A microfluidics approach towards high-throughput pathogen removal from blood using margination

Abstract

Sepsis is an adverse systemic inflammatory response caused by microbial infection in blood. This paper reports a simple microfluidic approach for intrinsic, non-specific removal of both microbes and inflammatory cellular components (platelets and leukocytes) from whole blood, inspired by the invivo phenomenon of leukocyte margination. As blood flows through a narrow microchannel (20 × 20 µm), deformable red blood cells (RBCs) migrate axially to the channel centre, resulting in margination of other cell types (bacteria, platelets, and leukocytes) towards the channel sides. By using a simple cascaded channel design, the blood samples undergo a 2-stage bacteria removal in a single pass through the device, thereby allowing higher bacterial removal efficiency. As an application for sepsis treatment, we demonstrated separation of Escherichia coli and Saccharomyces cerevisiae spiked into whole blood, achieving high removal efficiencies of ∼80% and ∼90%, respectively. Inflammatory cellular components were also depleted by >80% in the filtered blood samples which could help to modulate the host inflammatory response and potentially serve as a blood cleansing method for sepsis treatment. The developed technique offers significant advantages including high throughput (∼1 ml/h per channel) and label-free separation which allows non-specific removal of any blood-borne pathogens (bacteria and fungi). The continuous processing and collection mode could potentially enable the return of filtered blood back to the patient directly, similar to a simple and complete dialysis circuit setup. Lastly, we designed and tested a larger filtration device consisting of 6 channels in parallel (∼6 ml/h) and obtained similar filtration performances. Further multiplexing is possible by increasing channel parallelization or device stacking to achieve higher throughput comparable to convectional blood dialysis systems used in clinical settings.

Microfluidic-based measurement of erythrocyte sedimentation rate for biophysical assessment of blood in an in vivo malaria-infected mouse

“…RBCs loss their deformability, which leads to block microcirculation of vital organs. 48,49 To determine the biomechanical properties of malaria-infected RBCs, several methods including mechanicalbased approaches [48][49][50][51][52][53] and electrical impedance-based approaches 54,55 have been employed by using a microfluidic device. As a clinical demonstration using the proposed method, blood sample was collected from an in vivo malaria-infected mouse at indicated times.…”

Impact of microfluidic processing on bacterial ribonucleic acid expression

“…As this lateral force is smaller for bacterial cells ($0.25-1 lm), these are relatively marginated, similar to the strategy adopted in Ref. 21 ( Figure 1). Device manufacturing was performed by Epigem (Redcar, UK).…”

“…6 Several microfluidic devices have been reported for the continuous extraction of bacteria from blood, some relying on active forces, 14,15 on selective lysis 16 while others exploit label-free passive hydrodynamic methods. [17][18][19][20][21] However, given that shear stress is a known factor for mRNA deregulation in human 22 and bacterial cells, 23 it is critical to ensure that microfluidic processing does not impact upon the RNA expression profile. In this paper, we investigated the impact of microfluidic processing on the RNA expression of bacteria in blood, comparing on-chip sample processing to traditional benchtop methods.…”

A cell-based sensor of fluid shear stress for microfluidics

“…One way to characterize microfluidic technologies is by virtue of their operational flow rate and experimental duration. There is a whole gamut of devices which operate at high flow fluid rates for short durations, such as high-throughput cell sorters 2 , inertial-force devices 3 and droplet-based microsystems 4 . Such devices commonly use non-adherent cells, or adherent cells maintained in suspension, because cells are meant to have short residence durations within the device.…”