Fluorescent microsphere technique to measure cerebral blood flow in the rat

The present protocol describes a method for parallel measurement of cerebral blood flow (CBF) using fluorescent microspheres and structural assessment of the same material. The method is based on the standard microsphere technique, embolizing capillaries proportional to the blood flow, but requires dissolution of the tissue to retrieve the microspheres. To link the blood flow to the tissue morphology we modified the technique to fluorescent microspheres, which are quantified in cryo- or vibratome sections, allowing structural analysis by, for example, immunohistochemistry or standard histology. The protocol takes 8 h 50 min, without pauses, to complete, but additional flow measurements or specific protocols can increase the time needed.     

Intrahepatic Vascular Anatomy in Rats and Mice—Variations and Surgical Implications

Introduction

The intra-hepatic vascular anatomy in rodents, its variations and corresponding supplying and draining territories in respect to the lobar structure of the liver have not been described. We performed a detailed anatomical imaging study in rats and mice to allow for further refinement of experimental surgical approaches.

Methods

LEWIS-Rats and C57Bl/6N-Mice were subjected to ex-vivo imaging using μCT. The image data were used for semi-automated segmentation to extract the hepatic vascular tree as prerequisite for 3D visualization. The underlying vascular anatomy was reconstructed, analysed and used for determining hepatic vascular territories.

Results

The four major liver lobes have their own lobar portal supply and hepatic drainage territories. In contrast, the paracaval liver is supplied by various small branches from right and caudate portal veins and drains directly into the vena cava. Variations in hepatic vascular anatomy were observed in terms of branching pattern and distance of branches to each other. The portal vein anatomy is more variable than the hepatic vein anatomy. Surgically relevant variations were primarily observed in portal venous supply.

Conclusions

For the first time the key variations of intrahepatic vascular anatomy in mice and rats and their surgical implications were described. We showed that lobar borders of the liver do not always match vascular territorial borders. These findings are of importance for the design of new surgical procedures and for understanding eventual complications following hepatic surgery.     

Quantitative evaluation of the phagocytic activity of endothelial cells in culture

The phagocytic activity of endothelial cells (EC) from human umbilical vein was analysed quantitatively in primary culture. EC were incubated with fluorescent carboxylated microspheres (FCM) and the intensity of fluorescence was measured on spectrofluorimeter. It was found that EC phagocyted actively only FCM of limited diameter (not more than 0.26 mu). The most intensive phagocytosis occurred in the first 60 min of the experiment, the following incubation with FCM did not influence significantly the number of phagocyted particles but increased nonspecific binding. High doses of FCM stimulated phagocytosis within EC. The phagocytic activity of EC depended on the growth stage: it was maximum in proliferated cells and sharply decreased in confluent cultures. This method may be useful for the comparison of phagocytic activity of different cell types, as well as for drug testing.     

Comparison of Partial Volume Effects in Arterial and Venous Contrast Curves in CT Brain Perfusion Imaging

Purpose

In brain CT perfusion (CTP), the arterial contrast bolus is scaled to have the same area under the curve (AUC) as the venous outflow to correct for partial volume effects (PVE). This scaling is based on the assumption that large veins are unaffected by PVE. Measurement of the internal carotid artery (ICA), usually unaffected by PVE due to its large diameter, may avoid the need for partial volume correction. The aims of this work are to examine i) the assumptions behind PVE correction and ii) the potential of selecting the ICA obviating correction for PVE.

Methods

The AUC of the ICA and sagittal sinus were measured in CTP datasets from 52 patients. The AUCs were determined by i) using commercial CTP software based on a Gaussian curve-fitting to the time attenuation curve, and ii) by simple integration of the time attenuation curve over a time interval. In addition, frames acquired up to 3 minutes after first bolus passage were used to examine the ratio of arterial and venous enhancement. The impact of selecting the ICA without PVE correction was illustrated by reporting cerebral blood volume (CBV) measurements.

Results

In 49 of 52 patients, the AUC of the ICA was significantly larger than that of the sagittal sinus (p = 0.017). Measured after the first pass bolus, contrast enhancement remained 50% higher in the ICA just after the first pass bolus, and 30% higher 3 minutes later. CBV measurements were significantly lowered when the ICA was used without PVE correction.

