Mechanical Aspects of Angiogenesis Kretschmer, Maibritt; Rüdiger, Daniel; Zahler, Stefan
Cancers,
10/2021, Letnik:
13, Številka:
19
Journal Article
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Angiogenesis is of high clinical relevance as it plays a crucial role in physiological (e.g., tissue regeneration) and pathological processes (e.g., tumor growth). Besides chemical signals, such as ...VEGF, the relationship between cells and the extracellular matrix (ECM) can influence endothelial cell behavior during angiogenesis. Previously, in terms of the connection between angiogenesis and mechanical factors, researchers have focused on shear forces due to blood flow. However, it is becoming increasingly important to include the direct influence of the ECM on biological processes, such as angiogenesis. In this context, we focus on the stiffness of the surrounding ECM and the adhesion of cells to the ECM. Furthermore, we highlight the mechanical cues during the main stages of angiogenesis: cell migration, tip and stalk cells, and vessel stabilization. It becomes clear that the different stages of angiogenesis require various chemical and mechanical cues to be modulated by/modulate the stiffness of the ECM. Thus, changes of the ECM during tumor growth represent additional potential dysregulations of angiogenesis in addition to erroneous biochemical signals. This awareness could be the basis of therapeutic approaches to counteract specific processes in tumor angiogenesis.
Cancer cell migration is influenced by cellular phenotype and behavior as well as by the mechanical and chemical properties of the environment. Furthermore, many cancer cells show plasticity of their ...phenotype and adapt it to the properties of the environment. Here, we study the influence of fiber stiffness, confinement, and adhesion properties on cancer cell migration in porous collagen gels. Collagen gels with soft fibers abrogate migration and promote a round, non-invasive phenotype. Stiffer collagen fibers are inherently more adhesive and lead to the existence of an adhesive phenotype and in general confined migration due to adhesion. Addition of TGF-β lowers adhesion, eliminates the adhesive phenotype and increases the amount of highly motile amoeboid phenotypes. Highest migration speeds and longest displacements are achieved in stiff collagen fibers in pores of about cell size by amoeboid phenotypes. This elucidates the influence of the mechanical properties of collagen gels on phenotype and subsequently migration and shows that stiff fibers, cell sized pores, and low adhesion, are optimal conditions for an amoeboid phenotype and efficient migration.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Influenza A viruses (IAV) are commonly used to infect animal cell cultures for research purposes and vaccine production. Their replication is influenced strongly by the multiplicity of infection ...(MOI), which ranges over several orders of magnitude depending on the respective application. So far, mathematical models of IAV replication have paid little attention to the impact of the MOI on infection dynamics and virus yields. To address this issue, we extended an existing model of IAV replication in adherent MDCK cells with kinetics that explicitly consider the time point of cell infection. This modification does not only enable the fitting of high MOI measurements, but also the successful prediction of viral release dynamics of low MOI experiments using the same set of parameters. Furthermore, this model allows the investigation of defective interfering particle (DIP) propagation in different MOI regimes. The key difference between high and low MOI conditions is the percentage of infectious virions among the total virus particle release. Simulation studies show that DIP interference at a high MOI is determined exclusively by the DIP content of the seed virus while, in low MOI conditions, it is predominantly controlled by the de novo generation of DIPs. Overall, the extended model provides an ideal framework for the prediction and optimization of cell culture-derived IAV manufacturing and the production of DIPs for therapeutic use.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Cell culture-derived defective interfering particles (DIPs) are considered for antiviral therapy due to their ability to inhibit influenza A virus (IAV) production. DIPs contain a large internal ...deletion in one of their eight viral RNAs (vRNAs) rendering them replication-incompetent. However, they can propagate alongside their homologous standard virus (STV) during infection in a competition for cellular and viral resources. So far, experimental and modeling studies for IAV have focused on either the intracellular or the cell population level when investigating the interaction of STVs and DIPs. To examine these levels simultaneously, we conducted a series of experiments using highly different multiplicities of infections for STVs and DIPs to characterize virus replication in Madin-Darby Canine Kidney suspension cells. At several time points post infection, we quantified virus titers, viable cell concentration, virus-induced apoptosis using imaging flow cytometry, and intracellular levels of vRNA and viral mRNA using real-time reverse transcription qPCR. Based on the obtained data, we developed a mathematical multiscale model of STV and DIP co-infection that describes dynamics closely for all scenarios with a single set of parameters. We show that applying high DIP concentrations can shut down STV propagation completely and prevent virus-induced apoptosis. Interestingly, the three observed viral mRNAs (full-length segment 1 and 5, defective interfering segment 1) accumulated to vastly different levels suggesting the interplay between an internal regulation mechanism and a growth advantage for shorter viral RNAs. Furthermore, model simulations predict that the concentration of DIPs should be at least 10000 times higher than that of STVs to prevent the spread of IAV. Ultimately, the model presented here supports a comprehensive understanding of the interactions between STVs and DIPs during co-infection providing an ideal platform for the prediction and optimization of vaccine manufacturing as well as DIP production for therapeutic use.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Endothelial tube formation on a reconstituted basement membrane (Matrigel) is a well-established in vitro model for studying the processes of angiogenesis and vasculogenesis. However, to date, the ...organizing principles that underlie the morphogenesis of this network and that shape the initial process of cells’ finding one another remain elusive. Here, we identify a mechanism that allows cells to form networks by mechanically reorganizing and stiffening their extracellular matrix, independent of chemical guidance cues. Interestingly, we find that this cellular self-organization strongly depends on the connectivity, plasticity, and topology of the surrounding matrix; cell contractility; and cell density. Cells rearrange the matrix and form bridges of matrix material that are stiffer than their surroundings, thus creating a durotactic track for the initiation of cell protrusions and cell-cell contacts. This contractility-based communication via strain stiffening and matrix rearrangement might be a general organizing principle during tissue development or regeneration.
