Clinical Hemorheology and Microcirculation - Volume 55, issue 1

Authors: Franke, R.P. | Fuhrmann, R. | Jung, F.

Article Type: Research Article

Abstract: Radiographic contrast media (RCM) can vary widely in their physicochemical properties, e.g. the iodine concentration, osmolality, molecule structure, chemotoxicity, hydrophilicity, electric charge and viscosity. Besides the necessary effect of Roentgen ray absorption, which provides contrast-rich images of vessels, RCMs can have varying adverse effects. As one possible cause of microcirculatory disorders, changes in morphology and function of endothelial cells are discussed. Therefore, RCM media-induced release of nitric oxide from arterial as well as from venous endothelial cells in contact with two commercially available RCMs (Iodixanol and Iomeprol) was investigated. NO concentrations started to increase slightly in the HUVEC control cultures …after 3 min incubation time, however, NO concentrations in the cultures incubated with Iomeprol 350 and Iodixanol 320 did not change over time (Iomeprol 350: p = 0.4905; Iodixanol 320: p = 0.784). On the whole, the time-dependent NO release differed for the three groups (RCM × time: p = 0.00224). This difference was due to the fact that, after incubation with the two contrast agents (Iodixanol 320: p = 0.0003; Iomeprol 350: p = 0.0168), less NO was released by the exposed HUVEC at 3 minutes and after 12 hours than by the control cells. In the control cultures of arterial endothelial cells as well as in cultures incubated with 30% v/v Iodixanol supplemented culture medium the NO release did not change. In those cultures of arterial endothelial cells supplemented with 30% v/v Iomeprol the NO release was significantly less than in control cultures and in cultures supplemented with Iodixanol (p = 0.021; p = 0.043). Inspite of a missing shear stress in our static plane vessel wall model there was a RCM-dependent difference in NO release from endothelial cells in vitro. The NO release from venous endothelial cells differed significantly from the NO release from arterial endothelial cells. While the administration of Iomeprol induced a decrease in NO release no changes occurred after Iodixanol administration. Show more

Keywords: Radiographic contrast media, primary human endothelial cells, extracellular matrix, NO release

DOI: 10.3233/CH-131693

Citation: Clinical Hemorheology and Microcirculation, vol. 55, no. 1, pp. 95-100, 2013

Authors: Kim, Jongyoun | Chung, Hyemoon | Cho, Minhee | Lee, Byoung-Kwon | Karimi, Ali | Shin, Sehyun

Article Type: Research Article

Abstract: Increased aggregation of RBC is associated with many vascular diseases, including acute coronary syndrome (ACS). Critical shear-stress (CSS) as in index of red cell aggregation is defined as either the minimum shear-stress required dispersing the aggregates. The objective of this study is to access the role of CSS in ACS comparing to SA, and to evaluate the correlation with usual biomarkers for atherosclerosis such as fibrinogen, hs-CRP. 169 SA and 223 ACS patients were finally enrolled. A detailed medical history and laboratory data were obtained for each participant from clinical records. CSS is measured by simultaneous measurement of shear stress …and light backscattering using a small disposable kit with a microfluidic hemorheometer. We hypothesized that higher value of CSS might be associated increased thrombosis in ACS. As results, relatively younger age was shown and more male in ACS patients, and inflammatory markers (WBC, hs-CRP) were higher in ACS. Whole blood viscosities were significantly higher in ACS than SA along at all shear rates. CSS was 25.7% higher in ACS (333.8 ± 147.8) than in SA (265.4 ± 149.9 mPa) (p < 0.001). CSS was highly correlated white blood cell counts, hs-CRP, fibrinogen, and erythrocyte sedimentation rate (ESR). Among those variables, fibrinogen, and ESR were strongly correlated with CSS. We may suggest that CSS could be used as a novel risk marker for ACS. Show more

Keywords: Critical shear stress, RBC aggregation, acute coronary syndrome

DOI: 10.3233/CH-131694

Citation: Clinical Hemorheology and Microcirculation, vol. 55, no. 1, pp. 101-109, 2013

Authors: Krüger, A. | Mrowietz, C. | Lendlein, A. | Jung, F.

