scholarly journals Computer-Controlled Biaxial Bioreactor for Investigating Cell-Mediated Homeostasis in Tissue Equivalents

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
J. F. Eichinger ◽  
D. Paukner ◽  
J. M. Szafron ◽  
R. C. Aydin ◽  
J. D. Humphrey ◽  
...  
Keyword(s):  
Soft Tissues ◽  
Biological Tissues ◽  
Biaxial Stress ◽  
Model Systems ◽  
Mechanical State ◽  
Tissue Equivalents ◽  
Computer Controlled ◽  
The Impact ◽  
Homeostatic State

Abstract Soft biological tissues consist of cells and extracellular matrix (ECM), a network of diverse proteins, glycoproteins, and glycosaminoglycans that surround the cells. The cells actively sense the surrounding ECM and regulate its mechanical state. Cell-seeded collagen or fibrin gels, so-called tissue equivalents, are simple but powerful model systems to study this phenomenon. Nevertheless, few quantitative studies document the stresses that cells establish and maintain in such gels; moreover, most prior data were collected via uniaxial experiments whereas soft tissues are mainly subject to multiaxial loading in vivo. To begin to close this gap between existing experimental data and in vivo conditions, we describe here a computer-controlled bioreactor that enables accurate measurements of the evolution of mechanical tension and deformation of tissue equivalents under well-controlled biaxial loads. This device allows diverse studies, including how cells establish a homeostatic state of biaxial stress and if they maintain it in response to mechanical perturbations. It similarly allows, for example, studies of the impact of cell and matrix density, exogenous growth factors and cytokines, and different types of loading conditions (uniaxial, strip-biaxial, and biaxial) on these processes. As illustrative results, we show that NIH/3T3 fibroblasts establish a homeostatic mechanical state that depends on cell density and collagen concentration. Following perturbations from this homeostatic state, the cells were able to recover biaxial loading similar to homeostatic. Depending on the precise loads, however, they were not always able to fully maintain that state.

scholarly journals Latent Antigen Vaccination in a Model Gammaherpesvirus Infection

2001 ◽  
Vol 75 (17) ◽  
pp. 8283-8288 ◽  
Author(s):  
Edward J. Usherwood ◽  
Kimberley A. Ward ◽  
Marcia A. Blackman ◽  
James P. Stewart ◽  
David L. Woodland
Keyword(s):  
Latent Infection ◽  
Model Systems ◽  
Murine Gammaherpesvirus ◽  
Latently Infected ◽  
Associated Proteins ◽  
Infected Cells ◽  
The Impact ◽  
First Time

ABSTRACT Vaccines that can reduce the load of latent gammaherpesvirus infections are eagerly sought. One attractive strategy is vaccination against latency-associated proteins, which may increase the efficiency with which T cells recognize and eliminate latently infected cells. However, due to the lack of tractable animal model systems, the effect of latent-antigen vaccination on gammaherpesvirus latency is not known. Here we use the murine gammaherpesvirus model to investigate the impact of vaccination with the latency-associated M2 antigen. As expected, vaccination had no effect on the acute lung infection. However, there was a significant reduction in the load of latently infected cells in the initial stages of the latent infection, when M2 is expressed. These data show for the first time that latent-antigen vaccination can reduce the level of latency in vivo and suggest that vaccination strategies involving other latent antigens may ultimately be successfully used to reduce the long-term latent infection.

scholarly journals A Mouse Model Of Binge Alcohol Consumption andBurkholderiaInfection

2018 ◽  
Author(s):  
Victor Jimenez ◽  
Ryan Moreno ◽  
Erik Settles ◽  
Bart J Currie ◽  
Paul Keim ◽  
...  
Keyword(s):  
Alcohol Consumption ◽  
Binge Drinking ◽  
Burkholderia Pseudomallei ◽  
Alcohol Exposure ◽  
Model Systems ◽  
Phagocytic Cells ◽  
Intracellular Invasion ◽  
The Impact

