Large Volumes Of Cells Research Articles

A programmable microfluidic platform to monitor calcium dynamics in microglia during inflammation

Neuroinflammation is characterized by the elevation of cytokines and adenosine triphosphate (ATP), which in turn activates microglia. These immunoregulatory molecules typically form gradients in vivo, which significantly influence microglial behaviors such as increasing calcium signaling, migration, phagocytosis, and cytokine secretion. Quantifying microglial calcium signaling in the context of inflammation holds the potential for developing precise therapeutic strategies for neurological diseases. However, the current calcium imaging systems are technically challenging to operate, necessitate large volumes of expensive reagents and cells, and model immunoregulatory molecules as uniform concentrations, failing to accurately replicate the in vivo microenvironment. In this study, we introduce a novel calcium monitoring micro-total analysis system (CAM-μTAS) designed to quantify calcium dynamics in microglia (BV2 cells) within defined cytokine gradients. Leveraging programmable pneumatically actuated lifting gate microvalve arrays and a Quake valve, CAM-μTAS delivers cytokine gradients to microglia, mimicking neuroinflammation. Our device automates sample handling and cell culture, enabling rapid media changes in just 1.5 s, thus streamlining the experimental workflow. By analyzing BV2 calcium transient latency to peak, we demonstrate location-dependent microglial activation patterns based on cytokine and ATP gradients, offering insights contrasting those of non-gradient-based perfusion systems. By harnessing advancements in microsystem technology to quantify calcium dynamics, we can construct simplified human models of neurological disorders, unravel the intricate mechanisms of cell-cell signaling, and conduct robust evaluations of novel therapeutics.

Development of a cooling system for marine power batteries

For green shipping, lithium-ion battery-powered ships are rapidly developing. Compared with power batteries for electric vehicles, the large volume and capacity of cells in electric ships make it difficult to dissipate heat, thus requiring efficient cooling. Herein, a novel shape-stabilized phase change material (SSPCM) channel/thermoelectric cooler (TEC) cooling system for marine power batteries was proposed and experimentally studied. It uses TEC for localized cooling and seawater flowing inside the SSPCM as coolant. First, the arrangement of the TECs was experimentally determined. Then, the cooling performance of the system was verified by comparative experiments. The results show that, compared to the cooling system without TECs, the maximum temperature difference was reduced by 28.8 %, with the maximum temperature and temperature difference of 49.8 °C and 3.7 °C, respectively. Compared with the single cooling method, the maximum temperature and temperature difference were reduced by 15.5 % and 53.3 %, respectively. Finally, the experiments were conducted to explore the impact of various parameters on the cooling performance of the system. The unique combination of SSPCM channel, seawater, and TEC provides a new strategy for efficiently cooling marine power batteries at high charge/discharge rates.

An Image Processing Algorithm for Facile and Reproducible Quantification of Vomocytosis.

Vomocytosis is a process that occurs when internalized fungal pathogens escape from phagocytes without compromising the viability of the pathogen and the host cell. Manual quantification of time-lapse microscopy videos is currently used as the standard to study pathogen behavior and vomocytosis incidence. However, human-driven quantification of vomocytosis (and the closely related phenomenon, exocytosis) is incredibly burdensome, especially when a large volume of cells and interactions needs to be analyzed. In this study, we designed a MATLAB algorithm that measures the extent of colocalization between the phagocyte and fungal cell (Cryptococcus neoformans; CN) and rapidly reports the occurrence of vomocytosis in a high throughput manner. Our code processes multichannel, time-lapse microscopy videos of cocultured CN and immune cells that have each been fluorescently stained with unique dyes and provides quantitative readouts of the spatiotemporally dynamic process that is vomocytosis. This study also explored metrics, such as the rate of change of pathogen colocalization with the host cell, that could potentially be used to predict vomocytosis occurrence based on the quantitative data collected. Ultimately, the algorithm quantifies vomocytosis events and reduces the time for video analysis from over 1 h to just 10 min, a reduction in labor of 83%, while simultaneously minimizing human error. This tool significantly minimizes the vomocytosis analysis pipeline, accelerates our ability to elucidate unstudied aspects of this phenomenon, and expedites our ability to characterize CN strains for the study of their epidemiology and virulence.

