Clinical Hemorheology and Microcirculation - Volume 79, issue 1

Authors: Gori, T.

Article Type: Research Article

Abstract: The coronary circulation is a complex system in which vascular resistances are determined by an interplay of forces in at least three compartments: the epicardial, the microvascular, and the venous district. Cardiologists, and particularly interventional cardiologists, normallly place the focus of their attention on diseases of the epicardial coronary circulation as possible causes of coronary syndromes and neglect the importance of the other two compartments of coronary circulation. The study of the coronary microcirculation, an increasingly recognized source of ischemia, has long been disregarded, but is witnessing a revival since the (re-)introduction of diagnostic tools in the better equipped catheterization …laboratories. Unfortunately, to date our understanding of coronary microvascular disease remains incomplete and the numerous proposed classifications fail to reflect its complexity. Further, no specific therapy for these disorders is available. The coronary venous circulation is an even more neglected third vascular district. Its role in regulating coronary resistances is almost completely unexplored, but inital evidence suggests that the modulation of venous pressure might help improve coronary perfusion. Coronary sinus interventions are a group of invasive techniques (both surgical and catheter-based) that are designed to treat ischaemic heart disease by increasing coronary venous pressure and therefore redistributing coronary blood flow towards the endocardium. In this review paper, we revise the role of these interventions with particular focus on acute and chronic coronary microvascular disease. Show more

Keywords: Angina, coronary physiology, microcirculation, microvascular disease

DOI: 10.3233/CH-219103

Citation: Clinical Hemorheology and Microcirculation, vol. 79, no. 1, pp. 103-107, 2021

Authors: Bruno, Raphael Romano | Wernly, Bernhard | Hornemann, Johanna | Flaatten, Hans | FjØlner, Jesper | Artigas, Antonio | Bollen Pinto, Bernardo | Schefold, Joerg C. | Wolff, Georg | Baldia, Philipp Heinrich | Binneboessel, Stephan | Kelm, Malte | Beil, Michael | Sviri, Sigal | van Heerden, Peter Vernon | Szczeklik, Wojciech | Elhadi, Muhammed | Joannidis, Michael | Oeyen, Sandra | Kondili, Eumorfia | Wollborn, Jakob | Marsh, Brian | Andersen, Finn H. | Moreno, Rui | Leaver, Susannah | Boumendil, Ariane | De Lange, Dylan W. | Guidet, Bertrand | Jung, Christian | on behalf of the COVIP study group

Article Type: Research Article

Abstract: PURPOSE Critically ill elderly patients who suffer from Sars-CoV-2 disease are at high risk for organ failure. The modified MELD-XI score has not been evaluated for outcome prediction in these most vulnerable patients. METHODS The Corona Virus disease (COVID19) in Very Elderly Intensive Care Patients study (COVIP, NCT04321265) prospectively recruited patients on intensive care units (ICU), who were = 70 years. Data were collected from March 2020 to February 2021. The MELD-XI score was calculated using the highest serum bilirubin and creatinine on ICU admission. Univariate and multivariable logistic regression analyses were performed to assess associations between the …MELD-XI score and mortality. The primary outcome was 30-day-mortality, the secondary outcomes were ICU- and 3-month-mortality. RESULTS In total, data from 2,993 patients were analyzed. Most patients had a MELD-XI <12 on admission (76%). The patients with MELD-XI = 12 had a significantly higher 30-day-, ICU- and 3-month-mortality (44%vs 64%, and 42%vs. 59%, and 57%vs. 76%, p < 0.001). After adjustment for multiple confounders, MELD-XI = 12 remained significantly associated with 30-day- (aOR 1.572, CI 1.268–1.949, p < 0.001), ICU-, and 3-month-mortality. CONCLUSION In critically ill elderly intensive care patients with COVID-19, the MELD-XI score constitutes a valuable tool for an early outcome prediction. Show more

