Clinical Hemorheology and Microcirculation - Volume 46, issue 2-3

Authors: Fellner, Claudia | Jung, Ernst M. | Prantl, Lukas

Article Type: Research Article

Abstract: Early detection of a compromised circulation of free flaps and an immediate revision may lead to higher rates of flap salvage. The aim of this study was to evaluate the perfusion of the entire flap using dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI). DCE was performed in 11 patients after flap transplantation using an optimized 3D gradient echo sequence to cover the whole flap. The percentage increase of signal intensity over time was evaluated for the free flap as well as for a reference tissue. Furthermore, normalized signal increase was calculated as the ratio of signal increase within the flaps …to the signal increase in the reference tissue. Signal increase in free flaps and reference tissue was compared using the Wilcoxon-test (p < 0.05), normalized signal increase in normally perfused (n = 9) and in flaps with compromised perfusion (n = 2) using Mann-Whitney-test (p < 0.05). Signal increase within normally perfused flaps was similar to the reference tissue. In flaps with compromised perfusion the increase was significantly lower than in reference tissue. Normalized signal increase in adequately perfused flaps and flaps with compromised perfusion also showed a significant difference. DCE MRI may be a valuable non-invasive tool to evaluate tissue perfusion of the complete free flap. Show more

Keywords: MRI, tissue perfusion, DCE, free flaps, plastic surgery

DOI: 10.3233/CH-2010-1335

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 77-87, 2010

Authors: Jung, E.M. | Ross, C.J. | Rennert, J. | Scherer, M.N. | Farkas, S. | von Breitenbuch, P. | Schnitzbauer, A.A. | Piso, P. | Lamby, P. | Menzel, C. | Schreyer, A.G. | Feuerbach, S. | Schlitt, H.J. | Loss, M.

Article Type: Research Article

Abstract: Aim: Evaluation of high resolution linear ultrasound and intra-operative linear contrast enhanced ultrasound (CEUS) and its benefit for the detection and characterization of tumor lesions. Material and methods: Twenty patients were investigated preoperatively regarding tumor detection using CT (n = 8) or MRI (n = 12) and image fusion (VNav) (n = 3). All patients had surgery for their hepatic tumor (hepatocellular carcinoma (HCC), cholangiocellular carcinoma (CCC), metastasis, and adenoma). Ultrasound was performed intra-operatively first with B-scan using a convex probe. Than multifrequency linear transmitters (6–9 MHz, 6–15 MHz, LOGIQ E9, GE) were applied for B-scan, coulor coded Doppler sonography …(CCDS) and Power Doppler followed by dynamic CEUS with Contrast Harmonic Imaging (CHI) after bolus injection of a maximum of 15 mL SonoVue® . Results: In 9 cases with the use of intra-operative CEUS additional tumor lesions (diameter 4–15 mm) could be detected and were histologically confirmed after surgical resection (7 cases) or intra-operative biopsy (2 cases). Using intraoperative CEUS 64 tumor lesions could be detected compared to 51 tumor lesions detected by preoperative CT or MRI (p < 0.05). Using the 6–15 MHz multifrequency linear transducer with CHI, arterial perfusion of adenomas, neuroendocrine metastases and HCC lesions was detectable. In 3 cases a resection was not achievable. Two of these cases were treated with radio frequency ablation (RFA). The other case had no curable option due to multifocal tumor manifestation. Conclusion: The intra-operative use of high-resolution linear transducer techniques with CEUS offers new diagnostic perspectives for an effective liver surgery. Show more

DOI: 10.3233/CH-2010-1336

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 89-99, 2010

Authors: Ross, C.J. | Rennert, J. | Schacherer, D. | Girlich, C. | Hoffstetter, P. | Heiss, P. | Jung, W. | Feuerbach, S. | Zorger, N. | Jung, E.M.