Seeing cells without a lens: Compact 3D digital lensless holographic microscopy for wide-field imaging

Optical microscopy is an essential tool for biomedical discoveries and cell diagnosis at micro- to nano-scales. However, conventional microscopes rely on lenses to record 2-D images of samples, which limits in-depth inspection of large volumes of cells. This research project implements a novel 3-D lensless microscopic imaging system that achieves a wide field of view, high resolution, and an extremely compact, cost-effective design: the Digital Lensless Holographic Microscope (DLHM).A lensless holographic microscope is built with only a light source, a sample, and an imaging chip (with other non-essential supporting structures). The entire setup costs $500 to $600. A series of MATLAB-based algorithms were designed to reconstruct phase information of samples simultaneously from the recorded hologram with built-in high-resolution and phase unwrapping functions. This produces 3-D images of cell samples. The 3-D cell reconstruction of biological samples maintained a comparable resolution with conventional optical microscopes while covering a field of view of 36.2 mm2, which is 20-30 times larger. While most microscopes are extremely time-consuming and require professional expertise, the lensless holographic microscope is portable, low-cost, high-stability, and extremely simple. This makes it accessible for point-of-care testing (POCT) to a broader coverage, including developing regions with limited medical facilities.

Mapping acoustic properties of tissues at low temperatures for ultrasound rewarming

Cryopreservation of large volumes of cells and tissues, followed by successful rewarming, promises to revolutionize organ transplantation by extending organ preservation times. This technology addresses a critical issue: over 6,000 individuals in the UK are awaiting organ transplants, yet an alarming 60% of donated organs go unused due to current preservation time limitations. A significant challenge lies in providing a rapid and uniform rewarming method for cryopreserved tissues. Ultrasound, capable of converting sound power into heat as it propagates through tissue, offers a promising solution. Nonetheless, before tapping into ultrasound’s potential for rewarming experiments, a fundamental understanding of the acoustic properties of tissues, which vary with temperature and during phase change, is essential. This study employs the multiple-reflection method (MRM), with buffer-rod positioned between the transducer and sample, to measure the acoustic attenuation coefficient and sound speed in biological relevant materials and the primary components of tissues, such as water and lipids, across a temperature range of 20 to −100ºC. Concurrently, the acoustic properties of commonly used cryopreservation solutions were assessed. These data will facilitate computational simulation of acoustic power delivery and the resulting temperature distributions, enabling planning and monitoring of tissue rewarming, which is critical to its success.

An in silico study on the detectability of field cancerization through parenchymal analysis of digital mammograms.

Parenchymal analysis has shown promising performance for the assessment of breast cancer risk through the characterization of the texture features of mammography images. However, the working principles behind this practice are yet not well understood. Field cancerization is a phenomenon associated with genetic and epigenetic alterations in large volumes of cells, putting them on a path of malignancy before the appearance of recognizable cancer signs. Evidence suggests that it can induce changes in the biochemical and optical properties of thetissue. The aim of this work was to study whether the extended genetic mutations and epigenetic changes due to field cancerization, and the impact they have on the biochemistry of breast tissues are detecTable in the radiological patterns of mammography images. An in silico experiment was designed, which implied the development of a field cancerization model to modify the optical tissue properties of a cohort of 60 voxelized virtual breast phantoms. Mammography images from these phantoms were generated and compared with images obtained from their non-modified counterparts, i.e. without field cancerization. We extracted 33 texture features from the breast area to quantitatively assess the impact of the field cancerization model. We analyzed the similarity and statistical equivalence of texture features with and without field cancerization using the t-test, Wilcoxon sign rank test and Kolmogorov-Smirnov test, and performed a discrimination test using multinomial logistic regression analysis with lasso regularization. With modifications of the optical tissue properties on 3.9% of the breast volume, some texture features started to fail to show equivalence (p\le0.05). At 7.9% volume modification, a high percent of texture features showed statistically significant differences (p\le0.05) and non-equivalence. At this level, multinomial logistic regression analysis of texture features showed a statistically significant performance in the discrimination of mammograms from breasts with and without field cancerization (AUC= 0.89, 95% CI: 0.75 - 1.00). These results support the idea that field cancerization is a feasible underlying working principle behind the distinctive performance of parenchymal analysis in breast cancer riskassessment. This article is protected by copyright. All rights reserved.