Keywords: MELD-XI, elderly, intensive care medicine, COVID-19

DOI: 10.3233/CH-219202

Citation: Clinical Hemorheology and Microcirculation, vol. 79, no. 1, pp. 109-120, 2021

Authors: Saemann, Lars | Großkopf, Anne | Hoorn, Fabio | Veres, Gábor | Guo, Yuxing | Korkmaz-Icöz, Sevil | Karck, Matthias | Simm, Andreas | Wenzel, Folker | Szabó, Gábor

Article Type: Research Article

Abstract: BACKGROUND: Machine perfusion (MP) is a novel method for donor heart preservation. The coronary microvascular function is important for the transplantation outcome. However, current research on MP in heart transplantation focuses mainly on contractile function. OBJECTIVE: We aim to present the application of Laser-Doppler-Flowmetry to investigate coronary microvascular function during MP. Furthermore, we will discuss the importance of microcirculation monitoring for perfusion-associated studies in HTx research. METHODS: Porcine hearts were cardioplegically arrested and harvested (Control group, N = 4). In an ischemia group (N = 5), we induced global ischemia of the animal by the termination of mechanical ventilation before …harvesting. All hearts were mounted on an MP system for blood perfusion. After 90 minutes, we evaluated the effect of coronary perfusion pressures from 20 to 100 mmHg while coronary laser-doppler-flow (LDF) was measured. RESULTS: Ischemic hearts showed a significantly decreased relative LDF compared to control hearts (1.07±0.06 vs. 1.47±0.15; p  = 0.034). In the control group, the coronary flow was significantly lower at 100 mmHg of perfusion pressure than in the ischemia group (895±66 ml vs. 1112±32 ml; p  = 0.016). CONCLUSIONS: Laser-Doppler-Flowmetry is able to reveal coronary microvascular dysfunction during machine perfusion of hearts and is therefore of substantial interest for perfusion-associated research in heart transplantation. Show more

Keywords: Heart transplantation, myocardial microcirculation, coronary microvasculature, machine perfusion, microvascular dysfunction

DOI: 10.3233/CH-219116

Citation: Clinical Hemorheology and Microcirculation, vol. 79, no. 1, pp. 121-128, 2021

Authors: Greif, G. | Mrowietz, C. | Meyer-Sievers, H. | Ganter, M. | Jung, F. | Hiebl, B.

Article Type: Research Article

Abstract: In human cardiovascular research, sheep in particular are used as a large animal model in addition to pigs. In these animals, medical products, developed and tested for human medical purposes, are almost exclusively used in interventional studies. Therefore, the extent to which platelets from human and ovine blood differ in terms of adherence, aggregation and activation after a 4- or 8-minutes exposure to glass was investigated. Testing was performed with platelet-rich plasma (PRP) and a modified chandler loop-system, with 4- and 8-minute blood-material exposure times corresponding to 20 and 40 test cycles, respectively, through the entire silicone tube loop of …the test system. In sheep and human PRP, contact with the silicone tubing resulted in a decrease in platelet count after 4 minutes and 20 test cycles, respectively. Four more minutes (20 additional test cycles) caused a further decrease of the platelet count only in sheep PRP. When the silicon tube was partly filled with glass beads, these effects were more pronounced and stronger in sheep then in human PRP. The mean platelet volume, which was used as parameter for platelet aggregation, did not change over time in human PRP without glass exposure. With glass exposure in human and sheep PRP the mean platelet volume increased within 40 test cycles, but this increase was stronger in sheep than in human PRP. Regarding activation behavior, the activation markers CD62P and CD63 were detectable only in < 30% (sheep) and < 45% (human) of platelets, whereas after 8 min of glass exposure, the proportion of CD62P+ and CD63+ cells was more increased than before only in sheep. These results indicate that ovine platelets adhere more strongly to glass and show stronger aggregation behavior after glass contact than human platelets, but that ovine and human platelets differ only slightly in activability by glass. Show more