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•Endothelial cells communicate mechanically in a basement membrane material•A defined stiffness range, plasticity, and the presence of laminin are mandatory•Cells remodel the matrix forming stiff bridges, which precede cell protrusions•These processes are an organizing principle for vascular network formation
Rüdiger et al. identify plastic remodeling of the matrix by cellular contractility, formation of stiff fibers in a per se nonfibrous matrix, and alignment of the cells along these fibers as morphogenic principles for the formation of vascular tube networks. This might be a general organizing principle during development.
Defective interfering particles (DIPs) are regarded as potent broad-spectrum antivirals. We developed a mathematical model that describes intracellular co-infection dynamics of influenza standard ...virus (STV) and “OP7”, a new type of influenza DIP discovered recently. Based on experimental data from in vitro studies to calibrate the model and confirm its predictions, we deduce OP7’s mechanisms of interference, which were yet unknown. Simulations suggest that the “superpromoter” on OP7 genomic viral RNA enhances its replication and results in a depletion of viral proteins. This reduces STV genomic RNA replication, which appears to constitute an antiviral effect. Further, a defective viral protein (M1-OP7) likely causes the deficiency of OP7’s replication. It appears unable to bind to genomic viral RNAs to facilitate their nuclear export, a critical step in the viral life cycle. An improved understanding of OP7’s antiviral mechanism is crucial toward application in humans as a prospective antiviral treatment strategy.
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•Systems biology investigation of viral co-infection•Impact of mutations in OP7 genome on its replication•Antiviral effect likely mediated by OP7 superpromoter inducing depletion of proteins•Mechanistic understanding promotes development of OP7 as broad-spectrum antiviral
Biological sciences; Biological sciences research methodologies; Natural sciences
Background: Lameness in dairy cows is classified as a gait change caused by multifactorial process. The phase of the peripartum causes intense physiological changes for the adaptation of late ...gestation and onset of lactation. The aim of this study was to characterize the changes in the biochemical profile and productive performance in dairy cows with lameness during postpartum period.Materials, Methods & Results: This study was conducted at the University of São Paulo farm, in Pirassununga, São Paulo State, Brazil, from January to March 2017. A total, of 48 multiparous (2 to 3 lactations and 3-4 years old) dairy cows, that had the milk production of 9,200 kg/ dairy cow in a period of 305 days in the previous lactation, were included in the study. All cows were managed under the same conditions and nutritional regimen. Evaluation of body condition score was performed by a single person on -18, -12, -8, -5, and -2 days before parturition, at parturition, and on days 1, 7, 14, 21, 30, 45 and 60 after parturition. Milk production was recorded on days 7, 14, 21, 30, 45 and 60 after parturition and saved in the software program. Blood samples were performed on -18, -12, -8, -5, and -2 days before parturition, at parturition, and on days 1, 7, 14, 21, 30, 45 and 60 after parturition. Blood samples were assayed for albumin, calcium, cholesterol, triglycerides, non-esterified fatty acids, β-hydroxybutyrate, urea, creatinine, gamma-glutamil-transferase and total protein concentrations. Dairy cows were divided into a lame group (11) and normal group (37) based on locomotion score from parturition to seven days postpartum. Lame cows was classified if their score was > 2, and normal cows was classified if their score was ≤ 2 and free of any disease. Dairy cows that suffer by any health disorder other than lameness were excluded from this study. Cow diagnosed with lameness outside the diagnostic period were excluded from this study. The averages of the milk production, body condition score and biochemical profile were compared with the Tukey’s test. Lame cows showed lower (P < 0.05) concentrations of albumin (on days -18 -12, -8, -5, -2 relative to parturition, at parturition, and on days 7, 14, 21, 45 and 60 after parturition) calcium (on days -18, -12, -8, -5 and -2 before parturition, and on days 7, 14, 21, 45 and 60 after parturition), cholesterol (on days -12, -8, -5 before parturition and on days 7, 14, 21, 30, 45 and 60 after parturition) than normal cows. Cow with lameness showed higher (P < 0.05) concentration of triglyceride (on days 7, 14, 21, 30, 45 and 60 after parturition), non-esterified fatty acids (on days 1, 7, 14, 21, 30, 45 and 60 after parturition) and β-hydroxybutyrate (on days -12, -5 and -2 before parturition, at parturition, and on days 1, 14, 21 and 30 after parturition) than normal group. Cows with lameness presented higher (P < 0.05) values of body condition score on days -18, -12 and -8 before parturition, and lower (P < 0.05) values on days 7, 14, 21, 30, 45 and 60 after parturition than normal cows. Milk production was lower (P < 0.05) for cows with lameness (on days 7, 14, 21, 30, 45 and 60 after parturition) than normal cows.Discussion: The overall prevalence of lameness in the evaluated period was 22.92% (11/48). Among lame cows, 07 presented laminitis, 02 had interdigital hyperplasia and 02 had sole ulcer. Our findings prove that the biochemical profile and productivity of dairy cows during the peripartum and postpartum period were affected by lameness at the early lactation.