Validation of a flow-cytometry-based red blood cell antigen phenotyping method.

Current manual and automated phenotyping methods are based on visual detection of the antigen-antibody interaction. This approach has several limitations including the use of large volumes of patient and reagent red blood cells (RBCs) and antisera to produce a visually detectable reaction. We sought to determine whether the flow cytometry could be developed and validated to perform RBC phenotyping to enable a high-throughput method of phenotyping using comparatively miniscule reagent volumes via fluorescence-based detection of antibody binding. RBC phenotyping by flow cytometry was performed using monoclonal direct typing antisera (human IgM): anti-C, -E, -c, -e, -K, -Jka , -Jkb and indirect typing antisera (human IgG): anti-k, -Fya , -Fyb , -S, -s that are commercially available and currently utilized in our blood transfusion services (BTS) for agglutination-based phenotyping assays. Seventy samples were tested using both flow-cytometry-based-phenotyping and a manual tube standard agglutination assay. For all the antigens tested, 100% concordance was achieved. The flow-cytometry-based method used minimal reagent volume (0.5-1μl per antigen) compared with the volumes required for manual tube standard agglutination (50μl per antigen) CONCLUSION: This study demonstrates the successful validation of flow-cytometry-based RBC phenotyping. Flow cytometry offers many benefits compared to common conventional RBC phenotyping methods including high degrees of automation, quantitative assessment with automated interpretation of results and extremely low volumes of reagents. This method could be used for high-throughput, low-cost phenotyping for both blood suppliers and hospital BTS.

Optimizing Use of Automated Isovolemic Hemodilution Red-Cell Exchange in a Patient Cohort with Sickle Cell Disease: A Quality Improvement Intervention

Background: Red-cell exchange (RCE) is a mainstay of treatment for both acute and chronic complications of sickle cell disease (SCD). It is a resource-intensive intervention requiring transfusion of large volumes of antigen-matched red blood cells (RBC). Identifying suitable RBC units can be challenging due to variability in blood group phenotypes between patients with SCD and the donor population. This often results in use of O-negative units, which are a scarce resource. Efforts to reduce the volume of units transfused, while maintaining therapeutic efficacy is an important clinical need. Isovolemic hemodilution (IHD) prior to RCE reduces the required volume of RBCs. The aim of this project is to evaluate the effect of a change to IHD-RCE on RBC utilization in patients with SCD receiving standard RCE. Methods: All adult SCD patients receiving standard RCE at the Ottawa Hospital were identified. To safely attain a meaningful reduction in transfused RBCs, RCE treatment parameters were individualized for each patient (Table 1). Patient hematocrit was not allowed to decrease below 20% during the depletion phase, and IHD-RCE would be performed only if an estimated reduction in RBC volume of at least 200 mL was expected. Pregnant patients were excluded. Change in RCE protocol to IHD-RCE took place in January 2022. Transfusion and clinical data were obtained from databases at the Ottawa Hospital in the six months preceding and succeeding the change in RCE protocols to allow for a pre- and post-intervention comparison. Results: Thirty-four adults receiving regular RCE for SCD were identified. Twenty-two patients met criteria for a protocol change to IHD-RCE. The mean age of the IHD-RCE cohort was 31 years (SD 9.5). Males comprised 72.7% of this cohort, with the most frequent genotype of hemoglobin SS (68.2%). Over the one-year study period, 1963 RBC units were transfused: 1035 RBC units in the pre-intervention period, and 928 units in the post-intervention period, representing a reduction of 107 RBC units. 1958 (99.7%) of the RBC units transfused were transfused in the setting of RCE, with few (5 units; 0.03%) administered as simple RBC transfusions. Table 2 outlines patient outcomes during the study period. The mean number of RBC units transfused per patient in the pre- and post-intervention periods were 47 and 42.4 units, respectively. The mean number of RBC units per RCE session per patient was significantly reduced from 8.7 units in the pre-intervention period to 7.8 units in the IHD-RCE post-intervention period (mean difference: -0.9, 95% CI: -1.2 to -0.5). A total of 236 RCE sessions occurred during the study period. No difference in RCE session frequency was observed with a change to IHD-RCE during the six-month study period, nor time between RCE sessions. Therapeutic efficacy in attaining target hemoglobin S levels was not affected by the change to IHD-RCE. No adverse patient safety signals were observed during the IHD-RCE sessions to date. Conclusions: This study demonstrates that IHD-RCE, compared to standard RCE, substantially reduces RBC utilization. A total of 107 RBC units were conserved in our patient cohort of 22 chronic RCE patients directly from the transition to IHD-RCE from standard RCE. Based on local RBC per unit costs, this corresponds to an annualized saving of $95,444 CAD. With pressure on blood banks to provide appropriately matched units, and risks of alloimmunization and delayed hemolytic transfusion reactions amongst chronically transfused SCD patients, increased uptake of IHD-RCE should be considered for SCD patients on chronic RCE. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Single-particle orientation microscopy with quantum dots for bioimaging