AbstractBackgroundBinge drinking, a common form of alcohol consumption, is associated with increased mortality and morbidity; yet, its effects on the immune system’s ability to defend against infectious agents are poorly understood.Burkholderia pseudomallei, the causative agent of melioidosis can occur in healthy humans, yet binge alcohol use is progressively being recognized as a major risk factor. Although our previous studies demonstrated that binge alcohol exposure results in reduced alveolar macrophage function and increasedBurkholderiavirulencein vitro, no experimental studies have investigated the outcomes of binge alcohol onBurkholderiaspp. infectionin vivo.Principal FindingsWe used the close genetic relatives ofB. pseudomallei, B. thailandensisE264 andB. vietnamiensis, as useful BSL-2 model systems. Eight-week-old female C57BL/6 mice were administered alcohol comparable to human binge drinking episodes (4.4 g/kg) or PBS intraperitoneally 30 min before a non-lethal intranasal infection. In an initialB. thailandensisinfection (3 x 105), bacteria accumulated in the lungs and disseminated to the spleen in alcohol administered mice only, compared with PBS treated mice at 24 h post-infection (PI). The greatest bacterial load occurred withB. vietnamiensis(1 x 106) in lungs, spleen, and brain tissue by 72 h PI. Pulmonary cytokine expression (TNF-α, GM-CSF) decreased, while splenic cytokine (IL-10) increased in binge drunk mice. Increased lung and brain permeability was observed as early as 2 h post alcohol administrationin vivo.Trans-epithelial electrical resistance (TEER) was significantly decreased, while intracellular invasion of non-phagocytic cells increased with 0.2% v/v alcohol exposurein vitro.ConclusionsOur results indicate that a single binge alcohol dose suppressed innate immune functions and increased the ability of less virulentBurkholderiastrains to disseminate through increased barrier permeability and intracellular invasion of non-phagocytic cells.Author SummaryBurkholderia pseudomalleicauses the disease melioidosis, which occurs in most tropical regions across the globe. Exposure rarely evolves to significant disease in the absence of specific comorbidities, such as binge alcohol intoxication. In susceptible hosts, the disease is primarily manifested as pneumonic melioidosis and can be rapidly fatal if untreated. In this study, we utilizedB. thailandensis, a genetically similar strain toB. pseudomallei, and opportunisticB. vietnamiensis, a known human pathogen that utilizes similar virulence strategies asB. pseudomalleiin immunocompromised and cystic fibrosis patients. The study investigates the impact of a single binge alcohol episode on infectivity and immune responsein vivo. We show that a single binge alcohol episode prior to inhalingBurkholderiaspecies increases bacterial spread to the lungs and brain. We also identify alcohol-induced tissue permeability and epithelial cell invasion as modes of action for greater bacterial spread and survival inside the host. Our results support the public health responses being developed in melioidosis-endemic regions that emphasize the nature of binge drinking as a prime concern, especially around potential times of exposure to environmentalB. pseudomallei.

Modeling the CNS Tropism of Diffuse Large B-Cell Lymphomas in Vivo

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 576-576
Author(s):  
Maurice Reimann ◽  
Sven Masswig ◽  
Kolja Schleich ◽  
Andrea Herrmann ◽  
Philipp Lohneis ◽  
...  
Keyword(s):  
B Cell ◽  
B Cell Lymphoma ◽  
Gene Set Enrichment Analysis ◽  
Model Systems ◽  
B Cell Lymphomas ◽  
Cns Involvement ◽  
The Impact ◽  
The Brain ◽  
Large B Cell

Abstract Introduction: Central nervous system (CNS) manifestation accounts for dismal prognosis in patients diagnosed with systemic diffuse large B-cell lymphoma (DLBCL). Myc rearrangement, deletions encompassing the CDKN2A (a.k.a. INK4a/ARF) or ATM gene loci as well as NF-kB-hyperactivating mutations are frequently detected in primary and secondary CNS-tropic lymphoma, however, investigations that functionally link these lesions to CNS involvement in adequate in vivo model systems are missing. Methods: We generated primary Eµ-myc transgenic mouse lymphomas with and without distinct naturally occurring NF-kB mutations (within genes encoding for MyD88, CD79B, A20, IkBζ, IkBε or BIRC3) or deletions at the INK4a/ARF and ATM loci by retroviral gene transfer and crossbreeding to the respective knockout strains. A subset of the lymphomas was subjected to gene expression profiling and whole-exome sequencing (WES). Wild-type recipient mice propagated with lymphoma cells via tail vein injection were monitored for systemic lymphoma development, the time at which the brain was isolated and examined regarding lymphoma infiltration. Results: Underlining Myc's role as a putative co-driver of CNS involvement, we found in about 40% of primary Eµ-myc lymphomas (with no additional exogenous lesions) meningeal lymphoma manifestations, and transplantation of the same individual lymphomas into numerous recipients reproduced the CNS lymphoma status. Gene set enrichment analysis of genome-wide transcriptome profiles indicated NF-kB hyperactivation in the CNS-tropic lymphoma group, suggesting that constitutive NF-kB signaling may promote CNS-prone pathogenesis in vivo. Transplantation of Eµ-myc transgenic hematopoietic stem cells expressing a variety of NF-kB-activating mutants in myeloablated recipient mice resulted in a significant acceleration of Eµ-myc -driven lymphomagenesis, with some, but not all of these mutants conferring a CNS-tropic lymphoma phenotype. Global NF-kB suppression in CNS-tropic Eµ-myc lymphomas via the NF-kB-antagonizing IkBΔN super-repressor did not fully abrogate lymphoma infiltration of the brain, suggesting that additional factor(s) must contribute. Accordingly, targeted ablation of the INK4a/ARF and ATM loci robustly enhanced CNS tropism of Eµ-myc lymphomas. Conclusions: The Eµ-myc mouse lymphoma model is well-suited to genetically dissect and rebuild components of DLBCL-like CNS tropism. We identified CDKN2A or ATM deletions as critical determinants of CNS tropism in vivo. Our systematic analyses of different NF-kB mutants - so far rather recognized as functionally interchangeable - indicated that only distinct NF-kB mutants contribute to CNS tropism in B-cell lymphomas. WES data, results from compound genotypes (e.g. combining ATM deletions with an NF-kB-activating mutation), and the impact of the host's cellular immune status will be reported at the meeting. Our findings underscore the need for functional analyses of oncogenic network contexts, and provide important insights into candidate target lesions for personalized CNS-directed therapies in DLBCL patients in the future. Disclosures No relevant conflicts of interest to declare.