Article Type: Research Article

Abstract: Aim: The assessment of the immediate post-interventional microcirculation and perfusion following transcatheter arterial chemoembolization (TACE) with new real time imaging fusion technique (VNav) of computed tomography (CT) or magnetic resonance imaging (MRI) with contrast enhanced ultrasound (CEUS) compared to follow-up. Material: Following TACE an image fusion of CEUS with CT or MRI of the liver was performed in 20 patients (18 men, 2 women; age 29–75 years) with confirmed hepatocelluar carcinoma (HCC) to evaluate the post-interventional tumor vascularization and perfusion of HCC tumor lesions. Image fusion with CEUS performed immediately was compared with the result at the end of TACE …(DSA), with post TACE CT (non-enhanced CT within 24hours) and with follow up CT (enhanced CT after 6 weeks) after embolization. Ultrasound was performed using a 1–5 MHz multifrequency SonoVue transducer (LOGIQ 9/GE) after a bolus injection of 2–4ml SonoVue® with contrast harmonic imaging (CHI). Thirteen examinations were fused with a contrast enhanced CT, 7 with a MRI performed before TACE. Results: The post-interventional volume navigation image fusion of CT or MRI with CEUS showed differences regarding the residual tumor perfusion compared to other modalities. The correlation (Spearman-test) between the perfusion result at the end of TACE, non-enhanced CT after TACE and image fusion with CEUS was 0.42 and 0.50. The difference between the result at the end of TACE and the fusion with CEUS was significant (p < 0.05, Wilcoxon-test). The correlation between fusion of CEUS with CT/MRI and follow-up CT (after 6 weeks) was 0.64, the difference was not significant (p > 0.05). The differences between native CT within 24 hours after TACE and follow up CT after 6 weeks or fusion of CEUS and CT/MRI were significant (p < 0.05). The inter-observer variability was 0.61 at the end of TACE, 0.58 at non-enhanced CT (within 24 hours), 0.87 at fusion CEUS with CT/MRI and 0.74 at follow up CT after 6 weeks (Cohens Kappa test). Conclusion: Image fusion with volume navigation (VNav) of CEUS with CT or MRI allows an accurate localisation of foci in patients with HCC. This exact mapping permits an easier control and evaluation of the results after TACE. The fusion of CEUS and CT or MRI allows a better evaluation of the microcirculation and the residual tumor perfusion at an earlier point of time than usual modalities of therapy control like non-enhanced CT. This might lead to a more differentiated monitoring of therapy. Show more

DOI: 10.3233/CH-2010-1337

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 101-115, 2010

Authors: Zorger, Niels | Jung, Ernst-Michael | Schreyer, Andreas G. | Heiss, Peter | Mueller-Wille, René | Wiest, Reiner | Feuerbach, Stefan | Rennert, Janine

Article Type: Research Article

Abstract: Purpose: To show the feasibility of a combination of the advantages of modern contrast enhanced ultrasound (CEUS) with the technique of arterioportography to achieve the highest sensitivity of all different modalities. Material and methods: Ten patients (9 m, 1 f, age 52–73 years) with suspected hepatocellular carcinoma (HCC) in liver cirrhosis (8 ethyl toxic, 2 hepatitis) were included before transarterial chemo-embolization (TACE). In all patients during a 6-week period a double enhanced MRI (Gd-DTPA and SPIO) was performed. Before TACE a bolus <2 mL ultrasound contrast agent (SonoVue® , Bracco, Milan, Italy) was injected over a selectively placed catheter in …the superior mesenteric artery (SMA) and ultrasound of the liver (2.5–4 MHz, LOGIQ 9; GE Healthcare) was performed in arterioportographic phase (US-AP). Two independent readers evaluate number, size and localisation of detected lesion in MRI and US-AP. Additional diagnostic quality of both modalities was determined using a 4-point scale (1: excellent–4: not diagnostic). Differences were analysed for significance using a t-test. Interobserver variability was calculated (κ-value). Result: In all 10 patients (100 %) US-AP was feasible. Diagnostic quality was in all cases between 1–2 for both modalities and readers (MRI standard deviation (SD) −0.51, Sono-AP SD −0.421). US-AP detected with 33.5 vs. 24.5 lesions, significant more lesions than double enhanced MRI (p < 0.022). The interobserver variability was κ −0.965 for MRI and κ −0.898 for US-AP. Conclusion: US-AP for detection of liver lesions is feasible. Using this technique significantly more lesions in patients with hepatocellular carcinoma could be detected in comparison to MRI with liver-specific contrast agent. Show more