Orientational imaging of fluorescent probes has seen increasing use as a tool to study a variety of biological features, such as revealing the alignment of scaffolding and structural components in cells, or observing rotational dynamics of individual biomolecules. For high-throughput measurements, wide-field camera-based orientation imaging is the optimal approach for observing the large volumes of cells. These methods measure the polarization state of probe fluorescence to determine orientation.

Evaluation of the validity of large-scale serial sectioning TEM for three-dimensional reconstruction of rice mesophyll cells and chloroplasts.

Serial sectioning transmission electron microscopy (ssTEM) is a classical method of 3D reconstruction using serial sections obtained with an ultramicrotome. However, producing a long ribbon with homogeneity is difficult. Here, ultramicrotome movement was suspended after producing a ribbon of 15-30 serial sections (cutting intervals, 100nm), and then, the ribbon was mounted on an individual one-slot grid. However, as this ssTEM method may include influencing factors such as incorrect intervals of section thickness and distortion of sections, which is produced by cutting sections using a diamond knife and beam interaction under TEM observation, qualitative and quantitative data on rice mesophyll cells and chloroplasts were compared with those obtained from a focused ion beam scanning electron microscopy (FIB-SEM) (cutting intervals, 50nm). No structural distortion in 3D models was observed. In addition, no significant differences in the volume and surface area were observed between the two methods. The surface to volume ratio was significantly affected by the increase in section thickness, but not the difference of methodologies. Our method was useful for observing large volumes of plant cells and organelles, leading to the identification of various sizes and types of chloroplasts. The formation of a chloroplast pocket, which is a structure surrounding other intracellular compartments, was confirmed in rice leaves grown under moderate growth conditions using the ssTEM method. As only four out of 90 chloroplasts formed pocket structures, the formation was considered to be rare under the applied moderate growth conditions.

Ex vivo expanded allogeneic natural killer cells have potent cytolytic activity against cancer cells through different receptor-ligand interactions