scholarly journals Mechanical Response Changes in Porcine Tricuspid Valve Anterior Leaflet Under Osmotic-Induced Swelling

2019 ◽  
Vol 6 (3) ◽  
pp. 70 ◽  
Author(s):  
Samuel D. Salinas ◽  
Margaret M. Clark ◽  
Rouzbeh Amini
Keyword(s):  
Tricuspid Valve ◽  
Soft Tissues ◽  
Mechanical Response ◽  
Ex Vivo ◽  
Control Group ◽  
Anterior Leaflet ◽  
Buffer Solution ◽  
Tissue Samples ◽  
The Impact

Since many soft tissues function in an isotonic in-vivo environment, it is expected that physiological osmolarity will be maintained when conducting experiments on these tissues ex-vivo. In this study, we aimed to examine how not adhering to such a practice may alter the mechanical response of the tricuspid valve (TV) anterior leaflet. Tissue specimens were immersed in deionized (DI) water prior to quantification of the stress–strain responses using an in-plane biaxial mechanical testing device. Following a two-hour immersion in DI water, the tissue thickness increased an average of 107.3% in the DI water group compared to only 6.8% in the control group, in which the tissue samples were submerged in an isotonic phosphate buffered saline solution for the same period of time. Tissue strains evaluated at 85 kPa revealed a significant reduction in the radial direction, from 34.8% to 20%, following immersion in DI water. However, no significant change was observed in the control group. Our study demonstrated the impact of a hypo-osmotic environment on the mechanical response of TV anterior leaflet. The imbalance in ions leads to water absorption in the valvular tissue that can alter its mechanical response. As such, in ex-vivo experiments for which the native mechanical response of the valves is important, using an isotonic buffer solution is essential.

scholarly journals Application of Ultrasound on Monitoring the Evolution of the Collagen Fiber Reinforced nHAC/CS CompositesIn Vivo

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Yan Chen ◽  
Yuting Yan ◽  
Xiaoming Li ◽  
He Li ◽  
Huiting Tan ◽  
...  
Keyword(s):  
Collagen Fiber ◽  
Soft Tissues ◽  
Degradation Process ◽  
Ultrasound Images ◽  
Fiber Reinforced ◽  
Bone Mesenchymal Stem Cells ◽  
Feasible Alternative ◽  
The Impact

To date, fiber reinforce scaffolds have been largely applied to repair hard and soft tissues. Meanwhile, monitoring the scaffolds for long periodsin vivois recognized as a crucial issue before its wide use. As a consequence, there is a growing need for noninvasive and convenient methods to analyze the implantation remolding processin situand in real time. In this paper, diagnostic medical ultrasound was used to monitor thein vivobone formation and degradation process of the novel mineralized collagen fiber reinforced composite which is synthesized by chitosan (CS), nanohydroxyapatite (nHA), and collagen fiber (Col). To observe the impact of cells on bone remodeling process, the scaffolds were planted into the back of the SD rats with and without rat bone mesenchymal stem cells (rBMSCs). Systematic data of scaffoldsin vivowas extracted from ultrasound images. Significant consistency between the data from the ultrasound and DXA could be observedP<0.05. This indicated that ultrasound may serve as a feasible alternative for noninvasive monitoring the evolution of scaffoldsin situduring cell growth.

