Augmentation of transgenic expression by ultrasound‑mediated liposome microbubble destruction.

Mol Med Report. 2012 Jan 25;

Authors: Chen ZY, Sun XF, Liu JQ, Bing ST, Qiu RX, Liang K, Liu JH, Liang WX, Zhou XX, Zhang H, Yu JX

Abstract
Non-invasive, efficient and tissue-specific transgenic technologies could be valuable in gene therapy. Although non‑viral carriers may be safer and cheaper, they have a much lower transfection efficiency than viral gene carriers. The present study was designed to test the transgenic expression and safety of red fluorescent protein (RFP) in HeLa cells in vitro and in transplanted tumors of nude mice in vivo under ultrasound-mediated liposome microbubble destruction (UMLMD) conditions. Plasmids containing RFP were gently mixed with liposome microbubbles (LMs). The mixture was added to HeLa cells or injected into BALB/c mice by the tail vein under various ultrasound exposure and LM parameters, and then the transfection efficiencies were examined. The results in vivo and in vitro demonstrated that, following a comparison of the plasmid group, the ultrasound + plasmid group and the LM + plasmid group, UMLMD significantly increased the transgenic expression (P<0.01) without causing any apparent detrimental effect. From the study, we concluded that UMLMD could be a non-invasive, effective and promising non-viral technique for gene therapy and transgenic research.

PMID: 22294278 [PubMed - as supplied by publisher]

In vivo functional and transcriptional profiling of bone marrow stem cells after transplantation into ischemic myocardium.

Arterioscler Thromb Vasc Biol. 2012 Jan;32(1):92-102

Authors: Sheikh AY, Huber BC, Narsinh KH, Spin JM, van der Bogt K, de Almeida PE, Ransohoff KJ, Kraft DL, Fajardo G, Ardigo D, Ransohoff J, Bernstein D, Fischbein MP, Robbins RC, Wu JC

Abstract
OBJECTIVE: Clinical trials of bone marrow-derived stem cell therapy for the heart have yielded variable results. The basic mechanism(s) that underlies their potential efficacy remains unknown. In the present study, we evaluated the survival kinetics, transcriptional response, and functional outcome of intramyocardial bone marrow mononuclear cell (BMMC) transplantation for cardiac repair in a murine myocardial infarction model.
METHODS AND RESULTS: We used bioluminescence imaging and high-throughput transcriptional profiling to evaluate the in vivo survival kinetics and gene expression changes of transplanted BMMCs after their engraftment into ischemic myocardium. Our results demonstrate short-lived survival of cells following transplant, with less than 1% of cells surviving by 6 weeks posttransplantation. Moreover, transcriptomic analysis of BMMCs revealed nonspecific upregulation of various cell regulatory genes, with a marked downregulation of cell differentiation and maturation pathways. BMMC therapy caused limited improvement of heart function as assessed by echocardiography, invasive hemodynamics, and positron emission tomography. Histological evaluation of cell fate further confirmed findings of the in vivo cell tracking and transcriptomic analysis.
CONCLUSIONS: Collectively, these data suggest that BMMC therapy, in its present iteration, may be less efficacious than once thought. Additional refinement of existing cell delivery protocols should be considered to induce better therapeutic efficacy.

PMID: 22034515 [PubMed - indexed for MEDLINE]

Three-dimensional photoacoustic tomography based on the focal-line concept.

J Biomed Opt. 2011 Sep;16(9):090505

Authors: Xia J, Guo Z, Maslov K, Aguirre A, Zhu Q, Percival C, Wang LV

Abstract
A full ring ultrasonic array-based photoacoustic tomography system was recently developed for small animal brain imaging. The 512-element array is cylindrically focused in the elevational direction, and can acquire a two-dimensional (2D) image in 1.6 s. In this letter, we demonstrate the three-dimensional (3D) imaging capability of this system. A novel 3D reconstruction algorithm was developed based on the focal-line concept. Compared to 3D images acquired simply by stacking a series of 2D images, the 3D focal-line reconstruction method renders images with much less artifacts, and improves the elevational resolution by 30% and the signal-to-noise ratio by two times. The effectiveness of the proposed algorithm was first validated by numerical simulations and then demonstrated with a hair phantom experiment and an ex vivo mouse embryo experiment.

