scholarly journals Mechanical strength and hydrostatic testing of VIVO adhesive in sutureless microsurgical anastomoses: an ex vivo study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marius Heitzer ◽  
Julia Brockhaus ◽  
Kristian Kniha ◽  
Felix Merkord ◽  
Florian Peters ◽  
...  
Keyword(s):  
Animal Studies ◽  
Ex Vivo ◽  
Coronary Vessels ◽  
In Vitro Study ◽  
The Novel ◽  
Ex Vivo Model ◽  
Interrupted Suture ◽  
Tensile Forces

AbstractConventional anastomoses with interrupted sutures are challenging and inevitably associated with trauma to the vessel walls. The goal of this study was to evaluate a novel alternative adhesive-based suture-free anastomosis technique that uses an intraluminal stent. Overall, 120 porcine coronary vessels were analyzed in an ex vivo model and were examined for their mechanical (n = 20 per cohort) and hydrostatic strength (n = 20 per cohort). Anastomoses were made using the novel VIVO adhesive with an additional intraluminal nitinol stent and was compared to interrupted suture anastomosis and to native vessels. Sutureless anastomoses withstood pressures 299 ± 4.47 [mmHg] comparable to native vessels. They were performed significantly faster 553.8 ± 82.44 [sec] (p ≤ 0.001) and withstood significantly higher pressures (p ≤ 0.001) than sutured anastomoses. We demonstrate that the adhesive-based anastomosis can also resist unphysiologically high longitudinal tensile forces with a mean of 1.33 [N]. Within the limitations of an in vitro study adhesive-based suture-free anastomosis technique has the biomechanical potential to offer a seamless alternative to sutured anastomosis because of its stability, and faster handling. In vivo animal studies are needed to validate outcomes and confirm safety.

Effects of Two Different Doses of Hirudin on APTT, Determined with Eight Different Reagents

1995 ◽  
Vol 73 (02) ◽  
pp. 219-222 ◽  
Author(s):  
Manuel Monreal ◽  
Luis Monreal ◽  
Rafael Ruiz de Gopegui ◽  
Yvonne Espada ◽  
Ana Maria Angles ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Anticoagulant Activity ◽  
Subcutaneous Administration ◽  
In Vitro Study ◽  
Ex Vivo Model ◽  
Suitable Candidate ◽  
Significant Prolongation ◽  
High Doses ◽  
Different Doses

SummaryThe APTT has been considered the most suitable candidate to monitor the anticoagulant activity of hirudin. However, its use is hampered by problems of standardization, which make the results heavily dependent on the responsiveness of the reagent used. Our aim was to investigate if this different responsiveness of different reagents when added in vitro is to be confirmed in an ex vivo study.Two different doses of r-hirudin (CGP 39393), 0.3 mg/kg and 1 mg/kg, were administered subcutaneously to 20 New Zealand male rabbits, and the differences in prolongation of APTT 2 and 12 h later were compared, using 8 widely used commercial reagents. All groups exhibited a significant prolongation of APTT 2 h after sc administration of hirudin, both at low and high doses. But this prolongation persisted 12 h later only when the PTTa reagent (Boehringer Mannheim) was used. In general, hirudin prolonged the APTT most with the silica- based reagents.In a further study, we compared the same APTT reagents in an in vitro study in which normal pooled plasma was mixed with increasing amount of hirudin. We failed to confirm a higher sensitivity for silica- containing reagents. Thus, we conclude that subcutaneous administration of hirudin prolongs the APTT most with the silica-based reagents, but this effect is exclusive for the ex vivo model.

scholarly journals 64Cu-ATSM/64Cu-Cl2 and their relationship to hypoxia in glioblastoma: a preclinical study

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Elodie A. Pérès ◽  
Jérôme Toutain ◽  
Louis-Paul Paty ◽  
Didier Divoux ◽  
Méziane Ibazizène ◽  
...  
Keyword(s):  
Ex Vivo ◽  
In Vitro Study ◽  
Tumor Location ◽  
Preclinical Study ◽  
Significant Rise ◽  
Lower Oxygen ◽  
Cu Complexes ◽  
Ex Vivo Study