BackgroundRecently, allogeneic natural killer (NK) cells have gained considerable attention as promising immunotherapeutic tools due to their unique biological functions and characteristics. Although many NK expansion strategies have been reported previously, a deeper understanding of cryopreserved allogeneic NK cells is needed for specific therapeutic approaches.MethodsWe isolated CD3−CD56+ primary natural killer (pNK) cells from healthy donors and expanded them ex vivo using a GMP-compliant method without any feeder to generate large volumes of therapeutic pNK cells and cryopreserved stocks. After validation for high purity and activating phenotypes, we performed RNA sequencing of the expanded and cryopreserved pNK cells. The pNK cells were used against various cancer cell lines in 7-AAD/CFSE cytotoxicity assay. For in vivo efficacy study, NSG mice bearing subcutaneous cisplatin-resistant A2780cis xenografts were treated with our pNK cells or cisplatin. Antitumor efficacy was assessed by measuring tumor volume and weight.ResultsCompared to the pNK cells before expansion, pNK cells after expansion showed 2855 upregulated genes, including genes related to NK cell activation, cytotoxicity, chemokines, anti-apoptosis, and proliferation. Additionally, the pNK cells showed potent cytolytic activity against various cancer cell lines. Interestingly, our activated pNK cells showed a marked increase in NKp44 (1064-fold), CD40L (12,018-fold), and CCR5 (49-fold), and did not express the programmed cell death protein 1(PD-1). We also demonstrated the in vitro and in vivo efficacies of pNK cells against cisplatin-resistant A2780cis ovarian cancer cells having a high programmed death-ligand 1(PD-L1) and low HLA-C expression.ConclusionsTaken together, our study provides the first comprehensive genome wide analysis of ex vivo-expanded cryopreserved pNK cells. It also indicates the potential use of expanded and cryopreserved pNK cells as a highly promising immunotherapy for anti-cancer drug resistant patients.

Placental mosaicism and complications of pregnancy

Timely diagnosis of chromosomal aneuploidies plays an important role in determining the proper approach to the management of pregnancy. This article outlines the current ideas on the likelihood of occurrence of obstetric pathology, depending on the number of cells with genetic aberration, especially in the placenta. Such obstetric complications include fetal growth retardation, premature birth, and some forms of preeclampsia. The article describes the prenatal examination techniques, which help obtain timely information about the development of the fetus and predict pregnancy complications, more specifically, non-invasive prenatal DNA screening as a new technique with its advantages and limitations, based on the analysis of DNA of placental origin. It also highlights other latest diagnostic tools that allow to get more accurate information about placental mosaicism and the development of pathology. We have reviewed publications over the past 10 years, which are devoted to the factors responsible for the formation of placental mosaicism, the prenatal diagnostic procedures required for an accurate diagnosis, and the likelihood of obstetric pathology in case of prolonged pregnancy complicated by genetic aberrations. Foreign studies confirm the direct dependence of the likelihood of obstetric pathology on the number of cells with genetic aber ration. In accordance with the above study results, it would be only right to note that placental insufficiency can be observed in any case of genetic aberration, especially if a large volume of cells is involved in the pathological process at an early stage of differentiation. In addition, the article discusses the issue of need of thorough prenatal diagnosis to prevent the development of pregnancy pathology, including the use of the latest technologies and minimizing invasive methods.

A method to isolate and cryopreserve cerebrospinal fluid mononuclear cells from external ventricular drains to investigate immunological processes in acute brain injuries

The inflammatory response to acute brain injuries is a key contributor to subsequent outcome. The study of local central nervous system inflammatory responses is hindered by raised intracranial pressure precluding cerebrospinal fluid sampling by lumbar puncture. External ventricular drains are sited in some acute brain injury patients to divert cerebrospinal fluid and thus reduce intracranial pressure, and represent a potential route to safely gather large volumes of cerebrospinal fluid for immunological studies. In this manuscript we show that mononuclear cells can be isolated from cerebrospinal fluid collected from external ventricular drains, and that the large volumes of cerebrospinal fluid available yield sufficient mononuclear cells to allow cryopreservation. Prolonged storage of cerebrospinal fluid in the external ventricular drain collection bag can alter the phenotype of cells recovered, but the predicted effect of this can be estimated for a given flow cytometry panel by assessing the changes in peripheral blood mononuclear cells exposed to the same conditions. The described method will allow clinical studies of acute brain injuries to investigate the immunological processes occurring within the central nervous system compartment, rather than relying on changes in the peripheral circulation.