Conclusions

Contradicting the assumptions underlying PVE correction, contrast in the ICA was significantly higher than in the sagittal sinus, even 3 minutes after the first pass of the contrast bolus. PVE correction might lead to overestimation of CBV if the CBV is calculated using the AUC of the time attenuation curves.     

Tracking morphogenetic tissue deformations in the early chick embryo

Embryonic epithelia undergo complex deformations (e.g. bending, twisting, folding, and stretching) to form the primitive organs of the early embryo. Tracking fiducial markers on the surfaces of these cellular sheets is a well-established method for estimating morphogenetic quantities such as growth, contraction, and shear. However, not all surface labeling techniques are readily adaptable to conventional imaging modalities and possess different advantages and limitations. Here, we describe two labeling methods and illustrate the utility of each technique. In the first method, hundreds of fluorescent labels are applied simultaneously to the embryo using magnetic iron particles. These labels are then used to quantity 2-D tissue deformations during morphogenesis. In the second method, polystyrene microspheres are used as contrast agents in non-invasive optical coherence tomography (OCT) imaging to track 3-D tissue deformations. These techniques have been successfully implemented in our lab to study the physical mechanisms of early head fold, heart, and brain development, and should be adaptable to a wide range morphogenetic processes.     

超声造影对肝硬化和肝纤维化的应用价值

目的：评估超声造影对于肝硬化和肝纤维化的I临床应用价值。方法：选取2011年5月至2013年5月在我院接受诊治的慢性病毒性肝炎患者32例,其中肝纤维化24例,肝硬化12例,均经过超声造影下的肝功能检测和肝穿刺病理证实。另选取10例到我院经检查身体健康的志愿者作为对照组,无任何肝脏病史。采用实时灰阶造影,经肘静脉注射造影SonoVue,记录测定造影剂进入肝静脉到达时间（HVAT）、肝动脉到达时间（HAAT）及肝动静脉渡越时间（HAVTT）。结果：肝纤维化组超声造影剂到达肝静脉的时间较对照组明显延长,肝硬化组较对照组和肝纤维化组的超声造影剂到达肝静脉的时间要明显缩短,差异符合统计学意义（P〈0．05）;造影剂到达肝动脉的时间组间比较无统计学差异;肝硬化组肝动静脉渡越时间（HAVTT）较对照组时间明显缩短,组间比较具有统计学差异（P〈0．05）;HAVTT随着肝纤维化程度的升高而缩短,中、重度肝纤维化患者的时间缩短较明显,差异具有统计学意义（P〈0．05）。结论：超声造影在肝硬化和肝纤维化诊断上具有一定的临床诊断价值,尤其是对于诊断肝纤维化程度具有重要的参考价值,可以更好地指导临床治疗,但是对于轻度的肝纤维化的诊断的准确性上有些缺陷。     

Hepatic clearance of Sonazoid perfluorobutane microbubbles by Kupffer cells does not reduce the ability of liver to phagocytose or degrade albumin microspheres

This study has been performed to examine which cells are responsible for the hepatic clearance of the new ultrasound contrast agent Sonazoid and to study whether uptake of these gas microbubbles disturbs the function of the cells involved. Sonazoid was injected into rats and perfused fixed livers were studied by electron microscopy, which revealed that the Sonazoid microbubbles were exclusively internalised in Kupffer cells, i.e. by the macrophages located in the liver sinusoids, and not by parenchymal, stellate or endothelial cells. This is the first demonstration of intact phagocytosed gas microbubbles within Kupffer cells. Uptake of the Sonazoid perfluorobutane microbubbles by the Kupffer cells following injection of a dose corresponding to 20x the anticipated clinical dose for liver imaging did not result in measurable changes in the uptake and degradation of radioactively labelled albumin microspheres previously shown to be a useful indicator marker for Kupffer cell phagocytosis.     

