Biomedical Microdevices最新文献

We present a label-free microfluidic chip for the segregation of circulating leukemia cells (CLCs) from blood samples, with a focus on its clinical applications in Acute Myeloid Leukemia (AML). The microfluidic chip achieved an approximate capture efficiency of 92%. The study analyzed a comprehensive set of 66 blood specimens from AML patients in different disease stages, including newly diagnosed and relapsing cases, patients in complete remission, and those in partial remission. The results showed a significant difference in CLC counts between active disease stages and remission stages (p < 0.0001), with a proposed threshold of 5 CLCs to differentiate between the two. The microfluidic chip exhibited a sensitivity of 95.4% and specificity of 100% in predicting disease recurrence. Additionally, the captured CLCs were subjected to downstream molecular analysis using droplet digital PCR, allowing for the identification of genetic mutations associated with AML. Comparative analysis with bone marrow aspirate processing by FACS demonstrated the reliability and accuracy of the microfluidic chip in tracking disease burden, with highly agreement results obtained between the two methods. The non-invasive nature of the microfluidic chip and its ability to provide real-time insights into disease progression make it a promising tool for the proactive monitoring and personalized patient care of AML.

Macrophages are innate immune cells that prevent infections and help in wound healing and vascular inflammation. While these cells are natural helper cells, they also contribute to chronic diseases, e.g., by infiltrating the endothelial layer in early atherosclerosis and by promoting vascular inflammation. There is a crosstalk between inflammatory pathways and key players in thrombosis, such as platelets and endothelial cells – a phenomenon known as ‘thromboinflammation’. The role of the embedded macrophages in thromboinflammation in the context of vascular disease is incompletely understood. Blood vessels-on-chips, which are microfluidic vascular cell culture models, have been used extensively to study aspects of vascular disease, like permeability, immune cell adhesion and thrombosis. Blood perfusion assays in blood vessel-on-chip models benefit from multiple unique aspects of the models, such as control of microvessel structure and well-defined flow patterns, as well as the ability to perform live imaging. However, due to their simplified nature, blood vessels-on-chip models have not yet been used to capture the complex cellular crosstalk that is important in thromboinflammation. Using induced pluripotent stem cell-derived endothelial cells and polarized THP-1 monocytes, we have developed and systematically set up a 3D blood vessel-on-chip with embedded (lipid-laden) macrophages, which is created using sequential cell seeding in viscous finger patterned collagen hydrogels. We have set up a human whole blood perfusion assay for these 3D blood vessels-on-chip. An increased deposition of fibrin in the blood vessel-on-chip models containing lipid-laden macrophages was observed. We anticipate the future use of this advanced vascular in vitro model in drug development for early atherosclerosis or aspects of other vascular diseases.

Graphical Abstract

Surface acoustic waves in combination with microfluidics has become an attractive research field regarding its various medical and biological applications. It is sometimes preferred to solve just the fluid domain and apply some boundary conditions to represent other components rather than performing a coupled numerical solution. To account for the piezoelectric actuation, a conventional velocity distribution built by superposing the left-going and right-going surface waves is commonly used as the boundary condition, its correctness is assessed here by comparing it to a coupled solution. It was shown that the actual leaky surface acoustic wave in coupled solution has different wavelengths in its real and imaginary parts, sometimes gets out of being sinusoidal, and has a different form compared to the superposed formula. For the phase differences other than 0 and π between the left and right electrodes, the distance between the electrodes affects the streaming and acoustic fields in the microchannel thereby leading to deviations in particle traces. Furthermore, the ratio of the horizontal to vertical components of the surface wave was extracted from the coupled solutions and compared to its previously reported values. The sensitivity analysis showed that for small particles, this ratio does not affect the streaming pattern but changes its velocity magnitude causing a time lag. For larger particles, the ratio altered the movement direction. This study suggests not replacing the piezoelectric actuation with the boundary condition to avoid inaccuracy in resulting fields that are being used in calculations of particle tracing and acoustic radiation forces.

Reliability evaluation results of a manufacturable 32-channel cochlear electrode array are reported in this paper. Applying automated laser micro-machining process and a layer-by-layer silicone deposition scheme, authors developed the manufacturing methods of the electrode array for fine patterning and mass production. The developed electrode array has been verified through the requirements specified by the ISO Standard 14708-7. And the insertion trauma of the electrode array has been evaluated based on human temporal bone studies. According to the specified requirements, the electrode array was assessed through elongation & insulation, flexural, and fatigue tests. In addition, Temporal bone study was performed using eight fresh-frozen cadaver temporal bones with the electrode arrays inserted via the round window. Following soaking in saline condition, the impedances between conducting wires of the electrode array were measured over 100 kΩ (the pass/fail criterion). After each required test, it was shown that the electrode array maintained the electrical continuity and insulation condition. The average insertion angle of the electrode array inside the scala tympani was 399.7°. The human temporal bone studies exhibited atraumatic insertion rate of 60.3% (grade 0 or 1). The reliability of the manufacturable electrode array is successfully verified in mechanical, electrical, and histological aspects. Following the completion of a 32-channel cochlear implant system, the performance and stability of the 32-channel electrode array will be evaluated in clinical trials.

