Cell viability viscoelastic measurement in a rheometer used to stress and engineer tissues at low sonic frequencies

Abstract

Effects of vibration on human vocal fold extracellular matrix composition and the resultant tissue viscoelastic properties are difficult to study in vivo. Therefore, an in vitro bioreactor, simulating the in vivo physiological environment, was explored. A stress-controlled commercial rheometer was used to administer shear vibrations to living tissues at stresses and frequencies corresponding to male phonation, while simultaneously measuring tissue viscoelastic properties. Tissue environment was evaluated and adjustments made in order to sustain cell life for short term experimentation up to 6 h. Cell nutrient medium evaporation, osmolality, pH, and cell viability of cells cultured in three-dimensional synthetic scaffolds were quantified under comparably challenging environments to the rheometer bioreactor for 4 or 6 h. The functionality of the rheometer bioreactor was demonstrated by applying three vibration regimes to cell-seeded three-dimensional substrates for 2 h. Resulting strain was quantified throughout the test period. Rheologic data and cell viability are reported for each condition, and future improvements are discussed.

Tissue engineering-based therapeutic strategies for vocal fold repair and regeneration

“…In addition to custom-designed devices, commercial rheometers have been adapted and modified to administer physiologically relevant shear vibrations at 20–100Hz to natural or replacement tissues, while simultaneously measuring tissue viscoelastic properties. [208,209]…”

Adhesion of a Monolayer of Fibroblast Cells to Fibronectin under Sonic Vibrations in a Bioreactor

“…Our first-phase design 14,15 dealt primarily with the systematic and controlled application of a rotational shear stress (a cup-and-rotating plate design). Owing to tissue incompressibility at sonic frequencies, all vibrational deformation in vocal folds is essentially shear.…”

Development of a bilayer ring system for achieving high strain in commercial rheometers

“…The elastic properties of most materials are sufficient for achieving high strains, even when the amount of torque available is small (Klemuk et al, 2008). However, when investigating more fluid or gel-like materials for vocal fold applications, previous results using commercial rheometers have shown a limited ability to achieve large strains (above ~20%) or high frequencies (above 20Hz) (Chan et al, 2001; Chan and Titze, 1998; Kutty and Webb, 2009).…”