Hepatic fibrogenesis using chronic arsenic ingestion: studies in a murine model

Chronic oral arsenic (As) ingestion has been alleged to cause hepatic fibrosis, non-cirrhotic portal fibrosis and cirrhosis of the liver. The present study was aimed to investigate if hepatic fibrogenesis and non-cirrhotic portal fibrosis (NCPF) is caused by arsenic. A significant increase in the hepatic protein and collagen was seen compared with controls; hepatic 4-hydroxyproline levels, indicative of fibrogenesis, were increased 4-14 folds with different dosages of arsenic compared to the controls. Hepatocellular necrosis and inflammation were negligible to mild in all the groups. None of the animals developed significant splenomegaly or features of non-cirrhotic portal hypertension. The results suggest that (i) prolonged oral arsenic ingestion in mice leads to significant hepatic fibrogenesis and collagen synthesis with minimal hepato-cellular injury; (ii) arsenic ingestion alone is unlikely to cause non-cirrhotic portal fibrosis or cirrhosis of liver. This murine model of arsenic feeding could be used for the evaluation of new antifibrotic agents for the liver.     

Synthesis and Characterization of Dual-Functionalized Core-Shell Fluorescent Microspheres for Bioconjugation and Cellular Delivery

The efficient transport of micron-sized beads into cells, via a non-endocytosis mediated mechanism, has only recently been described. As such there is considerable scope for optimization and exploitation of this procedure to enable imaging and sensing applications to be realized. Herein, we report the design, synthesis and characterization of fluorescent microsphere-based cellular delivery agents that can also carry biological cargoes. These core-shell polymer microspheres possess two distinct chemical environments; the core is hydrophobic and can be labeled with fluorescent dye, to permit visual tracking of the microsphere during and after cellular delivery, whilst the outer shell renders the external surfaces of the microspheres hydrophilic, thus facilitating both bioconjugation and cellular compatibility. Cross-linked core particles were prepared in a dispersion polymerization reaction employing styrene, divinylbenzene and a thiol-functionalized co-monomer. These core particles were then shelled in a seeded emulsion polymerization reaction, employing styrene, divinylbenzene and methacrylic acid, to generate orthogonally functionalized core-shell microspheres which were internally labeled via the core thiol moieties through reaction with a thiol reactive dye (DY630-maleimide). Following internal labeling, bioconjugation of green fluorescent protein (GFP) to their carboxyl-functionalized surfaces was successfully accomplished using standard coupling protocols. The resultant dual-labeled microspheres were visualized by both of the fully resolvable fluorescence emissions of their cores (DY630) and shells (GFP). In vitro cellular uptake of these microspheres by HeLa cells was demonstrated conventionally by fluorescence-based flow cytometry, whilst MTT assays demonstrated that 92% of HeLa cells remained viable after uptake. Due to their size and surface functionalities, these far-red-labeled microspheres are ideal candidates for in vitro, cellular delivery of proteins.     

Development of high-sensitivity near-infrared fluorescence imaging device for early cancer detection

We have developed a high-sensitivity near-infrared (NIR) optical imaging system for noninvasive cancer detection based on the molecular-labeled fluorescent contrast agents. Recent developments in molecular beacons offer a way to selectively tag various precancer and cancer signatures and provide high tumor-to-background contrast. Near-infrared imaging can deeply probe tissue up to a couple of centimeters; thus, it possesses the potential for noninvasive detection of breast or lymph node cancer. A phase cancellation (in- and antiphase) device is used to increase the sensitivity in detecting fluorescent photons and the accuracy of tumor localization. The optoelectronic system consists of the laser diode sources, fiber optics, interference filter (to select the fluorescent photons), and the high-sensitivity photon detector (photomultiplier tube). The source-detector pair scans the tissue surface in multiple directions, and the localization image can be obtained by angular back-projection reconstruction. Simulations and experimental data demonstrated the feasibility of detection and localization offluorescent object embedded inside the highly scattering media. Tumor-bearing mouse model with injection of fluorescent contrast agents is used to simulate the human breast tumor labeled with molecular beacons. The system can detect fluorescent contrast agents as small as one nanomole at the depth of three centimeters, with a three-millimeter localization error. This instrument has the potential for tumor diagnosis and imaging, and the accuracy of the localization suggests that this system could help guide the clinical fine-needle biopsy. Also, this portable device would be complementary to x-ray mammography and provide add-on information on early diagnosis and localization of breast tumor.     