Correlative light and volume electron microscopy (vCLEM): How community participation can advance developing technologies.

Correlative light and electron microscopy is a valuable tool to image samples across resolution scales and link data on structure and function. While studies using this technique have been available since the 1960s, recent developments have enabled applying these workflows to large volumes of cells and tissues. Much of the development in this area has been facilitated through the collaborative efforts of microscopists and commercial companies to bring the methods, hardware and image processing technologies needed into laboratories and core imaging facilities. This is a prime example of how what was once a niche area can be brought into the mainstream of microscopy by the efforts of imaging pioneers who push the boundaries of possibility.

Adherens junction engagement regulates functional patterning of the cardiac pacemaker cell lineage.

Cardiac pacemaker cells (CPCs) rhythmically initiate the electrical impulses that drive heart contraction. CPCs display the highest rate of spontaneous depolarization in the heart despite being subjected to inhibitory electrochemical conditions that should theoretically suppress their activity. While several models have been proposed to explain this apparent paradox, the actual molecular mechanisms that allow CPCs to overcome electrogenic barriers to their function remain poorly understood. Here, we have traced CPC development at single-cell resolution and uncovered a series of cytoarchitectural patterning events that are critical for proper pacemaking. Specifically, our data reveal that CPCs dynamically modulate adherens junction (AJ) engagement to control characteristics including surface area, volume, and gap junctional coupling. This allows CPCs to adopt a structural configuration that supports their overall excitability. Thus, our data have identified a direct role for local cellular mechanics in patterning critical morphological features that are necessary for CPC electrical activity.

Coronavirus infection induces progressive restructuring of the endoplasmic reticulum involving the formation and degradation of double membrane vesicles

Coronaviruses rearrange endoplasmic reticulum (ER) membranes to form a reticulovesicular network (RVN) comprised predominantly of double membrane vesicles (DMVs) involved in viral replication. While portions of the RVN have been analyzed by electron tomography (ET), the full extent of the RVN is not known, nor how RVN formation affects ER morphology. Additionally the precise mechanism of DMV formation has not been observed. In this work, we examined large volumes of coronavirus-infected cells at multiple timepoints during infection using serial-section ET. We provide a comprehensive 3D analysis of the ER and RVN which gives insight into the formation mechanism of DMVs as well as the first evidence for their lysosomal degradation. We also show that the RVN breaks down late in infection, concurrent with the ER becoming the main budding compartment for new virions. This work provides a broad view of the multifaceted involvement of ER membranes in coronavirus infection.

Temporally gated molecular tools for tracking protein-protein interactions in live cells.

Protein-protein interactions (PPIs) are essential in most biological processes. Even though many methods were designed to detect PPIs, detecting PPIs in a large volume of cells with a temporal resolution remains challenging. Recent development of light gated transcriptional reporters, such as SPARK and iTANGO, enabled detection of PPI in a large population of cells with a temporal resolution on the order of minutes. In this chapter, we discussed in detail the application of SPARK to detect PPIs between the activated β-2 adrenergic receptor (B2AR) and both Gα mimic and β-arrestin2. Because SPARK is a multi-component system, the protein expression level is critical for its optimal performance. We also discussed the detailed protocols for using SPARK with either transfection or lentiviral infection in HEK296T/17 cells.

Blood product transfusion and mortality in neonatal extracorporeal membrane oxygenation.

