A Biochip with a 3D microfluidic architecture for trapping white blood cells

Identification and functional analysis of Mannose receptor in Asian swamp eel (Monopterus albus) in response to bacterial infection

Mannose receptor (MR), as a member of the C-type lectin (CLEC) family, plays an important role in the internalize pathogen-associated ligands and activate immune response. In the present study, MR was identified and characterized from Asian swamp eel (Monopterus albus) (namely MaMR). The open reading frame of MaMR was 4311 bp in length encoding 1437 amino acids of a ∼162.308 kDa protein, including a cysteine-rich (CR) domain, a fibronectin type II (FNII) domain, eight C-type lectin-like domains (CTLDs), a transmembrane domain and a short cytoplasmic domain. Phylogenetic analysis indicated that MaMR shared the highest similarity with that of Paralichthys olivaceus. The expression of MaMR was found in all the examined tissues, with the highest expression in the spleen and kidney. After injection with Edwardsiella tarda, the transcript level of MaMR was initially reduced and then significantly elevated in the liver, spleen, foregut and hindgut. In the isolated peripheral blood leukocytes, the expression of MaMR was significantly induced post stimulated with LPS and LTA. Then the MaMR-CTLD4-8 recombinant protein was purified. Bacterial agglutination and binding assay showed that rMaMR-CTLD4-8 could bind with both Gram-positive and Gram-negative bacteria and agglutinate bacteria in the presence of calcium in vitro. Further analysis revealed that MaMR and TLR2 coordinately induced the expression of TRAF6 and promoted the phosphorylation level of p65, leading to the expression of proinflammatory cytokines il-1β and tnf-α in EPC cells. Taken together, these results reveal that MaMR plays an important role in the immune response of fish to pathogen infections.

How single-cell immunology is benefiting from microfluidic technologies

The immune system is a complex network of specialized cells that work in concert to protect against invading pathogens and tissue damage. Imbalances in this network often result in excessive or absent immune responses leading to allergies, autoimmune diseases, and cancer. Many of the mechanisms and their regulation remain poorly understood. Immune cells are highly diverse, and an immune response is the result of a large number of molecular and cellular interactions both in time and space. Conventional bulk methods are often prone to miss important details by returning population-averaged results. There is a need in immunology to measure single cells and to study the dynamic interplay of immune cells with their environment. Advances in the fields of microsystems and microengineering gave rise to the field of microfluidics and its application to biology. Microfluidic systems enable the precise control of small volumes in the femto- to nanoliter range. By controlling device geometries, surface chemistry, and flow behavior, microfluidics can create a precisely defined microenvironment for single-cell studies with spatio-temporal control. These features are highly desirable for single-cell analysis and have made microfluidic devices useful tools for studying complex immune systems. In addition, microfluidic devices can achieve high-throughput measurements, enabling in-depth studies of complex systems. Microfluidics has been used in a large panel of biological applications, ranging from single-cell genomics, cell signaling and dynamics to cell-cell interaction and cell migration studies. In this review, we give an overview of state-of-the-art microfluidic techniques, their application to single-cell immunology, their advantages and drawbacks, and provide an outlook for the future of single-cell technologies in research and medicine.

Cytotoxic effects, inflammatory response and apoptosis induction of cyclophosphamide in the peripheral blood leukocyte of blunt snout bream (Megalobrama amblycephala)

The present study was aimed to evaluate the effects of the cyclophosphamide (CY) exposure (Control, 0.032, 0.32, 1.0, 1.6 and 3.2 mg/mL) on the damage in the peripheral blood leukocytes of blunt snout bream for 24 h, which including cell viability, apoptosis, lactate dehydrogenase (LDH) release, mitochondrial membrane potential (Δѱm), ROS, antioxidant enzyme activity and the relative mRNA levels of apoptosis. Results showed that cell viability and Δѱm effects of CY were greatly reduced, and occurred in a dose-dependent manner. CY exposure (0.32-3.2 mg/mL) significantly increased the LDH release and induced apoptosis accompanied by ΔΨm disruption and ROS generation compared to the control. The cellular ROS was significantly increased with increase of CY level from 0.032 mg/mL to 1 mg/mL and the plateau occurred at 0.32 mg/mL. Additionally CY exposure led to oxidative stress as evidenced by significantly the decrease of SOD and CAT and increase of MDA concentration after treating cells with 3.2 mg/mL of CY. Besides, the relative mRNA levels of caspase-3 in the dose of 0.032, 0.32 mg/mL CY, caspase-9 and interleukins-1β (IL-1β) in the dose of 0.32 mg/mL CY, tumor necrosis factor-alpha (TNF-α) in the dose of 0.032 mg/mL CY significantly higher than that of the control. In conclusion, 0.32-3.2 mg/mL CY could lead to cytotoxic effect, inflammatory response and induce the apoptosis of the peripheral blood leukocyte of Megalobrama amblycephala.