In this study, a three-step experiment was conducted to evaluate the effectiveness of orange essential oil (OEO) to reduce the severity of parasitic infection in lambs naturally infected with ...gastrointestinal parasites. In the first and second stages of the experiment, the lambs were distributed in groups (n = 10): without treatment (control), treated with levamisole (7.5 mg/kg), and treated either with 200, 300 or 400 mg/kg OEO in the first stage and with two doses of 300 or 350 mg/kg each of OEO with a six-hour interval in the second stage. In the third stage of the experiment, 20 lambs were distributed into control and treated groups (two doses of 350 mg/kg OEO) and slaughtered for determining the parasite count in the abomasum and small intestine. Evaluations were performed on D0, D3, D7, D10, and D14 by determining the egg count per gram of feces (EPG), and the percentage of EPG reduction was calculated in comparison to D0. Coproculture was performed on days D0 and D14 of the first and second stages of the study. In the first stage, the EPG increased by 20.90 and 100.99% and decreased by 5.54% on D14 in the groups treated with 200, 300, or 400 mg/kg OEO, respectively. At the second stage, the EPG of the OEO groups decreased by more than 96% on D3, but on D14 was decreased by 0.82% and 77.07% in the 2 × 300 and 2 × 350 mg/kg groups, respectively. Haemonchus sp. was the highest percentage of collected larvae in all coproculture tests, ranging from 90 to 100%. In the third stage, there was no difference (P > 0.05) in the mean number of parasites between the OEO groups and the control. Although the decrease in EPG of more than 96% on D3 did not persist in the other evaluations, and immature forms and adult parasites were collected at slaughter, the EPG reduction of 77.07% on D14 with the dose of 700 mg/kg (OEO2 × 350) suggests that OEO can help to reduce the severity of parasitic infection and, consequently, to diminish pastures contamination, when used together with other methods to control gastrointestinal parasites in sheep.
•We evaluated the EPG reduction in lambs treated with orange essential oil (OEO).•Doses of 200 mg/kg, 300 mg/kg and 400 mg/kg did not reduce the EPG on D14.•Two doses of 350 mg/kg OEO reduced the EPG by 96% on D3.•On D14 two doses of 350 mg/kg OEO reduced the EPG by 77%.•Necropsy revealed similar number of parasites in control and OEO-treated groups.
The major compound in orange essential oil (OEO) is limonene, which has in vitro anthelmintic properties; however, a safe in vivo dose has not been defined for animals. Therefore, a pilot study was ...conducted to evaluate the effect of an OEO formulation for the control of gastrointestinal nematodes in sheep and to investigate adverse reactions in lambs after OEO administration. A total of 17 lambs received an oral OEO formulation at a concentration of 600 mg/mL, in doses of 200, 300, and 600 mg/kg. The most common clinical signs observed were head shaking (88.8%), backward head movement (51.1%), and ataxia (74.4%). Lambs treated with 600 mg/kg of OEO showed more severe combined clinical signs and longer duration of symptoms, presenting adverse reactions for up to 2 h after OEO administration. Testing of different doses and formulations with slower release of the active ingredient is recommended to minimize or eliminate these effects.
•An oral orange essential oil (OEO) formulation was administered to lambs.•After doses of 200 mg/kg, 300 mg/kg and 600 mg/kg lambs showed adverse reactions.•The most common clinical signs observed were head shaking, backward head movement, and ataxia.•With dose of 600 mg/kg lambs showed more severe clinical signs and longer duration of symptoms.
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