F Kiessling

Publications of F Kiessling

• Imaging in the age of molecular medicine: Monitoring of anti-angiogenic treatments.

  Authors: W Lederle, M Palmowski, F Kiessling

  Current pharmaceutical biotechnology. 01/2012;

  Angiogenesis is a complex multistep process and a crucial pre-requisite for tumor growth, invasion and metastasis. A profound knowledge of the mechanisms including the elucidation of markers forAngiogenesis is a complex multistep process and a crucial pre-requisite for tumor growth, invasion and metastasis. A profound knowledge of the mechanisms including the elucidation of markers for angiogenic vessels is essential for the generation of new anti-angiogenic chemotherapeutic agents and the improvement of specific imaging techniques. During the last decades, numerous angiogenesis inhibitors have been developed and some of them have shown promising results in preclinical and clinical trials. However, the response to anti-angiogenic treatment is often delayed and shows high inter-individual variations. In order to improve anti-angiogenic therapy, new specific surrogate markers are necessary that allow the characterization of different angiogenic steps, especially at the early stage. In this respect, non-invasive imaging is a potent tool for characterizing the tumor vascularization and for sensitive and longitudinal treatment monitoring. In particular, new molecular imaging techniques might ultimately improve the characterization of the angiogenic tumor phenotype and stage. This review summarizes the current status of different imaging modalities e.g. MRI, CT, US, nuclear and optical imaging with respect to the imaging of tumor angiogenesis and of anti-angiogenic treatments. It also includes new approaches in molecular imaging, which give deep insight into the tumor stage and the response of tumor vessels to anti-angiogenic therapy. Thus, this may lead to a more personalized cancer therapy in future.

• Fully automated intrinsic respiratory and cardiac gating for small animal CT.

  Authors: J Kuntz, J Dinkel, S Zwick, T Bäuerle, M Grasruck, F Kiessling, R Gupta, W Semmler, S H Bartling

  Physics in medicine and biology. 04/2010; 55(7):2069-85.

  A fully automated, intrinsic gating algorithm for small animal cone-beam CT is described and evaluated. A parameter representing the organ motion, derived from the raw projection images, is used forA fully automated, intrinsic gating algorithm for small animal cone-beam CT is described and evaluated. A parameter representing the organ motion, derived from the raw projection images, is used for both cardiac and respiratory gating. The proposed algorithm makes it possible to reconstruct motion-corrected still images as well as to generate four-dimensional (4D) datasets representing the cardiac and pulmonary anatomy of free-breathing animals without the use of electrocardiogram (ECG) or respiratory sensors. Variation analysis of projections from several rotations is used to place a region of interest (ROI) on the diaphragm. The ROI is cranially extended to include the heart. The centre of mass (COM) variation within this ROI, the filtered frequency response and the local maxima are used to derive a binary motion-gating parameter for phase-sensitive gated reconstruction. This algorithm was implemented on a flat-panel-based cone-beam CT scanner and evaluated using a moving phantom and animal scans (seven rats and eight mice). Volumes were determined using a semiautomatic segmentation. In all cases robust gating signals could be obtained. The maximum volume error in phantom studies was less than 6%. By utilizing extrinsic gating via externally placed cardiac and respiratory sensors, the functional parameters (e.g. cardiac ejection fraction) and image quality were equivalent to this current gold standard. This algorithm obviates the necessity of both gating hardware and user interaction. The simplicity of the proposed algorithm enables adoption in a wide range of small animal cone-beam CT scanners.

• [Molecular imaging in oncology using targeted ultrasound contrast agents]

  Authors: M Palmowski, P Hauff, F Kiessling

  Praxis. 06/2009; 98(11):597-602.

