[FASEB] Controlling Hydrogen Sulfide concentrations via PDMS microfluidics for endothelial cell cult
BACKGROUND Hydrogen Sulfide (H2S), along with carbon monoxide and nitric oxide, has been found to be one of the cell gasotransmitters affecting vascular cell function, blood vessel growth as well as modulating the potassium-ATP channels . Delivery of consistent hydrogen sulfide levels to study its physiological effects has been a challenge because of the rapid degradation of the molecule and this represents an obstacle in the field. Current cell culture studies are implemented with hydrogen sulfide concentrations that are not stable with time as the donors used degrade with time.
PURPOSE To develop a system that would allow controllable hydrogen sulfide concentrations for cell cultures.
METHODS We developed a novel approach which delivers H2S via diffusion from microfluidic channels through a gas permeable membrane fabricated using PDMS soft lithography (Figure 1). The device consists of 3 different layers, the microfluidic channels, a 100μm thick PDMS membrane and a reservoir, where the cells can be seeded with appropriate amount of media. H2S molecules diffuse through the PDMS membrane to the cell culture reservoir. In this system, a defined mixture of sodium hydrogen sulfide (NaHS), used as a H2S donor, was injected through the microchannels using a syringe pump (Harvard Apparatus) . The detection of the H2S concentration was achieved using electrochemical sensors (Alphasense, Essex, UK). The electrical signal is acquired with a data acquisition system (NI-9205, National Instruments, TX) using Labview.
RESULTS It is shown that H2S concentration is dependent on the concentration of the solution of NaHS and the flow rate of the solution in the microchannels. In this way different concentrations of H2S can be obtained in a controllable way. Our microfluidic approach enables the study of H2S in the range of 0 – 4.2 ppm (0–123 μM) which corresponds to the physiological concentrations in the low μM range (0.5–120 μM) (figure 2 & 3) .
CONCLUSIONS Studying the impact of hydrogen sulfide in cell cultures is not yet well understood. We provide a method to control hydrogen sulfide for cell cultures. To our knowledge there is no other in vitro model that hydrogen sulfide concentration can be controlled.
Theodore Christoforidis1, Tom Driver2, Jalees Rehman3,4 and David T Eddington1 - Author Affiliations
1Bioengineering, University of Illinois at Chicago, Chicago, IL 2Chemistry, University of Illinois at Chicago, Chicago, IL 3Pharmacology, University of Illinois at Chicago, Chicago, IL 4Medicine, University of Illinois at Chicago, Chicago, IL