Integrated Microfluidic Handheld Cell Sorter for High-Throughput Label-Free Malignant Tumor Cell Sorting.

Handheld sample preparation devices are urgently required for point-of-care diagnosis in resource-limited settings. In this paper, we develop a novel handheld sorter with a multifunction integrated microfluidic chip. The integrated microfluidic handheld sorter (µHCS) is composed of three units, including cartridges, shells, and core integrated microchip. The integrated microchip contains two flow regulators for achieving the on-chip regulation of the input flows generated by a low-cost diaphragm pump to the desired flow rates and a spiral inertial microfluidic channel for size-based cell separation. After introducing the conceptual design of our µHCS system, the performances of the separate spiral channel and flow regulator are systematically characterized and optimized, respectively. Finally, the prototype of the µHCS is successfully assembled to separate the malignant tumor cells from the clinical pleural effusions. Our µHCS is simple to use, inexpensive, portable, and compact and can be used for high-throughput label-free separation of rare cells from large volume samples in resource-limited areas.

Ultrahigh throughput beehive-like device for blood plasma separation.

We report here a low-cost, rapid-prototyping, and beehive-like multilayer polymer microfluidic device for ultrahigh-throughput blood plasma separation. To understand the device physics and optimize the device structure, the effect of cross-sectional dimension and operational parameter on particle focusing behavior was explored using a single spiral microchannel device. Then, the blood plasma separation performance of the determined channel structure was validated using the blood samples with different hematocrits (HCTs). It was found that a high separation efficiency of 99% could be achieved using the blood sample with an HCT of 0.5% at a high throughput of 1 mL/min. Finally, a multilayer microfluidic device with a novel beehive-like multiplexing channel arrangement was developed for ultrahigh-throughput blood plasma separation. The prototype device could be fabricated within ∼1 hour utilizing the laser cutting and thermal lamination methods. The total processing throughput could reach up to 72 mL/min for 0.5% HCT sample with a plasma separation ratio close to 90%. Our device may hold potentials for the ultrahigh-throughput separation of blood plasma from large volume blood samples for downstream disease diagnosis.

Low-cost multi-core inertial microfluidic centrifuge for high-throughput cell concentration.

We developed a low-cost multi-core inertial microfluidic centrifuge (IM-centrifuge) to achieve a continuous-flow cell/particle concentration at a throughput of up to 20 mL/min. To lower the cost of our IM-centrifuge, we clamped a disposable multilayer film-based inertial microfluidic (MFIM) chip with two reusable plastic housings. The key MFIM chip was fabricated in low-cost materials by stacking different polymer-film channel layers and double-sided tape. To increase processing throughput, multiplexing spiral inertial microfluidic channels were integrated within an all-in-one MFIM chip, and a novel sample distribution strategy was employed to equally distribute the sample into each channel layer. Then, we characterized the focusing performance in the MFIM chip over a wide flow-rate range. The experimental results showed that our IM-centrifuge was able to focus various-sized particles/cells to achieve volume reduction. The sample distribution strategy also effectively ensured identical focusing and concentration performances in different cores. Finally, our IM-centrifuge was successfully applied to concentrate microalgae cells with irregular shapes and highly polydisperse sizes. Thus, our IM-centrifuge holds the potential to be employed as a low-cost, high-throughput centrifuge for disposable use in low-resource settings.

Microfluidics for label-free sorting of rare circulating tumor cells.

Circulating tumor cells (CTCs) have been widely considered as promising novel biomarkers for molecular research and clinical diagnosis of cancer. However, the sorting of CTCs is very challenging due to the rarity of CTCs in blood and the morphological similarity to blood cells. Although affinity-based CTC sorting methods could capture CTCs using specific biochemical markers, there are limitations such as the loss of cell viability after labeling and a requirement for expensive biochemical marker reagents. Emerging label-free CTC sorting methods rely on the physical properties of cells and can potentially overcome the aforementioned limitations. In this review, we highlight recent advances in label-free CTC sorting methods, with emphasis on device structures and performances. Specifically, we present a detailed discussion on label-free CTC sorting methods, including passive ones that depend on the channel structure or specific fluidic effects and active ones that use external force fields, as well as provide an overview of the principles, advantages, limitations, and applications of state-of-art label-free CTC sorting devices. Finally, we provide a future perspective of microfluidics for label-free CTC sorting and hope to inspire readers to develop new devices for applications in clinical cancer diagnoses and research.