  Molecular imaging enables to assess disease-associated processes at the cellular and molecular level. Nuclear medicine techniques are already available in the clinical routine. Besides theseMolecular imaging enables to assess disease-associated processes at the cellular and molecular level. Nuclear medicine techniques are already available in the clinical routine. Besides these techniques, intensive research has been performed in the field of ultrasound. The development of target-specific ultrasound contrast agents in combination with modern imaging systems transformed ultrasound to a capable molecular imaging technique. It has been shown that the expression of disease-associated endothelial receptors can be assessed using targeted microbubbles, demonstrating its high value in the diagnosis of several diseases. The broad availability of suitable ultrasound systems promises a wide utilisation in the clinical routine, once clinically approved contrast agents are available. This review summarizes the basics and the current status of molecular ultrasound imaging.

• Functional and molecular ultrasound imaging: concepts and contrast agents.

  Authors: F Kiessling, J Huppert, M Palmowski

  Current medicinal chemistry. 02/2009; 16(5):627-42.

  Contrast-enhanced ultrasound has shown convincing results for monitoring vessel morphology, surrogate markers of vascularization and changes in molecular marker expression in oncological andContrast-enhanced ultrasound has shown convincing results for monitoring vessel morphology, surrogate markers of vascularization and changes in molecular marker expression in oncological and cardiovascular diseases. Ultrasound contrast agents have the ability to increase the backscattering signal intensity of an ultrasound pulse. An interesting class of ultrasound contrast agents are gas filled microbubbles, which can be synthesized by external bubble encapsulation using sugar matrices or microspheres consisting of lipids or polymers with or without surfactant and by selecting gases with low blood solubility and diffusion coefficient such as perfluorocarbons or sulphur hexafluoride. Ultrasound contrast agents can be classified according to the rigidity of their shell. Soft-shell microbubbles are coated with a thin monolayer of surfactant molecules such as palmitic acid or phospholipids and are very sensitive to pressure changes. Hard-shell microbubbles have a rigid shell made of polymers such as polycyanoacrylate, which dramatically increases their stability. Depending on the acoustic properties of the microbubbles and on the purpose of the examination either destructive or non destructive methods are preferred for their detection. Microbubbles can be detected by destructive and non-destructive methods. Both soft- and hard-shell microbubbles coated with target-specific molecules can also be used for molecular imaging. Using target-specific approaches, the expression of several angiogenic markers such as VEGFR2, alpha(v)beta(3) Integrins, ICAM, and E-selectin has been investigated in neoplastic and vascular diseases. This article summarizes the synthesis and properties of contrast agents as well as the indications, limitations and future potential of contrast-enhanced functional and molecular ultrasound.

• Statistical corrections for the precise estimation of cyanoacrylate microbubble concentration in targeted imaging

  Authors: M. Siepmann, G. Schmitz, M. Palmowski, F. Kiessling

  Ultrasonics Symposium, 2008. IUS 2008. IEEE; 12/2008

  The precise quantification of microbubble concentration is crucial for ultrasound molecular imaging. However, for high concentrations direct quantification approaches fail to precisely estimate theThe precise quantification of microbubble concentration is crucial for ultrasound molecular imaging. However, for high concentrations direct quantification approaches fail to precisely estimate the concentration of aggregated microbubbles (MB). Thus Sensitive Particle Acoustic Quantification (SPAQ) was proposed by Reinhardt et al. by destroying all MBs in an image and then moving the transducer in sub-millimeter increments in elevation direction the destruction volume is reduced. Individual destruction events become visible in Doppler imaging and are quantified by measuring the color pixel density. To calculate MB concentration from color pixel density, in only an approximation was derived. Now we derive a statistical model of SPAQ allowing the precise count of MBs even if the individual destruction events are not distinguishable. For this, only the average color pixel area of a single destruction event has to be known. The resulting correction was applied to SPAQ images of 8 gelatine phantoms with concentrations of MB ranging from 0.6*10⁶ - 2.1*10⁷ MBs / ml. A high frequency ultrasound system using the 3D Power Doppler mode was employed to obtain the images. The exact concentrations were determined optically. The corrected acoustic quantification showed the expected linear dependence on the MB concentration. The filling factor of colored pixels in the ROI ranged from 12% to 93% for the highest concentration. The optical analysis showed that only 46% of the bubbles were counted in the acoustic analysis. However, since a linear relationship was found between optical and acoustical counts, one can derive the total concentration from the acoustic measurement. This is not possible without a correction where the highest concentration is underestimated by 74%. Thus, the proposed correction improves quantification considerably.