PMID: 21950908 [PubMed - indexed for MEDLINE]

A fluorescent chromophore TOTO-3 as a 'smart probe' for the assessment of ultrasound-mediated local drug delivery in vivo.

Contrast Media Mol Imaging. 2011 Jul-Aug;6(4):267-74

Authors: Deckers R, Yudina A, Cardoit LC, Moonen CT

Abstract
Many potent anti-cancer drugs have an intracellular mode of action, but are limited in crossing the cell membrane, resulting in a reduced clinical efficacy. Ultrasound (US) is known to facilitate the penetration of drugs into tumors cells. However (molecular) imaging techniques that monitor in vivo the underlying processes of US-triggered drug delivery are lacking. The objective of this study was to demonstrate the feasibility of using a fluorescent nuclear acid stain (TOTO-3) as a model drug to monitor in real-time US-mediated delivery by in vivo fluorescence imaging. Following co-injection of TOTO-3 and microbubbles US was applied to the tumor. The time course of the drug delivery process was monitored by fluorescence imaging. Immunohistological analysis and in vitro experiments were performed to investigate the results in more detail. A significant signal intensity enhancement of the US-treated tumor was observed that indicates intracellular delivery of the dye. In the control tumor TOTO-3 signal was strongly associated with macrophages, which was not the case for the sonicated tumor. The capability of macrophages to uptake TOTO-3 was confirmed in vitro. This study demonstrates that an optical contrast agent with similar characteristics to an anti-cancer drug may be used for continuous in vivo monitoring of the drug delivery process.

PMID: 21861287 [PubMed - indexed for MEDLINE]

Investigation of glucose-modified liposomes using polyethylene glycols with different chain lengths as the linkers for brain targeting.

Int J Nanomedicine. 2012;7:163-75

Authors: Xie F, Yao N, Qin Y, Zhang Q, Chen H, Yuan M, Tang J, Li X, Fan W, Zhang Q, Wu Y, Hai L, He Q

Abstract
BACKGROUND: An intimidating challenge to transporting drugs into the brain parenchyma is the presence of the blood-brain barrier (BBB). Glucose is an essential nutritional substance for brain function sustenance, which cannot be synthesized by the brain. Its transport primarily depends on the glucose transporters on the brain capillary endothelial cells. In this paper, the brain-targeted properties of glucose-modified liposomes using polyethylene glycols with different chain lengths as the linkers were compared and evaluated to establish an optimized drug-delivery system.
METHODS: Coumarin 6-loaded liposomes (GLU200-LIP, GLU400-LIP, GLU1000-LIP, and GLU2000-LIP) composed of phospholipids and glucose-derived cholesterols were prepared by thin-film dispersion-ultrasound method. The BBB model in vitro was developed to evaluate the transendothelial ability of the different liposomes crossing the BBB. The biodistribution of liposomes in the mice brains was identified by in vivo and ex vivo nearinfrared fluorescence imaging and confocal laser scanning microscopy and further analyzed quantitatively by high-performance liquid chromatography.
RESULTS: Glucose-derived cholesterols were synthesized and identified, and coumarin 6-loaded liposomes were prepared successfully. The particle sizes of the four types of glucose-modified liposomes were around or smaller than 100 nm with a polydispersity index less than 0.300. GLU400-LIP, GLU1000-LIP, and GLU2000-LIP achieved higher cumulative cleared volumes on BBB model in vitro after 6 hours compared with GLU200-LIP (P < 0.05) and were significantly higher than that of the conventional liposome (P < 0.001). The qualitative and quantitative biodistribution results in the mice showed that the accumulation of GLU1000-LIP in the brain was the highest among all the groups (P < 0.01 versus LIP).
CONCLUSION: The data indicated that GLU400-LIP, GLU1000-LIP, and GLU2000-LIP all possess the potential of brain targeting, among which GLU1000-LIP, as a promising drug-delivery system, exhibited the strongest brain delivery capacity.

