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This paper describes a reproducible method for μm precision alignment of polydimethylsiloxane (PDMS) microchannels with coplanar electrodes using a conventional mask aligner for lab-on-a-chip applications. It is based on the use of a silicon mold in combination with a PMMA sarcophagus for precise control of the parallelism between the top and bottom surfaces of molded PDMS. The alignment of the fabricated PDMS slab with electrodes patterned on a glass chip is then performed using a conventional mask aligner with a custom-made steel chuck and magnets. This technique allows to bond and align chips with a resolution of less than 2 μm. [ABSTRACT FROM AUTHOR]

Surface charge is a critical feature of microbes that affects their interactions with other cells and their environment. Because bacterial surface charge is difficult to measure directly, it is typically indirectly inferred through zeta potential measurements. Existing tools to perform such characterization are either costly and ill-suited for non-spherical samples or rely on microfluidic techniques requiring expensive fabrication equipment or specialized facilities. Here, we report the application of commercially available PMMA microfluidic chips and open-source data analysis workflows for facile electrokinetic characterization of particles and cells after prior zeta potential measurement with a Zetasizer for calibration. Our workflows eliminate the need for microchannel fabrication, increase measurement reproducibility, and make zeta potential measurements more accessible. This novel methodology was tested with functionalized 1 μm and 2 μm polystyrene beads as well as Escherichia coli MG1655 strain. Measured zeta potentials for these samples were in agreement with literature values obtained by conventional measurement methods. Taken together, our data demonstrate the power of this workflow to broadly enable critical measurements of particle and bacterial zeta potential for numerous applications.

Polyphenols are naturally derived organic compounds that have long been used as food additives, antioxidants, and adhesives owing to their intrinsic physicochemical properties. Recently, there has been growing interest in the fabrication of coordination networks based on the self-assembly of polyphenols and metal ions, termed metal-phenolic networks (MPNs), for multiple biological applications including bioimaging, drug delivery, and cell encapsulation. The as-synthesized MPN complexes feature pH responsiveness, controllable size and rigidity, and tunable permeability based on the choice of polyphenol-metal ion pairs. The aim of this Review is to introduce the physicochemical properties of MPNs, highlight their recent biological applications in cancer theranostics and single-cell encapsulation, and discuss the future utility of MPNs for biomedical applications.

Living materials combine a material scaffold, that is often porous, with engineered cells that perform sensing, computing, and biosynthetic tasks. Designing such systems is difficult because little is known regarding signaling transport parameters in the material. Here, the development of a porous microplate is presented. Hydrogel barriers between wells have a porosity of 60% and a tortuosity factor of 1.6, allowing molecular diffusion between wells. The permeability of dyes, antibiotics, inducers, and quorum signals between wells were characterized. A "sentinel" strain was constructed by introducing orthogonal sensors into the genome of Escherichia coli MG1655 for IPTG, anhydrotetracycline, L-arabinose, and four quorum signals. The strain's response to inducer diffusion through the wells was quantified up to 14 mm, and quorum and antibacterial signaling were measured over 16 h. Signaling distance is dictated by hydrogel adsorption, quantified using a linear finite element model that yields adsorption coefficients from 0 to 0.1 mol m -3 . Parameters derived herein will aid the design of living materials for pathogen remediation, computation, and self-organizing biofilms., (© 2022 The Authors. Published under the terms of the CC BY 4.0 license.)