DOI: 10.3233/CH-2010-1338

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 117-126, 2010

Authors: Helck, A. | Hoffmann, R.T. | Sommer, W.H. | Notohamiprodjo, M. | Albyaa, H. | Reiser, M. | Clevert, D.A.

Article Type: Research Article

Abstract: Purpose: We describe the presentation of renal artery pseudoaneurysm (RAP) in different imaging modalities (CT, DSA, standard US, contrast enhanced ultrasound (CEUS)). In particular the benefit of CEUS with regards to therapy monitoring and follow up care shall be highlighted. Materials and methods: Three patients with renal artery pseudoaneurysm after renal surgery were investigated with CT and/or US (grey-scaled US, color duplex US, CEUS), respectively. The therapy (angiography-coiling) was monitored using contrast-enhanced ultrasound. Results: Accurate diagnosis of RAP in our study was yielded using color duplex US and CEUS. CEUS was very practical for therapy monitoring of coil embolization with …the potential of shortening the invasive DSA. Thus, CEUS has potential of radiation dose reduction and the potential of saving coils with the result of cost reduction. Conclusion: CEUS is an appropriate approach for monitoring coil embolization of RAP. Show more

DOI: 10.3233/CH-2010-1339

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 127-137, 2010

Authors: Stock, K.F. | Klein, B.S. | Vo Cong, M.T. | Sarkar, O. | Römisch, M. | Regenbogen, C. | Büttner, M. | Schuster, T. | Matevossian, E. | Amann, K. | Clevert, D.A. | Heemann, U. | Küchle, C.

Article Type: Research Article

Abstract: Background and purpose: Until recently clinical diagnosis of chronic renal allograft dysfunction could only be established invasively by renal biopsy. Given the risks of that procedure, a non-invasive, diagnostic test would be very advantageous. Novel ultrasound-based elasticity tools, using “Acoustic Radiation Force Impulse (ARFI)” technology are now available. Previously this technique has been utilised to quantify liver fibrosis. First results of these studies are promising. The purpose of our study was to investigate correlation between stiffness values obtained by ARFI-quantification and histological fibrosis score in renal transplants. Methods: We employed “Virtual Touch™ tissue quantification” (Siemens Acuson, S2000) to quantitatively measure …tissue stiffness in the cortex of transplant kidneys. Eighteen patients were included in this prospective study, recording close temporal ARFI-quantification and fibrosis measurements. All patients undergoing renal transplant biopsy were examined with ARFI-quantification (15 measurements per transplant kidney). Resistive indices were also calculated from pulsed-wave Doppler ultrasound. Transplant biopsies were histologically evaluated by a reference nephropathologist and graded according to the percentage of fibrosis and to the BANFF-score. Due to the non-normal distribution of the data the Spearman-correlation-coefficient (rho) was used to assess the bivariate relationship of ARFI and fibrosis in the transplant kidney. Results: There was a significant positive moderate correlation between mean ARFI-values and the grade of fibrosis (rho = +0.465; p = 0.026). This correlation was also valid for the mean ARFI-values and the BANFF-category (rho = +0.468; p = 0.025). There was no significant correlation between the mean ARFI-values and the resistive indices in the transplant kidney (rho = +0.034; p = 0.904). Nevertheless, a positive correlation between the mean RI-values of the kidney and the grade of fibrosis was established (rho = +0.563; p = 0.015). Conclusion: The mean values of ARFI measurements and the resistive indices are potentially independent explanation variables for evaluating the grade of fibrosis in transplant kidneys. Show more

Keywords: Ultrasonography, elasticity imaging techniques, kidney, kidney transplantation, Doppler ultrasonography, pathology, fibrosis, BANFF-classification, ARFI

DOI: 10.3233/CH-2010-1340

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 139-148, 2010

Authors: Paprottka, P.M. | Cyran, C.C. | Zengel, P. | von Einem, J. | Wintersperger, B. | Nikolaou, K. | Reiser, M.F. | Clevert, D.A.