Neonates receiving extracorporeal membrane oxygenation (ECMO) support are transfused large volumes of red blood cells (RBCs) and platelets (PLTs). Transfusions are often administered in response to specific, but largely unstudied thresholds. The aim of this study is to examine the relationship between RBC and PLT transfusion rates and mortality in neonates receiving ECMO support. We retrospectively examined outcomes of neonates receiving ECMO support in the neonatal intensive care unit (NICU) for respiratory failure between 2010 and 2016 at a single quaternary-referral NICU. We examined the association between RBC and PLT transfusion rate (mL per kg per day) and in-hospital mortality, adjusting for confounding by using a validated composite baseline risk score (Neo-RESCUERS). Among the 110 neonates receiving ECMO support, in-hospital mortality was 28%. The median RBC transfusion rate (mL/kg/d) after cannulation was greater among non-survivors, compared to survivors: 12.4 (IQR 9.3-16.2) versus 7.3 (IQR 5.1-10.3), p < 0.001. Similarly, PLT transfusion rate was greater among non-survivors: 22.9 (9.3-16.2) versus 12.1 (8.4-20.1), p = 0.02. After adjusting for baseline mortality risk, both RBC transfusion (adjusted relative risk per 5 mL/kg/d increase: 1.33; 95% CI 1.05-1.69, p = 0.02) and PLT transfusion (adjusted relative risk per 5 mL/kg/d increase: 1.12; 95% CI 1.02-1.23, p = 0.02) were both associated with in-hospital mortality. RBC and PLT transfusion rates are associated with in-hospital mortality among neonates receiving ECMO. These data provide a basis for future studies evaluating more restrictive transfusion practices for neonates receiving ECMO support.

A generalized massively parallel ultra-high order FFT-based Maxwell solver

Dispersion-free ultra-high order FFT-based Maxwell solvers have recently proven to be paramount to a large range of applications, including the high-fidelity modeling of high-intensity laser–matter interactions with Particle-In-Cell (PIC) codes. To enable a massively parallel scaling of these solvers, a novel parallelization technique was recently proposed, which consists in splitting the simulation domain into several processor sub-domains, with guard regions appended at each sub-domain boundary. Maxwell’s equations are advanced independently on each sub-domain using local shared-memory FFTs (instead of a single distributed global FFT). This implies small truncation errors at sub-domain boundaries, the amplitude of which depends on guard regions sizes and order of the Maxwell solver. For moderate guard region sizes, this ’local’ technique proved to be highly scalable on up to a million cores and notably enabled the 3D modelingof so-called plasma mirrors, for which 8 guard cells only were enough to prevent truncation error growth. Yet, for other applications, the required number of guard cells might be much higher, which would severely limit the parallel efficiency of this technique due to the large volume of guard cells to be exchanged between sub-domains. In this context, we propose a novel parallelization technique that ensures very good scaling of FFT-based solvers with an arbitrarily high number of guard cells. Our ’hybrid’ technique consists in performing distributed FFTs on local groups of processors with guard regions now appended to boundaries of each group of processors. It uses a dual domain decomposition method for the Maxwell solver and other parts of the PIC cycle to keep the simulation load-balanced. This ’hybrid’ technique was implemented in the open source exascale library PICSAR. Benchmarks show that for a large number of guard cells (>16), the ’hybrid’ technique offers up to ×3 speed-up and ×8 memory savings compared to the ’local’ one.

Microparticles for Suspension Culture of Mammalian Cells

The focus of this work is to develop a technology for the synthesis of polymer microcarriers that demonstrate mammalian cell culture adhesion on the surface of the microcarriers. Most mammalian cells are adherent in nature that requires multilayer vessels, large volume, expensive cell culture media, high manufacturing time, and high costs of cell culture supplies for the commercial-scale manufacturing of cells. The development of an efficient, scalable technology for producing large volumes of cells is a need in bioprocess industries to improve product potency. We developed a method of synthesizing soft biocompatible US FDA approved polymer based microparticle carrier system of approximately 260 ± 27 μm in diameter that serves as an adherent platform for human umbilical vein endothelial cells (HUVEC) to grow in suspension. Our preliminary experimental results showed that using the polymeric microcarrier system cell adhesion to the surface of the microcarriers was 2-3-fold higher than conventional cell culture flasks while using 10-fold lower cell culture media in a bioreactor than a tissue-culture treated flask. The survival of HUVEC on microparticles was confirmed by live cell staining (green fluorescent calcein AM), dead cell staining (ethidium homodimer-1), nuclear DAPI staining, actin cytoskeleton staining, confocal microscopy, and flow cytometry analysis. This technology will provide high cell culture productivity while reducing the costs of growing adherent cells.