Selective retrieval of individual cells from microfluidic arrays combining dielectrophoretic force and directed hydrodynamic flow
Ontology highlight
ABSTRACT: Hydrodynamic-based microfluidic platforms enable single-cell arraying and analysis over time. Despite the advantages of established microfluidic systems, long term analysis and proliferation of cells selected in such devices require off-chip recovery of cells as well as an investigation of on-chip analysis on cell phenotype; requirements still largely unmet. Here, we introduce a device for single-cell isolation, selective retrieval and off-chip recovery. To this end, singularly addressable three-dimensional electrodes are embedded within a microfluidic channel, allowing, through application of a negative dielectrophoretic (DEP) force, the selective release of single cells from their trapping site. Selective capture and release is carried out in standard culture medium and cells can be subsequently single cell mitigated towards a recovery well using hybrid SU-8/PDMS pneumatic valves. Importantly, transcriptional analysis of recovered cells revealed only marginal alteration of the molecular profile upon DEP application, underscored by equivocal minor transcriptional changes induced upon injection into the microfluidics device. Therefore, the established microfluidic system combining targeted DEP manipulation with down-stream hydrodynamic coordination of single cells, provides the means to handle and manipulate individual cells within one device.
Project description:Investigation in bacterial transcriptomics is widely used to investigate gene regulation, bacterial susceptibility to antibiotics, host-pathogen interactions, and pathogenesis. Transcriptomics is crucially dependent on suitable methods to isolate and detect bacterial RNA. Microfluidic approaches offer ways of creating integrated point-of-care systems, analysing a sample from preparation, RNA isolation through to detection. Critical for on-chip diagnostics to deliver on their promise is that mRNA expression is not altered through the use microfluidic sample processing. Here, we investigate the impact on the use of a microfluidic sample processing system based on hydrodynamic separation upon RNA expression of bacteria isolated from blood to prove its suitability for further microfluidic test development. A 10 array study using total RNA recovered from bacteria isolated using the microfluidic device and total RNA recovered from bacteria that were not separated using the device were compared. Arrays were performed in 5 biological replicates from each condition
Project description:Tissues are composed of highly heterogeneous mixtures of cell subtypes, and this diversity is increasingly being characterized using high-throughput single cell analysis methods. However, these efforts are hindered by the fact that tissues must first be dissociated into single cell suspensions that are viable and still accurately represent phenotypes from the original tissue. Current methods for breaking down tissues are inefficient, labor-intensive, subject to high variability, and potentially biased towards cell subtypes that are easier to release. Here, we present a microfluidic platform consisting of three different tissue processing technologies that can perform the complete tissue to single cell workflow, including digestion, disaggregation, and filtration. First, we developed a new microfluidic digestion device that can be loaded with minced tissue specimens quickly and easily, and then use the combination of proteolytic enzyme activity and fluid shear forces to accelerate tissue breakdown. Next, we integrated dissociation and filter technologies into a single device, which enhanced single cell numbers and fully prepared the sample for single cell analysis. The final multi-device platform was then evaluated using a diverse array of tissue types that exhibited a wide range of properties. For murine kidney and mammary tumor, we found that microfluidic processing produced 2.5-fold more single, viable cells. Single cell RNA sequencing (scRNA-seq) further revealed that device processing enriched for endothelial cells, fibroblasts, and basal epithelium, and did not increase stress responses. For murine liver and heart, which are softer tissues containing fragile cell types, processing time could be reduced to 15 min, and even as short as 1 min. We also demonstrated that periodic recovery at defined time intervals produced substantially more hepatocytes and cardiomyocytes than continuous operation, most likely by preventing damage to fragile cell types. In future work, we will seek to integrate additional operations such as upstream tissue preparation and downstream microfluidic cell sorting and detection to create powerful point-of-care single cell diagnostic platforms.
Project description:Microfluidic devices provide a low-input and efficient platform for single-cell RNA-seq (scRNA-Seq). Here we present microfluidic diffusion-based RNA-seq (MID-RNA-seq) for conducting scRNA-seq with a diffusion-based reagent swapping scheme. This device incorporates cell trapping, lysis, reverse transcription and PCR amplification all in one microfluidic chamber. MID-RNA-Seq provides high data quality that is comparable to existing scRNA-seq methods while implementing a simple device design that permits multiplexing. The robustness and scalability of MID-RNA-Seq device will be important for transcriptomic studies of scarce cell samples.
Project description:We used microfluidic single cell RNA-seq on adult isolated CC10-CreERT2 (negative) integrin beta4(pos) cells lung epithelial cells in order to determine the transcriptional profile of this putative progenitor population. CC10-CreERT2 / tdTomato (negative) integrin beta4(pos) cells were isolated by FACS, as were Krt5-CreERT2 / tdTomato (positive) cells. These cells were pooled and loaded onto the Fluidigm C1 device.
Project description:We present a microfluidic device for rapid gene expression profiling in single cells using multiplexed quantitative polymerase chain reaction (qPCR). This device integrates all processing steps, including cell isolation and lysis, complementary DNA synthesis, pre-amplification, sample splitting, and measurement in twenty separate qPCR reactions. Each of these steps is performed in parallel on up to 200 single cells per run. Experiments performed on dilutions of purified RNA establish assay linearity over a dynamic range of at least 104, a qPCR precision of 15 %, and detection sensitivity down to a single cDNA molecule. We demonstrate the application of our device for rapid profiling of microRNA expression in single cells. Measurements performed on a panel of twenty miRNA in two types of cells revealed clear cell-to-cell heterogeneity, with evidence of spontaneous differentiation manifest as distinct expression signatures. Highly multiplexed microfluidic RT-qPCR fills a gap in current capabilities for single-cell analysis, providing a rapid and cost-effective approach for profiling panels of marker genes, thereby complementing single-cell genomics methods that are best suited for global analysis and discovery. We expect this approach to enable new studies requiring fast, cost-effective, and precise measurements across hundreds of single cells.