Reconfigurable microfluidic device with integrated antibody arrays for capture, multiplexed stimulation, and cytokine profiling of human monocytes

Microfluidic system for immune cell activation and inflammatory cytokine profiling: Application to screening of dietary supplements for anti-inflammatory properties

A versatile and reconfigurable microfluidic chip has been fully in-house fabricated and tested for immune cell culture, activation, and quantification of multi-cytokine secretion. The chip comprises three vertically stacked fluidic layers for perfusion, cell culture and cytokine capture, and quantification, respectively. The perfused media were separated from the cell culture by employing a biomimetic membrane as a model of the intestinal epithelial layer. Time-resolved detection and quantification of several secreted cytokines were enabled by an array of parallel channels, which are interfaced with the cell culture by a porous membrane. Each channel hosts magnetic beads conjugated with a specific antibody against the cytokine of interest. Magnetic bead-assisted agitation enables homogenization of the cell culture supernatant and perfusion of the cytokines through the bottom immune assay channels. As a proof of concept, THP-1 monocytic cells and their induced macrophages were used as a model of immune-responsive cells. The cells were sequentially stimulated by lipopolysaccharides and two dietary supplements, namely, docosahexaenoic acid (DHA) and curcumin, which are known to possess inflammasome-modulating activity. Both DHA and curcumin have shown anti-inflammatory effects by downregulating the secretion of TNFα, IL-6, IL-1β, and IL-10. Treatment of the cells with DHA and curcumin together lowered the TNFα secretion by ∼54%. IL-6 secretion was lowered upon cell treatment with curcumin, DHA, or DHA and curcumin co-treatment by 69%, 78%, or 67%, respectively. IL-1β secretion was lowered by 67% upon curcumin treatment and 70% upon curcumin and DHA co-treatment. IL-10 secretion was also lowered upon treating the cells with DHA, curcumin, or DHA and curcumin together by 7%, 53%, or 54%, respectively. The limit of the detection of the assay was determined as 25 pg/ml. Four cytokine profiling was demonstrated, but the design of the chip can be improved to allow a larger number of cytokines to be simultaneously detected from the same set of cells.

Ultrasensitive Multiparameter Phenotyping of Rare Cells Using an Integrated Digital-Molecular-Counting Microfluidic Well Plate

Integrated microfluidic cellular phenotyping platforms provide a promising means of studying a variety of inflammatory diseases mediated by cell-secreted cytokines. However, immunosensors integrated in previous microfluidic platforms lack the sensitivity to detect small signals in the cellular secretion of proinflammatory cytokines with high precision. This limitation prohibits researchers from studying cells secreting cytokines at low abundance or existing at a small population. Herein, the authors present an integrated platform named the "digital Phenoplate (dPP)," which integrates digital immunosensors into a microfluidic chip with on-chip cell assay chambers, and demonstrates ultrasensitive cellular cytokine secretory profile measurement. The integrated sensors yield a limit of detection as small as 0.25 pg mL-1 for mouse tumor necrosis factor alpha (TNF-α). Each on-chip cell assay chamber confines cells whose population ranges from ≈20 to 600 in arrayed single-cell trapping microwells. Together, these microfluidic features of the dPP simultaneously permit precise counting and image-based cytometry of individual cells while performing parallel measurements of TNF-α released from rare cells under multiple stimulant conditions for multiple samples. The dPP platform is broadly applicable to the characterization of cellular phenotypes demanding high precision and high throughput.

Monocyte Distribution Width: A Novel Indicator of Sepsis-2 and Sepsis-3 in High-Risk Emergency Department Patients

Supplemental Digital Content is available in the text.

Objectives:

Most septic patients are initially encountered in the emergency department where sepsis recognition is often delayed, in part due to the lack of effective biomarkers. This study evaluated the diagnostic accuracy of peripheral blood monocyte distribution width alone and in combination with WBC count for early sepsis detection in the emergency department.

Design:

An Institutional Review Board approved, blinded, observational, prospective cohort study conducted between April 2017 and January 2018.

Setting:

Subjects were enrolled from emergency departments at three U.S. academic centers.

Patients:

Adult patients, 18–89 years, with complete blood count performed upon presentation to the emergency department, and who remained hospitalized for at least 12 hours. A total of 2,212 patients were screened, of whom 2,158 subjects were enrolled and categorized per Sepsis-2 criteria, such as controls (n = 1,088), systemic inflammatory response syndrome (n = 441), infection (n = 244), and sepsis (n = 385), and Sepsis-3 criteria, such as control (n = 1,529), infection (n = 386), and sepsis (n = 243).

