Clinical Hemorheology and Microcirculation - Volume 61, issue 2

Authors: Jung, Christian | Kelm, Malte

Article Type: Research Article

Abstract: Adequate monitoring of patients on intensive care units is of highest priority to provide optimal treatment and to detect patients at risk. Within recent years the microcirculation became more and more attention due to its central importance for the outcome of patients. Microcirculatory disorders may include capillary flow disturbances as well as changes in the density of perfused vessels. In the clinical setting, the most often used parameter to detect alterations in the microcirculation is serum lactate. Since this parameter is characterized by major limitations, other strategies including non-invasive methods to quantify microvascular perfusion have been developed. A successful surveillance …of the microcirculation in the individual patient may guide diagnostic and treatment strategies in order to optimize organ perfusion and oxygenation, subsequently leading to an individualized therapy. Intravital microscopy has been used to stratify patients at risk and to predict patients’ outcome. The aim of this review is to evaluate clinical correlates of microcirculatory disorders as well as giving an overview of newer diagnostic devices that may directly or indirectly evaluate the microcirculation and are available for use in critically ill patients. Show more

Keywords: Microcirculation, critically ill, intensive care, intravital microscopy

DOI: 10.3233/CH-151994

Citation: Clinical Hemorheology and Microcirculation, vol. 61, no. 2, pp. 213-224, 2015

Authors: Braune, S. | Zhou, S. | Groth, B. | Jung, F.

Article Type: Research Article

Abstract: BACKGROUND: Platelet adhesion to artificial surfaces is one of the most important indicators for the thrombogenicity of implant materials. Currently, a variety of enzyme activity-based colorimetric assays or microscopy-based techniques are commonly in use to assess this characteristic. Studies about how data of colorimetric assays correlate with the image-based quantification of adherent platelets are scarce. To address this question, the present study compared two colorimetric assays (lactate dehydrogenase (LDH) and acid phosphatase (ACP)) with an image-based quantification of the density of platelets adhering on polymer-based biomaterial surfaces. MATERIALS AND METHODS: Tri-sodium citrated whole blood was collected from apparently …healthy subjects and platelet rich plasma (PRP) was prepared according to a standardized protocol. An in vitro static thrombogenicity test was applied to study platelet adhesion from PRP adjusted to 50,000 platelets per μL on three different polymers: medical grade polytetrafluoroethylene (PTFE), silicone and polyethylene terephthalate (PET). For the direct image-based approach, surface adherent platelets were fixed, fluorescently labelled and microscopically visualized. The image-based determination of platelet densities provided reference values for the comparison with data of the colorimetric assays. Correlation between standard platelet concentrations and ACP/LDH absorbance measurements were analysed to estimate accuracy and association of both parameters. ACP and LDH release from resting and ADP-stimulated platelets was studied to estimate how platelet activation influences colorimetric assay results. RESULTS: The density of adherent platelets ranged from 15,693 ± 2,487 platelets·mm–2 (PTFE) to 423 ± 99 platelets·mm–2 (silicone) and 4,621 ± 1,427 platelets·mm–2 (PET) and differed significantly between the three polymers (ANOVA: p  <  0.05). Correlation coefficients between microscopic and colorimetric determination of platelet densities ranged between r  = 0.93 (LDH, p  <  0.001) and r  = 0.94 (ACP, p  <  0.001). ACP absorbance measurements of platelet standards with different concentrations corresponded well to an ideal linear regression, while LDH data either deceeded or exceeded the expected values. The LDH release during ADP-induced platelet activation was significantly higher compared to the release of ACP. CONCLUSION: For an adjusted platelet concentration of 50,000 platelets·μL−1 , both colorimetric assays (ACP and LDH) allowed a similar accurate quantification of the mean platelet density compared to the microscopic evaluation. Better linearity of the assay standards, less variability of the results and a lower influence of platelet activation on the measurements mark the ACP assay as more suitable for the assessment of material surface adherent platelets compared to the LDH assay, particularly, if near physiological platelet concentrations are applied. Show more

Keywords: Platelet, biomaterial, thrombogenicity, lactate dehydrogenase, acid phosphatase, colorimetric assay, microscopy

DOI: 10.3233/CH-151995

Citation: Clinical Hemorheology and Microcirculation, vol. 61, no. 2, pp. 225-236, 2015

Authors: Toguri, J.T. | Moxsom, R. | Szczesniak, A.M. | Zhou, J. | Kelly, M.E.M. | Lehmann, C.

