A thermoplastic microfluidic microphysiological system to recapitulate hepatic function and multicellular interactions

Abstract

Hepatic in vitro platforms ranging from multi-well cultures to bioreactors and microscale systems have been developed as tools to recapitulate cellular function and responses to aid in drug screening and disease model development. Recent developments in microfabrication techniques and cellular materials enabled fabrication of next-generation, advanced microphysiological systems (MPSs) that aim to capture the cellular complexity and dynamic nature of the organ presenting highly controlled extracellular cues to cells in a physiologically relevant context. Historically, MPSs have heavily relied on elastomeric materials in their manufacture, with unfavorable material characteristics (such as lack of structural rigidity) limiting their use in high-throughput systems. Herein, we aim to create a microfluidic bilayer model (microfluidic MPS) using thermoplastic materials to allow hepatic cell stabilization and culture, retaining hepatic functional phenotype and capturing cellular interactions. The microfluidic MPS consists of two overlapping microfluidic channels separated by a porous tissue-culture membrane that acts as a surface for cellular attachment and nutrient exchange; and an oxygen permeable material to stabilize and sustain primary human hepatocyte (PHH) culture. Within the microfluidic MPS, PHHs are cultured in the top channel in a collagen sandwich gel format with media exchange accomplished through the bottom channel. We demonstrate PHH culture for 7 days, exhibiting measures of hepatocyte stabilization, secretory and metabolic functions. In addition, the microfluidic MPS dimensions provide a reduced media-to-cell ratio in comparison with multi-well tissue culture systems, minimizing dilution and enabling capture of cellular interactions and responses in a hepatocyte-Kupffer coculture modelunder an inflammatory stimulus. Utilization of thermoplastic materials in the model and ability to incorporate multiple hepatic cells within the system is our initial step towards the development of a thermoplastic-based high-throughput microfluidic MPS platform for hepatic culture. We envision the platform to find utility in development and interrogation of disease models of the liver, multi-cellular interactions and therapeutic responses.

Advanced Organ-on-a-Chip Devices to Investigate Liver Multi-Organ Communication: Focus on Gut, Microbiota and Brain

“…Table 1. Advanced liver-on-a-chip devices to study hepatic functions and liver-based multi-organ communication [53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69].…”

“…To efficiently fill this gap, Bavli and co-workers proposed tissue-embedded microparticles loaded with a ruthenium-based dye [54]. To avoid the invasiveness of tissue-embedded sensors, Bale and colleagues preferred a modified microfluidic advanced microphysiological system (MPS) incorporating strip-based oxygen sensing foils [60].…”

“…In the liver compartment, the bottom contained three concentric grooves 1 mm deep to segregate the spheroids. The system was optically accessible and compatible with manual measurements of the TEER with chopstick electrodes [60]. The pumping system ensured automatic recirculation of the medium while a manual medium refresh was necessary every day.…”

“…The advantages of the devices developed so far and a multi-organ platform modeling the liver as an active element communicating with the epithelial barrier and indirectly with the brain, could be combined to study in vitro the liver-mediated communication between the gut and the brain. For instance, the device proposed by Esch and colleagues could be made optically accessible and continuously perfused with fresh medium, as in Theobald's system [58,60]. To examine the effects of the liver on the integrity of the epithelial barrier, the system should be implemented with the possibility of measuring the TEER, as in Esch's and Bovard's systems [59,60].…”

“…For instance, the device proposed by Esch and colleagues could be made optically accessible and continuously perfused with fresh medium, as in Theobald's system [58,60]. To examine the effects of the liver on the integrity of the epithelial barrier, the system should be implemented with the possibility of measuring the TEER, as in Esch's and Bovard's systems [59,60]. Finally, to integrate the interconnection with the brain, the device could be expanded, by adding, for instance, a third microfluidic chamber in series for neuronal cells.…”