scholarly journals Comparative analysis of indentation and magnetic resonance elastography for measuring viscoelastic properties

2021 ◽  
Author(s):  
Yu Chen ◽  
Suhao Qiu ◽  
Zhao He ◽  
Fuhua Yan ◽  
Ruokun Li ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Viscoelastic Properties ◽  
Soft Tissues ◽  
Biological Tissues ◽  
Magnetic Resonance Elastography ◽  
Small Samples ◽  
Model Parameters ◽  
In Vivo Measurement ◽  
Pathological Behavior

Abstract Measurement the viscoelastic properties is important for studying the developmental and pathological behavior of soft biological tissues. Magnetic resonance elastography (MRE) is a non-invasive method for in vivo measurement of tissue viscoelasticity. As a flexible method capable of testing small samples, indentation has been widely used for characterizing soft tissues. Using 2nd-order Prony series and dimensional analysis, we analyzed and compared the model parameters estimated from both indentation and MRE. Conversions of the model parameters estimated from the two methods were established. We found that the indention test is better at capturing the dynamic response of tissues at a frequency less than 10 Hz, while MRE is better for describing the frequency responses at a relatively higher range. The results provided helpful information for testing soft tissues using indentation and MRE. The models analyzed are also helpful for quantifying the frequency response of viscoelastic tissues. Graphic Abstract

scholarly journals Zebrafish as a Screening Model to Study the Single and Joint Effects of Antibiotics

2021 ◽  
Vol 14 (6) ◽  
pp. 578
Author(s):  
Roxana Jijie ◽  
Gabriela Mihalache ◽  
Ioana-Miruna Balmus ◽  
Stefan-Adrian Strungaru ◽  
Emanuel Stefan Baltag ◽  
...  
Keyword(s):  
Animal Model ◽  
Developmental Stages ◽  
Model Systems ◽  
In Vivo Studies ◽  
Research Papers ◽  
Vertebrate Model ◽  
Efficacy Assessment ◽  
Potential Impact ◽  
The Impact

The overuse of antibiotics combined with the limitation of wastewater facilities has resulted in drug residue accumulation in the natural environment. Thus, in recent years, the presence of antibiotic residues in the environment has raised concerns over the potential harmful effects on ecosystems and human health. The in vivo studies represent an essential step to study the potential impact induced by pharmaceutical exposure. Due to the limitations of traditional vertebrate model systems, zebrafish (Danio rerio) has recently emerged as a promising animal model to study the toxic effects of drugs and their therapeutic efficacy. The present review summarizes the recent advances made on the toxicity of seven representative classes of antibiotics, namely aminoglycosides, β-lactams, macrolides, quinolones, sulfonamides, tetracyclines and polyether antibiotics, in zebrafish, as well as the combined effects of antibiotic mixtures, to date. Despite a significant amount of the literature describing the impact of single antibiotic exposure, little information exists on the effects of antibiotic mixtures using zebrafish as an animal model. Most of the research papers on this topic have focused on antibiotic toxicity in zebrafish across different developmental stages rather than on their efficacy assessment.

scholarly journals Optical flow analysis reveals that Kinesin-mediated advection impacts on the orientation of microtubules in the Drosophila oocyte

2019 ◽  
Author(s):  
Maik Drechsler ◽  
Lukas F. Lang ◽  
Layla Al-Khatib ◽  
Hendrik Dirks ◽  
Martin Burger ◽  
...  
Keyword(s):  
Optical Flow ◽  
Cytoplasmic Streaming ◽  
Flow Analysis ◽  
Growth Direction ◽  
Model Systems ◽  
Microtubule Orientation ◽  
A Cell ◽  
The Impact