Keywords: Sheep, platelet, activation, platelet volume, CD42a, CD61, CD62P, CD63

DOI: 10.3233/CH-219104

Citation: Clinical Hemorheology and Microcirculation, vol. 79, no. 1, pp. 129-136, 2021

Authors: Bietar, Bashir | Zhou, Juan | Lehmann, Christian

Article Type: Research Article

Abstract: BACKGROUND: Stroke, traumatic brain injury, or other forms of central nervous system (CNS) injury initiate a local inflammatory response. Compensatory anti-inflammatory pathways are activated to limit secondary damage due to inflammation. The associated release of immunosuppressing neuromodulators can result in system-wide immune dysregulation (CNS injury-induced immune-depression syndrome –CIDS). OBJECTIVE: To establish an experimental stroke model where CIDS can be studied by intravital microscopy (IVM). METHODS: We used the photothrombotic stroke (PTS) model in C57BL/6 mice and studied its effects on peripheral immunity following challenge with lipopolysaccharide (LPS). Leukocyte activation, as well as capillary perfusion of the …microcirculation, were assessed using intestinal intravital microscopy (IVM). RESULTS: PTS caused a significant reduction in the number of adhering leukocytes in submucosal venules of the terminal ileum of mice challenged with LPS compared to LPS-challenged animals without stroke. Leukocyte rolling was also impacted by PTS in the submucosal venules. Following stroke, we also observed decreased mucosal functional capillary density (FCD). CONCLUSIONS: Our results suggest that PTS with subsequent LPS challenge poses as a viable model to further study CIDS using intravital microscopy of the intestinal microcirculation. Show more

Keywords: Stroke, microcirculation, intravital microscopy, photothrombosis, immunodepression

DOI: 10.3233/CH-219109

Citation: Clinical Hemorheology and Microcirculation, vol. 79, no. 1, pp. 137-147, 2021

Authors: Greif, G. | Mrowietz, C. | Wendt, M. | Jung, F. | Hiebl, B. | Meyer-Sievers, H.

Article Type: Research Article

Abstract: The pig is the most widely used large animal model in Europe, with cardiovascular research being one of the main areas of application. Adequate refinement of interventional studies in this field, meeting the requirements of Russel and Burchs’ 3 R concept, can only be performed if blood-contacting medical devices are hemocompatible. Because most medical devices for cardiovascular interventional procedures are developed for humans they are tested mostly for compatibility with human blood. The aim of this study was therefore to determine whether there are differences in behavior of porcine and human platelets when they come into contact with glass, which was …used as an exemplary thrombogenic material. For this purpose changes of platelet count, platelet volume and platelet expression of the activation markers CD61, CD62P and CD63 were measured using a modified chandler loop-system simulating the fluidic effects of the blood flow. Minipig and human platelets showed significant differences in number and volume, but not in activation after 4–8 min exposure to glass. Show more

Keywords: Pig, minipig, platelet activation, platelet count, platelet volume, FACS, monoclonal antibody, CD42, CD61, CD62P, CD63

DOI: 10.3233/CH-219201

Citation: Clinical Hemorheology and Microcirculation, vol. 79, no. 1, pp. 149-155, 2021

Authors: Kohl, Cynthia | Aung, Thiha | Haerteis, Silke | Papathemelis, Thomas

Article Type: Research Article

Abstract: BACKGROUND: Breast cancer is the most common malignant tumor in women and highly heterogeneous with a variety of different molecular subtypes. The analysis of the individual tumor biology is necessary to develop a specific and individualized treatment plan for every patient. The chick chorioallantoic membrane (CAM) model, a 3D-in-vivo -tumor-model, could potentially provide a methodology that facilitates the gain of additional information regarding the tumor biology as well as the testing of the tumor’s individual sensitivity to different therapies. OBJECTIVE: The objective was to establish the grafting of different breast cancer primaries onto the CAM for tumor profiling …and the investigation of different parameters. METHODS: Breast cancer primary tissue of different patients was grafted onto the CAM. Subsequently, 3D volume and perfusion measurements were performed during the engraftment period. Histological analyses of the tumors were carried out after the engraftment period. RESULTS: The grafting of the breast cancer primaries onto the CAM was successful. The tumors remained partially vital and displayed angiogenic development on the CAM. CONCLUSIONS: Breast cancer primary material can be grafted onto the CAM and we observed visible and measurable changes of perfusion over time. Show more

