regenerating epithelium during the acute phase of injury. Ki67, growth factor, and EGFR expression peaked at day 3 post-injury. Presence of cytoplasmic and intercellular EGF and TGFβ1 staining occurred up to 5 days post-injury, consistent with a role for epithelial cells in synthesizing and secreting these growth factors. To confirm that epithelial cells contributed to the cytokine secretion, we examined epithelial cell growth factor secretion in vitro using polymerase chain reaction (PCR). Cultured pig vocal fold epithelial cells expressed both EGF and TGFβ1. Our in vivo and in vitro findings indicate that epithelial cells are active participants in the wound healing process. The exact mechanisms underlying their roles in autocrine and paracrine signaling guiding wound healing await study in a controlled, in vitro environment.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Hydrocortisone, BioReagent, suitable for cell culture
Sigma-Aldrich
Hydrocortisone, ≥98% (HPLC)
Sigma-Aldrich
Hydrocortisone, γ-irradiated, powder, BioXtra, suitable for cell culture
Supelco
Hydrocortisone, Pharmaceutical Secondary Standard; Certified Reference Material
Hydrocortisone, European Pharmacopoeia (EP) Reference Standard
USP
Hydrocortisone, United States Pharmacopeia (USP) Reference Standard
Sigma-Aldrich
Hydrocortisone, meets USP testing specifications
Hydrocortisone for peak identification, European Pharmacopoeia (EP) Reference Standard
Supelco
Hydrocortisone, VETRANAL®, analytical standard
Hydrocortisone, British Pharmacopoeia (BP) Assay Standard