These steps not only complicate and extend the overall process but may also introduce unwanted variability in baseline tissue conditions, a significant hurdle in designing quality screening applications. Potential complications may also arise upon the introduction of cells into these devices, including a tissue transfer step to another device after tissue formation for long-term culture 8, 10, 13, 14, 15, or a transfer step to a measurement device such as a force transducer 7, 9, 16, 17 to measure contractile force. Another challenge typically associated with these microfluidic- and microstructure-based devices is adaptation to existing tissue culture equipment such as microscope stage adapters and liquid dispensing tools. Furthermore, these methods are restrictive to specific design geometries (for instance, vertical walls spanning either the micrometer or centimeter scale but not both) and are occasionally expensive to prototype (due to requiring access to a cleanroom, cost of materials, and time). Unfortunately, some of these systems are difficult to manufacture on a macroscale, and production often requires a high level of skill. Miniaturization of self-organizing cardiac organoids is a strategic approach to address these challenges using photolithography- and micromachining-based fabrication techniques 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Screening using engineered heart tissue is limited by the high cost associated with the large cell numbers required for high-fidelity in vitro cardiac models, the lack of long-term function and viability of the tissues, and the challenge of imaging for data acquisition.
This platform represents an open-source contractile force screening system useful for drug screening and tissue engineering applications. The unique tissue fabrication properties of the platform, and the consequent effects on tissue function, were demonstrated upon adding hPSC-derived epicardial cells to the system. Additionally, we developed automated protocols for CaMiRi seeding, image acquisition, and analysis to enable the measurement of contractile force with increased throughput. We validated the contractile force response of CaMiRi using selected cardiotropic compounds with known effects. Platform responses were robust and comparable across wells, and we used it to determine an optimal tissue formulation. The contractile force exerted by the CaMiRi is measured and calculated using the deflection of the cantilevers.
The wells are seeded with cell-laden collagen, which, in response to the gradual slope of the circumferential ramp, self-organizes around tip-gated microcantilevers to form contracting CaMiRi. Within each well, two elastomeric microcantilevers are situated above a circumferential ramp. We report a 96-well-based array of 3D human pluripotent stem cell (hPSC)-derived cardiac microtissues - termed Cardiac MicroRings (CaMiRi) - in custom 3D-print-molded multiwell plates capable of contractile force measurement.
To accelerate the cardiac drug discovery pipeline, we set out to develop a platform that would be capable of quantifying tissue-level functions such as contractile force and be amenable to standard multiwell-plate manipulations.
0 kommentar(er)
