Chamber and microfluidic probe for microperfusion of organotypic brain slices

Abstract

Microfluidic systems are increasingly being used for the culture and study of dissociated cells because they require only minute amounts of materials while enabling drug screening and chemotaxis studies down to the single cell level. However, the culture of organized tissue, such as brain slices, has been more difficult to adapt to microfluidic devices. Here, we present a microfluidic system, comprising (i) a perfusion chamber for the culture of organotypic slices that is compatible with high resolution imaging on inverted microscopes, and (ii) a novel transparent microfluidic probe (MFP) for the localized microperfusion of the brain tissue. The MFP is made in poly(dimethylsiloxane), features six micrometre-scale apertures and can be assembled within a few hours in a standard laboratory. Each aperture can indiscriminately be used either for the injection or aspiration of solutions, giving rise to many possible combinations. The MFP was successfully used for the perfusion of a small number of cells in a brain slice with concurrent confocal fluorescence imaging of the perfused dye and sub-cellular structures within the tissue.

Hydrodynamic Flow Confinement Technology in Microfluidic Perfusion Devices

“…Upscaling is limited by the polishing step, and the advantage of a more facile fabrication route has to be traded in for the limitation to a linear array of channels. The vertical device developed two years earlier by Queval et al [18] features a two dimensional array of channels. A soft lithography approach using the optically transparent elastomer poly (dimethylsiloxane) (PDMS) was chosen.…”

“…There is currently only a relatively small number of HCF devices presented in the literature, as this novel class of device has just started to progress into a research area [16][17][18][19][20][21][22][23][24][25][26][27]. The pronounced advantages of the technology, being highly localized confinement, the ability to work on adherent cell cultures, and the possibility to use familiar and well-established culture protocols, come at the cost of low throughput.…”

“…HCF devices are limited to relatively slow movements inside the open volume, as rapid shifts in position cause turbulences and distortions of the confined volume, which causes loss of confinement and contamination of the open volume. HCF devices are currently best suited for adherent single cell handling [16,19], some excel in surface processing [24,27] and analysis [23], and others can be advantageously applied to tissue cultures [18], which are typically too large to be introduced into closed channel devices. Some devices can be used in conjunction with other probes, such as patch clamp needles or external electrodes [26].…”

“…This device can be positioned at an angle α to the surface, since the three channel design with one injection port and two adjacent aspiration ports is supported by a thin bottom membrane, which allows close surface proximity. The fabrication procedure for the multilayered PDMS device by Queval et al [18] is similar to the one depicted here, but requires an alignment of the channels prior to bonding; (D-F) Photographic images of the devices of (A-C), as shown in the original publications. Figure 3 summarizes three current concepts of hydrodynamically confined flow devices, the microfluidic multipurpose probe (MFP), the vertical microfluidic probe (vMFP), and the multifunctional micropipette (MFπ), pioneered by different research groups.…”

Hydrodynamically Confined Flow Devices

“…Material transport across the boundary is only possible by diffusion. There is only a relatively small number of HCF devices present in the literature, as this novel class of devices has just started to progress into a research area [5][6][7][8][9][10][11][12][13][14] . The contributions of the different research groups are summarized in table 1.…”