Article Type: Research Article

Abstract: Endothelialisation of polymer-based cardiovascular implants is one strategy to render biomaterials hemocompatible. The evaluation of the functionality and the confluence of an endothelial cell (EC) monolayer in vitro is therefore of crucial importance, because a non-functional or non-confluent EC monolayer can contribute to the failure of vascular grafts. Moreover, the comparison of different potential biomaterials regarding their ability to induce the formation of a functional confluent EC monolayer is of great value. Most of the currently reported in vitro studies focus on direct or indirect markers of EC behaviour. However, these studies still lack the final proof that the EC …monolayer, which can be developed on polymers is confluent and functional. In this study, we investigated the suitability of an in vitro co-culture of human umbilical vein endothelial cells (HUVEC) with platelets to predict the functionality of an EC monolayer. The interaction of platelets with HUVEC was evaluated depending on the concentration of the platelets in the added plasma and of the reactivity of the platelets to pharmacological stimuli. For this purpose, HUVEC were seeded in a 24 well plate. After three days of cultivation, platelets were added to the HUVEC cell culture medium to final concentrations of 200, 2,000 or 20,000 platelets/μl (n = 7 each). The platelets were processed immediately after blood collection and added to the HUVEC culture after a 30 minutes resting period. As a first control, an EC monolayer just cultured with EC medium was used. As a second control EC supplemented with plasma without platelets were applied. The HUVEC monolayer was investigated microscopically after 1 hour of platelet exposition. The addition of thrombocytes to EC affected the EC adherence dependent on the initial cell seeding number of HUVEC, the platelet concentration and also on the reactivity of platelets added. In both controls no significant EC detachment was detected. The results demonstrated a significant influence of platelet concentration and reactivity on the adherence of EC in a static model. Show more

Keywords: Endothelialisation, platelets, hemocompatibility, in vitro test system

DOI: 10.3233/CH-131695

Citation: Clinical Hemorheology and Microcirculation, vol. 55, no. 1, pp. 111-120, 2013

Authors: Feng, Jiantao | Tang, Yong | Xu, Yonggang | Sun, Quanmei | Liao, Fulong | Han, Dong

Article Type: Research Article

Abstract: Substrate stiffness has been proven to play a critical role in vitro tumor proliferation; however, pharmacological studies on antitumor drug screening are still routinely carried out in regular plastic culture plates. In the article, polydimethylsiloxane (PDMS) substrates with different stiffness (mimicking articular cartilage, collagenous bone and mammary tumor respectively) and plastic substrate were employed to establish the mechanical microenvironment for the in vitro drug screening platform. We studied the influences of stiffness on the responses of MCF-7 cells to typical antitumor drugs, cisplatin and taxol. Results showed that for both the treatment IC50 value to MCF-7 cells decreased significantly …(p < 0.01) on the rigid substrate, indicating that MCF-7 cells on soft substrate have a resistance to cytotoxicity of antitumor drugs. The sensitivity of MCF-7 cells on rigid substrate to drug cytotoxicity was attributed to the increased cell cycle progression, implying that agents proven to be effective in vitro by conventional screening approach might be inefficient in a soft microenvironment in vivo. We conclude that stiffness of the substrates, as a critical mechanical factor, should be concerned for screening antitumor agents in vitro. As an extrapolation, the extensively used drug screening system needs to be revalued and redesigned. Show more

Keywords: Stiffness, tumor, microenvironment, pharmacology, drug screening system

DOI: 10.3233/CH-131696

Citation: Clinical Hemorheology and Microcirculation, vol. 55, no. 1, pp. 121-131, 2013

Authors: Krüger, A. | Görs, J. | Zaupa, A. | Löwenberg, C. | Pierce, B.F. | Wischke, C. | Neffe, A.T. | Jung, F. | Lendlein, A.