We present a novel concept for the controlled trapping and releasing of beads and cells in a PDMS microfluidic channel without obstacles present around the particle or in the channel. The trapping principle relies on a two-level microfluidic configuration: a top main PDMS channel interconnected to a buried glass microchannel using round vias. As the fluidic resistances rule the way the liquid flows inside the channels, particles located in the streamlines passing inside the buried level are immobilized by the round via with a smaller diameter, leaving the object motionless in the upper PDMS channel. The particle is maintained by the difference of pressure established across its interface and acts as an infinite fluidic resistance, virtually cancelling the subsequent buried fluidic path. The pressure is controlled at the outlet of the buried path and three modes of operation of a trap are defined: idle, trapping and releasing. The pressure conditions for each mode are defined based on the hydraulic-electrical circuit equivalence. The trapping of polystyrene beads in a compact array of 522 parallel traps controlled by a single pressure was demonstrated with a trapping efficiency of 94%. Pressure conditions necessary to safely trap cells in holes of different diameters were determined and demonstrated in an array of 25 traps, establishing the design and operation rules for the use of planar hydrodynamic traps for biological assays.

Besides the main cortical inputs to the basal ganglia, via the corticostriatal projection, there is another input via the corticosubthalamic projection (CSTP), terminating in the subthalamic nucleus (STN). The present study investigated and compared the CSTPs originating from the premotor cortex (PM) or the primary motor cortex (M1) in two groups of adult macaque monkeys. The first group includes six intact monkeys, whereas the second group was made up of four monkeys subjected to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication producing Parkinson's disease (PD)-like symptoms and subsequently treated with an autologous neural cell ecosystem (ANCE) therapy. The CSTPs were labeled with the anterograde tracer biotinylated dextran amine (BDA), injected either in PM or in M1. BDA-labeled axonal terminal boutons in STN were charted, counted, and then normalized based on the number of labeled corticospinal axons in each monkey. In intact monkeys, the CSTP from PM was denser than that originating from M1. In two PD monkeys, the CSTP originating from PM or M1 were substantially increased, as compared to intact monkeys. In one other PD monkey, there was no obvious change, whereas the last PD monkey showed a decrease of the CSTP originating from M1. Interestingly, the linear relationship between CSTP density and PD symptoms yielded a possible dependence of the CSTP re-organization with the severity of the MPTP lesion. The higher the PD symptoms, the larger the CSTP densities, irrespective of the origin (from both M1 or PM). Plasticity of the CSTP in PD monkeys may be related to PD itself and/or to the ANCE treatment., (Copyright © 2020 Borgognon, Cottet, Badoud, Bloch, Brunet and Rouiller.)

Microfluidic electrical impedance flow cytometry is now a well-known and established method for single-cell analysis. Given the richness of the information provided by impedance measurements, this non-invasive and label-free approach can be used in a wide field of applications ranging from simple cell counting to disease diagnostics. One of its major limitations is the variation of the impedance signal with the position of the cell in the sensing area. Indeed, identical particles traveling along different trajectories do not result in the same data. The positional dependence can be considered as a challenge for the accuracy of microfluidic impedance cytometers. On the other hand, it has recently been regarded by several groups as an opportunity to estimate the position of particles in the microchannel and thus take a further step in the logic of integrating sensors in so-called "Lab-on-a-chip" devices. This review provides a comprehensive overview of the physical grounds of the positional dependence of impedance measurements. Then, both the developed strategies to reduce position influence in impedance-based assays and the recent reported technologies exploiting that dependence for the integration of position detection in microfluidic devices are reviewed.

Background . Autologous neural cell ecosystem (ANCE) transplantation improves motor recovery in MPTP monkeys. These motor symptoms were assessed using semi-quantitative clinical rating scales, widely used in many studies. However, limitations in terms of sensitivity, combined with relatively subjective assessment of their different items, make inter-study comparisons difficult to achieve. Objective . The aim of this study was to quantify the impact of MPTP intoxication in macaque monkeys on manual dexterity and assess whether ANCE can contribute to functional recovery. Methods . Four animals were trained to perform 2 manual dexterity tasks. After reaching a motor performance plateau, the animals were subjected to an MPTP lesion. After the occurrence of a spontaneous functional recovery plateau, all 4 animals were subjected to ANCE transplantation. Results . Two of 4 animals underwent a full spontaneous recovery before the ANCE transplantation, whereas the 2 other animals (symptomatic) presented moderate to severe Parkinson's disease (PD)-like symptoms affecting manual dexterity. The time to grasp small objects using the precision grip increased in these 2 animals. After ANCE transplantation, the 2 symptomatic animals underwent a significant functional recovery, reflected by a decrease in time to execute the different tasks, as compared with the post-lesion phase. Conclusions . Manual dexterity is affected in symptomatic MPTP monkeys. The 2 manual dexterity tasks reported here as pilot are pertinent to quantify PD symptoms and reliably assess a treatment in MPTP monkeys, such as the present ANCE transplantation, to be confirmed in a larger cohort of animals before future clinical applications.

