Temperature alters lipopolysaccharide-induced cytokine secretion by RAW 264.7 cells

Assay of Genome-Wide Transcriptome and Secreted Proteins on the Same Single Immune Cells by Microfluidics and RNA Sequencing

Given vast heterogeneity of immune cells, searching for gene expression and transcriptional networks belonging to specific cellular functions such as cytokine production has been challenging. To overcome this limitation, we developed a splittable single-cell microchip that integrates a high-density antibody array for cytokine protein detection, while the same single cells with protein profiles can be subsequently sequenced to obtain the genome-wide transcriptome. Combined with bioinformatics algorithms, we discovered a subgroup of highly coexpressed genes correlating with TNFα secretion in mouse macrophage cells. This technology and the data analysis may lead to an unprecedented understanding of regulation mechanisms of the immune system and have the potential to impact disease treatment and drug discovery.

Single-cell-based sensors and synchrotron FTIR spectroscopy: a hybrid system towards bacterial detection

Microarrays of single macrophage cell-based sensors were developed and demonstrated for potential real-time bacterium detection by synchrotron FTIR microscopy. The cells were patterned on gold electrodes of silicon oxide substrates by a surface engineering technique, in which the gold electrodes were immobilized with fibronectin to mediate cell adhesion and the silicon oxide background was passivated with polyethylene glycol (PEG) to resist protein adsorption and cell adhesion. Cell morphology and IR spectra of single, double, and triple cells on gold electrodes exposed to lipopolysaccharide (LPS) of different concentrations were compared to reveal the detection capability of this cell-based sensing platform. The single-cell-based system was found to generate the most significant and consistent IR spectrum shifts upon exposure to LPS, thus providing the highest detection sensitivity. Changes in cell morphology and IR shifts upon cell exposure to LPS were found to be dependent on the LPS concentration and exposure time, which established a method for the identification of LPS concentration and infected cell population. Possibility of using this single-cell system with conventional IR spectroscopy as well as its limitation was investigated by comparing IR spectra of single-cell arrays with gold electrode surface areas of 25, 100, and 400 microm2 using both synchrotron and conventional FTIR spectromicroscopes. This cell-based platform may potentially provide real-time, label-free, and rapid bacterial detection, and allow for high-throughput statistical analyses, and portability.