Keywords: Breast cancer primary material, breast cancer, CAM model, 3D-in-vivo-tumor-model

DOI: 10.3233/CH-219113

Citation: Clinical Hemorheology and Microcirculation, vol. 79, no. 1, pp. 157-166, 2021

Authors: Dittfeld, C. | Winkelkotte, M. | Behrens, S. | Schmieder, F. | Jannasch, A. | Matschke, K. | Sonntag, F. | Tugtekin, SM.

Article Type: Research Article

Abstract: BACKGROUND/AIM: Tissue pathogenesis of aortic valve (AV) stenosis is research focus in cardiac surgery. Model limitations of conventional 2D culture of human or porcine valvular interstitial/endothelial cells (VIC/VECs) isolated from aortic valve tissues but also limited ability of (small) animal models to reflect human (patho)physiological situation in AV position raise the need to establish an in vitro setup using AV tissues. Resulting aim is to approximate (patho)physiological conditions in a dynamic pulsatile Microphysiological System (MPS) to culture human and porcine AV tissue with preservation of tissue viability but also defined ECM composition. MATERIALS/METHODS: A tissue incubation chamber …(TIC) was designed to implement human or porcine tissues (3×5 mm2 ) in a dynamic pulsatile culture in conventional cell culture ambience in a MPS. Cell viability assays based on lactate dehydrogenase (LDH)-release or resazurin-conversion were tested for applicability in the system and applied for a culture period of 14 days with interval evaluation of tissue viability on every other day. Resazurin-assay setup was compared in static vs. dynamic culture using varying substance saturation settings (50–300μM), incubation times and tissue masses and was consequently adapted. RESULTS: Sterile dynamic culture of human and porcine AV tissue segments was established at a pulsatile flow rate range of 0.9–13.4μl/s. Implementation of tissues was realized by stitching the material in a thermoplastic polyurethane (TPU)-ring and insertion in the TIC-MPS-system. Culture volume of 2 ml caused LDH dilution not detectable in standard membrane integrity assay setup. Therefore, detection of resazurin-conversion of viable tissue was investigated. Optimal incubation time for viability conversion was determined at two hours at a saturated concentration of 300μM resazurin. Measurement in static conditions was shown to offer comparable results as dynamic condition but allowing optimal handling and TIC sterilization protocols for long term culture. Preliminary results revealed favourable porcine AV tissue viability over a 14 day period confirmed via resazurin-assay comparing statically cultured tissue counterparts. CONCLUSIONS: Human and porcine AV tissue can be dynamically cultured in a TIC-MPS with monitoring of tissue viability using an adapted resazurin-assay setup. Preliminary results reveal advantageous viability of porcine AV tissues after dynamic TIC-MPS culture compared to static control. Show more

Keywords: Aortic valve stenosis, dynamic tissue culture, tissue viability, resazurin reduction, microphysiological system, human aortic valve

DOI: 10.3233/CH-219112

Citation: Clinical Hemorheology and Microcirculation, vol. 79, no. 1, pp. 167-178, 2021

Authors: Jannasch, Anett | Rix, Jan | Welzel, Cindy | Schackert, Gabriele | Kirsch, Matthias | König, Ulla | Koch, Edmund | Matschke, Klaus | Tugtekin, Sems Malte | Dittfeld, Claudia | Galli, Roberta