PMID: 22275832 [PubMed - in process]

Efficient suppression of murine ICAM-1 using ultrasound-responsive and mannose-modified lipoplexes inhibits acute hepatic inflammation.

Hepatology. 2012 Jan 23;

Authors: Un K, Kawakami S, Yoshida M, Higuchi Y, Suzuki R, Maruyama K, Yamashita F, Hashida M

Abstract
Hepatitis is often associated with the over-expression of various adhesion molecules. In particular, intracellular adhesion molecule-1 (ICAM-1), which is expressed on hepatic endothelial cells (HECs) in the early stage of inflammation, is involved in serious illnesses. Therefore, ICAM-1 suppression in HECs enables the suppression of inflammatory responses. Here, we developed an ICAM-1 siRNA transfer method using ultrasound (US)-responsive and mannose-modified liposome/ICAM-1 siRNA complexes (Man-PEG(2000) bubble lipoplexes; Man-PEG(2000) BLs), and achieved efficient HEC-selective ICAM-1 siRNA delivery in combination with US exposure. Moreover, the sufficient ICAM-1 suppression effects were obtained by this ICAM-1 siRNA transfer in vitro and in vivo, and potent anti-inflammatory effects were observed in various types of inflammation, such as lipopolysaccharide (LPS), dimethylnitrosamine (DMN), carbon tetrachloride (CCl(4) ), and ischemia-reperfusion (IR)-induced inflammatory mouse models. CONCLUSION: In the present study, we demonstrated that HEC-selective and efficient ICAM-1 siRNA delivery using Man-PEG(2000) BLs and US exposure enables to suppress various types of acute hepatic inflammation. This novel siRNA delivery method may offer a valuable system for medical treatment where the targeted cells are HECs. (HEPATOLOGY 2012.).

PMID: 22271390 [PubMed - as supplied by publisher]

Combination of ultrasound and bubble liposome enhance the effect of doxorubicin and inhibit murine osteosarcoma growth.

Cancer Biol Ther. 2011 Aug 15;12(4):270-7

Authors: Ueno Y, Sonoda S, Suzuki R, Yokouchi M, Kawasoe Y, Tachibana K, Maruyama K, Sakamoto T, Komiya S

Abstract
If ultrasound (US) is applied to cells, permeability across the cell membrane temporarily increases, making it easier for drugs to be taken into the cells from around the cell membrane. Moreover, when used in combination with Bubble liposome (BL: liposomes which entrap an ultrasound imaging gas), even low-power ultrasound can facilitate drug delivery into cells. In the present study, we constructed a new drug delivery system (DDS) involving concomitant use of US and BL with doxorubicin (DOX), a key drug in the chemotherapy of osteosarcoma, and demonstrated both in vitro and in vivo that it markedly inhibited the proliferation of osteosarcoma cells. Furthermore, this system achieved an equivalent antitumor effect at about 1/5 the dose of antitumor agent employed in monotherapy with DOX. These findings suggest the possibility of reduction of adverse events. In this experiment, US and liposomes were tested, both of which are already in use in clinical practice. US and liposomes are both very safe in the body. The DDS composed of these elements we designed can be applied in simple and site-specific fashion and is therefore promising as a new, clinically feasible method of treatment.

PMID: 21613828 [PubMed - indexed for MEDLINE]

High-Frequency Ultrasound for In Vivo Measurement of Colon Wall Thickness in Mice.