Article Type: Research Article

Abstract: Gelatins functionalized with desaminotyrosine (DAT) or desaminotyrosyl tyrosine (DATT) form physically crosslinked hydrogels, due to the interactions between the introduced aromatic moieties and gelatin triple helices, whose extent depends on the thermal treatment of the material. The G-modulus of these hydrogels can be tailored to the range of the natural extracellular matrix by adjusting the degree of crosslinking. While these gelatin-based materials have been shown to be not angiogenic, the aim of the study was to evaluate whether these biomaterials influence the regulation of blood vessels when positioned on the chorionallantoic membrane (CAM) of fertilized eggs. The results clearly indicate …that the DAT-functionalized gelatin led to an increase of the diameter of the blood vessels in the CAM, which at the same time is probably associated with an increased blood flow in these CAM vessels. The vessel diameters of the four groups (DAT-functionalized gelatin, DATT-functionalized gelatin, plain gelatin, control group without gelatin, each n = 10) differed significantly (p < 0.0001). Vessels in the CAM exposed to the DAT-functionalized gelatin showed with 36.4 μm ± 3.4 μm the largest mean diameters compared to the mean diameters of the samples exposed to DATT gelatin (16.0 μm ± 0.8 μm; p < 0.05) and the plain gelatin (21.2 μm ± 1.0 μm; p < 0.05), which both did not differ significantly from the vessels of the control group. The biocompatibility of the materials in vitro motivates the exploration of their application as matrix in local drug-release systems with short half-life times (one hour up to several days). Show more

Keywords: HETCAM assay, gelatin, tyrosin

DOI: 10.3233/CH-131697

Citation: Clinical Hemorheology and Microcirculation, vol. 55, no. 1, pp. 133-142, 2013

Authors: Xu, Xun | Kratz, Karl | Wang, Weiwei | Li, Zhengdong | Roch, Toralf | Jung, Friedrich | Lendlein, Andreas | Ma, Nan

Article Type: Research Article

Abstract: Accumulating evidence demonstrated many physical and chemical cues from the local microenvironment could influence mesenchymal stem cells (MSCs) maintenance and differentiation. In this study, we systematically investigated the interaction of rat bone marrow-derived mesenchymal stem cells (rBMSCs) and polymeric substrates. Adhesion, proliferative capacity, cytoskeleton alteration, cytotoxicity, apoptosis, senescence, and adipogenesis potential of rBMSCs were determined on these polymeric inserts prepared from polyetherurethane (PEU) and poly(ether imide) (PEI). Inserts for culture plates were applied to ensure that the rBMSCs were solely in contact to the tested material. The explored inserts exhibited advancing contact angles of 84° (PEU) and 93° (PEI). Finally, …the micromechanical properties determined by atomic force microscopy (AFM) indentation varied in the range from 6 GPa (PEU) to 13 GPa (PEI). We found that both PEU and PEI showed a good cell compatibility to rBMSCs. rBMSCs could adherent on both polymeric surfaces with the similar adhesion ratio and subsequent division rate. However, cells cultured on PEU exhibited higher apoptosis level and senescence ratio, which resulted in lower cell density (22061 ± 3000/cm2 ) compared to that on PEI (68395 ± 8000/cm2 ) after 20 days cultivation. Morphological differences of rBMSCs were detected after 5 days cultivation. Cells on PEU exhibited flat and enlarged shape with rearranged filamentous actin (F-actin) cytoskeleton, while cells on PEI and tissue culture plate (TCP) had similar spindle-shape morphology and oriented F-actin. After 20 days, lipid droplets were spontaneously formed in rBMSCs on PEU and PEI but not on TCP. Both PEU and PEI might trigger rBMSCs towards spontaneous adipogenic commitment, whereas PEI provided better cell compatibility on rBMSCs apoptosis, senescence and proliferation. Show more