• Initial Experience with a Novel Low-Dose Micro-CT System.

  Authors: W Stiller, M Kobayashi, K Koike, U Stampfl, G M Richter, W Semmler, F Kiessling

  RöFo : Fortschritte auf dem Gebiete der Röntgenstrahlen und der Nuklearmedizin. 08/2007; 179(7):669-75.

  PURPOSE: Investigation of the hardware and image characteristics of a novel micro-CT system and evaluation of its potential to image animals and tissue samples. MATERIALS AND METHODS: The scanner wasPURPOSE: Investigation of the hardware and image characteristics of a novel micro-CT system and evaluation of its potential to image animals and tissue samples. MATERIALS AND METHODS: The scanner was characterized by phantom studies regarding image homogeneity, CT number stability, soft-tissue contrast, spatial resolution and X-ray dose. The phantoms used were specially designed to evaluate the imaging of mice and rats. Scans of hearts with coronary stents were performed and the tissue morphology and vascularization of tumor-bearing rodents were studied with dynamic contrast-enhanced (DCE) CT. RESULTS: The CT numbers of the acrylic phantoms were reproducible with a 4 HU deviation. The inter-pixel deviation was low but depended on the scan mode. The correlation coefficient between CT number and iodine concentration (0 - 6000 HU) was 0.99. Single wires, lumen and endo-luminal plaques of heart stents were distinguishable. The density-time courses were reliably recorded and made it possible to distinguish the tumor and muscle tissue in DCE micro-CT scans CONCLUSION: The novel micro-CT scanner is suitable for studying tissue densities and contrast agent kinetics.

• Contrast agents and applications to assess tumor angiogenesis in vivo by magnetic resonance imaging.

  Authors: F Kiessling, B Morgenstern, C Zhang

  Current medicinal chemistry. 02/2007; 14(1):77-91.

  Angiogenesis plays a key role in the development of cancer and is precondition for tumor growth, invasion and spread. Therefore, numerous angiogenesis inhibitors have been developed, of which someAngiogenesis plays a key role in the development of cancer and is precondition for tumor growth, invasion and spread. Therefore, numerous angiogenesis inhibitors have been developed, of which some show potential to defeat cancer in preclinical and clinical trials. However, response to antiangiogenic treatments is often delayed and marked by high interindividual variability making a closely mashed and efficient observation of the patient necessary. Therefore, surrogate markers which specifically catch early response to tumor therapy are highly desirable. Functional parameters like relative blood volume, perfusion and vessel permeability can be assessed using T(1) and T(2)*-weighted dynamic contrast-enhanced (DCE) MRI. Various reports are available on this topic but results are controversial. During antiangiogenic therapies some authors describe pronounced changes in blood volume: others find effects only on vessel permeability or perfusion. These conflictive observations can be attributed to the different tumor models, therapies, measurement techniques and contrast agents (CA). Particularly the choice of the optimal CA is considered to be essential for a successful characterization of tumor angiogenesis. Often therapy effects on vessel permeability only become apparent, when blood pool CA are used. This article reviews the current state of DCE and molecular MRI of angiogenesis. Besides a general introduction of the different measurement and postprocessing methods and its previous applications, design, structure and use of different types of CA are the main focus of this article.

• [Multimodal diagnosis of multiple and heterogeneous liver lesions in a young patient]

  Authors: F Kiessling, H P Schlemmer

  Der Radiologe. 11/2005; 45(10):937-40.

