Multilayer PDMS microfluidic chamber for controlling brain slice microenvironment

Abstract

A novel three-layer microfluidic polydimethylsiloxane (PDMS) device was constructed with two fluid chambers that holds a brain slice in place with microposts while maintaining laminar perfusate flow above and below the slice. Our fabrication technique permits rapid production of PDMS layers that can be applied to brain slices of different shapes and sizes. In this study, the device was designed to fit the shape and thickness (530-700 μm) of a medullary brain slice taken from P0-P4 neonatal rats. Medullary slices in this chamber spontaneously produced rhythmic, respiratory-related motor output for up to 3 h, thereby demonstrating that brain slice viability was maintained for prolonged periods. This design is unique in that it achieves independent control of fluids through multiple channels in two separate fluid chambers. The laminar flow exhibited by the microfluidic chamber allows controlled solutions to target specific areas of the brain slice based on the input flow rates. To demonstrate this capability, a stream of Na + -free solution was focused on one half of a medullary slice to abolish spontaneous neural activity in only that half of the brain slice, while the other half remained active. We also demonstrated that flow of different solutions can be focused over the midline of the brain slice. The multilayer brain slice chamber design can integrate several traditional types of electrophysiology tools that are commonly used to measure neurophysiological properties of brain slices. Thus, this new microfluidic chamber is advantageous for experiments that involve controlled drug or solution delivery at high spatiotemporal resolution.

Study of ethanol induced toxicity in liver explants using microfluidic devices

“…However, tissue-based microfluidic applications are still in their infancy. The first micro fluidic studies using tissue slices were the culture of ex vivo brain tissue employing either a hollow SU-8 microneedles on 2.7 mm circular disks within a micro fluidic system (Choi et al 2007) to perfuse 400 μm thick hippocampal rat brain tissue at 40 μl min −1 or a three-layer PDMS device incorporating 530-700 μm thick medullary brain slices from neonatal rats perfused at 1 ml min −1 (Blake et al 2007). Using these approaches cell viability was found to be lost after 4 h at 36°C in the case of the microneedle device and 3 h in the PDMS system, this is a shorter viability period than traditional methods as shown in a earlier section.…”

Parallel microfluidic chemosensitivity testing on individual slice cultures

“…Microfluidic devices have shown the potential for delivering reagents locally to an intact tissue slice 17,18 . However, the difficulty in device operation and low throughputs (one drug application per slice) make such devices unappealing for clinical use.…”

The membrane chamber: A new type of in vitro recording chamber

“…It is sometimes supported by a piece of filter paper or nylon mesh to facilitate perfusion, or it can be held in place by a small weight (a 'slice holddown', White et al, 1978;Scholfield, 1978;Nicoll and Alger, 1981;Koerner and Cotman, 1983;Zbicz and Weight, 1985;Sakmann et al, 1989;Fujii and Toita, 1991;Tominaga et al, 2000;Blake et al, 2007;Hájos and Mody, 2009). The main advantage of the submerged chamber is the high diffusion rate of bath-applied drugs into and out of the slice.…”