Ultrasound Med Biol. 2012 Jan 20;

Authors: Abdelrahman MA, Marston G, Hull MA, Markham AF, Jones PF, Evans JA, Coletta PL

Abstract
Mouse models are becoming increasingly important in the study of molecular mechanisms of colorectal disease and in the development of novel therapeutics. To enhance this phase of preclinical research, cost-effective, easy to use noninvasive imaging is required to detect and monitor changes in the colon wall associated with disease pathology. This study investigated the feasibility of using 40-MHz (high frequency) B-mode ultrasound (HF-US) to image the normal mouse colon and measure its thickness in vivo by establishing a robust imaging protocol and conducting a blinded comparison of colon wall thickness (CWT) measurement between and within operators. The in vivo and ex vivo appearance of mouse colon under HF-US revealed distinct patterns. Colon wall thickness was reproducibly and accurately measured using HF-US compared with histology measurement. The technique was more sensitive in detecting changes in CWT in distal than proximal colon as it showed the highest level of inter- and intraoperator reproducibility. Using the protocol described, it is possible to detect changes in thickness of 0.09 mm and 0.25 mm in distal and proximal colon, respectively. In conclusion, HF-US provides an easy to use and noninvasive method to perform anatomical investigations of mouse colon and to monitor changes in CWT.

PMID: 22266235 [PubMed - as supplied by publisher]

Cardiac-specific mindin overexpression attenuates cardiac hypertrophy via blocking AKT/GSK3β and TGF-β1-Smad signalling.

Cardiovasc Res. 2011 Oct 1;92(1):85-94

Authors: Yan L, Wei X, Tang QZ, Feng J, Zhang Y, Liu C, Bian ZY, Zhang LF, Chen M, Bai X, Wang AB, Fassett J, Chen Y, He YW, Yang Q, Liu PP, Li H

Abstract
AIMS: Mindin is a secreted extracellular matrix protein, an integrin ligand, and an angiogenesis inhibitor, other examples of which are all key players in the progression of cardiac hypertrophy. However, its function during cardiac hypertrophy remains unclear. This study was aimed to identify the effect of mindin on cardiac hypertrophy and the underlying mechanisms.
METHODS AND RESULTS: A significant down-regulation of mindin expression was observed in human failing hearts. To further investigate the role of mindin in cardiac hypertrophy, we used cultured neonatal rat cardiomyocytes with gain and loss of mindin function and cardiac-specific Mindin-overexpressing transgenic (TG) mice. In cultured cardiomyocytes, mindin negatively regulated angiotensin II (Ang II)-mediated hypertrophic growth, as detected by [(3)H]-Leucine incorporation, cardiac myocyte area, and hypertrophic marker protein levels. Cardiac hypertrophy in vivo was produced by aortic banding (AB) or Ang II infusion in TG mice and their wild-type controls. The extent of cardiac hypertrophy was evaluated by echocardiography as well as by pathological and molecular analyses of heart samples. Mindin overexpression in the heart markedly attenuated cardiac hypertrophy, fibrosis, and left ventricular dysfunction in mice in response to AB or Ang II. Further analysis of the signalling events in vitro and in vivo indicated that these beneficial effects of mindin were associated with the interruption of AKT/glycogen synthase kinase 3β (GSK3β) and transforming growth factor (TGF)-β1-Smad signalling.
CONCLUSION: The present study demonstrates for the first time that mindin serves as a novel mediator that protects against cardiac hypertrophy and the transition to heart failure by blocking AKT/GSK3β and TGF-β1-Smad signalling.

PMID: 21632881 [PubMed - indexed for MEDLINE]

Novel approach to admittance to volume conversion for ventricular volume measurement.

Conf Proc IEEE Eng Med Biol Soc. 2011 Aug;2011:2514-7

Authors: Kottam A, Dubois J, McElligott A, Henderson KK

Abstract
The conductance catheter is a widely used tool to determine ventricular volumes in animal models. A tetra-polar catheter is inserted into the ventricle to measure instantaneous conductance, which is a combination of ventricular blood and surrounding myocardium. Various techniques have been used to separate the blood conductance signal from the combined measured signal [1], [2]. The blood conductance is then converted to volume using a linear relationship proposed by Baan [1] or an improved non linear relationship proposed by Wei [3]. We propose a novel approach that uses the combined blood-muscle signal to calculate volume, thereby eliminating the need to subtract out the muscle. In vivo experiments were performed in mice to validate this new approach and the results were compared with volumes obtained using ultrasound imaging.

