Instrumented Microphysiological Systems for Real-Time Measurement and Manipulation of Cellular Electrochemical Processes

Abstract

Recent advancements in electronic materials and subsequent surface modifications have facilitated real-time measurements of cellular processes far beyond traditional passive recordings of neurons and muscle cells. Specifically, the functionalization of conductive materials with ligand-binding aptamers has permitted the utilization of traditional electronic materials for bioelectronic sensing. Further, microfabrication techniques have better allowed microfluidic devices to recapitulate the physiological and pathological conditions of complex tissues and organs in vitro or microphysiological systems (MPS). The convergence of these models with advances in biological/biomedical microelectromechanical systems (BioMEMS) instrumentation has rapidly bolstered a wide array of bioelectronic platforms for real-time cellular analytics. In this review, we provide an overview of the sensing techniques that are relevant to MPS development and highlight the different organ systems to integrate instrumentation for measurement and manipulation of cellular function. Special attention is given to how instrumented MPS can disrupt the drug development and fundamental mechanistic discovery processes.

Keywords: Bioelectronics; Bioengineering; Biotechnology.

Graphical abstract

Figure 1

Overview of MPSs across the Body and Modes of Electric-Based Sensing

Figure 2

Overview of Types of Passive and Active Electric-Based Sensing Integrated in MPSs

Figure 3

Examples of Instrumented Organ-on-chip Models of the Peripheral and Central Nervous System (A and B) Extracellular activity and connectivity of compartmentalized cortical neurons via an MEA. (C and D) Extracellular recordings of neural activity and 3D connectivity via a 3D MEA. (E) Extracellular recordings and impedance detection to quantify firing frequency and cell adhesion of neuronal cells exposed to sodium valproic acid via an MEA and an interdigitated electrode structure. (F) Extracellular recordings of spontaneous and stimulated autonomic neuron activity for regulating cardiac beating via an MEA. (G) CV of myelinated and nonmyelinated sensory neurons via a microchannel-electrode approach. (H) Single-unit action potentials and CV of intact sciatic nerves exposed to ultrasound stimuli via a multi-wire electrode array. (I) CAP and CV of intact sciatic nerves via a microchannel-electrode approach. (J, K, and L) (J) CAP recording in 3D rodent sensory neuron, (K) 3D myelinated rodent sensory neurons, and (L) 3D human stem cell-derived sensory neuron models via stimulating and recording wire electrodes. Reprinted and adapted with permission from: A (Kanagasabapathi et al., 2011); B (Pan et al., 2015); C (Rowe et al., 2007); D (Musick et al., 2009); E (Koester et al., 2010a); F (Oiwa et al., 2016); G (Sakai et al., 2017); H (Chen et al., 2017); I (Gribi et al., 2018); J (Huval et al., 2015); K (Khoshakhlagh et al., 2018); and L (Sharma et al., 2019). MEA, multielectrode array; CV, conduction velocity; CAP, compound action potential.

Figure 4

Examples of Instrumented Organ-on-chip Models of the Heart (A) Extracellular recordings of micropatterned stem-cell-derived CMs to study cardiac beating, field potentials, and conduction velocity via an MEA under vascular-like perfusion. (B) Extracellular field potential duration and beat rate measurements from a CM/endothelial cell bilayer coculture model to assess the pharmacodynamics of altered vascular permeability via an MEA. (C) Concurrent assessment of cardiac electrophysiology, beat rate, contractility, and viability via an MEA and IDEs with interpenetrating geometries for measuring field potentials and impedance, respectively. (D) Parallel quantification of cardiac contraction force and electrophysiology of patterned stem-cell-derived CMs via independent cantilever system and MEA, respectively. (E) Real-time cardiac tissue force quantification via the change in resistance caused by the deformation of piezoelectric MTF chips. Reprinted and adapted with permission from: A (Kujala et al., 2016); B (Maoz et al., 2017); C (Qian et al., 2017); D (Oleaga et al., 2019); and E (Agarwal et al., 2013, Grosberg et al., 2011, Lind et al., 2017). CMs, cardiomyocytes; MEA, multielectrode array; IDEs, interdigitated electrodes; MTF, muscle thin films.