Article Type: Research Article

Abstract: BACKGROUND: Leukocyte adhesion to the endothelium and decreased microvascular blood flow causing microcirculatory dysfunction are hallmarks of systemic inflammation. We studied the impact of cannabinoid receptor activation on the iridial microcirculation, which is accessible non-invasively in vivo , in systemic inflammation induced by endotoxin challenge. METHODS: 40 Lewis rats were used in the experiments. Endotoxemia was induced by 2 mg/kg i.v. lipopolysaccharide (LPS). Cannabinoid receptors (CBRs) were stimulated by i.v. administration of WIN 55212-2 (WIN; 1 mg/kg). CB1 R antagonist (AM281; 2.5 mg/kg i.v.) or CB2 R antagonist (AM630; 2.5 mg/kg i.v.) treatment prior to WIN was applied to identify the anti-inflammatory …effects underlying each CBR subtype. Leukocyte-endothelial interactions were examined in rat iridial microvas culature by intravital microscopy at baseline and 1 and 2 h post-LPS. Additionally, systemic (mean arterial pressure, heart rate) and local (laser Doppler flow) hemodynamic variables were measured prior to and during cannabinoid treatments. RESULTS: Endotoxemia resulted in severe inflammation as shown by significantly increased numbers of adherent leukocytes at 1 and 2 h observation time post-LPS challenge and decreased microcirculatory blood flow at 2 h within the iridial microcirculation. WIN treatment significantly reduced leukocyte adhesion in iridial microvessels with a diameter greater and less than 25 μm during endotoxemia (p  <  0.05). Pre-treatment of animals by CB1 R antagonist, AM281, did not affect WIN effects on LPS-induced leukocyte adhesion. When pre-treated with the CB2 R antagonist, AM630, a reversal of the WIN-induced reduction in leukocyte adhesion was noticed in vessels with a diameter of less than 25 μm (p  <  0.05). Cannabinoid treatment significantly increased the local iridial microcirculatory blood flow 2 hours after systemic LPS administration (p  <  0.05). CONCLUSIONS: Systemic administration of the CBR agonist, WIN, decreased leukocyte-adhesion and improved iridial microvascular blood flow. This effect is most likely mediated by CB2 R activation. Our findings indicate that the iris microvasculature can serve as a model to study the microcirculation during systemic inflammation and help to identify potential therapies to treat microcirculatory dysfunction in diseases such as sepsis. Show more

Keywords: Endotoxemia, microcirculation, cannabinoid receptor, WIN 55212-2

DOI: 10.3233/CH-151996

Citation: Clinical Hemorheology and Microcirculation, vol. 61, no. 2, pp. 237-249, 2015

Authors: Thalhammer, Christoph | Alvarez, Elena | Husmann, Marc | Staub, Daniel | Kaspar, Mathias | Aschwanden, Markus | Amann-Vesti, Beatrice R.

Article Type: Research Article

Abstract: To perform a long term follow-up after endovascular brachytherapy (EVBT) and balloon angioplasty (PTA) regarding vessel patency and diameter. EVBT had been successfully used to decrease restenosis in short term, but long term data are lacking. Participants of a randomized study comparing EVBT and balloon angioplasty alone were invited for follow-up examination ten years after intervention. Using a standardized protocol measurement of the patency and vessel diameter was performed of femoral and popliteal arteries. 44 patients were included, 21 had been treated with EVBT and 23 had received PTA alone. Target lesion patency was similar between the two groups (90.5% …vs. 87.0%). Vessel diameter of the target lesion was significantly greater in the EVBT group (6.4 mm, range 3.9–9.9) compared to the controls (5.0 mm, range 3.1–7.4; p  = 0.002). Ten years after EVBT of femoro-popliteal arteries vessel diameter is significantly increased whereas patency rate is not different compared to angioplasty alone. Show more

Keywords: Endovascular brachytherapy, femoro-popliteal artery, long term follow-up, duplex sonography, peripheral artery disease, aneurysm

DOI: 10.3233/CH-151997

Citation: Clinical Hemorheology and Microcirculation, vol. 61, no. 2, pp. 251-257, 2015