  The classification of liver lesions is often problematic in particular if they are multiple and show an heterogeneous shape. Here we report of a young patient with multiple liver lesions of up to 3The classification of liver lesions is often problematic in particular if they are multiple and show an heterogeneous shape. Here we report of a young patient with multiple liver lesions of up to 3 cm size. Using ultrasound, the lesions were hyper-, hypoechogen or mixed. In serial contrast enhanced CT scans some of the lesions showed the typical enhancement pattern of hemangiomas, however, the diagnosis could still not be faithfully determined for all lesions. Therefore, the patient was conducted to contrast enhanced MRI (Gd-DTPA and MnDPDP). While with Gd-DTPA some of the lesions showed a strong enhancement, they remained hypointense after administration of MnDPDP. Finally to exclude a metastatic disease a (99m)Tc-erythrocyte SPECT was performed confirming the diagnosis of hemangiomas for most of the lesions. Diagnosis was not assessed by biopsy because this would only clarify the diagnosis for one or few of the lesions. The patient was subsequently followed up for 3 years and all lesions remained unchanged. This case clearly illustrates the difficulty to get a certain diagnosis of multiple liver lesions with heterogeneous appearance despite the multimodal diagnostic conduct.

• Perfusion CT in patients with advanced bronchial carcinomas: a novel chance for characterization and treatment monitoring?

  Authors: F Kiessling, J Boese, C Corvinus, J R Ederle, I Zuna, S O Schoenberg, G Brix, A Schmähl, S Tuengerthal, F Herth, H U Kauczor, M Essig

  European radiology. 07/2004; 14(7):1226-33.

  Advanced bronchial carcinomas by means of perfusion and peak enhancement using dynamic contrast-enhanced multislice CT are characterized. Twenty-four patients with advanced bronchial carcinoma wereAdvanced bronchial carcinomas by means of perfusion and peak enhancement using dynamic contrast-enhanced multislice CT are characterized. Twenty-four patients with advanced bronchial carcinoma were examined. During breathhold, after injection of a contrast-medium (CM), 25 scans were performed (1 scan/s) at a fixed table position. Density-time curves were evaluated from regions of interest of the whole tumor and high- and low-enhancing tumor areas. Perfusion and peak enhancement were calculated using the maximum-slope method of Miles and compared with size, localization (central or peripheral) and histology. Perfusion of large tumors (> 50 cm3) averaged over both the whole tumor (P = 0.001) and the highest enhancing area (P = 0.003) was significantly lower than that of smaller ones. Independent of size, central carcinomas had a significantly (P = 0.04) lower perfusion (mean 27.9 ml/min/100 g) than peripheral ones (mean 66.5 ml/min/100 g). In contrast, peak enhancement of central and peripheral carcinomas was not significantly different. Between non-small-cell lung cancers and small-cell lung cancers, no significant differences were observed in both parameters. In seven tumors, density increase after CM administration started earlier than in the aorta, indicating considerable blood supply from pulmonary vessels. Tumor perfusion was dependent on tumor size and localization, but not on histology. Furthermore, perfusion CT disclosed blood supply from both pulmonary and/or bronchial vessels in some tumors.

• [Pulmonary nodules in a patient with high temperature. Acute pulmonary histoplasmosis]

  Authors: F Kiessling, T Junghanss, K Tintelnot, H P Schlemmer

  Der Radiologe. 11/2003; 43(10):856-60.

• [Time-resolved multiphasic 3D MR angiography in the diagnosis of the pulmonary vascular system in children]

  Authors: C Fink, J Eichhorn, F Kiessling, M Bock, S Delorme

  RöFo : Fortschritte auf dem Gebiete der Röntgenstrahlen und der Nuklearmedizin. 08/2003; 175(7):929-35.