Article Type: Research Article

Abstract: Purpose: To evaluate the different ultrasound techniques for quantification of contrast enhanced ultrasound (CEUS) in an experimental rat prostate carcinoma model. Method and materials: Prostate carcinoma (MLLB-2) cells were subcutaneously injected into the right flank of male rat (Charles River, Sulzfeld, Germany, 180 to 220 g body weight). Following 18 days of subcutaneous tumor growth 9 rats underwent CEUS examination. Real time CEUS was performed after a bolus injection of SonoVue (0.2 ml, Bracco, Italy) via the lateral tail vein using a high end ultrasound system (Siemens Sequoia 512® /Acuson, Mountain View) with an 15 Mhz probe. Two different CEUS …techniques, pure contrast (pc) and contrast with background (cbg) examination, were analyzed (CPS-software). Exported signal intensity (SI)-time curves and the normalized area under the curve (AUC) for the active tumor tissue, whole tumor and necrosis were compared. Results: The mean normalized AUC for the active tumor tissue and the whole tumor was 0.84 and 0.5 in the pure contrast examination group and 0.49 and 0.3 for the contrast examination with background signal. Therefore the signal intensity of the pc group was in every examination significant higher than of the cbg group (p < 0.02). The advantage of using the additional background information is to detect the anatomic landmarks in the solid tumor model in comparison to the pure contrast enhanced ultrasound examination. Conclusion: The complete extension of the tumor is much easier to detect with the cbg technique due to orientation of the anatomic landmarks. As the signal intensity of the pc group is always significant higher we recommend this technique for quantification of contrast enhanced ultrasound, especially for the follow up of tumor microcirculation. Show more

Keywords: CEUS, prostate carcinoma, pure contrast, contrast with background, contrast enhanced ultrasound

DOI: 10.3233/CH-2010-1341

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 149-158, 2010

Authors: Horster, S. | Mandel, P. | Zachoval, R. | Clevert, D.A.

Article Type: Research Article

Abstract: Purpose: Acoustic Radiation Force Impulse Imaging (ARFI) is a new ultrasound elastography technology (Siemens ACUSON S2000 Virtual Touch™ Tissue Quantification), which is integrated in conventional ultrasound equipment. In preliminary studies, ARFI sheer wave speed (SWS) in liver tissue correlated well with transient elastography (TE) values and liver fibrosis stages. Materials and methods: Sixty-eight healthy male and female volunteers were measured with ARFI with two ultrasound tranducers, three measuring positions and during valsalva manoeuvre. A TE (FibroScan™, Echosens, France) was performed in 60 volunteers. Results: Volunteers had a mean age of 28 years and a mean BMI of 22.3. There was …no significant difference of ARFI SWS between the 4C1 and 4V1 ultrasound probes in either intercostal or abdominal approach to liver segment 8 but a higher variance of ARFI SWS with the 4V1/abdominal compared to the intercostal approach (p = 0.0368). The 4C1/intercostal approach had the highest success rates (97.2%), comparable to those of TE (97.18%). Left liver lobe measurements obtained both significantly higher ARFI SWS and value variance (p = 0.0016 and p = 0.0198) compared to 4C1/intercostal approach. Mean ARFI SWS was 1.19 m/s (range 0.77–1.63). Mean TE was 5.39 kPa (range 3.3–9.0 kPa). Valsalva manoeuvre did not significantly alter ARFI SWS and variance. Skin-liver distance significantly influenced ARFI SWS (p < 0.05), while age and gender did not. Conclusion: These results might constitute a first impression of the chances of ARFI SWS to assess liver stiffness, especially in patients with liver diseases due to increased venous pressure. Show more

