Vocal fold fibroblasts (VFF) constitute the main cell type of the vocal fold’s lamina propria, produce the extracellular matrix and thereby determine the tissue characteristics. To study VFF behavior under in vitro conditions it is important to mimic the dynamic environment of the in vivo state. The aim of our study was to develop and validate a novel phonomimetic bioreactor system mainly based on commercially available components. The use of cell culture dishes with flexible silicone bottoms in combination with a suitable loudspeaker made it possible to expose the cells to various kinds of phonatory stimuli. The fundamental vibration characteristics of silicone membranes were investigated with and without cell culture medium by laser Doppler vibrometry. Human VFF were seeded in flexible-bottomed plates and placed in a custom-made housing containing a loudspeaker. After the cells were exposed to a predefined audio stimulation protocol, cell viability was assessed and gene as well as protein expression levels were compared to static controls. Laser Doppler vibrometry revealed that addition of cell culture medium changed the resonance frequencies of vibrating membranes. Gene expression of hyaluronan synthase 2, collagen III, fibronectin and TGFβ-1 was significantly upregulated in VFF exposed to vibration, compared to static control. Vibration also significantly upregulated collagen I gene and protein expression. We present a new type of phonomimetic bioreactor. Compared to previous models, our device is easy to assemble and cost-effective, yet can provide a wide spectrum of phonatory stimuli based on the entire dynamic range of the human voice. Gene expression data of VFF cultured in our phonomimetic bioreactor show a significant effect of vibration on ECM metabolism, which illustrates the efficacy of our device.
Introduction Voice rest following phonotrauma or phonosurgery has a considerable clinical impact, but clinical recommendations are inconsistent due to inconclusive data. As biopsies of the vocal folds (VF) for molecular biology studies in humans are unethical, we established a new in vitro model to explore the effects of vibration on human vocal fold fibroblasts (hVFF) in an inflammatory and normal state, which is based on previously published models. Methods By using a phonomimetic bioreactor we were able to apply predefined vibrational stress patterns on hVFF cultured under inflammatory or normal conditions. Inflammatory and pro-fibrotic stimuli were induced by interleukin (IL)1β and transforming growth factor (TGF)β1, respectively. Mechanical stimulation was applied four hours daily, over a period of 72 hours. Outcome measurements comprised assessment of extracellular matrix (ECM)-related components, angiogenic factors, and inflammatory and fibrogenic markers on gene expression and protein levels. Results Under inflammatory conditions, the inflammatory cytokine IL11, as well as the myofibroblast marker alpha smooth muscle actin (α-SMA) were significantly reduced when additional vibration was applied. The desirable anti-fibrotic ECM component hyaluronic acid was increased following cytokine treatment, but was not diminished following vibration. Conclusion Our experiments revealed the effect of vibrational stress on hVFF in an inflammatory state. Elevated levels of certain pro-inflammatory/pro-fibrotic factors could be mitigated by additional vibrational excitation in an in vitro setting. These findings corroborate clinical studies which recommend early voice activation following an acute event.
Zusammenfassung Hintergrund Trotz erheblicher Fortschritte in der laryngologischen Forschung gibt es eine Reihe von (benignen) Stimmlippenerkrankungen, die kausal nicht therapierbar sind. Das liegt an der eingeschränkten Zugänglichkeit sowie der sensiblen Mikroarchitektur der Stimmlippen, die nicht auf zellulärer Ebene erforscht werden können. Das pathophysiologische Verständnis endet dadurch häufig in der makroskopischen Ebene, die Folgen von Interventionen werden großteils endoskopisch oder mit indirekten Methoden evaluiert. Fragestellung Im nachfolgenden Beitrag stellen die Autor(inn)en biotechnologische State-of-the-Art-Methoden vor, die in der laryngologischen Forschung Anwendung finden, verbunden mit praktischen Beispielen. Ergebnisse Tierversuche und Zellkulturexperimente haben in den letzten Jahren zu einer signifikanten Wissenserweiterung beigetragen, dies insbesondere in den Bereichen Stimmlippeninflammation und -narbenbildung. Dem Stimmlippenfibroblasten, als wichtigstem zellulärem Bestandteil der Lamina propria, kommt dabei eine zentrale Rolle zu. Schlussfolgerungen Mittlerweile besteht bei einigen Krankheitsbildern ein tieferes Verständnis von Makroanatomie und Makropathophysiologie als je zuvor. In-vitro-Versuche zeigten beispielsweise, dass Stimmlippenfibroblasten in einem inflammatorischen Setting weniger profibrotische und proinflammatorische Zytokine sezernierten, wenn sie Vibrationen ausgesetzt sind. Umgesetzt auf die Klinik könnte das bedeuten, dass eine frühe Stimmaktivierung nach operativen Eingriffen an den Stimmlippen zu besserer Heilung und besseren stimmlichen Ergebnissen führt. Unsere Vision lautet, dass die molekulare Laryngologie ein gesichertes Fundament an Wissen bereitstellen soll, auf das in weiterer Folge klinische Studien aufgebaut werden können.
Der okkulte Fremdkörper im Larynx Anamnese Eine 61-jährige Frau wurde mit Zuweisung vom Zahnarzt wegen eines Fremdkörpergefühls in unserer HNO-Notaufnahme vorstellig. Sie berichtete, im Rahmen der zahnärztlichen Behandlung sei es zu einem Verlust einer Schraube ihrer Zahnprothese gekommen, seither hätte sie das Gefühl, die Schraube würde in ihrem Hals feststecken. Ansonsten war die Patientin völlig beschwerdefrei, insbesondere konnten keinerlei respiratorische Symptome wie Dyspnoe erhoben werden.
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