Keywords: Mesenchymal stem cells, polymeric surface, cell-material interaction, cellular senescence, spontaneous differentiation

DOI: 10.3233/CH-131698

Citation: Clinical Hemorheology and Microcirculation, vol. 55, no. 1, pp. 143-156, 2013

Authors: Roch, Toralf | Kratz, Karl | Ma, Nan | Jung, Friedrich | Lendlein, Andreas

Article Type: Research Article

Abstract: Dendritic cells (DC) have a pivotal role during inflammation. DC efficiently present antigens to T cells and shape the subsequent immune response by the secretion of pro- or anti-inflammatory cytokines and by the expression of co-stimulatory molecules. They respond to “danger signals” such as microbial products or fragments from necrotic cells or tissues, but were also described to be reactive towards biomaterials. However, how mechanical and physical properties of the subjacent substrate influences the DC activation is currently poorly understood. In this study micro patterned inserts prepared from polystyrene (PS) as well as from poly (ether imide) (PEI) with three …different roughness levels of i) Rq = 0.29 μm (PS) and 0.23 μm (PEI); ii) Rq = 3.47 μm (PS) and 3.92 μm (PEI); and iii) Rq = 22.16 μm (PS) and 22.65 μm (PEI) were analyzed for their capacity to influence the activation of human monocytes derived DC. Since the DC were directly cultured in the inserts, the effects of the testing material alone could be investigated and influences from additional culture dish material could be excluded. The viability, the expression of the DC activation markers, and their cytokine/chemokine secretion were determined after the incubation with the different inserts in vitro. Both the PS and the PEI inserts did not influence the survival of the DC and their expression of co-stimulatory molecules. The expression of inflammatory cytokines was not altered by the PEI and PS inserts. However, the secretion of chemokines such as CCL2, CCL3, and CCL4 was influenced by the different roughness levels, indicating that material roughness has the capacity to modulate the DC phenotype. The data presented here will help to understand the interaction of DC with structured polymer surfaces. Biomaterial-induced immuno-modulatory effects mediated by DC may promote tissue regeneration or could potentially reduce inflammation caused by the implant material. Show more

Keywords: Biomaterials, roughness, dendritic cells, cell culture devices

DOI: 10.3233/CH-131699

Citation: Clinical Hemorheology and Microcirculation, vol. 55, no. 1, pp. 157-168, 2013

Authors: Meier, J.K. | Prantl, L. | Geis, S. | Mueller, S. | Hullmann, M. | Liebsch, G. | Gosau, M.

Article Type: Research Article

Abstract: BACKGROUND: In a preliminary trial, we were able to show first promising results in the analysis of perioperative and postoperative perfusion of free flaps by means of a new monitoring system for detecting thrombotic vessel occlusion before clinical signs become evident. OBJECTIVE: We investigated whether flap monitoring by measuring perfusion-dependent parameters differs between radial forearm and fibular free flaps and whether a threshold value requiring anastomosis revision could be determined. METHODS: 37 radial forearm flaps (RF) and 15 fibular flaps (FF) were harvested and transplanted. Perfusion was determined by measuring a fluorescent oxygen sensor foil covering a flap's skin surface …with a handheld fluorescence microscope. The sensor contained an oxygen reservoir, which was consumed by the tissue corresponding to the perfusion status of the flap. Measurements were done before explantation, after successful anastomosis and one day after surgery. RESULTS: We found a significant difference (p < 0.005) in the relative transdermal oxygen consumption (RTOC) between clinically well-perfused grafts (RF: mean: 0.13 ± 0.08; FF: mean: 0.15 ± 0.07) and clinically poorly perfused grafts (RF: mean: 0.40 ± 0.09; FF: mean: 0.55 ± 0.28). A threshold RTOC value of 0.3 for differentiating between well-perfused and poorly perfused flaps was confirmed for both RF and FF. Show more

Keywords: Free flap, microvascular, FRMI, pO$_2$ imaging, fluorescent optical sensor

DOI: 10.3233/CH-131700

Citation: Clinical Hemorheology and Microcirculation, vol. 55, no. 1, pp. 169-182, 2013

Authors: Clevert, D.A. | Gürtler, V.M. | Meimarakis, G. | D'Anastasi, M. | Weidenhagen, R. | Reiser, M.F. | Becker, C.R.