DOI: 10.3233/CH-2010-1342

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 159-168, 2010

Authors: Waldow, Thomas | Witt, Wolfgang | Matschke, Klaus

Article Type: Research Article

Abstract: Recent studies on the mechanisms of ischemic preconditioning in myocardial tissue have presented convincing evidence that multiple protective pathways converge on inhibition of glycogen synthase kinase-3β (GSK-3β). To directly address the role of GSK-3β in ischemia and reperfusion (I/R) of the lung, a rat model of left lung in situ ischemia was used. The specific non-competitive inhibitor of GSK-3β, TDZD-8, was injected (3 mg/kg, vehicle in controls) 5 min before the left lung hilum was occluded for 60 min. Animals in the ischemia group underwent the same treatment, but without administration of TDZD-8. Lung functional and biochemical parameters were determined …at time points 15 min and 60 min reperfusion. Treatment with TDZD-8 improved gas exchange (arterial pO2 ), but I/R-induced inflammation (plasma interleukin-6, leukocyte invasion) was not affected. The I/R cycle induced a rapid (15 min reperfusion) increase of protein tyrosine phosphorylation, including the activating phosphorylation of focal adhesion kinase at Tyr397, Tyr407, Tyr577, and Tyr861, and the non-receptor kinase Src at Tyr416. The phosphorylation was blocked by the GSK inhibitor. This effect may be related to the reduced plasma level of the strong effector of focal adhesion kinase, transforming growth factor-β1, in the TDZD group. The underlying mechanisms are elusive, but they deserve further investigation, especially in relation to the early increase of lung permeability in this rat model of I/R injury. In conclusion, the results suggest that inhibition of GSK-3β improves rat lung function during an I/R cycle, but only during the early reperfusion phase. Show more

Keywords: Glycogen synthase kinase, ischemia/reperfusion, focal adhesion kinase, TGF-beta1, Src

DOI: 10.3233/CH-2010-1343

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 169-181, 2010

Authors: Stephan, B. | Schenk, J.F. | Pindur, G. | Meiss, C. | Borchers, H. | Nemeh, A. | Weinrich, M. | Wagner, B.

Article Type: Research Article

Abstract: Changes in haemorheology and haemostasis may contribute to bleeding or thrombosis, which is of concern particularly in surgery. Blood loss itself has a major influence on both parameters being closely involved in the clinical outcome. In order to analyze the underlying interrelations, a prospective study with 122 patients (64 females, 58 males) aged between 18 and 83 years (mean: 51.8 years) was conducted. All patients were electively submitted to orthopaedic surgery. Haemorheological parameters included measurements of plasma viscosity, red body cell (RBC) and platelet aggregation index preoperatively, as well as by day 1 and day 7 after surgery. Additionally hematological …and haemostaseological parameters including leukocyte and platelet counts, haematocrit and fibrinogen were investigated. Bleeding was defined as high (>500 ml) or low blood loss (≤500 ml) according to the drainage volume. High but not low blood loss was associated with an increase of RBC aggregation by day 1 and 7 after surgery. Plasma viscosity decreased significantly by day 1, returning to normal 7 days after surgery. Platelet count decreased significantly, concurrent with the haematocrit, by day 1 postoperatively, whereas by day 7 a significant increase was observed, being more distinct in high blood loss. Platelet aggregation index did not change under the influence of blood loss. Plasma fibrinogen, clearly corresponding to the extend of blood loss, showed a continuous postoperative increase, which was significantly higher at day 7. Leukocytes increased moderately but significantly in particular in high blood loss. In conclusion, the postoperative decrease of plasma viscosity and of platelet counts, concurrent with the haematocrit, provides evidence of being clearly dependent on blood loss which is regarded as a dilution effect corresponding with the haemorrhagic risk. The increase of RBC aggregation at the early postoperative stage is solely observed in high blood loss and is esteemed as a result of volume therapy. The marked increase of platelet counts and plasma fibrinogen at the late postoperative stage, being more pronounced in high blood loss, might contribute to an elevated prothrombotic risk and is ascribed to an inflammatory response to surgery. In summary, it is concluded, that bleeding tendency corresponding with haemorheologic parameters is enhanced in the early, whereas the prothrombotic risk, well correlating with haemostaseologic parameters, is elevated in the later stage after surgery. Show more