Inertial Microfluidic Syringe Cell Concentrator.

Low-cost, easy-to-use cell concentration tools are in urgent demand for biomedical diagnosis in resource-poor settings. Herein, we propose a novel inertial microfluidic syringe cell (IMSC) concentrator that employs inertial focusing to increase cell concentration through ordering the cell and removing the cell-free fluid. A three-part structure, consisting of a cap-shaped upper housing, a circular gasket, and a lower housing with a spiral channel, is adopted for simple fabricating and assembling, which enables the seamless translation of our IMSC concentrator into commercial outcomes without additional redesigning. The performance characterization indicates that our IMSC concentrator is capable of processing samples with different initial concentrations over a broad flow rate range. The satisfactory concentration performances over a broad driving flow rate range make it possible for our IMSC concentrator to be driven by pushing the syringe with single hand. Finally, pollen particles and MCF-7 cells are successfully concentrated at a high throughput of 3.0 mL/min (up to 4.2 × 107 counts/mL) under the hand-powered drive. We envision wide applications of our IMSC concentrator as "centrifugation on a syringe tip" to various cell concentration pretreatments in resource-poor settings.

Locally instilled tumor necrosis factor α antisense oligonucleotide contributes to inhibition of TH 2-driven pulmonary fibrosis via induced CD4+ CD25+ Foxp3+ regulatory T cells.

BACKGROUND: Anti-tumor necrosis factor α therapeutics has the potential to alleviate pulmonary fibrosis. However, the systemic administration of anti-tumor necrosis factor α agents has brought about contradictory results and frequent adverse effects, such as infections, immunogenicity and malignancies, amongst others. In the present study, we attempted the local administration of tumor necrosis factor α antisense oligonucleotide and evaluated the treatment effects on pulmonary fibrosis in a bleomycin-induced pulmonary fibrosis mouse model. METHODS: Flow cytometry for regulatory T cells, reverse transcriptase-polymerase chain reaction for crucial gene expression, western blotting for crucial protein products, immunofluorescent analysis for T(H)2 cells and myofibroblasts, as well as histology analysis for pathological examination, were used. RESULTS: By local administration of tumor necrosis factor α antisense oligonucleotide, we investigated whether tumor necrosis factor α expression in epithelial cells was significantly inhibited and extracellular matrix overexpression was dramatically reduced. These treatment effects were associated with induced regulatory T cells, reduced T(H)2 cells and generally decreased T(H)2-type cytokine expression. Systemic immunosuppression was not triggered by local antisense oligonucleotide administration because the proportion of regulatory T cells in the blood, thymus or spleen was not affected. CONCLUSIONS: These findings demonstrate that local administration of tumor necrosis factor α antisense oligonucleotide contributes to anti-fibrotic action via a sustained up-regulated level of regulatory T cells, which inhibits T(H)2-biased responses, pro-fibrotic mediator production and extracellular matrix deposition, with no systemic immunosupression associated with systemically induced regulatory T cells.

A microfluidic approach for early prediction of thrombosis in patients with cancer.

Li and colleagues have made a notable advancement in predicting cancer-associated thrombosis with a microfluidic device that monitors circulating platelet activity.1 This tool could improve the management of thrombotic events in patients with cancer, guiding timely treatment and potentially reducing mortality.

A Novel Computational Biomechanics Framework to Model Vascular Mechanopropagation in Deep Bone Marrow.