Figure 5

Examples of Instrumented Organ-on-chip Models of the Adrenal Gland (A) Amperometric detection of catecholamines released from immobilized PC12 cells after calcium/potassium stimulation via platinum/indium tin oxide electrodes. (B) Fluorescent detection of dopamine release from immobilized PC12 cells via electrophoretic-based separation of catecholamines. (C) Simultaneous electrochemical detection of dopamine and norepinephrine from immobilized PC12 cells via microchip electrophoresis and carbon ink microelectrodes. (D) Electrochemical detection of single-cell catecholamine exocytosis from cytophobically/fluidically trapped bovine chromaffin cells via a multielectrode array. (E) Electrochemical detection of catecholamines from multiple individual bovine chromaffin cells via a 10 × 10 potentiostat electrode array. (F) Spatiotemporal amperometric spike detection from bovine chromaffin cell clusters in repose to physiologically relevant secretagogues to assess the kinetics of adrenal catecholamine exocytosis via interdigitated electrodes. Reprinted and adapted with permission from: A (Li et al., 2005, Sun and Gillis, 2006); B (Li and Martin, 2008); C (Bowen and Martin, 2010); D (Barizuddin et al., 2010, Liu et al., 2011); E (Kim et al., 2013); and F (Ges et al., 2013).

Figure 6

Examples of Instrumented Organ-on-chip Models of the Vasculature System (A) Permeability study of a mouse-brain-derived endothelial cell (bEnd.3) monolayer cultured on the membrane of a bilayer chip via TEER electrodes. (B) Barrier integrity assessment of bEnd3 cell monolayer cocultured with a murine astrocytic cell line (C8D1A) in a multilayer chip under flow via TEER. (C) Human brain endothelial cell line (hCMEC/D3) tight junction integrity investigated within a bilayer chip with vasculature-like flow via TEER electrodes. (D) BBB integrity assessed within a perfusable trilayer chip, containing brain endothelial cells, astrocytes, and pericytes, in response to physiological stresses via TEER electrodes. (E and F) (E) BBB permeability quantified in using a 2D and (F) 3D side-by-side orientated vascular channel and the brain compartment microfluidic device via TEER electrodes. (G) Electrochemical assessment of red blood cell nitric oxide production via an integrated amperometric detector. Reprinted and adapted with permission from: A (Douville et al., 2010); B (Booth and Kim, 2012); C (Walter et al., 2016); D (Brown et al., 2015); E (Deosarkar et al., 2015); F (Xu et al., 2016); and G (Selimovic et al., 2014). TEER, transepithelial electrical resistance; BBB, blood brain barrier; IDEs, interdigitated electrodes.

Figure 7

Examples of Instrumented Organ-on-chip Models of the Gut (A) TEER measurements from a human Caco-2 intestinal epithelial cell monolayer exposed to microbial flora and intestinal peristalsis-like motions and flow via insertable wire electrodes. (B) Gastrointestinal barrier integrity quantified in response to bacterial colonization in an anaerobic environment via chopstick style TEER electrodes. (C and D) Intestinal monolayer barrier formation and villi differentiation assessed by measuring TEER and cell layer capacitance via integrated four-point impedance electrodes. Reprinted and adapted with permission from: A (Kim et al., 2012); B (Shah et al., 2016); C (Henry et al., 2017); and D (van der Helm et al., 2019). TEER, transepithelial electrical resistance.