Abstract Background Diacetyl-bis(N4-methylthiosemicarbazone), labeled with 64Cu (64Cu-ATSM) has been suggested as a promising tracer for imaging hypoxia. However, various controversial studies highlighted potential pitfalls that may disable its use as a selective hypoxic marker. They also highlighted that the results may be tumor location dependent. Here, we first analyzed uptake of Cu-ATSM and its less lipophilic counterpart Cu-Cl2 in the tumor over time in an orthotopic glioblastoma model. An in vitro study was also conducted to investigate the hypoxia-dependent copper uptake in tumor cells. We then further performed a comprehensive ex vivo study to compare 64Cu uptake to hypoxic markers, specific cellular reactions, and also transporter expression. Methods μPET was performed 14 days (18F-FMISO), 15 days (64Cu-ATSM and 64Cu-Cl2), and 16 days (64Cu-ATSM and 64Cu-Cl2) after C6 cell inoculation. Thereafter, the brains were withdrawn for further autoradiography and immunohistochemistry. C6 cells were also grown in hypoxic workstation to analyze cellular uptake of Cu complexes in different oxygen levels. Results In vivo results showed that Cu-ASTM and Cu-Cl2 accumulated in hypoxic areas of the tumors. Cu-ATSM also stained, to a lesser extent, non-hypoxic regions, such as regions of astrogliosis, with high expression of copper transporters and in particular DMT-1 and CTR1, and also characterized by the expression of elevated astrogliosis. In vitro results show that 64Cu-ATSM showed an increase in the uptake only in severe hypoxia at 0.5 and 0.2% of oxygen while for 64Cu-Cl2, the cell retention was significantly increased at 5% and 1% of oxygen with no significant rise at lower oxygen percentages. Conclusion In the present study, we show that Cu-complexes undoubtedly accumulate in hypoxic areas of the tumors. This uptake may be the reflection of a direct dependency to a redox metabolism and also a reflection of hypoxic-induced overexpression of transporters. We also show that Cu-ATSM also stained non-hypoxic regions such as astrogliosis.

scholarly journals Considerations to Model Heart Disease in Women with Preeclampsia and Cardiovascular Disease

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 899
Author(s):  
Clara Liu Chung Ming ◽  
Kimberly Sesperez ◽  
Eitan Ben-Sefer ◽  
David Arpon ◽  
Kristine McGrath ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Cardiovascular Disease ◽  
Ex Vivo ◽  
Myocardial Damage ◽  
Cardiovascular Disorder ◽  
Model Systems ◽  
Ex Vivo Model ◽  
Disease Manifestation

Preeclampsia is a multifactorial cardiovascular disorder diagnosed after 20 weeks of gestation, and is the leading cause of death for both mothers and babies in pregnancy. The pathophysiology remains poorly understood due to the variability and unpredictability of disease manifestation when studied in animal models. After preeclampsia, both mothers and offspring have a higher risk of cardiovascular disease (CVD), including myocardial infarction or heart attack and heart failure (HF). Myocardial infarction is an acute myocardial damage that can be treated through reperfusion; however, this therapeutic approach leads to ischemic/reperfusion injury (IRI), often leading to HF. In this review, we compared the current in vivo, in vitro and ex vivo model systems used to study preeclampsia, IRI and HF. Future studies aiming at evaluating CVD in preeclampsia patients could benefit from novel models that better mimic the complex scenario described in this article.

scholarly journals Considerations to Model Heart Disease in Women with Preeclampsia and Cardiovascular Disease

2021 ◽  
Author(s):  
Clara Liu Chung Ming ◽  
Kimberly Sesperez ◽  
Eitan Ben-Sefer ◽  
David Arpon ◽  
Kristine McGrath ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Cardiovascular Disease ◽  
Ex Vivo ◽  
Myocardial Damage ◽  
Cardiovascular Disorder ◽  
Model Systems ◽  
Ex Vivo Model ◽  
Disease Manifestation

Preeclampsia is a multifactorial cardiovascular disorder diagnosed after 20 weeks of gestation that is the leading cause of death for both mothers and babies in pregnancy. The pathophysiology remains poorly understood due to variability and unpredictability of disease manifestation when studied in animal models. After preeclampsia, both mothers and offspring have a higher risk of cardiovascular disease (CVD) including myocardial infarction or heart attack and heart failure (HF). Myocardial infarction is an acute myocardial damage that can be treated through reperfusion, however, that therapeutic approach leads to ischemic/reperfusion injury (IRI) often leading to HF. In this review, we compared the current in vivo, in vitro and ex vivo model systems used to study preeclampsia, IRI and HF. Future studies aiming at evaluating CVD in preeclampsia patients could benefit from novel models that better mimic the complex scenario described in this article.