PMID: 22254852 [PubMed - in process]

In vivo flow cytometry: a horizon of opportunities.

Cytometry A. 2011 Oct;79(10):737-45

Authors: Tuchin VV, Tárnok A, Zharov VP

Abstract
Flow cytometry (FCM) has been a fundamental tool of biological discovery for many years. Invasive extraction of cells from a living organism, however, may lead to changes in cell properties and prevents studying cells in their native environment. These problems can be overcome by use of in vivo FCM, which provides detection and imaging of circulating normal and abnormal cells directly in blood or lymph flow. The goal of this review is to provide a brief history, features, and challenges of this new generation of FCM methods and instruments. Spectrum of possibilities of in vivo FCM in biological science (e.g., cell metabolism, immune function, or apoptosis) and medical fields (e.g., cancer, infection, and cardiovascular disorder) including integrated photoacoustic-photothermal theranostics of circulating abnormal cells are discussed with focus on recent advances of this new platform.

PMID: 21915991 [PubMed - indexed for MEDLINE]

In utero assessment of cardiovascular function in the embryonic mouse heart using high-resolution ultrasound biomicroscopy.

Methods Mol Biol. 2012;843:245-63

Authors: Golden HB, Sunder S, Liu Y, Peng X, Dostal DE

Abstract
Murine models are currently the preferred approach for studying the molecular mechanisms of cardiac dysfunction resulting from changes in gene expression. Transgenic and gene-targeting methods can be used to generate mice with altered cardiac size and function, and as a result, in vivo techniques are indispensible in evaluating cardiac phenotype. Traditionally, the pathologic assessment of sacrificed hearts was used to study cardiac pathophysiology in small animals. Below we describe the use of ultrasound biomicroscopy-Doppler analysis to temporally assess cardiac function in mouse embryos. Methods are described for obtaining 2D, pulsed-wave Doppler, and M-mode imaging using standard clinical cardiac ultrasound imaging planes.

PMID: 22222538 [PubMed - in process]

MR-guided pulsed high intensity focused ultrasound enhancement of docetaxel combined with radiotherapy for prostate cancer treatment.

Phys Med Biol. 2012 Jan 4;57(2):535-545

Authors: Mu Z, Ma CM, Chen X, Cvetkovic D, Pollack A, Chen L

Abstract
The purpose of this study is to evaluate the efficacy of the enhancement of docetaxel by pulsed focused ultrasound (pFUS) in combination with radiotherapy (RT) for treatment of prostate cancer in vivo. LNCaP cells were grown in the prostates of male nude mice. When the tumors reached a designated volume by MRI, tumor bearing mice were randomly divided into seven groups (n = 5): (1) pFUS alone; (2) RT alone; (3) docetaxel alone; (4) docetaxel + pFUS; (5) docetaxel + RT; (6) docetaxel + pFUS + RT, and (7) control. MR-guided pFUS treatment was performed using a focused ultrasound treatment system (InSightec ExAblate 2000) with a 1.5T GE MR scanner. Animals were treated once with pFUS, docetaxel, RT or their combinations. Docetaxel was given by i.v. injection at 5 mg kg(-1) before pFUS. RT was given 2 Gy after pFUS. Animals were euthanized 4 weeks after treatment. Tumor volumes were measured on MRI at 1 and 4 weeks post-treatment. Results showed that triple combination therapies of docetaxel, pFUS and RT provided the most significant tumor growth inhibition among all groups, which may have potential for the treatment of prostate cancer due to an improved therapeutic ratio.

PMID: 22217916 [PubMed - as supplied by publisher]

Label-free oxygen-metabolic photoacoustic microscopy in vivo.