Transarterial RAdioembolization versus ChemoEmbolization for the treatment of hepatocellular carcinoma (TRACE): study protocol for a randomized controlled trial

ABSTRACT: BACKGROUND: Hepatocellular carcinoma is a primary malignant tumor of the liver that accounts for an important health problem worldwide. Only 10 to 15% of hepatocellular carcinoma patients are suitable candidates for treatment with curative intent, such as hepatic resection and liver transplantation. A majority of patients have locally advanced, liver restricted disease (Barcelona Clinic Liver Cancer (BCLC) staging system intermediate stage). Transarterial loco regional treatment modalities offer palliative treatment options for these patients; transarterial chemoembolization (TACE) is the current standard treatment. During TACE, a catheter is advanced into the branches of the hepatic artery supplying the tumor, and a combination of embolic material and chemotherapeutics is delivered through the catheter directly into the tumor. Yttrium-90 radioembolization (90Y-RE) involves the transarterial administration of minimally embolic microspheres loaded with Yttrium-90, a beta-emitting isotope, delivering selective internal radiation to the tumor. 90Y-RE is increasingly used in clinical practice for treatment of intermediate stage hepatocellular carcinoma, but its efficacy has never been prospectively compared to that of the standard treatment (TACE). In this study, we describe the protocol of a multicenter randomized controlled trial aimed at comparing the effectiveness of TACE and 90Y-RE for treatment of patients with unresectable (BCLC intermediate stage) hepatocellular carcinoma.Methods/designIn this pragmatic randomized controlled trial, 140 patients with unresectable (BCLC intermediate stage) hepatocellular carcinoma, with Eastern Cooperative Oncology Group performance status 0 to 1 and Child-Pugh A to B will be randomly assigned to either 90Y-RE or TACE with drug eluting beads. Patients assigned to 90Y-RE will first receive a diagnostic angiography, followed by the actual transarterial treatment, which can be divided into two sessions in case of bilobar disease. Patients assigned to TACE will receive a maximum of three consecutive transarterial treatment sessions. Patients will undergo structural follow-up for a timeframe of two years post treatment. Post procedural magnetic resonance imaging (MRI) will be performed at one and three months post trial entry and at three-monthly intervals thereafter for two years to assess tumor response. Primary outcome will be time to progression. Secondary outcomes will be overall survival, tumor response according to the modified RECIST criteria, toxicities/adverse events, treatment related effect on total liver function, quality of life, treatment-related costs and cost-effectiveness.Trial registrationNCT01381211.     

Quantitative phase imaging of cells in a flow cytometry arrangement utilizing Michelson interferometer‐based off‐axis digital holographic microscopy

We combined Michelson‐interferometer‐based off‐axis digital holographic microscopy (DHM) with a common flow cytometry (FCM) arrangement. Utilizing object recognition procedures and holographic autofocusing during the numerical reconstruction of the acquired off‐axis holograms, sharply focused quantitative phase images of suspended cells in flow were retrieved without labeling, from which biophysical cellular features of distinct cells, such as cell radius, refractive index and dry mass, can be subsequently retrieved in an automated manner. The performance of the proposed concept was first characterized by investigations on microspheres that were utilized as test standards. Then, we analyzed two types of pancreatic tumor cells with different morphology to further verify the applicability of the proposed method for quantitative live cell imaging. The retrieved biophysical datasets from cells in flow are found in good agreement with results from comparative investigations with previously developed DHM methods under static conditions, which demonstrates the effectiveness and reliability of our approach. Our results contribute to the establishment of DHM in imaging FCM and prospect to broaden the application spectrum of FCM by providing complementary quantitative imaging as well as additional biophysical cell parameters which are not accessible in current high‐throughput FCM measurements.     

The use of CdTe quantum dot fluorescent microspheres in fluoro-immunoassays and a microfluidic chip system.