We present a microfluidic platform allowing dielectrophoresis-assisted formation of cell aggregates of controlled size and composition under flow conditions. When specific experimental conditions are met, negative dielectrophoresis allows efficient concentration of cells towards electric field minima and subsequent aggregation. This bottom-up assembly strategy offers several advantages with respect to the targeted application: first, dielectrophoresis offers precise control of spatial cell organization, which can be adjusted by optimizing electrode design. Then, it could contribute to accelerate the establishment of cell-cell interactions by favoring close contact between neighboring cells. The trapping geometry of our chip is composed of eight electrodes arranged in a circle. Several parameters have been tested in simulations to find the best configurations for trapping in flow. Those configurations have been tested experimentally with both polystyrene beads and human embryonic kidney cells. The final design and experimental setup have been optimized to trap cells and release the created aggregates on demand., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Dielectrophoresis (DEP) and electrorotation (ROT) are two electrokinetic phenomena exploiting nonuniform electric fields to exert a force or torque on biological particles suspended in liquid media. They are widely used in lab-on-chip devices for the manipulation, trapping, separation, and characterization of cells, microorganisms, and other particles. The DEP force and ROT torque depend on the respective polarizabilities of the particle and medium, which in turn depend on their dielectric properties and on the field frequency. In this work, we present a new software, MyDEP, which implements several particle models based on concentric shells with adjustable dielectric properties. This tool enables the study of the variation in DEP and ROT spectra according to different parameters, such as the field frequency and medium conductivity. Such predictions of particle behavior are very useful for choosing appropriate parameters in DEP experiments. The software also enables the study of the homogenized properties of spherical or ellipsoidal multishell particles and provides a database containing published cell properties. Equivalent electrical conductivity and relative permittivity of the cell alone and in suspension can be calculated. The software also offers the ability to create graphs of the evolution of the crossover frequencies with the electric field frequency. These graphs can be directly exported from the software., (Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.)

Functional recovery from central nervous system injury is likely to be partly due to a rearrangement of neural circuits. In this context, the corticobulbar (corticoreticular) motor projections onto different nuclei of the ponto-medullary reticular formation (PMRF) were investigated in 13 adult macaque monkeys after either, primary motor cortex injury (MCI) in the hand area, or spinal cord injury (SCI) or Parkinson's disease-like lesions of the nigro-striatal dopaminergic system (PD). A subgroup of animals in both MCI and SCI groups was treated with neurite growth promoting anti-Nogo-A antibodies, whereas all PD animals were treated with autologous neural cell ecosystems (ANCE). The anterograde tracer BDA was injected either in the premotor cortex (PM) or in the primary motor cortex (M1) to label and quantify corticobulbar axonal boutons terminaux and en passant in PMRF. As compared to intact animals, after MCI the density of corticobulbar projections from PM was strongly reduced but maintained their laterality dominance (ipsilateral), both in the presence or absence of anti-Nogo-A antibody treatment. In contrast, the density of corticobulbar projections from M1 was increased following opposite hemi-section of the cervical cord (at C7 level) and anti-Nogo-A antibody treatment, with maintenance of contralateral laterality bias. In PD monkeys, the density of corticobulbar projections from PM was strongly reduced, as well as that from M1, but to a lesser extent. In conclusion, the densities of corticobulbar projections from PM or M1 were affected in a variable manner, depending on the type of lesion/pathology and the treatment aimed to enhance functional recovery., (© 2018 The Authors. European Journal of Neuroscience published by Federation of European Neuroscience Societies and John Wiley & Sons Ltd.)