  PURPOSE: To evaluate time-resolved, multiphasic 3D MR angiography (MRA) for the non-invasive assessment of the pulmonary vascular system in children. MATERIALS AND METHODS: 10 children aged 6 to 15PURPOSE: To evaluate time-resolved, multiphasic 3D MR angiography (MRA) for the non-invasive assessment of the pulmonary vascular system in children. MATERIALS AND METHODS: 10 children aged 6 to 15 years (mean age 10 years) ware examined on a 1.5 T whole body MR system with time-resolved, multiphasic 3D MRA after injection of 0.2 mmol/kg body weight of Gd-DTPA. With the use of an ultrafast gradient echo pulse sequence with asymmetric k-space filling and very short echo and repetition times, a nominal spatial resolution of 1.4 x 1.4 x 2.0 mm3 could be achieved with a scan time of 5.6 and 6.2 seconds for a single 3D data set. Two radiologists, who were blinded to the clinical diagnosis, analyzed the image data in consensus. The image analysis included the assessment of the image contrast and artifacts as well as a quantitative analysis of the signal-to-noise (SNR) and contrast-to-noise ratios (CNR) for central and peripheral lung vessel segments. RESULTS: The children tolerated all examinations without any side effects. The referral diagnosis, which was based on echocardiography, catheter angiography and surgery, was confirmed by MRA in all cases. The image contrast was rated at least satisfactory in all but one case (19 of 20) and no artifacts were observed. The quantitative analysis of the SNR and CNR in the pulmonary arteries and veins confirmed the reader analysis of a high and uniform contrast throughout the entire pulmonary circulation. CONCLUSION: Time-resolved multiphasic 3D MRA allows a non-invasive diagnostic evaluation of the pulmonary circulation in children. In view of the excellent image quality, MRA may replace conventional diagnostic catheter angiography in the near future.

• [Detection of prostate carcinomas with T1-weighted dynamic contrast-enhanced MRI. Value of two-compartment model]

  Authors: F Kiessling, M Lichy, R Grobholz, N Farhan, M Heilmann, M S Michel, L Trojan, A Werner, J Rabe, S Delorme, H U Kauczor, H P Schlemmer

  Der Radiologe. 07/2003; 43(6):474-80.

  AIM: The suitability of dynamic parameters of the two-compartment model for detecting prostate carcinomas and its correlation with tumor microvascular density were evaluated. METHODS: The studyAIM: The suitability of dynamic parameters of the two-compartment model for detecting prostate carcinomas and its correlation with tumor microvascular density were evaluated. METHODS: The study included 43 patients with biopsy-proven prostate carcinoma: 28 were examined by 1.0-T MRI (Turbo-FLASH) and 15 by 1.5-T MRI (FLASH) with infusion of 0.1 mmol/kg Gd-DTPA. Signal time curves were parametrized with an open two-compartment model in amplitude and exchange rate constants (k(ep)).The microvascular density of resected prostate carcinomas was determined. RESULTS: The microvascular density in the tumors was significantly higher than in the adjacent healthy prostate tissue and correlated in both sequences with k(ep). Prostate carcinomas of the peripheral zone were demarcated by amplitude and k(ep). In the Turbo-FLASH sequence there was a significant difference between the tumor tissue and healthy peripheral zone in terms of k(ep) and in the FLASH sequence in terms of amplitude. CONCLUSION: Prostate carcinomas can be visualized with dynamic T1-weighted MR sequences using a two-compartment model. Moreover, the parameter k(ep) reveals the microvascular density in the tumor and can thus provide valuable clinical information for characterizing the tumors.

• [Hemodynamic and metabolic characterization of orthotopic rat prostate carcinomas using dynamic MRI and proton magnetic resonance spectroscopy]

  Authors: F Kiessling, M Lichy, R Grobholz, M Heilmann, P E Huber, J Meding, P Peschke, H U Kauczor, H P Schlemmer

  Der Radiologe. 07/2003; 43(6):489-94.