Keywords: Haemostasis, haemorheology, bleeding, surgery

DOI: 10.3233/CH-2010-1344

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 183-188, 2010

Authors: Bahramsoltani, Mahtab | Spiegelaere, Ward De | Janczyk, Pawel | Hiebl, Bernhard | Cornillie, Pieter | Plendl, Johanna

Article Type: Research Article

Abstract: Angiogenic therapy is considered to be a promising tool for treatment of ischemic diseases. Many in vivo and in vitro assays have been developed to identify potential proangiogenic drugs and to investigate their mode of action. However, until now no validated system exists that would allow quantitation of angiogenesis in vitro in only one assay. Here, a previously established all-in-one in vitro assay based on staging of the angiogenic cascade was validated by quantitation of the effects of the known proangiogenic factors VEGF-A and FGF-2. Both growth factors were applied separately or in combination to human endothelial cell cultures derived …from the heart and the foreskin, and angiogenesis was quantitated over 30 days of culture. Additionally, gene expression of VEGFR-1, VEGFR-2 and FGFR-1 at 3, 10, 20 or 40 days of cultivation was quantitated by RT-qPCR. In both cultures, VEGF-A as well as FGF-2 induced a run through all defined stages of angiogenesis in vitro. Application of VEGF-A only led to formation of irregular globular endothelial structures, while FGF-2 resulted in development of regular capillary-like structures. Quantitation of the angiogenic effects of VEGF-A and transcripts of VEGFR-1 and VEGFR-2 showed that a high VEGFR-1/VEGFR-2 ratio evoked deceleration of angiogenesis. Show more

Keywords: Angiogenesis, quantitative in vitro assay, VEGF-A, FGF-2

DOI: 10.3233/CH-2010-1345

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 189-202, 2010

Authors: Urschel, Katharina | Wörner, Anja | Daniel, Werner G. | Garlichs, Christoph D. | Cicha, Iwona

Article Type: Research Article

Abstract: Background: Atherosclerotic plaques develop at arterial regions subjected to non-uniform shear stress, and are initiated by increased leukocyte-endothelial interactions. In this study, we investigated the effects of distinct shear stress patterns on endothelial recruitment of monocytic cells. Methods: Human umbilical vein endothelial cells (ECs) were exposed to laminar or non-uniform shear stress in bifurcating flow-through slides, followed by 2 h stimulation with TNF-α. To study cell adhesion, ECs were perfused with medium containing THP-1 monocytic cells for 1 h. Endothelial protein expression was determined by immunofluorescence. Results: Exposure to non-uniform shear stress and TNF-α lead to progressive induction of adhesion …molecules and increase in monocytic cell adhesion observed over 0.5–3 h. To investigate the relative role of the shear stress patterns in monocytic cell recruitment, ECs were exposed to reduced levels of shear stress, resulting in a reduced gradient steepness in the non-uniform shear stress regions. Lowering the shear stress from 10 to 5 and 2 dyne/cm2 resulted in increased monocytic cell adhesion under laminar shear stress. However, in these conditions, adherent monocytic cells under non-uniform shear stress were strongly reduced. Moreover, in the region exposed to shear stress gradient parallel to flow direction, monocytic cell adhesion was significantly lower than in the region of non-uniform shear stress, characterized by transversal gradient. Conclusion: Exposure to non-uniform shear stress results in progressive induction of adhesion molecules and monocytic cell recruitment in response to circulating TNF-α. Enhanced monocytic cell recruitment at bifurcations is affected not only by the magnitude and steepness of shear stress gradient, but also by its direction in relation to the flow. Show more

Keywords: Shear stress, monocyte adhesion, adhesion molecules, endothelial cell, bifurcations

DOI: 10.3233/CH-2010-1346

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 203-210, 2010

Authors: Hiebl, B. | Bog, S. | Mrowietz, C. | Jünger, M. | Jung, F. | Lendlein, A. | Franke, R.-P.