scholarly journals The MEMIC: An ex vivo system to model the complexity of the tumor microenvironment

2021 ◽  
Author(s):  
Libuše Janská ◽  
Libi Anandi ◽  
Nell C. Kirchberger ◽  
Zoran S. Marinkovic ◽  
Logan T. Schachtner ◽  
...  
Keyword(s):  
Tumor Microenvironment ◽  
Tumor Cells ◽  
Ex Vivo ◽  
Tumor Stroma ◽  
Stem Cell Differentiation ◽  
Blood Stream ◽  
Direct Access ◽  
Ex Vivo Model

There is an urgent need for accurate, scalable, and cost-efficient experimental systems to model the complexity of the tumor microenvironment. Here, we detail how to fabricate and use the Metabolic Microenvironment Chamber (MEMIC) – a 3D-printed ex vivo model of intratumoral heterogeneity. A major driver of the cellular and molecular diversity in tumors is the accessibility to the blood stream that provides key resources such as oxygen and nutrients. While some tumor cells have direct access to these resources, many others must survive under progressively more ischemic environments as they reside further from the vasculature. The MEMIC is designed to simulate the differential access to nutrients and allows co-culturing different cell types, such as tumor and immune cells. This system is optimized for live imaging and other microscopy-based approaches, and it is a powerful tool to study tumor features such as the effect of nutrient scarcity on tumor-stroma interactions. Due to its adaptable design and full experimental control, the MEMIC provide insights into the tumor microenvironment that would be difficult to obtain via other methods. As a proof of principle, we show that cells sense gradual changes in metabolite concentration resulting in multicellular spatial patterns of signal activation and cell proliferation. To illustrate the ease of studying cell-cell interactions in the MEMIC, we show that ischemic macrophages reduce epithelial features in neighboring tumor cells. We propose the MEMIC as a complement to standard in vitro and in vivo experiments, diversifying the tools available to accurately model, perturb, and monitor the tumor microenvironment, as well as to understand how extracellular metabolites affect other processes such as wound healing and stem cell differentiation.

Detection of allergen-induced airway hyperresponsiveness in isolated mouse lungs

2006 ◽  
Vol 291 (3) ◽  
pp. L466-L472 ◽  
Author(s):  
Martin Witzenrath ◽  
Birgit Ahrens ◽  
Stefanie M. Kube ◽  
Armin Braun ◽  
Heinz G. Hoymann ◽  
...  
Keyword(s):  
Airway Hyperresponsiveness ◽  
Ex Vivo ◽  
Whole Body ◽  
Strongly Correlated ◽  
Ex Vivo Model ◽  
Isolated Lungs ◽  
Spontaneously Breathing

Airway hyperresponsiveness (AHR) is a hallmark of bronchial asthma. Important features of this exaggerated response to bronchoconstrictive stimuli have mostly been investigated in vivo in intact animals or in vitro in isolated tracheal or bronchial tissues. Both approaches have important advantages but also certain limitations. Therefore, the aim of our study was to develop an ex vivo model of isolated lungs from sensitized mice for the investigation of airway responsiveness (AR). BALB/c mice were sensitized by intraperitoneal ovalbumin (Ova) and subsequently challenged by Ova inhalation. In vivo AR was measured in unrestrained animals by whole body plethysmography after stimulation with aerosolized methacholine (MCh) with determination of enhanced pause ( Penh). Twenty-four hours after each Penh measurement, airway resistance was continuously registered in isolated, perfused, and ventilated lungs on stimulation with inhaled or intravascular MCh or nebulized Ova. In a subset of experiments, in vivo AR was additionally measured in orotracheally intubated, spontaneously breathing mice 24 h after Penh measurement, and lungs were isolated further 24 h later. Isolated lungs of allergen-sensitized and -challenged mice showed increased AR after MCh inhalation or infusion as well as after specific provocation with aerosolized allergen. AR was increased on days 2 and 5 after Ova challenge and had returned to baseline on day 9. AHR in isolated lungs after aerosolized or intravascular MCh strongly correlated with in vivo AR. Pretreatment of isolated lungs with the β2-agonist fenoterol diminished AR. In conclusion, this model provides new opportunities to investigate mechanisms of AHR as well as pharmacological interventions on an intact organ level.