The effects of emodin on cell viability, respiratory burst and gene expression of Nrf2-Keap1 signaling molecules in the peripheral blood leukocytes of blunt snout bream (Megalobrama amblycephala)

We determined the effects of emodin on the cell viability, respiratory burst activity, mRNA levels of antioxidative enzymes (Cu-Zn SOD, CAT and NOX2), and gene expressions of the Nrf2-Keap1 signaling molecules in the peripheral blood leukocytes of blunt snout bream. Triplicate groups of cultured cells were treated with different concentrations of emodin (0.04-25 μg/ml) for 24 h. Results showed that the emodin caused a dramatic loss in cell viability, and occurred in a dose-dependent manner. Emodin exposure (1-25 μg/ml) were significantly induced the ROS generation compared to the control. The respiratory burst and NADPH oxidase activities were significantly induced at a concentration of 0.20 μg/ml, and inhibited at 25 μg/ml. Besides, mRNA levels of antioxidant enzyme genes were dramatically regulated by emodin exposure for 24 h. During low concentrations of exposure, mRNA levels of Cu-Zn SOD in the cells treated with 0.04, 0.20 μg/ml, CAT, NOX2 and Nrf2 in the cells treated with 1 μg/ml were sharply increased, respectively. Whereas, high concentrations were dramatically down-regulated the gene expressions of CAT in the cells treated with 5, 25 μg/ml and NOX2 in the cells treated with 25 μg/ml. Furthermore, sharp increase in Keap1and Bach1 expression levels were observed a dose-dependent manner. In conclusion, this study demonstrated that emodin could induce antioxidant defenses which were involved in cytotoxic activities, respiratory burst and the transcriptional regulation levels of antioxidant enzymes and Nrf2-Keap1 signaling molecules.

High-throughput screening approaches and combinatorial development of biomaterials using microfluidics

From the first microfluidic devices used for analysis of single metabolic by-products to highly complex multicompartmental co-culture organ-on-chip platforms, efforts of many multidisciplinary teams around the world have been invested in overcoming the limitations of conventional research methods in the biomedical field. Close spatial and temporal control over fluids and physical parameters, integration of sensors for direct read-out as well as the possibility to increase throughput of screening through parallelization, multiplexing and automation are some of the advantages of microfluidic over conventional, 2D tissue culture in vitro systems. Moreover, small volumes and relatively small cell numbers used in experimental set-ups involving microfluidics, can potentially decrease research cost. On the other hand, these small volumes and numbers of cells also mean that many of the conventional molecular biology or biochemistry assays cannot be directly applied to experiments that are performed in microfluidic platforms. Development of different types of assays and evidence that such assays are indeed a suitable alternative to conventional ones is a step that needs to be taken in order to have microfluidics-based platforms fully adopted in biomedical research. In this review, rather than providing a comprehensive overview of the literature on microfluidics, we aim to discuss developments in the field of microfluidics that can aid advancement of biomedical research, with emphasis on the field of biomaterials. Three important topics will be discussed, being: screening, in particular high-throughput and combinatorial screening; mimicking of natural microenvironment ranging from 3D hydrogel-based cellular niches to organ-on-chip devices; and production of biomaterials with closely controlled properties. While important technical aspects of various platforms will be discussed, the focus is mainly on their applications, including the state-of-the-art, future perspectives and challenges.

STATEMENT OF SIGNIFICANCE

Microfluidics, being a technology characterized by the engineered manipulation of fluids at the submillimeter scale, offers some interesting tools that can advance biomedical research and development. Screening platforms based on microfluidic technologies that allow high-throughput and combinatorial screening may lead to breakthrough discoveries not only in basic research but also relevant to clinical application. This is further strengthened by the fact that reliability of such screens may improve, since microfluidic systems allow close mimicking of physiological conditions. Finally, microfluidic systems are also very promising as micro factories of a new generation of natural or synthetic biomaterials and constructs, with finely controlled properties.

McCLEC, a robust and stable enzymatic based microreactor platform

A microfluidic chip for cross-linked enzyme crystals (McCLEC) is presented and demonstrated to be a stable, reusable and robust biocatalyst-based device with very promising biotechnological applications. The cost-effective microfluidic platform allows in situ crystallization, cross-linking and enzymatic reaction assays on a single device. A large number of enzymatic reuses of the McCLEC platform were achieved and a comparative analysis is shown illustrating the efficiency of the process and its storage stability for more than one year.

Composite ECM-alginate microfibers produced by microfluidics as scaffolds with biomineralization potential

A novel approach to produce artificial bone composites (microfibers) with distinctive features mimicking natural tissue was investigated. Currently proposed inorganic materials (e.g. apatite matrixes) lack self-assembly and thereby limit interactions between cells and the material. The present work investigates the feasibility of creating "bio-inspired materials" specifically designed to overcome certain limitations inherent to current biomaterials. We examined the dimensions, morphology, and constitutive features of a composite hydrogel which combined an alginate based microfiber with a gelatin solution or a particulate form of urinary bladder matrix (UBM). The effectiveness of the composite microfibers to induce and modulate osteoblastic differentiation in three-dimensional (3D) scaffolds without altering the viability and morphological characteristics of the cells was investigated. The present study describes a novel alginate microfiber production method with the use of microfluidics. The microfluidic procedure allowed for precise tuning of microfibers which resulted in enhanced viability and function of embedded cells.

Preparation and validation of low cost microfluidic chips using a shrinking approach

The present paper describes the production of microfluidic chips using an approach based on shrinkable biocompatible polymers (i.e. agarose) for the production of size controlled microfluidic channels. In addition, all steps of chip production were carried out using an inexpensive approach that uses low cost chemicals and equipment. The produced chips were then validated by producing monodisperse polymeric microparticles for drug delivery and hydrogel microfibers for cell embedding.