A microfluidic oxygen sink to create a targeted cellular hypoxic microenvironment under ambient atmospheric conditions

Abstract

Specific manipulation of oxygen concentrations in cultured cells' microenvironment is important when mimicking low-oxygen tissue conditions and pathologies such as tissue infarction or cancer. We utilised a sodium sulfite-based in-liquid chemical reaction to consume dissolved oxygen. When this liquid was pumped into a microfluidic channel, lowered oxygen levels could be measured outside the channel through a polydimethylsiloxane PDMS membrane allowing only for gaseous exchange. We then utilised this setup to deplete oxygen from the microenvironment of cultured cells, and showed that cells responded to hypoxia on molecular level. Our setup can be used for specifically removing oxygen from the cell culture microenvironment for experimental purposes and for generating a low oxygen environment that better mimics the cells' original tissue environments.

A Microfluidic Chip Architecture Enabling a Hypoxic Microenvironment and Nitric Oxide Delivery in Cell Culture

“…For experiments on microfluidic chips, the sensor membranes were coated with PDMS and then integrated to the chip. The method for preparation of oxygen scavenger water and analyzing oxygen signals in a microchip on oxygen sensor foil were explained in our previous publication [27]. To calibrate the sensor, the PDMS membrane was coated on oxygen sensor foil and calibrated with oxygen-depleted water (835 mM Na 2 SO 3 ) as 0 level (marked as black in the images) and oxygen saturated water as 100 level (marked as white in the images).…”

“…Cells were cultured in Dulbecco's Modified Eagle Medium (DMEM, Gibco, Thermo Fisher Scientific Inc, Waltham, MA, USA) with 10% fetal bovine serum (FBS, Gibco) and antibiotics (penicillin, streptomycin). The microfluidic chips were prepared for cell culture experiments in the same way as in our previous publication [27].…”

“…Based on our previous publication [27], we used sodium sulphite to generate hypoxia (shown in Chemical Formula (1). 2Na 2…”

“…In our previous work [27], we showed a configuration where hypoxia was induced on HEK-293 cells cultured in a well that was separated from an underlying oxygen scavenging channel network by a thin PDMS membrane. Here, we provide a first insight into a microfluidic ship architecture for simultaneous patterning of oxygen and nitric oxide microenvironments in cell culture.…”

Metabolic Switching of Tumor Cells under Hypoxic Conditions in a Tumor-on-a-chip Model

“…In a different approach, and by taking advantage of the gas permeability of PDMS or similar silicone materials, dedicated channels perfused with pre-conditioned fluids were placed on the top [15,[32][33][34] or next to culture chambers [35,36], allowing a quick switch of the oxygen tension in a 3D tumor model [37], to create oxygen gradients in cellular models [38,39] or to simply supply enough oxygen to hepatocytes [15]. Along a similar line, solutions supplemented with an oxygen-scavenging chemical were utilized to create hypoxic conditions [40] or oxygen gradients [41][42][43][44][45], in combination in one report with a thick oxygen-impermeable material (PMMA or polymethylmethacrylate) sheet placed on the top of the device [46].…”