Patients with supernumerary phantom limb report experiencing an additional limb duplicating its physical counterpart, usually following a stroke with sensorimotor disturbances. Here, we report a short-lasting case of a right upper supernumerary phantom limb with unusual visuomotor features in a healthy participant during a pure Jacksonian motor seizure unexpectedly induced by continuous Theta-Burst Stimulation over the left primary motor cortex. Electromyographic correlates of the event followed the phenomenological pattern of sudden appearance and brutal dissolution of the phantom, adding credit to the hypothesis that supernumerary phantom limb results from a dynamic resolution of conflictual multimodal information.

Chondrocalcin is among the most highly synthesized polypeptides in cartilage. This protein is released from its parent molecule, type II pro-collagen, after secretion by chondrocytes. A participation of extracellular, isolated chondrocalcin in mineralization was proposed more than 25 years ago, but never demonstrated. Here, exogenous chondrocalcin was found to trigger MMP13 secretion and cartilage destruction ex vivo in human cartilage explants and did so by modulating the expression of interleukin-1β in primary chondrocyte cultures in vitro. Chondrocalcin was found internalized by chondrocytes. Uptake was found mediated by a single 18-mer peptide of chondrocalcin, which does not exhibit homology to any known cell-penetrating peptide. The isolated peptide, when artificially linked as a tetramer, inhibited gene expression regulation by chondrocalcin, suggesting a functional link between uptake and gene expression regulation. At the same time, the tetrameric peptide potentiated chondrocalcin uptake by chondrocytes, suggesting a cooperative mechanism of entry. The corresponding peptide from type I pro-collagen supported identical cell-penetration, suggesting that this property may be conserved among C-propeptides of fibrillar pro-collagens. Structural modeling localized this peptide to the tips of procollagen C-propeptide trimers. Our findings shed light on unexpected function and mechanism of action of these highly expressed proteins from vertebrates., (© 2013. Published by Elsevier B.V. All rights reserved.)

The extracellular matrix (ECM) has long been viewed primarily as an organized network of solid-phase ligands for integrin receptors. During degenerative processes, such as osteoarthritis, the ECM undergoes deterioration, resulting in its remodeling and in the release of some of its components. Matrilin-3 (MATN3) is an almost cartilage specific, pericellular protein acting in the assembly of the ECM of chondrocytes. In the past, MATN3 was found required for cartilage homeostasis, but also involved in osteoarthritis-related pro-catabolic functions. Here, to better understand the pathological and physiological functions of MATN3, its concentration as a circulating protein in articular fluids of human osteoarthritic patients was determined and its functions as a recombinant protein produced in human cells were investigated with particular emphasis on the physical state under which it is presented to chondrocytes. MATN3 down-regulated cartilage extracellular matrix (ECM) synthesis and up-regulated catabolism when administered as a soluble protein. When artificially immobilized, however, MATN3 induced chondrocyte adhesion via a α5β1 integrin-dependent mechanism, AKT activation and favored survival and ECM synthesis. Furthermore, MATN3 bound directly to isolated α5β1 integrin in vitro. TGFβ1 stimulation of chondrocytes allowed integration of exogenous MATN3 into their ECM and ECM-integrated MATN3 induced AKT phosphorylation and improved ECM synthesis and accumulation. In conclusion, the integration of MATN3 to the pericellular matrix of chondrocytes critically determines the direction toward which MATN3 regulates cartilage metabolism. These data explain how MATN3 plays either beneficial or detrimental functions in cartilage and highlight the important role played by the physical state of ECM molecules., (Copyright © 2012 International Society of Matrix Biology. Published by Elsevier B.V. All rights reserved.)