  AIM: The aim of this study was the noninvasive characterization of prostate carcinoma orthotopically implanted in rats using Gd-DTPA-assisted dynamic MRI (dMRI) and proton magnetic resonanceAIM: The aim of this study was the noninvasive characterization of prostate carcinoma orthotopically implanted in rats using Gd-DTPA-assisted dynamic MRI (dMRI) and proton magnetic resonance spectroscopy ((1)H-MRS). MATERIAL AND METHODS: After surgical exposure of the prostate, Dunning R3327 orthotopic prostate carcinoma was induced by injecting cells of the MAT-LyLu subline. Six rats were examined 5 and 14 days after tumor induction with dMRI and (1)H-MRS at 1.5 T. Six tumor-free rats served as controls. Using an open two-compartment model, the parameters A (amplitude) and k(ep) (exchange rate constants) were calculated from the signal time curves of the dMRI. The relative signal intensities (Cho/Cr) of the resonances of choline (Cho) and the creatine-phosphocreatine complex (Cr) were computed from the MR spectra. RESULTS: Already after 5 days, the tumors in the prostate could be clearly identified based on the decrease in signal intensity to T2w and increase of A and k(ep). High Cho/Cr levels and resonances of two lipid fractions (Lip(1) at 0.8-1.5 ppm and Lip(2) at 2.0-2.2 ppm) were observed by MRS in the highly necrotic tumors. CONCLUSIONS: The orthotopic rat prostate carcinoma model resembles human prostate carcinoma in regard to MR morphology, dMRI, and (1)H-MRS. The noninvasive characterization of perfusion and metabolism makes a comparative examination of different treatment modalities possible.

• [Apical pulmonary coin lesion. Sarcoidosis]

  Authors: F Kiessling, K Kayser, M Essig

  Der Radiologe. 09/2002; 42(8):655-7.

• Magnetic resonance imaging of nude mice with heterotransplanted high-grade squamous cell carcinomas: use of a low-loaded, covalently bound Gd-Hsa conjugate as contrast agent with high tumor affinity.

  Authors: F Kiessling, C Fink, M Hansen, M Bock, H Sinn, H H Schrenk, M Krix, T Egelhof, N E Fusenig, S Delorme

  Investigative radiology. 05/2002; 37(4):193-8.

  RATIONALE: Malignant tumors often show an increased uptake and metabolism of plasma proteins, especially albumin. OBJECTIVES: Determine whether the accumulation of low loaded Gd-albumin improvesRATIONALE: Malignant tumors often show an increased uptake and metabolism of plasma proteins, especially albumin. OBJECTIVES: Determine whether the accumulation of low loaded Gd-albumin improves visualization of malignant tumors by MRI. METHODS: Twelve nude mice with heterotransplanted squamous cell carcinomas were studied. The signal intensity of tumor, blood, liver, kidney and muscle tissue was studied in MR images after application of Gd-albumin during a period of 144 hours. MRI results were histologically correlated after simultaneously injection of Gd- and fluorescein-labeled albumins in 9 nude mice. RESULTS: Although liver and kidney had a maximum increase in signal intensity within 30 minutes, tumors showed a delayed 51% increase in the 24 hours after application. Histologic and fluorescence evaluation demonstrated albumin localization in tumors predominantly in stroma and necroses. CONCLUSIONS: Gd-albumin is efficiently accumulated in SCC transplants. MRI with low loaded Gd-albumin may offer relevant opportunities for recognizing tumors sensitive to a therapy with cyostic drug-labeled albumins.

• [Recurrent epigastric pain with weight loss and loss of appetite]

  Authors: F Kiessling, K H Seitz, H P Schlemmer

  Der Radiologe. 10/2001; 41(9):783-5.

• Influence of intercellular junctions on endothelin secretion of human umbilical vein endothelial cells in vitro.

  Authors: F Kiessling, D Becker, E V Ullisch, W Kübler, C Haller

  Basic research in cardiology. 09/2000; 95(4):299-307.