Authors: Matuszak, Jasmin | Dörfler, Philipp | Zaloga, Jan | Unterweger, Harald | Lyer, Stefan | Dietel, Barbara | Alexiou, Christoph | Cicha, Iwona

Article Type: Research Article

Abstract: Superparamagnetic iron oxide nanoparticles (SPIONs) are versatile and easily functionalized agents with high potential for diagnostic and therapeutic intravascular applications. In this study, we analyzed the responses of endothelial (ECs) and monocytic cells to three different types of SPIONs, in order to assess the influence of physico-chemical properties on the biological reactions to SPIONs. The following formulations were used: (1) Lauric acid-coated and BSA-stabilized SPION-1,(2) Lauric acid/BSA-coated SPION-2 and (3) dextran-coated SPION-3. SPION-1 were strongly internalized by ECs and reduced their viability in static conditions. Additionally, they had a dose-dependent inhibitory effect on monocytic cell chemotaxis to MCP-1, but did …not affect monocytic cell recruitment by ECs. SPION-2 uptake was less pronounced, both in ECs and monocytic cells, and these particles were better tolerated by the vascular cells. Not being internalized by endothelial or monocytic cells, SPION-3 did not induce relevant effects on cell viability, motility or endothelial-monocytic cell interactions. Taken together, localized accumulation of circulating SPION under physiologic-like flow conditions and their cellular uptake depends on the physicochemical characteristics. Our findings suggest that SPION-2 are suitable for magnetic targeting of atherosclerotic plaques. Due to their excellent biocompatibility and low internalization, SPION-3 may represent a suitable imaging agent for intravascular applications. Show more

Keywords: Atherosclerosis, magnetic nanoparticles, SPION uptake, endothelial-monocytic cell interactions, endothelial migration, monocytic cell chemotaxis, live-cell analysis

DOI: 10.3233/CH-151998

Citation: Clinical Hemorheology and Microcirculation, vol. 61, no. 2, pp. 259-277, 2015

Authors: Haubner, F. | Muschter, D. | Schuster, N. | Pohl, F. | Ahrens, N. | Prantl, L. | Gassner, H.G.

Article Type: Research Article

Abstract: BACKGROUND: Platelet-rich plasma (PRP) products are currently suggested in the treatment of chronic wounds due to possible pro-angiogenic effects. Microvascular compromise represents the major component in radiogenic wound healing complications. The effects of PRP on irradiated cells of the cutaneous wound healing process are still poorly understood. MATERIAL AND METHODS: Human dermal microvascular endothelial cells (HDMEC) and human adipose derived stem cells (hASC) were cultured and irradiated with doses of 2 to 12 Gy. PRP was activated, characterized and added to the incubation media in different concentrations after external radiation. Cell count was determined 48 h after radiation using a …semi-automated cell counting system. Levels of interleukin-6 (IL-6), basic fibroblast growth factor (bFGF) and soluble intercellular adhesion molecule-1 (sICAM-1) in the supernatants of HDMEC and hASC co-cultures were determined by enzyme-linked immunosorbent assay (ELISA). Non-irradiated hASC and HDMEC served as controls. RESULTS: The employed PRP preparations were characterized and contained platelet derived growth factor (PDGF-AB), vascular endothelial growth factor (VEGF), bFGF and high levels of sICAM-1. Addition of PRP to irradiated cultures of HDMEC and hASC prevented profound radiation-induced decline in cell numbers. 10% PRP restored cell numbers to levels of untreated, non-irradiated cultures. Basic FGF expression was decreased significantly in hASC monocultures treated with 10% PRP without external radiation and after irradiation with 6 and 12 Gy. These inhibitory effects of PRP were also observed in HDMEC. In contrast, co-cultures of HDMEC-ASC showed a dose-dependent increase in bFGF expression when treated with 5 or 10% PRP. Doses of 6 and 12 Gy increased IL-6 expression in cultures stimulated with 5% PRP. CONCLUSIONS: Use of PRP in co-cultures of hASC and HDMEC restores proliferative defects caused by external radiation probably by induction of bFGF. Under irradiated conditions, PRP might induce pro-inflammatory stimuli which could be beneficial in treatment of chronic wounds where healing processes are defective. Combined use of hASC and PRP products might be helpful in the treatment of radiogenic wounds. Show more