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During respiratory infection, barrier dysfunction in alveolar tissue can result from “cytokine storm” caused by overly reactive immune response. Particularly, interleukin 6 (IL-6) is implicated as a key biomarker of cytokine storm responsible for and further progression to pulmonary edema. In this study, alveolar-like tissue was reconstructed in a microfluidic device with: (1) human microvascular lung endothelial cells (HULEC-5a) cultured under flow-induced shear stress and (2) human epithelial cells (Calu-3) cultured at air–liquid interface. The effects of IL-6 and the soluble form of its receptor (sIL-6R) on the permeability, electrical resistance, and morphology of the endothelial and epithelial layers were evaluated. The diffusion barrier properties of both the endothelial and epithelial layers were significantly degraded only when IL-6 treatment was combined with sIL-6R. As suggested by recent review and clinical studies, our results provide unequivocal evidence that the barrier dysfunction occurs through trans-signaling in which IL-6 and sIL-6R form a complex and then bind to the surface of endothelial and epithelial cells, but not by classical signaling in which IL-6 binds to membrane-expressed IL-6 receptor. This finding suggests that the role of both IL-6 and sIL-6R should be considered as important biomarkers in developing strategies for treating cytokine storm.

Graphical Abstract

In this paper we demonstrate how the use of frequencies ranging from 50 kHz to 5 GHz in the analysis of cells by electrorotation can open the path to the identification of differences not detectable by conventional set-ups. Earlier works usually reported electrorotation devices operating below 20 MHz, limiting the response obtained to properties associated with the cell membrane. Those devices are thus unable to resolve the physiological properties in the cytoplasm. We used microwave-based technology to extend the frequency operation to 5 GHz. At high frequencies (from tens of MHz to GHz), the electromagnetic signal passes through the membrane and allows probing the cytoplasm. This enables several applications, such as cell classification, and viability analysis. Additionally, the use of conventional microfabrication techniques reduces the cost and complexity of analysis, compared to other non-invasive methods. We demonstrated the potential of this set-up by identifying two different populations of T-lymphocytes not distinguishable through visual assessment. We also assessed the effect of calcein on cell cytoplasmic properties and used it as a controlled experiment to demonstrate the possibility of this method to detect changes happening predominantly in the cytoplasm.

Graphical Abstract

This paper presents a portable point-of-care testing (POCT) device to conduct simultaneous and on-site tests of ABO and Rh(D) forward blood typing and hemophilia diagnosis using only a small amount of human whole blood sample. The POCT device consisted of a spinning module, a measuring circuit, an interdigitated electrode (IDE) for hemophilia diagnosis, and three disposable microfluidic chips for bioassays with anti-A, anti-B, and anti-D, respectively, and measurement of the concentration of factor VIII. Agglutination will occur if red blood cells (RBCs) are exposed to the corresponding antibody. To evaluate the degree of RBC agglutination, a linear sweep voltage, ranging from − 0.5 to + 0.5 V, was applied to the electrodes of the microfluidic chip and the resulting current was measured. For different levels of agglutination, the measured I–V curves were explicitly discriminated, providing five clinical levels from non-agglutination (level 0) to strong agglutination (level 4). The quantitative norm obtained from cubic fitting function of each I–V curve served as the criterion to represent this agglutination level. The ABO blood type was determined by both agglutination levels of the blood sample reacting with anti-A and anti-B. The degree of agglutination with anti-D gave the Rh(D) type. Moreover, the concentration of factor VIII was detected for the determination of hemophilia. Without requiring expensive equipment, this POCT device is especially suitable for usage in emergency or natural disasters to provide quantitative testing in rescue and relief operations.

Trans-endothelial electrical resistance (TEER) is one of the most widely used indicators to quantify the barrier integrity of endothelial layers. Over the last decade, the integration of TEER sensors into organ-on-a-chip (OOC) platforms has gained increasing interest for its efficient and effective measurement of TEER in OOCs. To date, microfabricated electrodes or direct insertion of wires has been used to integrate TEER sensors into OOCs, with each method having advantages and disadvantages. In this study, we developed a TEER-SPE chip consisting of carbon-based screen-printed electrodes (SPEs) embedded in a poly(methyl methacrylate) (PMMA)-based multi-layered microfluidic device with a porous poly(ethylene terephthalate) membrane in-between. As proof of concept, we demonstrated the successful cultures of hCMEC/D3 cells and the formation of confluent monolayers in the TEER-SPE chip and obtained TEER measurements for 4 days. Additionally, the TEER-SPE chip could detect changes in the barrier integrity due to shear stress or an inflammatory cytokine (i.e., tumor necrosis factor-α). The novel approach enables a low-cost and facile fabrication of carbon-based SPEs on PMMA substrates and the subsequent assembly of PMMA layers for rapid prototyping. Being cost-effective and cleanroom-free, our method lowers the existing logistical and technical barriers presenting itself as another step forward to the broader adoption of OOCs with TEER measurement capability.