  The endothelium plays a pivotal role in the rheological regulation of blood flow by the secretion of vasoactive factors. The interaction between shear forces and the endothelium is determined by theThe endothelium plays a pivotal role in the rheological regulation of blood flow by the secretion of vasoactive factors. The interaction between shear forces and the endothelium is determined by the mechanical properties of the endothelial cell layer which are associated with intercellular junctions. Cell-cell contacts could therefore modulate the secretion of vasocative factors in response to rheological stimuli. We investigated the relationship between intercellular junctions and the secretion of the vasoconstrictor peptide endothelin and the coagulation co-factor von Willebrand factor (vWF). Human umbilical vein endothelial cells (HUVECs) were used as in vitro endothelial model system. Intercellular junctions were reversibly disrupted by calcium chelation or hypertonic stress; alternatively, the formation of intercellular junctions was inhibited by culturing the cells in suspension or by plating them in the presence of an inhibitory anti-VE-cadherin antibody. The opening of intercellular junctions was verified by assessing transmonolayer electrical resistance (TMR) and immunofluorescence morphology. The concentration of endothelin and vWF was measured in the cell culture supernatants using specific ELISAs. The secretion of endothelin was inhibited by EGTA (5 mM) and stimulated by incubation with tumor necrosis factor alpha (TNFalpha, 40 ng/ml). Treatment with hypertonic medium (glycerol, 1,200 mosmol/l) for 10 minutes opened intercellular junctions and markedly reduced the secretion of endothelin. HUVECs in suspension culture did not secrete endothelin and failed to respond to TNFalpha, but readily resumed these functions upon forming a new monolayer on plastic. The reconstitution of intercellular junctions after suspension culture could be inhibited using a specific anti-VE-cadherin antibody. This antibody, but not a non-specific anti-human-IgG antibody reduced endothelin secretion. The secretion of von Willebrand Factor was less dependent on intercellular junctions. The opening of intercellular junctions did not induce cell death, since the cells continued to exclude trypan blue. The results of this study suggest a novel and potentially pathophysiologically/clinically relevant correlation between intercellular junctions and the secretion of endothelin in endothelial cells.

• Cell-cell contacts in the human cell line ECV304 exhibit both endothelial and epithelial characteristics.

  Authors: F Kiessling, J Kartenbeck, C Haller

  Cell and tissue research. 08/1999; 297(1):131-40.

  Endothelial cells separate the intra- and extravascular space and regulate transport processes between these compartments. Since intercellular junctions are required for these specific cellEndothelial cells separate the intra- and extravascular space and regulate transport processes between these compartments. Since intercellular junctions are required for these specific cell functions, the cell-cell contacts in the permanent cell line ECV304 were systematically analyzed and compared with human umbilical vein endothelial cells (HUVECs) in primary culture and with the epithelial Madin Darby Canine Kidney (MDCK) cell line. Filter-grown ECV304 cells generate a distinct electrical resistance and a permeability barrier between cell culture compartments. Electron microscopy of ECV304 cells revealed lateral membrane interdigitations, typically found in endothelial cells in vivo, with direct membrane contact sites, which prevented the diffusion of lanthanum. By immunoblot and immunofluorescence analysis, the expression and cellular localization of the tight junction and adherens-type junction proteins occludin, ZO-1, symplekin, beta-catenin, and plakoglobin were analyzed. ECV304 cells display further characteristics of endothelial cells, including the expresssion of thrombomodulin and of the vitronectin receptor CD51, as well as the secretion of plasminogen activator inhibitor 1 (PAI-1) and endothelin. However, ECV304 cells also express proteins characteristically found in epithelial cells, including E-cadherin and the desmosomal proteins desmoplakin, desmocollin, and desmoglein; occasionally desmosomal structures can be identified by electron microscopy. In conclusion, ECV304 cells express many endothelial markers and form specialized intercellular junctions that display some epithelial features. Thus this reportedly endothelial-derived permanent human cell line may be dedifferentiated toward an epithelial phenotype.