Keywords: Microvascular endothelial cells, human adipose-derived stem cells, endothelial dysfunction, cytokines, adhesion molecules, growth factors, radiation therapy

DOI: 10.3233/CH-151982

Citation: Clinical Hemorheology and Microcirculation, vol. 61, no. 2, pp. 279-290, 2015

Authors: Neuber, Christin | Pufe, Johanna | Pietzsch, Jens

Article Type: Research Article

Abstract: Survivors of Hodgkin’s disease as well as of breast and lung cancer are at risk of radiation-associated cardiovascular disease. Recent studies demonstrated a correlation between cardiovascular risk factors and circulating endothelial microparticles (EMP) and thereby suggest increased EMP levels in circulation to be an early biomarker of endothelial dysfunction and cardiovascular risk. This prompted us to analyze the amount of EMP released by human aortic endothelial cells (HAEC) after exposure to different doses of X-ray (0.4, 2, 4, 6, and 20 Gy) using antibodies against the endothelial cell markers CD31, CD144, and CD146 by flow cytometry. In this pilot experiment only …CD146 proved appropriate for quantification of HAEC-derived EMP. Exposure of HAEC to different doses of X-ray did not significantly influence formation of CD146-positive EMP. However, low doses (0.4 Gy) tended to decrease EMP formation, whereas higher doses (2 or 4 Gy) slightly increased release of CD146-positive EMP. By contrast, inflammatory activation of HAEC by TPA significantly increased EMP release about 15-fold (P  <  0.01). In conclusion, under the present experimental conditions EMP did not prove a suitable biomarker for radiation-induced endothelial dysfunction in vitro . Show more

Keywords: Radiation-associated cardiovascular disease, radiation therapy, endothelial dysfunction, human aortic endothelial cells (HAEC), flow cytometry, CD146

DOI: 10.3233/CH-151987

Citation: Clinical Hemorheology and Microcirculation, vol. 61, no. 2, pp. 291-299, 2015

Authors: Wang, Weiwei | Kratz, Karl | Behl, Marc | Yan, Wan | Liu, Yue | Xu, Xun | Baudis, Stefan | Li, Zhengdong | Kurtz, Andreas | Lendlein, Andreas | Ma, Nan

Article Type: Research Article

Abstract: Polyether ether ketone (PEEK) as a high-performance, thermoplastic implant material entered the field of medical applications due to its structural function and commercial availability. In bone tissue engineering, the combination of mesenchymal stem cells (MSCs) with PEEK implants may accelerate the bone formation and promote the osseointegration between the implant and the adjacent bone tissue. In this concept the question how PEEK influences the behaviour and functions of MSCs is of great interest. Here the cellular response of human adipose-derived MSCs to PEEK was evaluated and compared to tissue culture plate (TCP) as the reference material. Viability and morphology of …cells were not altered when cultured on the PEEK film. The cells on PEEK presented a high proliferation activity in spite of a relatively lower initial cell adhesion rate. There was no significant difference on cell apoptosis and senescence between the cells on PEEK and TCP. The inflammatory cytokines and VEGF secreted by the cells on these two surfaces were at similar levels. The cells on PEEK showed up-regulated BMP2 and down-regulated BMP4 and BMP6 gene expression, whereas no conspicuous differences were observed in the committed osteoblast markers (BGLAP, COL1A1 and Runx2). With osteoinduction the cells on PEEK and TCP exhibited a similar osteogenic differentiation potential. Our results demonstrate the biofunctionality of PEEK for human MSC cultivation and differentiation. Its clinical benefits in bone tissue engineering may be achieved by combining MSCs with PEEK implants. These data may also provide useful information for further modification of PEEK with chemical or physical methods to regulate the cellular processes of MSCs and to consequently improve the efficacy of MSC-PEEK based therapies. Show more

Keywords: Polyether ether ketone, mesenchymal stem cells, biocompatibility, cell-material interaction, osteogenic differentiation

DOI: 10.3233/CH-152001

Citation: Clinical Hemorheology and Microcirculation, vol. 61, no. 2, pp. 301-321, 2015

Authors: Thieme, Stefan F. | Vahldiek, Janis L. | Tummler, Katja | Poch, Franz | Gemeinhardt, Ole | Hiebl, Bernhard | Lehmann, Kai S. | Hamm, B. | Niehues, Stefan M.