scholarly journals Ex Vivo Enteroids Recapitulate In Vivo Citrulline Production in Mice

2018 ◽  
Vol 148 (9) ◽  
pp. 1415-1420 ◽  
Author(s):  
Xiaoying Wang ◽  
Yang Yuan ◽  
Inka C Didelija ◽  
Mahmoud A Mohammad ◽  
Juan C Marini
Keyword(s):  
Ex Vivo ◽  
Transcript Abundance ◽  
Mutant Mice ◽  
Ex Vivo Model ◽  
Endogenous Production ◽  
Gene Coding ◽  
Cycle Disorders ◽  
Deficient Mice

Abstract Background The endogenous production of arginine relies on the synthesis of citrulline by enteral ornithine transcarbamylase (OTC). Mutations in the gene coding for this enzyme are the most frequent cause of urea cycle disorders. There is a lack of correlation between in vivo metabolic function and DNA sequence, transcript abundance, or in vitro enzyme activity. Objective The goal of the present work was to test the hypothesis that enteroids, a novel ex vivo model, are able to recapitulate the in vivo citrulline production of wild-type (WT) and mutant mice. Methods Six-week-old male WT and OTC-deficient mice [sparse fur and abnormal skin (spf-ash) mutation] were studied. Urea and citrulline fluxes were determined in vivo, and OTC abundance was measured in liver and gut tissue. Intestinal crypts were isolated and cultured to develop enteroids. Ex vivo citrulline production and OTC abundance were determined in these enteroids. Results Liver OTC abundance was lower (mean ± SE: 0.16 ± 0.01 compared with 1.85 ± 0.18 arbitrary units; P < 0.001) in spf-ash mice than in WT mice, but there was no difference in urea production. In gut tissue, OTC was barely detectable in mutant mice; despite this, a lower but substantial citrulline production (67 ± 3 compared with 167 ± 8 µmol · kg−1 · h−1; P < 0.001) was shown in the mutant mice. Enteroids recapitulated the in vivo findings of a very low OTC content accompanied by a reduced citrulline production (1.07 ± 0.20 compared with 4.64 ± 0.44 nmol · µg DNA−1 · d−1; P < 0.001). Conclusions Enteroids recapitulate in vivo citrulline production and offer the opportunity to study the regulation of citrulline production in a highly manipulable system.

scholarly journals Biomechanical-Based Protocol for in vitro Study of Cartilage Response to Cyclic Loading: A Proof-of-Concept in Knee Osteoarthritis

2021 ◽  
Vol 9 ◽  
Author(s):  
Paolo Caravaggi ◽  
Elisa Assirelli ◽  
Andrea Ensini ◽  
Maurizio Ortolani ◽  
Erminia Mariani ◽  
...  
Keyword(s):  
Ex Vivo ◽  
In Vitro Study ◽  
Cartilage Explants ◽  
Joint Loading ◽  
Design And Optimization ◽  
Cartilage Metabolism ◽  
Beneficial Effects ◽  
Physiological Loading

Osteoarthritis (OA) is an evolving disease and a major cause of pain and impaired mobility. A deeper understanding of cartilage metabolism in response to loading is critical to achieve greater insight into OA mechanisms. While physiological joint loading helps maintain cartilage integrity, reduced or excessive loading have catabolic effects. The main scope of this study is to present an original methodology potentially capable to elucidate the effect of cyclic joint loading on cartilage metabolism, to identify mechanisms involved in preventing or slowing down OA progression, and to provide preliminary data on its application. In the proposed protocol, the combination of biomechanical data and medical imaging are integrated with molecular information about chondrocyte mechanotransduction and tissue homeostasis. The protocol appears to be flexible and suitable to analyze human OA knee cartilage explants, with different degrees of degeneration, undergoing ex vivo realistic cyclic joint loading estimated via gait analysis in patients simulating mild activities of daily living. The modulation of molecules involved in cartilage homeostasis, mechanotransduction, inflammation, pain and wound healing can be analyzed in chondrocytes and culture supernatants. A thorough analysis performed with the proposed methodology, combining in vivo functional biomechanical evaluations with ex vivo molecular assessments is expected to provide new insights on the beneficial effects of physiological loading and contribute to the design and optimization of non-pharmacological treatments limiting OA progression.

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