The mechanical stimuli generated by body exercise can be transmitted from cortical bone into the deep bone marrow (mechanopropagation). Excitingly, a mechanosensitive perivascular stem cell niche is recently identified within the bone marrow for osteogenesis and lymphopoiesis. Although it is long known that they are maintained by exercise-induced mechanical stimulation, the mechanopropagation from compact bone to deep bone marrow vasculature remains elusive of this fundamental mechanobiology field. No experimental system is available yet to directly understand such exercise-induced mechanopropagation at the bone-vessel interface. To this end, taking advantage of the revolutionary in vivo 3D deep bone imaging, an integrated computational biomechanics framework to quantitatively evaluate the mechanopropagation capabilities for bone marrow arterioles, arteries, and sinusoids is devised. As a highlight, the 3D geometries of blood vessels are smoothly reconstructed in the presence of vessel wall thickness and intravascular pulse pressure. By implementing the 5-parameter Mooney-Rivlin model that simulates the hyperelastic vessel properties, finite element analysis to thoroughly investigate the mechanical effects of exercise-induced intravascular vibratory stretching on bone marrow vasculature is performed. In addition, the blood pressure and cortical bone bending effects on vascular mechanoproperties are examined. For the first time, movement-induced mechanopropagation from the hard cortical bone to the soft vasculature in the bone marrow is numerically simulated. It is concluded that arterioles and arteries are much more efficient in propagating mechanical force than sinusoids due to their stiffness. In the future, this in-silico approach can be combined with other clinical imaging modalities for subject/patient-specific vascular reconstruction and biomechanical analysis, providing large-scale phenotypic data for personalized mechanobiology discovery.

3D spheroid-microvasculature-on-a-chip for tumor-endothelium mechanobiology interplay.

During the final stage of cancer metastasis, tumor cells embed themselves in distant capillary beds, from where they extravasate and establish secondary tumors. Recent findings underscore the pivotal roles of blood/lymphatic flow and shear stress in this intricate tumor extravasation process. Despite the increasing evidence, there is a dearth of systematic and biomechanical methodologies that accurately mimic intricate 3D microtissue interactions within a controlled hydrodynamic microenvironment. Addressing this gap, we introduce an easy-to-operate 3D spheroid-microvasculature-on-a-chip (SMAC) model. Operating under both static and regulated flow conditions, the SMAC model facilitates the replication of the biomechanical interplay between heterogeneous tumor spheroids and endothelium in a quantitative manner. Serving as anin vitromodel for metastasis mechanobiology, our model unveils the phenomena of 3D spheroid-induced endothelial compression and cell-cell junction degradation during tumor migration and expansion. Furthermore, we investigated the influence of shear stress on endothelial orientation, polarization, and tumor spheroid expansion. Collectively, our SMAC model provides a compact, cost-efficient, and adaptable platform for probing the mechanobiology of metastasis.

Platelet Mechanobiology Inspired Microdevices: From Hematological Function Tests to Disease and Drug Screening.

Platelet function tests are essential to profile platelet dysfunction and dysregulation in hemostasis and thrombosis. Clinically they provide critical guidance to the patient management and therapeutic evaluation. Recently, the biomechanical effects induced by hemodynamic and contractile forces on platelet functions attracted increasing attention. Unfortunately, the existing platelet function tests on the market do not sufficiently incorporate the topical platelet mechanobiology at play. Besides, they are often expensive and bulky systems that require large sample volumes and long processing time. To this end, numerous novel microfluidic technologies emerge to mimic vascular anatomies, incorporate hemodynamic parameters and recapitulate platelet mechanobiology. These miniaturized and cost-efficient microfluidic devices shed light on high-throughput, rapid and scalable platelet function testing, hematological disorder profiling and antiplatelet drug screening. Moreover, the existing antiplatelet drugs often have suboptimal efficacy while incurring several adverse bleeding side effects on certain individuals. Encouraged by a few microfluidic systems that are successfully commercialized and applied to clinical practices, the microfluidics that incorporate platelet mechanobiology hold great potential as handy, efficient, and inexpensive point-of-care tools for patient monitoring and therapeutic evaluation. Hereby, we first summarize the conventional and commercially available platelet function tests. Then we highlight the recent advances of platelet mechanobiology inspired microfluidic technologies. Last but not least, we discuss their future potential of microfluidics as point-of-care tools for platelet function test and antiplatelet drug screening.