Polystyrene fluorescent microspheres prepared by deposition of CdTe quantum dots (QDs) are used in an immunoassay in this study. CdTe QDs/polyelectrolyte multilayers on the surface of polystyrene microspheres have been formed by layer-by-layer self-assembly via electrostatic interactions. As a model antigen, rabbit IgG has been bound to the outermost layer of the fluorescent microspheres. The immunoreaction between fluorescent microspheres/rabbit IgG and the corresponding antibody was confirmed by change of the fluorescence spectrum and competitive immunoassay. This approach allowed detection of the antigen (rabbit IgG) in the range 1-500 mg/L, based on the change in the fluorescence intensity of the reporter (fluorescent microspheres/rabbit IgG). A novel microfluidic chip device with a laser-induced fluorescence system was established and used for the detection of fluorescent microspheres in this study.     

X-ray Phase Contrast Imaging of Cell Isolation with Super-Paramagnetic Microbeads

Super-paramagnetic microbeads are widely used for cell isolation. Evaluation of the binding affinity of microbeads to cells using optical microscopy has been limited by its small scope. Here, magnetic property of microbeads was first investigated by using synchrotron radiation (SR) in-line x-ray phase contrast imaging (PCI). The cell line mouse LLC (Lewis lung carcinoma) was selected for cell adhesion studies. Targeted microbeads were prepared by attaching anti-VEGFR2 (vascular endothelial growth factor receptor-2) antibody to the shell of the microbeads. The bound microbeads were found to better adhere to LLC cells than unbound ones. PCI dynamically and clearly showed the magnetization and demagnetization of microbeads in PE-50 tube. The cells incubated with different types of microbeads were imaged by PCI, which provided clear and real-time visualization of the cell isolation. Therefore, PCI might be considered as a novel and efficient tool for further cell isolation studies.     

Proximal embolic protection in patients undergoing primary angioplasty for acute myocardial infarction (PREPARE): core lab adjudicated angiographic outcomes of a randomised controlled trial

Background. Patients with ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI) with the Proxis system (St. Jude Medical, St. Paul, MN, USA) achieved significantly better microvascular flow as measured by ST-segment resolution. However, no differences were observed in left ventricular ejection fraction or infarct size as obtained by cardiovascular magnetic resonance imaging. The goal of the present study was to evaluate the effect of combined proximal embolic protection and thrombus aspiration on core-lab adjudicated angiographic outcomes.Methods. In the PRoximal Embolic Protection in Acute myocardial infarction and Resolution of ST-Elevation (PREPARE) study, patients were randomised to primary PCI with the Proxis system (n=141) or primary PCI alone (n=143). An independent core laboratory re-evaluated all angiograms and adjudicated the angiographic outcomes and computerised quantitative blush evaluation (QuBE) value.Results. There were no significant differences in Thrombolysis In Myocardial Infarction (TIMI) flow grade, myocardial blush grade, or angiographic signs of distal embolisation among the two arms. QuBE values did not significantly differ between the Proxis-treated patients and control patients (15.1±5.4 vs. 15.8±5.5, respectively, p=0.34).Conclusion. Primary PCI with combined proximal embolic protection and thrombus aspiration in STEMI patients more frequently resulted in complete immediate ST resolution compared with control patients. However, there were no significant differences in core laboratory adjudicated angiographic outcomes. (Neth Heart J 2010;18:531–6.)     

HER2 targeted molecular MR imaging using a de novo designed protein contrast agent

The application of magnetic resonance imaging (MRI) to non-invasively assess disease biomarkers has been hampered by the lack of desired contrast agents with high relaxivity, targeting capability, and optimized pharmacokinetics. We have developed a novel MR imaging probe targeting to HER2, a biomarker for various cancer types and a drug target for anti-cancer therapies. This multimodal HER20targeted MR imaging probe integrates a de novo designed protein contrast agent with a high affinity HER2 affibody and a near IR fluorescent dye. Our probe can differentially monitor tumors with different expression levels of HER2 in both human cell lines and xenograft mice models. In addition to its 100-fold higher dose efficiency compared to clinically approved non-targeting contrast agent DTPA, our developed agent also exhibits advantages in crossing the endothelial boundary, tissue distribution, and tumor tissue retention over reported contrast agents as demonstrated by even distribution of the imaging probe across the entire tumor mass. This contrast agent will provide a powerful tool for quantitative assessment of molecular markers, and improved resolution for diagnosis, prognosis and drug discovery.     