Article Type: Research Article

Abstract: Monocytes/macrophages are known to exhibit pro-angiogenic activities after VEGF stimulation. Recently, it was shown that VEGF stimulated macrophages can support growth of microvascular endothelial cells from the lung when both cell types were cocultured using a cell ratio of 1:1. However, endothelial cells can have different phenotypic characteristics and metabolism depending on the originating vascular bed and tissues, and only few data have been published regarding the regiospecific sensitivity of microvascular endothelial cells for angiogenic stimuli. Reports about differences in the microvascular bed of the lung and the skin motivated to investigate angiogenic effects of VEGF stimulated macrophages (mΦa) on …the doubling time and the cell growth behaviour of skin derived microvascular endothelial cells (HMVEC/S). During the study period of 60 days, mΦa supported growth and proliferation of the HMVEC/S, when mΦa and HMVEC/S were cocultured at a ratio of 0.5:1. However, these effects were not seen in a 1:1 coculture. This result indicates that there is a positive correlation between the pro-angiogenic effects of mΦa and the number of endothelial cells in the direct neighbourhood of the mΦa and also suggests a different sensitivity of microvascular endothelial cells to angiogenic stimuli depending on the tissue from which they were isolated. Show more

Keywords: Monocyte, microvascular endothelial cell, coculture, VEGF, angiogenesis

DOI: 10.3233/CH-2010-1347

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 211-216, 2010

Authors: Mayer, A. | Lee, S. | Jung, F. | Grütz, G. | Lendlein, A. | Hiebl, B.

Article Type: Research Article

Abstract: The establishment of a stable endothelial layer on a biomaterial suture is a well known strategy to achieve hemocompatibility. The endothelialisation is supported by factors as e.g. vascular endothelial growth factor (VEGF), which can be secreted by monocytes/macrophages (mo/mΦ) in an angiogenic milieu. In order to avoid detrimental inflammation triggered by these mo/mΦ, we established a protocol for the generation of alternatively activated macrophages and studied their response towards VEGF-A165 . We could generate sufficient amounts of these CD14+ CD163+ IL-10+ mo/mΦ from buffy coats(8.6 ± 4.7 × 105 cells/mlbuffy coat). Furthermore, we achieved a VEGF-A165 …secretion in the nanogram range. The VEGF-A165 secretion increased 2.1-fold within 14 days from 7.6 ± 2.2 to 16.1 ± 2.5ng/ml when the cells were grown with a VEGF-A165 supplemented (10ng/ml) cell culture medium. Within this time period the secretion levels of other pro-angiogenic growth factors (bFGF, PDGF-BB) and immunomodulatory cytokines (IL-10, IL-12, IL-1ra, TNFα, IFNγ) reached only the picogram range. These results suggest that angiogenically stimulated CD14+ CD163+ IL-10+ mo/mΦ might be useful as a cellular cytokine delivery system supporting endothelialisation of biomaterials without inducing pro-inflammatory effects. Show more

Keywords: Monocytes, CD14, CD163, IL-10, VEGF, cytokine delivery

DOI: 10.3233/CH-2010-1348

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 217-223, 2010

Authors: Franke, R.P. | Minkow, A. | Hiebl, B. | Fuhrmann, R. | Mrowietz, C. | Jung, F.