Figure 8

Examples of Instrumented Organ-on-chip Models of the Lungs and Skin (A) Lung epithelial A549 cell tight junction integrity investigated within a bilayer chip with vasculature-like flow via TEER electrodes. (B) Human airway epithelial cell mucociliary differentiation and barrier functionality quantified using capacitance and TEER measurements recorded overtime after establishing an air-liquid interface via integrated four-point impedance electrodes. (C) Barrier integrity and chloride ion channel activity was assessed within an airway epithelial, stromal, and vascular endothelial cell coculture system via integrated TEER and short circuit current electrodes. (D) Airway epithelial barrier permeability under physiological cyclic strain quantified via integrated TEER electrodes. (E) Cell-substrate interactions, cell viability, and metabolic activity of foreskin-derived dermal fibroblasts in response to stimulation with circulating proinflammatory molecules quantified via interdigitated electrodes. (F) Epidermal barrier functionality measured in response to skin allergens or physical stresses in a keratinocytes/immune cells coculture model via TEER electrodes. (G) Barrier integrity of a full-thickness 3D human skin equivalent assessed via TEER electrodes. (H) Capacitance of a vascularized 3D skin model measured via two electrodes was placed on either the dermal or the epidermal layers. (I) Barrier stability, metabolic activity, and tissue breakdown measured simultaneously via TEER and extracellular acidification rate of L929 fibroblasts. Reprinted and adapted with permission from: A (Walter et al., 2016); B (Henry et al., 2017); C (Skardal et al., 2017); D (Stucki et al., 2018); E (Charwat et al., 2014); F (Ramadan and Ting, 2016); G (Sriram et al., 2018); H (Mori et al., 2017); and I (Alexander et al., 2018). TEER, transepithelial electrical resistance.

Figure 9

Examples of Instrumented Organ-on-chip Models of the Liver and Kidneys (A) Detection of TGF-β1 within a reconfigurable device to allow communication between injured hepatocytes and stellate cells via an aptamer-based electrochemical sensor. (B) On-chip detection of the hepatocyte growth factor and TGF-β1 secreted by primary hepatocytes via a fluorescent-bead-based optical sensor. (C) Transferrin and albumin production from human primary hepatocytes cultured in the bioreactor quantified via a bead-based electrochemical immunosensor. (D) Continuous real-time monitoring of hepatocyte metabolic function via a glucose/lactate enzyme-based electrochemical sensors and oxygen sensing phosphorescent microprobes. (E) Hepatocyte oxygen consumption rate assessed via inkjet-printed electrochemical dissolved oxygen sensors and commercial Clark-type sensors. (F) Permeability study of an MDCK-2 cell monolayer cultured on the membrane of a bilayer chip via TEER electrodes. (G) Assessment of renal epithelial cell growth and tight junction integrity quantified within a continuous fluid shear stress model via integrated TEER electrodes. (H) TEER measurements from a human renal epithelial cell monolayer cultured in a multi-use microfluidic device with integrated electrodes. (I) Electrical cell–substrate impedance monitoring of MDCK-2 cells to investigate wound healing and barrier integrity via an organic electrochemical transistor. (J) Electrochemical measurement of dissolved oxygen, Na⁺ and K⁺ ion concentration, and pH in kidney exactments via potentiometric and amperometric electrodes. Reprinted and adapted with permission from: A (Zhou et al., 2015); B (Son et al., 2017); C (Riahi et al., 2016); D (Bavli et al., 2016); E (Moya et al., 2018b); F (Douville et al., 2010); G (Ferrell et al., 2010); H (Brakeman et al., 2016); I (Curto et al., 2017); and J (Moya et al., 2018a). TGF-β1, transforming growth factor; MDCK-2, Madin Darby canine kidney-2; TEER, transepithelial electrical resistance.

Figure 10

Examples of Instrumented Organ-on-chip Models of Cancer (A) Electrical cell–substrate impedance sensing to monitor cancer cell metastasis via an electrode array. (B) Malignant cell invasion quantified in response to biomimetic cytokine stimulation via interdigitated electrodes. (C) Oxygen concentration, biochemical profiles, temperature, and pH changes resulting from cancer and its treatment quantified by plumbing together biochemical, physical, and chemical sensing modules. (D) Monitoring T98G human brain cancer cells metabolism within a single device via miniaturized pH and oxygen electrodes and amperometric biosensors for glucose, lactate, and peroxide. Reprinted and adapted with permission from: A (Nguyen et al., 2013); B (Lei et al., 2016); C (Zhang et al., 2017); D (Weltin et al., 2013).