Pneumatic unidirectional cell stretching device for mechanobiological studies of cardiomyocytes

Abstract

In this paper, we present a transparent mechanical stimulation device capable of uniaxial stimulation, which is compatible with standard bioanalytical methods used in cellular mechanobiology. We validate the functionality of the uniaxial stimulation system using human-induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CMs). The pneumatically controlled device is fabricated from polydimethylsiloxane (PDMS) and provides uniaxial strain and superior optical performance compatible with standard inverted microscopy techniques used for bioanalytics (e.g., fluorescence microscopy and calcium imaging). Therefore, it allows for a continuous investigation of the cell state during stretching experiments. The paper introduces design and fabrication of the device, characterizes the mechanical performance of the device and demonstrates the compatibility with standard bioanalytical analysis tools. Imaging modalities, such as high-resolution live cell phase contrast imaging and video recordings, fluorescent imaging and calcium imaging are possible to perform in the device. Utilizing the different imaging modalities and proposed stretching device, we demonstrate the capability of the device for extensive further studies of hiPSC-CMs. We also demonstrate that sarcomere structures of hiPSC-CMs organize and orient perpendicular to uniaxial strain axis and thus express more maturated nature of cardiomyocytes.

Recent Advances in Maturation of Pluripotent Stem Cell-Derived Cardiomyocytes Promoted by Mechanical Stretch

“…Uniaxial stretch is the primary parameter adjusted for mechanical stretching of engineered tissue [ 17 , 22 , 23 ] and is dependent on the design of the bioreactors. Various axial directions can be used when trying to differentiate stem cells into SC-CMs by mechanical stretch, including biaxial, equiaxial, and multiaxial stretching [ 24 – 26 ]; however, they are rarely used when trying to improve the maturity of PSC-CMs [ 20 ].…”

Brick Strex – A Robust Device Built of LEGO® Bricks for Mechanical Manipulation of Cells

“…in the epithelium 71 . Finally, during the recent years it has become evident that in addition to cell membrane associated adhesion sites, forces can be sensed also deeper in the cells 39,[72][73][74] . Mechanical forces rising from the ECM can be transmitted into the cells and they have been shown to directly affect even cell nuclei and chromatin 75 .…”

Maturation strategies and limitations of induced pluripotent stem cell-derived cardiomyocytes

“…Correspondingly, the appropriate increase in EHTs contractile resistance also promotes a more mature phenotype, specifically increasing the sarcomere length, cell area and elongation, improving Ca 2+ handling, and increasing the expression of sarcomere and ion channel-related genes [78]. orientation perpendicular to the applied strain can be observed, which indicates that the structural maturity of the CMs is improved [80]. LaBarge's team [76] used iPSC-CMs to prepare myocardial spheres, placed them in a device with PDMS channels, and exposed to cyclic uniaxial stretching, and performed a 7-day cyclic pull at 10% stress and 1 Hz frequency stretch.…”

“…At 8% peak-to-peak cyclic strain of 0.8 Hz, iPSC-CMs successfully attached and survived. Moreover, a more uniform sarcomere orientation perpendicular to the applied strain can be observed, which indicates that the structural maturity of the CMs is improved [ 80 ]. LaBarge et al [ 76 ] used iPSC-CMs to prepare myocardial spheres, placed them in a device with PDMS channels, and exposed to cyclic uniaxial stretching, and performed a 7-day cyclic pull at 10% stress and 1 Hz frequency stretch.…”