Article Type: Research Article

Abstract: The incubation of erythrocytes (RBC) or endothelial cells (HUVEC) in radiographic contrast media (RCM) could induce morphological alterations of or at the cell membranes, e.g. the generation of echinocytes or the formation of stress fibres coinciding with a massive buckling of HUVEC into the vascular lumen, as was demonstrated in several examinations in the recent years. The apposition or embedding of RCM at or in the cell membranes was discussed as possible causative mechanisms because the embedding of molecules into the internal leaflet of the cell membrane bilayer is expected to bulge the cell membrane to the outside, thus inducing …e.g. the generation of echinocytes. The examination presented here is based therefore on high resolution scanning electron microscopy (SEM) analyses if iodine as marker element of RCM molecules can be found near the inside of or in RBC membranes (co-localisation study). Morphological analyses exploited secondary electron images (SE) while the analysis of elements exploited either back scattered electrons (BSE) or energy dispersive X-ray analysis (EDX) or the areal display of elements in high lateral resolution in the Bit-map modus. Even at the highest convenient magnification (1:40,000) it was impossible to detect RBC membrane associated iodine (I) after RBC incubation in RCM (Iodixanol, Iopromide) in vitro. Neither in the birds view on the samples nor looking from the side on the freeze fractured samples carrying the RBC was it possible to detect either the signal cohorts typical of I in the sum spectra or the main Lα1-peak in trace analysis. Show more

Keywords: Radiographic contrast media, Iodixanol, Iopromid, echinocyte formation

DOI: 10.3233/CH-2010-1349

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 225-232, 2010

Authors: Hiebl, B. | Mrowietz, C. | Goers, J. | Bahramsoltani, M. | Plendl, J. | Kratz, K. | Lendlein, A. | Jung, F.

Article Type: Research Article

Abstract: Multiblock copolymers with shape-memory capability attracted tremendous interest as promising candidate materials for smart, degradable implants. In the present study the hen's egg-chorioallantoic membrane test (HET-CAM test) was used to investigate the angiogenic properties of a thermoplastic, biodegradable multiblock copolymer PDC composed of poly(p-dioxanone) hard segments (PPDO) and crystallizable poly(ε-caprolactone) switching segments (PCL), whereby PPDO and PCL homopolymers were investigated as controls. According to our HET-CAM test data, only PDC induced significant microvessel attraction and formation in the contact area of the test specimen after 48hours of incubation showing newly formed blood vessels along the outer edge of the material. …In contrast, no newly formed blood vessels were observed around the PPDO or PCL specimen after the same incubation period. These in vivo results indicate that the multiblock copolymer PDC possibly possesses an angiogenic effect and it can induce blood vessel formation in its direct vicinity when it is implanted in vivo. Show more

Keywords: Angiogenesis, resorbable biomaterials, HET-CAM test, multiblock copolymer

DOI: 10.3233/CH-2010-1350

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 233-238, 2010

Authors: Braune, S. | Lange, M. | Richau, K. | Lützow, K. | Weigel, T. | Jung, F. | Lendlein, A.

Article Type: Research Article

Abstract: The processing of polymers for blood contacting devices can have a major influence on surface properties. In this study, we fabricated poly(ether imide) (PEI) membranes and films to investigate the effects of the processing on physicochemical surface properties by atomic force microscopy (AFM), scanning electron microscopy, contact angle as well as zeta potential measurements. A static platelet adhesion test was performed to analyze the thrombogenicity of both devices. While contact angle measurements showed similar levels of hydrophobicity and zeta potential values were equivalent, mean surface roughness as well as surface energies in the dispersive part were found to be increased …for the PEI membrane. The static platelet adhesion test showed a significantly decreased number of adherent platelets per surface area on the PEI film (178.98 ± 102.70/45000 μm2 ) compared to the PEI membrane (504 ± 314.27/45000μm2 ) and, consequently, revealed evidence for higher thrombogenicity of the PEI membrane. This study shows that processing can have a significant effect on platelet adhesion to biomaterials, even though, molar weight was identical. Thrombogenicity of polymer-based cardiovascular devices, therefore, have to be evaluated at the final product level, following the entire processing procedure. Show more

DOI: 10.3233/CH-2010-1351

Citation: Clinical Hemorheology and Microcirculation, vol. 46, no. 2-3, pp. 239-250, 2010