Article Type: Research Article

Abstract: PURPOSE: To evaluate the feasibility of the classification of endoleaks following endovascular aortic aneurysm repair using the time-to-peak of the contrast agent in CEUS examinations. MATERIAL AND METHODS: In this retrospective study, a cohort of 171 patients with a total of 489 CEUS follow-up examinations after EVAR were included. In 254 of the 489 examinations, an endoleak was seen and the time-to-peak was measured in seconds. Existence of an endoleak was confirmed by CT as the gold standard. RESULTS: We evaluated 254 CEUS video sequences showing an endoleak out of a total of 489 examinations. Kruskal-Wallis test revealed with p …= 0.001 differences between the single endoleak types based on the time to peak. Correction after Bonferroni showed significant differences between type Ia compared to Ib and to IIa over inferior mesenteric artery (IMA) and IIa over lumbar artery (LA). There are also disparities between type Ib and type IIa IMA and type III, furthermore between type IIa IMA compared to IIa LA and type III as well as type IIa LA matched to type III. CONCLUSION: CEUS is an important method for the follow-up after EVAR. The time-to-peak does not seem to be a useful additional feature in classifying endoleaks, although there are differences between the time-to-peak of the single endoleak types and it is possible to make an order of the different endoleak types referring to the mean values. Show more

Keywords: endoleak, EVAR, AAA, CEUS, time-to-peak

DOI: 10.3233/CH-131701

Citation: Clinical Hemorheology and Microcirculation, vol. 55, no. 1, pp. 183-191, 2013

Authors: Kim, Jong Youn | Yoon, Jihyun | Cho, Minhee | Lee, Byoung-Kwon | Karimi, Ali | Shin, Sehyun

Article Type: Research Article

Abstract: PWV, a surrogate marker for vascular stiffness, can be also expressed by the Bramwell-Hill equation. The effect of blood density to PWV has been ignored, because variation of blood density is assumed to be negligible. In some clinical situation, blood density could be changed, and blood density as a mechanical property of blood flow might affect to PWV. While the elastic property plays an important role in determining the wave propagation in an elastic tube, our assumption is that there might be some relation between blood flow and vascular wall, and that the characteristics of blood flow might influence PWV. …This study was objected to investigate the role of mechanical and hemorheologic parameters on PWV in subjects with cardiovascular disease. We have measured and analyzed the PWV, hemorheologic parameters, and other clinical parameters in 814 patients with coronary arterial disease scheduled for coronary angiography. There is no commercial method for measuring whole blood density. So, we defined the density score, which is sum of hemoglobin and total protein. And the hemorheologic parameters were measured within 4 hours after sampling by automated microfluidic hemorheometer. And the effect of all the clinical and hemorheologic parameter on PWV was analyzed by multiple linear regression analysis. Many clinical parameters including age and blood pressure, high shear WBV and ESR as hemorheologic parameters, and density score were correlated well with ba-PWV. However, many clinical variables, high shear WBV and ESR lost the independent significance on multivariable regression analysis. Only age, SBP, and density score were independent variables (p < 0.001). In conclusion, density score as a mechanical property of blood might be suggested as an independent variable influencing PWV in addition to age and blood pressure, but hemorheologic parameters, such as RBC deformability, aggregation, and whole blood viscosity do not affect PWV independently. Show more

Keywords: Vascular stiffness, pulse wave velocity, blood density

DOI: 10.3233/CH-131702

Citation: Clinical Hemorheology and Microcirculation, vol. 55, no. 1, pp. 193-203, 2013