J Biomed Opt. 2011 Jul;16(7):076003

Authors: Yao J, Maslov KI, Zhang Y, Xia Y, Wang LV

Abstract
Almost all diseases, especially cancer and diabetes, manifest abnormal oxygen metabolism. Accurately measuring the metabolic rate of oxygen (MRO(2)) can be helpful for fundamental pathophysiological studies, and even early diagnosis and treatment of disease. Current techniques either lack high resolution or rely on exogenous contrast. Here, we propose label-free metabolic photoacoustic microscopy (mPAM) with small vessel resolution to noninvasively quantify MRO(2) in vivo in absolute units. mPAM is the unique modality for simultaneously imaging all five anatomical, chemical, and fluid-dynamic parameters required for such quantification: tissue volume, vessel cross-section, concentration of hemoglobin, oxygen saturation of hemoglobin, and blood flow speed. Hyperthermia, cryotherapy, melanoma, and glioblastoma were longitudinally imaged in vivo. Counterintuitively, increased MRO(2) does not necessarily cause hypoxia or increase oxygen extraction. In fact, early-stage cancer was found to be hyperoxic despite hypermetabolism.

PMID: 21806264 [PubMed - indexed for MEDLINE]

Physiology and cell biology of acupuncture observed in calcium signaling activated by acoustic shear wave.

Pflugers Arch. 2011 Oct;462(4):587-97

Authors: Li G, Liang JM, Li PW, Yao X, Pei PZ, Li W, He QH, Yang X, Chan QC, Cheung PY, Ma QY, Lam SK, Cheng PY, Yang ES

Abstract
This article presents a novel model of acupuncture physiology based on cellular calcium activation by an acoustic shear wave (ASW) generated by the mechanical movement of the needle. An acupuncture needle was driven by a piezoelectric transducer at 100 Hz or below, and the ASW in human calf was imaged by magnetic resonance elastography. At the cell level, the ASW activated intracellular Ca(2+) transients and oscillations in fibroblasts and endothelial, ventricular myocytes and neuronal PC-12 cells along with frequency-amplitude tuning and memory capabilities. Monitoring in vivo mammalian experiments with ASW, enhancement of endorphin in blood plasma and blocking by Gd(3+) were observed; and increased Ca(2+) fluorescence in mouse hind leg muscle was imaged by two-photon microscopy. In contrast with traditional acupuncture models, the signal source is derived from the total acoustic energy. ASW signaling makes use of the anisotropy of elasticity of tissues as its waveguides for transmission and that cell activation is not based on the nervous system.

PMID: 21796340 [PubMed - indexed for MEDLINE]

Failure of annexin-based apoptosis imaging in the assessment of antiangiogenic therapy effects.

EJNMMI Res. 2011;1(1):26

Authors: Lederle W, Arns S, Rix A, Gremse F, Doleschel D, Schmaljohann J, Mottaghy FM, Kiessling F, Palmowski M

Abstract
UNLABELLED: ABSTRACT:
BACKGROUND: Molecular apoptosis imaging is frequently discussed to be useful for monitoring cancer therapy. We demonstrate that the sole assessment of therapy effects by apoptosis imaging can be misleading, depending on the therapy effect on the tumor vasculature.
METHODS: Apoptosis was investigated by determining the uptake of Annexin Vivo by optical imaging (study part I) and of 99 mTc-6-hydrazinonicotinic [HYNIC]-radiolabeled Annexin V by gamma counting (study part II) in subcutaneous epidermoid carcinoma xenografts (A431) in nude mice after antiangiogenic treatment (SU11248). Optical imaging was performed by optical tomography (3D) and 2D reflectance imaging (control, n = 7; therapy, n = 6). Accumulation of the radioactive tracer was determined ex vivo (control, n = 5; therapy, n = 6). Tumor vascularization was investigated with an optical blood pool marker (study part I) and contrast-enhanced ultrasound (both studies). Data were validated by immunohistology.
RESULTS: A significantly higher apoptosis rate was detected in treated tumors by immunohistological terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining (area fraction: control, 0.023 ± 0.015%; therapy, 0.387 ± 0.105%; P < 0.001). However, both 2D reflectance imaging using Annexin Vivo (control, 13 ± 15 FI/cm2; therapy, 11 ± 7 FI/cm2) and gamma counting using 99 mTc-HYNIC-Annexin V (tumor-to-muscle ratio control, 5.66 ± 1.46; therapy, 6.09 ± 1.40) failed in showing higher accumulation in treated tumors. Optical tomography even indicated higher probe accumulation in controls (control, 81.3 ± 73.7 pmol/cm3; therapy, 27.5 ± 34.7 pmol/cm3). Vascularization was strongly reduced after therapy, demonstrated by contrast-enhanced ultrasound, optical imaging, and immunohistology.
CONCLUSIONS: The failure of annexin-based apoptosis assessment in vivo can be explained by the significant breakdown of the vasculature after therapy, resulting in reduced probe/tracer delivery. This favors annexin-based apoptosis imaging only in therapies that do not severely interfere with the vasculature.