Interventions:

The primary outcome determined whether an monocyte distribution width of greater than 20.0 U, alone or in combination with WBC, improves early sepsis detection by Sepsis-2 criteria. Secondary endpoints determined monocyte distribution width performance for Sepsis-3 detection.

Measurements and Main Results:

Monocyte distribution width greater than 20.0 U distinguished sepsis from all other conditions based on either Sepsis-2 criteria (area under the curve, 0.79; 95% CI, 0.76–0.82) or Sepsis-3 criteria (area under the curve, 0.73; 95% CI, 0.69–0.76). The negative predictive values for monocyte distribution width less than or equal to 20 U for Sepsis-2 and Sepsis-3 were 93% and 94%, respectively. Monocyte distribution width greater than 20.0 U combined with an abnormal WBC further improved Sepsis-2 detection (area under the curve, 0.85; 95% CI, 0.83–0.88) and as reflected by likelihood ratio and added value analyses. Normal WBC and monocyte distribution width inferred a six-fold lower sepsis probability.

Conclusions:

An monocyte distribution width value of greater than 20.0 U is effective for sepsis detection, based on either Sepsis-2 criteria or Sepsis-3 criteria, during the initial emergency department encounter. In tandem with WBC, monocyte distribution width is further predicted to enhance medical decision making during early sepsis management in the emergency department.

Integrated Microfluidic Device for Functional Secretory Immunophenotyping of Immune Cells

Integrated platforms for automatic assessment of cellular functional secretory immunophenotyping could have a widespread use in the diagnosis, real-time monitoring, and therapy evaluation of several pathologies. We present a microfluidic platform with integrated biosensors and culture chambers to measure cytokine secretion from a consistent and uniform number of immune cells. The biosensor relies on a fluorescence sandwich immunoassay enabled by the mechanically induced trapping of molecular interactions method. The platform contains 32 cell culture chambers, each patterned with an array of 492 microwells, to capture and analyze both adherent and nonadherent immune cells. Multiple stimuli can be delivered to a set of culture chambers. Per chamber, we were able to capture consistently 1113 ± 191 of blood-derived monocytes and neutrophils and 348 ± 37 THP-1 monocytes. Good occupancy efficiencies of ∼70% with a uniformity of ∼90% across all of the culture chambers of the device were achieved. Furthermore, we demonstrate that up to 96% of cells remain viable for the first 48 h. The employment of epoxy-modified glass substrates and active mixing enhanced the biosensing performance compared to the use of bare glass and simple diffusion. Finally, we performed functional secretory analysis of interleukin-8 and tumor necrosis factor alpha from human neutrophils and monocytes, stimulated with various doses of lipopolysaccharide and phorbol 12-myristate 13-acetate-ionomycin, respectively. We foresee the employment of our microfluidic platform in the diagnosis of different pathologies where alterations in cytokine secretion patterns can be used as biomarkers.

Recent Progress in Lab-On-a-Chip Systems for the Monitoring of Metabolites for Mammalian and Microbial Cell Research

Lab-on-a-chip sensing technologies have changed how cell biology research is conducted. This review summarises the progress in the lab-on-a-chip devices implemented for the detection of cellular metabolites. The review is divided into two subsections according to the methods used for the metabolite detection. Each section includes a table which summarises the relevant literature and also elaborates the advantages of, and the challenges faced with that particular method. The review continues with a section discussing the achievements attained due to using lab-on-a-chip devices within the specific context. Finally, a concluding section summarises what is to be resolved and discusses the future perspectives.

Big insights from small volumes: deciphering complex leukocyte behaviors using microfluidics

Inflammation is an indispensable component of the immune response, and leukocytes provide the first line of defense against infection. Although the major stereotypic leukocyte behaviors in response to infection are well known, the complexities and idiosyncrasies of these phenotypes in conditions of disease are still emerging. Novel tools are indispensable for gaining insights into leukocyte behavior, and in the past decade, microfluidic technologies have emerged as an exciting development in the field. Microfluidic devices are readily customizable, provide tight control of experimental conditions, enable high precision of ex vivo measurements of individual as well as integrated leukocyte functions, and have facilitated the discovery of novel leukocyte phenotypes. Here, we review some of the most interesting insights resulting from the application of microfluidic approaches to the study of the inflammatory response. The aim is to encourage leukocyte biologists to integrate these new tools into increasingly more sophisticated experimental designs for probing complex leukocyte functions.