Biology subjects

Chebotarev, O.

Publications and source records attributed to Chebotarev, O..

3 recordsLinked to original sources

bioRxiv2023

A microfluidic platform with integrated porous membrane cell-substrate impedance spectroscopy (PM-ECIS) for biological barrier assessment

Traditionally, biological barriers are assessed in vitro by measuring trans-endothelial/epithelial electrical resistance (TEER) across a monolayer using handheld chopstick electrodes. Implementation of TEER into organ-on-chip (OOC) setups is a challenge however, due to non-uniform current distribution and interference from biomaterials typically found in such systems. In this work, we address the pitfalls of standard TEER measurement through the application of porous membrane electrical cell-substrate impedance sensing (PM-ECIS) to an OOC setup. Gold leaf electrodes (working electrode diameters = 250, 500, 750 {micro}m) were incorporated onto porous membranes and combined with biocompatible tape to assemble microfluidic devices. PM-ECIS resistance at 4 kHz was not influenced by presence of collagen hydrogel in bottom channels, compared to TEER measurements in same devices, which showed a difference of 1723 {+/-} 381.8 {Omega} (p=0.006) between control and hydrogel conditions. A proof of concept, multi-day co-culture model of the blood-brain barrier was also demonstrated in these devices. PM-ECIS measurements were robust to fluid shear (5 dyn/cm2) in cell-free devices, yet were highly sensitive to flow-induced changes in an endothelial barrier model. Initiation of perfusion (0.06 dyn/cm2) in HUVEC-seeded devices corresponded to significant decreases in impedance at 40 kHz (p<0.01 for 750 and 500 {micro}m electrodes) and resistance at 4 kHz (p<0.05 for all electrode sizes) relative to static control cultures, with minimum values reached at 6.5 to 9.5 hours after induction of flow. Our microfluidic PM-ECIS platform enables sensitive, non-invasive, real-time measurements of barrier function in setups integrating critical OOC features like 3D co-culture, biomaterials and shear stress.

bioengineering↗

bioRxiv2023

Sensitivity and validation of porous membrane electrical cell substrate impedance spectroscopy (PM-ECIS) for measuring endothelial barrier properties

Conventional trans-endothelial electrical resistance (TEER) setups are invasive and cannot directly measure monolayer integrity in co-culture. These limitations are addressed by porous membrane electrical cell-substrate impedance sensing (PM-ECIS), which measures barrier integrity in cell monolayers grown directly on permeable membranes patterned with electrodes. Here we advance the design and utility of PM-ECIS by investigating its sensitivity to working electrode size and correlation to TEER. Gold electrodes were fabricated on porous membrane inserts using hot embossing and UV lithography, with working electrode diameters of 250, 500, and 750 {micro}m within the same insert. Frequency scans of confluent primary endothelial monolayers showed normalized resistance peaking at 4 kHz, consistent with traditional solid substrate ECIS. Sensitivity to resistance changes (4 kHz) during endothelial barrier formation was inversely proportional to electrode size, with the smallest electrodes being the most sensitive (p<0.001). Similarly, smaller electrodes were most sensitive to changes in impedance (40 kHz) corresponding to cell spreading and proliferation (p<0.001). Barrier disruption with EGTA was detectable by 250 and 750 {micro}m (p<0.01), and 500 {micro}m electrodes (p=0.058). Resistances measured by PM-ECIS vs. TEER for sodium chloride solutions were positively and significantly correlated for all electrode sizes (r>0.9; p<0.0001), but only with 750 {micro}m electrodes for endothelial monolayers (r=0.71; p=0.058). These data inform design and selection of PM-ECIS electrodes for specific applications, and support PM-ECIS as a promising alternative to conventional TEER due to its capacity for direct, non-invasive, and real-time assessment of cells cultured on porous membranes.

bioengineering↗

bioRxiv2023

Porous membrane electrical cell-substrate impedance spectroscopy for versatile assessment of biological barriers in vitro

Cell culture models of endothelial and epithelial barriers typically use porous membrane inserts (e.g., Transwell inserts) as a permeable substrate on which barrier cells are grown, often in co-culture with other cell types on the opposite side of the membrane. Current methods to characterize barrier function in porous membrane inserts can disrupt the barrier or provide bulk measurements that cannot isolate barrier cell resistance alone. Electrical cell-substrate impedance sensing (ECIS) addresses these limitations but its implementation on porous membrane inserts has been limited by costly manufacturing and low sensitivity. Here we present porous membrane ECIS (PM-ECIS), a cost-effective method to adapt ECIS technology to porous substrate-based in vitro models. We demonstrate high fidelity patterning of electrodes on porous membranes that can be incorporated into well plates of a variety of sizes with excellent cell biocompatibility with mono- and co-culture set ups. PM-ECIS provided sensitive, real-time measurement of isolated changes in endothelial cell barrier impedance with cell growth and barrier disruption. Barrier function characterized by PM-ECIS resistance correlated well with permeability coefficients obtained from molecular tracer permeability assays performed on the same cultures, validating the device. Integration of ECIS into conventional porous cell culture inserts provides a versatile, sensitive, and automated alternative to current methods to measure barrier function in vitro, including molecular tracer assays and transepithelial/endothelial electrical resistance (TEER).

bioengineering↗