Article Type: Research Article

Abstract: BACKGROUND: Heart valves are exposed to a highly dynamic environment and underlie high tensile and shear forces during opening and closing. Therefore, analysis of mechanical performance of novel heart valve bioprostheses materials, like SULEEI-treated bovine pericardium, is essential and usually carried out by uniaxial tensile tests. Nevertheless, major drawbacks are the unidirectional strain, which does not reflect the in vivo condition and the deformation of the sample material. An alternative approach for measurement of biomechanical properties is offered by Brillouin confocal microscopy (BCM), a novel, non-invasive and three-dimensional method based on the interaction of light with acoustic waves. …OBJECTIVE: BCM is a powerful tool to determine viscoelastic tissue properties and is, for the first time, applied to characterize novel biological graft materials, such as SULEEI-treated bovine pericardium. Therefore, the method has to be validated as a non-invasive alternative to conventional uniaxial tensile tests. METHODS: Vibratome sections of SULEEI-treated bovine pericardium (decellularized, riboflavin/UV-cross-linked and low-energy electron irradiated) as well as native and GA-fixed controls (n  = 3) were analyzed by BCM. In addition, uniaxial tensile tests were performed on equivalent tissue samples and Young’s modulus as well as length of toe region were analyzed from stress-strain diagrams. The structure of the extracellular matrix (ECM), especially collagen and elastin, was investigated by multiphoton microscopy (MPM). RESULTS: SULEEI-treated pericardium exhibited a significantly higher Brillouin shift and hence higher tissue stiffness in comparison to native and GA-fixed controls (native: 5.6±0.2 GHz; GA: 5.5±0.1 GHz; SULEEI: 6.3±0.1 GHz; n  = 3, p  < 0.0001). Similarly, a significantly higher Young’s modulus was detected in SULEEI-treated pericardia in comparison to native tissue (native: 30.0±10.4 MPa; GA: 31.8±10.7 MPa; SULEEI: 42.1±7.0 MPa; n  = 3, p  = 0.027). Native pericardia showed wavy and non-directional collagen fibers as well as thin, linear elastin fibers generating a loose matrix. The fibers of GA-fixed and SULEEI-treated pericardium were aligned in one direction, whereat the SULEEI-sample exhibited a much denser matrix. CONCLUSION: BCM is an innovative and non-invasive method to analyze elastic properties of novel pericardial graft materials with special mechanical requirements, like heart valve bioprostheses. Show more

Keywords: Biomechanics, Brillouin confocal microscopy, heart valve prosthesis, Young’s modulus

DOI: 10.3233/CH-219119

Citation: Clinical Hemorheology and Microcirculation, vol. 79, no. 1, pp. 179-192, 2021

Authors: Krüger-Genge, A. | Jung, C.G.H. | Braune, S. | Harb, K. | Westphal, S. | Klöpzig, S. | Küpper, J.-H. | Jung, F.

Article Type: Research Article

Abstract: Arthrospira platensis (AP ) and some of its derived products have well-established biological activities as antioxidants or as agents to reduce cardiovascular disease risk factors. Furthermore, AP products have gained increasing importance as potential anti-cancer agents. However, the ingredients of the available products vary greatly with the origin, the type of production and processing, which could have significant consequences for their biological effects. Therefore, the composition and biological influence of five distinct AP powders, which were acquired commercially or produced at a public biotechnology institute, were investigated in regard to their endothelialization capacity using a cell impedance- …(CI) based measurement method. The study revealed that the AP composition and especially the influence on HUVEC proliferation differed significantly between the five AP powders up to 109%. Thus, it could be shown that the method used allows the reliable detection of quantitative differences in biological effects of different AP preparations. Show more

Keywords: Arthrospira platensis, spirulina, endothelial cells

DOI: 10.3233/CH-219200

Citation: Clinical Hemorheology and Microcirculation, vol. 79, no. 1, pp. 193-203, 2021