• Polarized expression of heterologous membrane proteins transfected in a human endothelial-derived cell line.

  Authors: C Haller, F Kiessling, W Kübler

  European journal of cell biology. 05/1998; 75(4):353-61.

  The generation and maintenance of cell polarity in endothelial cells is poorly understood, partly because of a lack of a permanent endothelial in vitro model system. Here we evaluated theThe generation and maintenance of cell polarity in endothelial cells is poorly understood, partly because of a lack of a permanent endothelial in vitro model system. Here we evaluated the spontaneously immortalized human endothelial-derived cell line ECV304 as an in vitro model system for the study of the polarized expression of heterologous membrane proteins. Several stable ECV304 clones were generated by calcium phosphate transfection/G418 selection with cDNAs encoding membrane proteins of known cell surface distribution in the epithelial Madin Darby canine kidney (MDCK) cell line: influenza hemagglutinin and uvomorulin/E-cadherin were used as markers for the apical, respectively lateral cell membrane, the human lymphocyte surface marker CD7 served as an example of a circumferentially distributed membrane protein. Analysis of the transfected ECV304 clones using conventional and confocal immunofluorescence microscopy and immunoelectron microscopy revealed the same membrane distribution of the heterologous proteins in ECV304 cells as in MDCK cells. This polarized expression of heterologous membrane proteins in the endothelial-derived ECV304 cell line indicates efficient protein sorting/membrane trafficking mechanisms. The apical, lateral and basal cell membrane domains could be distinguished in ECV304 cells by confocal immunofluorescence microscopy. The permanent endothelial-derived ECV304 cell line may be a useful in vitro model system for the study of endothelial cell polarity.

• Molecular profiling of angiogenesis with targeted ultrasound imaging: early assessment of antiangiogenic therapy effects

  Authors: M. Palmowski, J. Huppert, G. Ladewig, P. Hauff, M. Reinhardt, M. M. Mueller, E. C. Woenne, J. W. Jenne, M. Maurer, G. W. Kauffmann, W. Semmler, F. Kiessling

  Mol Cancer Ther. 7(1):101-9.

  Molecular ultrasound is capable of elucidating the expression of angiogenic markers in vivo. However, the capability of the method for volumetric "multitarget quantification" and for the assessmentMolecular ultrasound is capable of elucidating the expression of angiogenic markers in vivo. However, the capability of the method for volumetric "multitarget quantification" and for the assessment of antiangiogenic therapy response has rather been investigated. Therefore, we generated cyanoacrylate microbubbles linked to vascular endothelial growth factor receptor 2 (VEGFR2) and alphavbeta3 integrin binding ligands and quantified their accumulation in squamous cell carcinoma xenografts (HaCaT-ras-A-5RT3) in mice with the quantitative volumetric ultrasound scanning technique, sensitive particle acoustic quantification. Specificity of VEGFR2 and alphavbeta3 integrin binding microbubbles was shown, and changes in marker expression during matrix metalloproteinase inhibitor treatment were investigated. In tumors, accumulation of targeted microbubbles was significantly higher compared with nonspecific ones and could be inhibited competitively by addition of the free ligand in excess. Also, multimarker imaging could successfully be done during the same imaging session. Molecular ultrasound further indicated a significant increase of VEGFR2 and alphavbeta3 integrin expression during tumor growth and a considerable decrease in both marker densities after matrix metalloproteinase inhibitor treatment. Histologic data suggested that the increasing VEGFR2 and alphavbeta3 integrin concentrations in tumors during growth are related to an up-regulation of its expression by the endothelial cells, whereas its decrease under therapy is more related to the decreasing relative vessel density. In conclusion, targeted ultrasound appears feasible for the longitudinal molecular profiling of tumor angiogenesis and for the sensitive assessment of therapy effects in vivo.