PMID: 22214377 [PubMed - in process]

In Vivo Monitoring of Venous Thrombosis in Mice.

J Thromb Haemost. 2011 Dec 30;

Authors: Aghourian MN, Lemarié CA, Blostein MD

Abstract
Background: Venous thrombosis (VT) is an important cause of morbidity and mortality in clinical medicine. Animal models studying venous thrombosis are scarce and, in most cases, very crude and rely on sacrificing the animals to excise formed thrombi. Developing an in vivo murine model of venous thrombosis can be a powerful tool for studying venous thrombosis. Objectives: We sought to use a high-frequency ultrasound system (HFUS) to dynamically and noninvasively monitor thrombus formation in the inferior vena cava (IVC) of mice. Methods: We developed a murine model of venous thrombosis using, for detection, the Vevo 770(®) , a micro-imaging HFUS. Two different thrombosis models were used to generate thrombi in the IVC of C57Bl/6NCr mice: 1) ligation and 2) application of ferric chloride (FeCl(3) ). We then assessed venous thrombosis by HFUS. Results: In both models, measurements of the clot pathologically correlated favorably with measurements acquired with HFUS. Thrombus develops less than an hour after ligation or FeCl(3) -induced injury of the IVC and the size of the clot increases over time for up to 24 hours. Importantly, we demonstrate that HFUS can be used to monitor the effect of an anticoagulant such as dalteparin until complete resolution of the thrombus. Conclusions: These data show that HFUS assesses venous thrombosis in mice reliably and non-invasively. Developing a murine model of thrombosis using more accurate, and clinically more relevant techniques such as ultrasonography, is a step towards a better understanding of the pathophysiology of venous thromboembolism.

PMID: 22212403 [PubMed - as supplied by publisher]

Direct measurement of tissue blood flow and metabolism with diffuse optics.

Philos Transact A Math Phys Eng Sci. 2011 Nov 28;369(1955):4390-406

Authors: Mesquita RC, Durduran T, Yu G, Buckley EM, Kim MN, Zhou C, Choe R, Sunar U, Yodh AG

Abstract
Diffuse optics has proven useful for quantitative assessment of tissue oxy- and deoxyhaemoglobin concentrations and, more recently, for measurement of microvascular blood flow. In this paper, we focus on the flow monitoring technique: diffuse correlation spectroscopy (DCS). Representative clinical and pre-clinical studies from our laboratory illustrate the potential of DCS. Validation of DCS blood flow indices in human brain and muscle is presented. Comparison of DCS with arterial spin-labelled MRI, xenon-CT and Doppler ultrasound shows good agreement (0.50<r<0.95) over a wide range of tissue types and source detector distances, corroborating the potential of the method to measure perfusion non-invasively and in vivo at the microvasculature level. All-optical measurements of cerebral oxygen metabolism in both rat brain, following middle cerebral artery occlusion, and human brain, during functional activation, are also described. In both situations, the use of combined DCS and diffuse optical spectroscopy/near-infrared spectroscopy to monitor changes in oxygen consumption by the tissue is demonstrated. Finally, recent results spanning from gene expression-induced angiogenic response to stroke care and cancer treatment monitoring are discussed. Collectively, the research illustrates the capability of DCS to quantitatively monitor perfusion from bench to bedside, providing results that match up both with literature findings and with similar experiments performed with other techniques.