ABSTRACTThe orientation of microtubule networks is exploited by motors to deliver cargoes to specific intracellular destinations, and is thus essential for cell polarity and function. Reconstituted in vitro systems have largely contributed to understanding the molecular framework regulating the behavior of microtubule filaments. In cells however, microtubules are exposed to various biomechanical forces that might impact on their orientation, but little is known about it. Oocytes, which display forceful cytoplasmic streaming, are excellent model systems to study the impact of motion forces on cytoskeletons in vivo. Here we implement variational optical flow analysis as a new approach to analyze the polarity of microtubules in the Drosophila oocyte, a cell that displays distinct Kinesin-dependent streaming. After validating the method as robust for describing microtubule orientation from confocal movies, we find that increasing the speed of flows results in aberrant plus end growth direction. Furthermore, we find that in oocytes where Kinesin is unable to induce cytoplasmic streaming, the growth direction of microtubule plus ends is also altered. These findings lead us to propose that cytoplasmic streaming - and thus motion by advection – contributes to the correct orientation of MTs in vivo. Finally, we propose a possible mechanism for a specialised cytoplasmic actin network (the actin mesh) to act as a regulator of flow speeds; to counteract the recruitment of Kinesin to microtubules.HIGHLIGHT SUMMARYCytoskeletal networks do not exist in isolation, but experience crowded and dynamic intracellular environments. However, microtubule-environment interactions are not well understood, and such system-environment interactions are an unresolved question in biology that demands bridging across disciplines. Here we introduce an optical flow motion estimation approach to study microtubule orientation in the Drosophila oocyte, a cell displaying substantial cytoplasmic streaming. We show that microtubule polarity is affected by the regime of these flows, and furthermore, that the presence of flows is necessary for MTs to adopt their proper polarity. With these findings we are contributing to further understanding how microtubules organize in their impacting natural environment.

scholarly journals Generation of focal mutations and large genomic deletions in the pancreas using inducible in vivo genome editing

2019 ◽  
Vol 41 (3) ◽  
pp. 334-344
Author(s):  
Amrendra Mishra ◽  
Fatemeh Emamgholi ◽  
Zulrahman Erlangga ◽  
Björn Hartleben ◽  
Kristian Unger ◽  
...  
Keyword(s):  
Embryonic Stem ◽  
Genetic Alterations ◽  
Model Systems ◽  
Ductal Adenocarcinoma ◽  
In Vivo Model ◽  
Precision Oncology ◽  
Kras Mutations ◽  
Genomic Deletions ◽  
The Impact

Abstract Beyond the nearly uniform presence of KRAS mutations, pancreatic cancer is increasingly recognized as a heterogeneous disease. Preclinical in vivo model systems exist, but with the advent of precision oncology, murine models with enhanced genetic flexibility are needed to functionally annotate genetic alterations found in the human malignancy. Here, we describe the generation of focal gene disruptions and large chromosomal deletions via inducible and pancreas-specific expression of Cas9 in adult mice. Experimental mice are derived on demand directly from genetically engineered embryonic stem cells, without the need for further intercrossing. To provide initial validation of our approach, we show that disruption of the E3 ubiquitin ligase Rnf43 accelerates KrasG12D-dependent tumourigenesis. Moreover, we demonstrate that this system can be used to rapidly interrogate the impact of complex cancer-associated alleles through the generation of a previously unstudied 1.2 megabase deletion surrounding the CDKN2A and CDKN2B tumour suppressors. Thus, our approach is capable of reproducibly generating biallelic and precise loss of large chromosomal fragments that, in conjunction with mutant Kras, leads to development of pancreatic ductal adenocarcinoma with full penetrance.

scholarly journals Influence of Microgravity on Apoptosis in Cells, Tissues, and Other Systems In Vivo and In Vitro

2020 ◽  
Vol 21 (24) ◽  
pp. 9373
Author(s):  
Binod Prasad ◽  
Daniela Grimm ◽  
Sebastian M. Strauch ◽  
Gilmar Sidnei Erzinger ◽  
Thomas J. Corydon ◽  
...  
Keyword(s):  
Cosmic Radiation ◽  
Current Knowledge ◽  
Life Forms ◽  
Model Systems ◽  
Space Environment ◽  
Cellular Damage ◽  
The Impact ◽  
In Cells

All life forms have evolved under the constant force of gravity on Earth and developed ways to counterbalance acceleration load. In space, shear forces, buoyance-driven convection, and hydrostatic pressure are nullified or strongly reduced. When subjected to microgravity in space, the equilibrium between cell architecture and the external force is disturbed, resulting in changes at the cellular and sub-cellular levels (e.g., cytoskeleton, signal transduction, membrane permeability, etc.). Cosmic radiation also poses great health risks to astronauts because it has high linear energy transfer values that evoke complex DNA and other cellular damage. Space environmental conditions have been shown to influence apoptosis in various cell types. Apoptosis has important functions in morphogenesis, organ development, and wound healing. This review provides an overview of microgravity research platforms and apoptosis. The sections summarize the current knowledge of the impact of microgravity and cosmic radiation on cells with respect to apoptosis. Apoptosis-related microgravity experiments conducted with different mammalian model systems are presented. Recent findings in cells of the immune system, cardiovascular system, brain, eyes, cartilage, bone, gastrointestinal tract, liver, and pancreas, as well as cancer cells investigated under real and simulated microgravity conditions, are discussed. This comprehensive review indicates the potential of the space environment in biomedical research.

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