Chondrogenic tumors that exhibit benign or malignant behaviors synthesize variable amounts of cartilage-like extracellular matrix. To define the regulators of these phenotypes, we performed a proteomic comparison of multiple human chondrogenic tumors, which revealed differential accumulation of the C-propeptides of procollagens Ialpha1 and II (PC1CP and PC2CP) in malignant versus benign tumors, respectively. Expression patterns of PC1CP correlated with levels of tumor vascularization, whereas expression patterns of PC2CP suggested its susceptibility to immobilization within the extracellular matrix. Prompted by these observations, we investigated the functions of recombinant PC1CP and PC2CP in the extracellular matrix in soluble or immobilized states. Each induced beta1 integrin-mediated chondrocyte adhesion by distinct domains and efficacies, suggesting that they initiated distinct signaling pathways. Indeed, immobilized PC2CP, but not PC1CP, induced apoptosis of primary chondrocytes and EAhy926 endothelial cells. In contrast, soluble PC1CP, but not PC2CP, induced the migration of EAhy926 cells and increased vascular endothelial growth factor (VEGF) and CXCR4 expression in chondrocytes. Soluble PC2CP also increased VEGF expression, but along with a more pronounced effect on CXCR4 and matrix metalloproteinase 13 expression. Our findings suggest that PC1CP favors angiogenesis and tumor progression, but that PC2CP acts in a more complex manner, exerting antitumor and antiangiogenic properties through apoptosis induction when immobilized, but progression and metastasis when soluble. In summary, the relative levels of PC1CP and PC2CP and their interactions within the extracellular matrix contribute to tumor progression, angiogenesis, and metastasis in chondrogenic tumors., (Copyright 2010 AACR.)

Renowned authors, when studying arterial diseases, use indifferently the words atheroma, atheromatosis, atherosclerosis or arteriosclerosis. The historical record of these words permits the justification of a selective choice. The word atheroma was created by Celsius, two thousand years ago; he have it the meaning of fatty tumor, which was kept till the middle of the nineteenth century. The word atheromatosis appeared on 1815, since J. Hodgson defined so the fatty arterial degeneration. Marchand, from Leipzig, proposed on 1904 the word atherosclerosis which has always been with us. The term arteriosclerosis was well defined on 1833 by Lobstein, from Strasbourg. The authors propose to reserve the word atherosclerosis to the arterial disease described by the WHO, to keep the words atheroma and atheromatosis to anatomical lesions well-defined. Arteriosclerosis is a disease which invades an extensive arterial network, with a particular anatomical image.

Among the risk factors for atherosclerosis, lipoproteins play a central role, particularly in the development of coronary artery disease. The plasma cholesterol level was the first definite indicator of the risk factor. Thereafter, technical progress has permitted the measurement of the cholesterol fractions, LDL cholesterol which is positively correlated with atherosclerosis, and HDL cholesterol, which is protective. However, the measurement of these fractions in a subject does not permit accurate determination of the risk to the subject. Likewise the measurement of apo A-I and B has brought an improvement in determining the risk factor but is still insufficient. The clarification of new markers would allow better definition of the potential atherogenic risk to a given individual Lp A-I (lipoproteins containing apo A-I but not apo A-II) level is probably an important indicator. Similarly, Lp(a) level is certainly an atherogenic lipoprotein and the apo E phenotype modulates the development of atherosclerosis. All these new markers and others, in the future, will better define the risk for an asymptomatic subject, with regard of atherosclerosis and therefore help to prevent it.

The determination of blood amino-acids by column chromatography has been carried out on 53 patients, 17 with acute myeloid leukemia, 22 with chronic myeloid leukemia. A comparison was made with 25 normal subjects. These determination has shown a significant increase in glycin, cystin and a non significant increase of tryptophan. A positive relationship may exist between uricemia and content of glycin and glutamin, both amino-acids which are messengers of uric acid. A positive correlation has been found between glycin tryptophan and the number of myeloblasts.