Development of a Self-Oscillating Mechanical Model to Investigate the Biological Response of Human Vocal Fold Fibroblasts to Phono-Mimetic Stimulation

The human vocal folds are subjected to complex dynamic biomechanical stimulation during phonation. The aim of the present study was to develop and evaluate an airflow-induced self-oscillating mechanical model, i.e., a bioreactor, which mimics the geometry and the mechanical microenvironment of the human vocal folds. The bioreactor consisted of two composite synthetic vocal fold replicas loaded into a custom-built airflow supplied tube. A cell-scaffold mixture was injected into cavities within the replicas. The folds were phonated using a variable speed centrifugal blower for two hours a day over a period of seven days. The static and dynamic subglottal pressures and the dynamic supraglottal pressure were monitored. A similar bioreactor without mechanical excitation was used as positive control. The cell-scaffold mixture was harvested for cell viability and collagen type I immunohistochemistry tests seven days after injection. The flow-induced self-oscillations of the vocal fold replicas were shown to produce mechanical excitations that are typical of those in the human vocal fold lamina propria during phonation. The results confirmed that human vocal fold fibroblasts survived inside the present bioreactor, and maintained cellular functions of protein production.