Article Type: Research Article

Abstract: BACKGROUND: Radiofrequency ablation (RFA) is an evolving technique in treatment of hepatic malignant tumors. By heating local tissue it leads to coagulative necrotic areas around the ablation probe. Temperature falls with increasing distance to the probe, risking incomplete necrosis at the margins of the RFA-induced lesion. Therefore, immediate non-invasive and precise detection of incomplete ablation is necessary for early enlargement of the ablation if needed. OBJECTIVES: This in vivo pig study compares early experiences of immediate post-interventional computed tomography (CT) perfusion volume analysis to macroscopic and CT image evaluation in healthy pig liver. MATERIAL AND …METHODS: RFA was performed in vivo in healthy pig livers. Different CT perfusion algorithms (Maximum slope analysis and Patlak plot) were used to quantify three different perfusion parameters. Data points were acquired from rectangular grids. These grids were semiautomatically overlayed to macroscopic images documented after liver explantation. Each data point was visually assigned to zones defined as “inner” and “outer necrotic zone”, “margin” or “vital tissue”. RESULTS: Significant differences between necrotic zones and vital tissue are shown for equivalent blood volume (p  <  0.0001), arterial flow (p  <  0.01) and flow extraction product (p  <  0.001). Looking at equivalent blood volume and flow extraction product, there were also significant differences (EquivBV: p  <  0.0001, FE: p  <  0.001) between margins, necrotic and vital areas. CONCLUSIONS: In a porcine model these early results could show that all of the used CT perfusion parameters allowed discrimination of necrosis from vital tissue after RFA at high levels of significance. In addition, the parameters EquivBV and FE that give an estimate of the tissue blood volume and the permeability, were able to precisely discern different zones also seen macroscopically. From this data CT perfusion analysis could be precise tool for measurement and visualization of ablated liver lesions and for immediate detection of incomplete ablation areas. Show more

Keywords: Liver, animal model, radiofrequency ablation (RFA), interventional radiology, multidetector computed tomography (CT), perfusion CT

DOI: 10.3233/CH-152000

Citation: Clinical Hemorheology and Microcirculation, vol. 61, no. 2, pp. 323-331, 2015

Authors: Pschierer, K. | Grothues, D. | Rennert, J. | da Silva, N. Platz Batista | Schreyer, A.G. | Melter, M. | Stroszczysnski, C. | Jung, E.M.

Article Type: Research Article

Abstract: OBJECTIVE: Comparison of the diagnostic findings of MRI, CT and CEUS in children with benign and malignant and portal venous anomalies of the liver. MATERIALS/METHODS: Retrospective analysis of the diagnostic findings of CEUS, MRI and CT scans in 56 children (age 0–17 years) with a total of 60 benign and malignant liver lesions and anomalies of the portal vein/perfusion. All patients underwent CEUS using sulphur hexafluoride microbubbles and a multi-frequency probe (1–5 MHz, 6–9 MHz). Cine-loops were stored up to 3 minutes. MRI was performed in 38 lesions. CT was performed in 8 lesions. RESULTS: Out of the …56 patients 49 liver lesions (48 benign, 1 malignant), 9 anomalies of the portal vein/perfusion and 2 of the biliary system were detected. 16/49 lesions were analyzed histopathologically. Using CEUS, the characterization of the lesions was possible in 45 out of 49 cases. In 32 cases, CEUS provided the exact diagnosis. Only two benign lesions were falsely categorized as malignant. Findings of MRI and CEUS were concordant in 84% of cases (n  = 32/38). CEUS considered 1 benign lesion to be malignant. 2 lesions were not detectable and in 3 lesions no definite diagnosis was established using MRI. Findings of CT and CEUS were concordant in 5 of 8 cases. In 21 lesions CEUS as the only imaging modality was found to be sufficient for diagnostics. CONCLUSION: Despite the restricted indications for using CEUS in children, it offers a high diagnostic detection rate (93%) for characterization of liver lesions and portal vein anomalies. Show more

Keywords: Contrast enhanced ultrasound (CEUS), children, liver, diagnostic value, safety

DOI: 10.3233/CH-152003

Citation: Clinical Hemorheology and Microcirculation, vol. 61, no. 2, pp. 333-345, 2015