Portal venous endothelium in developing human liver contains haematopoietic and epithelial progenitor cells

Future treatments for chronic liver disease are likely to involve manipulation of liver progenitor cells (LPCs). In the human, data characterising the regenerative response is limited and the origin of adult LPCs is unknown. However, these remain critical factors in the design of cell-based liver therapies. The developing human liver provides an ideal model to study cell lineage derivation from progenitors and to understand how foetal haematopoiesis and liver development might explain the nature of the adult LPC population. In 1st trimester human liver, portal venous endothelium (PVE) expressed adult LPC markers and markers of haematopoietic progenitor cells (HPCs) shared with haemogenic endothelium found in the embryonic dorsal aorta. Sorted PVE cells were able to generate hepatoblast-like cells co-expressing CK18 and CK19 in addition to Dlk/pref-1, E-cadherin, albumin and fibrinogen in vitro. Furthermore, PVE cells could initiate haematopoiesis. These data suggest that PVE shares phenotypical and functional similarities both with adult LPCs and embryonic haemogenic endothelium. This indicates that a temporal relationship might exist between progenitor cells in foetal liver development and adult liver regeneration, which may involve progeny of PVE.     

大鼠门静脉分支残端置管模型构建及细胞移植途径的评价

目的：大鼠肝部分切除模型被广泛的应用于肝脏疾病的研究,随着干细胞治疗肝损伤及护肝药物研究的发展,对大鼠肝损伤模型也提出了很多新的要求。本实验拟在大鼠肝部分切除术的基础上改进以建立大鼠肝断面门静脉分支残端的静脉置管模型,并进行细胞移植实验,对比分析新模型的优劣。方法：60只F344大鼠分为三组。A、B组行行85％肝切除术;C组行85％肝切除术＋肝断面门静脉分支残端置管术。术中B组经门静脉注入4×105个表达GFP（greenfluorescenceprotein,GFP）的胎肝干细胞（fetalliverstern／progenitorcells,FLSPCs）。c组经留置导管注射入同等量的FLSPCs,A组注射同等剂量的培养液。72小时取血清,测定肝功能ALT、AST,统计死亡率;取肝脏组织切片观察其修复情况。统计学采用方差分析和LSD—t检验。结果：B、C组F344大鼠72小时肝功指标（ALT、AST）均明显优于A组;B组、C组肝脏组织学的病理损伤的恢复分别较A组快。B、C组间肝功指标无统计学意义。结论：经门静脉分支残端置管途径移植FLSPCs效果等同于经门静脉穿刺途径,且该模型具有可反复、可选时、减少创伤等优点。     

Comparative Assessment of Substrates and Activity Based Probes as Tools for Non-Invasive Optical Imaging of Cysteine Protease Activity

Recent advances in the field of non-invasive optical imaging have included the development of contrast agents that report on the activity of enzymatic targets associated with disease pathology. In particular, proteases have proven to be ideal targets for development of optical sensors for cancer. Recently developed contrast agents for protease activity include both small peptides and large polymer-based quenched fluorescent substrates as well as fluorescently labeled activity based probes (ABPs). While substrates produce a fluorescent signal as a result of processing by a protease, ABPs are retained at the site of proteolysis due to formation of a permanent covalent bond with the active site catalytic residue. Both methods have potential advantages and disadvantages yet a careful comparison of substrates and ABPs has not been performed. Here we present the results of a direct comparison of commercially available protease substrates with several recently described fluorescent ABPs in a mouse model of cancer. The results demonstrate that fluorescent ABPs show more rapid and selective uptake into tumors as well as overall brighter signals compared to substrate probes. These data suggest that the lack of signal amplification for an ABP is offset by the increased kinetics of tissue uptake and prolonged retention of the probes once bound to a protease target. Furthermore, fluorescent ABPs can be used as imaging reagents with similar or better results as the commercially available protease substrates.