Microfluidic approach for direct and uniform laser irradiation to study biochemical state changes on Jurkat-T cells

Abstract

We investigated the potential for using polydimethylsiloxane microfluidic devices in a biological assay to explore the cellular stress response (CSR) associated with hyperthermia induced by exposure to laser radiation. In vitro studies of laser-tissue interaction traditionally involved exposing a monolayer of cells. Given the heating-cooling dynamics of the cells and nutrient medium, this technique produces a characteristic "bulls-eye" temperature history that plagues downstream molecular analyses due to the nonuniform thermal experience of exposed cells. To circumvent this issue, we devised an approach to deliver single cells to the laser beam using a microfluidic channel, allowing homogeneous irradiation and collection of sufficient like-treated cells to measure changes in CSR after laser heating. To test this approach, we irradiated Jurkat-T cells with a 2-μm-wavelength laser in one branch of a 100-μm-wide bifurcated channel while unexposed control cells were simultaneously passing through the other, identical channel. Cell viability was measured using vital dyes, and expression of HSPA1A was measured using reverse transcription polymerase chain reaction. The laser damage threshold was 25 ± 2 J/cm2, and we found a twofold increase in expression at that exposure. This approach may be employed to examine transcriptome-wide/proteome changes and further comparative work across stressors and cell types.

Advances in three-dimensional rapid prototyping of microfluidic devices for biological applications

“…Flow cytometry analysis, 34 cell-based assays (such as cytotoxicity 35 or induced cellular stress assays 36 ), sorting, manipulation and imaging of single-cells, 37 and cell/tissue engineering, 38,39 are just some of the current applications of microfluidics in biology. Microfluidics also offer the means to create and maintain environments that closely resemble those encountered in vivo.…”