Real-time physiological sensor-based liver-on-chip device for monitoring drug toxicity

Abstract

Organ-on-chip models, known as microphysiological systems, are created to mimic the anatomy and physiology of a human organ at the micro-level. Besides being pivotal in the reverse engineering of human organs and pathogenesis studies, they serve as an alternative to animal testing and the development of pharmaceutics. Monitoring the extracellular stromal environment is the basis for gaining in-depth knowledge of the pathophysiology of cell culture. Hence, it is extensively employed as an essential tool in the fields of organ-on-chip and in vitro toxicology. In this study, we explore the vitality of a microfluidic system for the automated, online detection of drug-induced physical changes in cellular viability by continual monitoring of a microfluidic 2D monolayer cell culture. Trans-epithelial electrical resistance (TEER) values and pH changes of the immortal HepG2 cell line were measured continuously using microfluidic-based electrical and photoelectric sensors. A chip-embedded transparent, flat, non-toxic sensor and in-house 3D manufactured portable digital microscope supersedes the conventional manual, expensive confocal microscopic assays, and off-line operated isolated sensor systems. The cytotoxicity was induced by various concentrations of doxorubicin, epirubicin and lapatinib, and the acute metabolic and physical response of cells was examined by detecting the variations in TEER, pH and other biological markers. Thus, our liver-on-chip device provides real-time online data on drug-induced liver injury in vitro.

Real-time monitoring of liver fibrosis through embedded sensors in a microphysiological system

“…The monolayer formed on the 3rd day or 72 h. In the current study, the TEER value 370–390 Ω/mm 2 represents a monolayer formation. However, in previous research, the TEER range of 345–395 Ω/mm 2 indicates a compact HepG2 monolayer formation [ 13 ]. The difference from the previously reported TEER range could be due to the co-culture of HepG2 cells with fibroblasts in the present work.…”

“…Physiological shear stress induces better monolayer formation and CYP450 enzyme activity [ 36 ]. Hence, the shear stress of 0.5 dyn/cm 2 was applied to achieve better monolayer formation than static cell culture [ 13 , 36 , 37 ]. The TEER values of liver MPS were taken at every 1-h interval for 144 h, as shown in Fig.…”

“…Yet, the use of poly- l -lysine in organ-on-chip technology for cell attachment is still not studied. In liver-on-chip studies, collagen and fibronectin are the most commonly used ECM [ 13 , 59 , 63 , 64 ]. Here, we explored the choice of the most vibrant ECM for liver fibrosis-on-chip development and its effect on the TEER and ROS sensor response and biomarker yield.…”

“…OOC is also termed as microphysiological systems (MPS) [ 10 ]. To date, several liver-on-chip (LOC) models have been introduced for studying hepatic anomalies [ 11 , 12 ] and compound toxicity [ 13 , 14 ]. Lee et al developed a liver fibrosis-on-a-chip model to investigate the impact of gelatin bioinks through cell printing technology.…”

“…TEER estimation is a quick and non-invasive method to measure in vitro cells' differentiation and the epithelial monolayer integrity [ 19 ]. It was previously employed in OOC to assess the cell monolayer barrier integrity, cell viability, cell–cell tight junction formation, and drug toxicity response [ 13 , 20 , 21 ]. However, TEER impedance spectroscopy has not been used to monitor liver fibrosis development in a microfluidic system.…”