PMID: 22006897 [PubMed - indexed for MEDLINE]

Hemodynamics of the mouse abdominal aortic aneurysm.

J Biomech Eng. 2011 Dec;133(12):121008

Authors: Ford MD, Black AT, Cao RY, Funk CD, Piomelli U

Abstract
The abdominal aortic aneurysm (AAA) is a significant cause of death and disability in the Western world and is the subject of many clinical and pathological studies. One of the most commonly used surrogates of the human AAA is the angiotensin II (Ang II) induced model used in mice. Despite the widespread use of this model, there is a lack of knowledge concerning its hemodynamics; this study was motivated by the desire to understand the fluid dynamic environment of the mouse AAA. Numerical simulations were performed using three subject-specific mouse models in flow conditions typical of the mouse. The numerical results from one model showed a shed vortex that correlated with measurements observed in vivo by Doppler ultrasound. The other models had smaller aneurysmal volumes and did not show vortex shedding, although a recirculation zone was formed in the aneurysm, in which a vortex could be observed, that elongated and remained attached to the wall throughout the systolic portion of the cardiac cycle. To link the hemodynamics with aneurysm progression, the remodeling that occurred between week one and week two of the Ang II infusion was quantified and compared with the hemodynamic wall parameters. The strongest correlation was found between the remodeled distance and the oscillatory shear index, which had a correlation coefficient greater than 0.7 for all three models. These results demonstrate that the hemodynamics of the mouse AAA are driven by a strong shear layer, which causes the formation of a recirculation zone in the aneurysm cavity during the systolic portion of the cardiac waveform. The recirculation zone results in areas of quiescent flow, which are correlated with the locations of the aneurysm remodeling.

PMID: 22206425 [PubMed - in process]

The Impact of Simplified Boundary Conditions and Aortic Arch Inclusion on CFD Simulations in the Mouse Aorta: A Comparison With Mouse-specific Reference Data.

J Biomech Eng. 2011 Dec;133(12):121006

Authors: Trachet B, Bols J, De Santis G, Vandenberghe S, Loeys B, Segers P

Abstract
Computational fluid dynamics (CFD) simulations allow for calculation of a detailed flow field in the mouse aorta and can thus be used to investigate a potential link between local hemodynamics and disease development. To perform these simulations in a murine setting, one often needs to make assumptions (e.g. when mouse-specific boundary conditions are not available), but many of these assumptions have not been validated due to a lack of reference data. In this study, we present such a reference data set by combining high-frequency ultrasound and contrast-enhanced micro-CT to measure (in vivo) the time-dependent volumetric flow waveforms in the complete aorta (including seven major side branches) of 10 male ApoE -/- deficient mice on a C57Bl/6 background. In order to assess the influence of some assumptions that are commonly applied in literature, four different CFD simulations were set up for each animal: (i) imposing the measured volumetric flow waveforms, (ii) imposing the average flow fractions over all 10 animals, presented as a reference data set, (iii) imposing flow fractions calculated by Murray's law, and (iv) restricting the geometrical model to the abdominal aorta (imposing measured flows). We found that - even if there is sometimes significant variation in the flow fractions going to a particular branch - the influence of using average flow fractions on the CFD simulations is limited and often restricted to the side branches. On the other hand, Murray's law underestimates the fraction going to the brachiocephalic trunk and strongly overestimates the fraction going to the distal aorta, influencing the outcome of the CFD results significantly. Changing the exponential factor in Murray's law equation from 3 to 2 (as suggested by several authors in literature) yields results that correspond much better to those obtained imposing the average flow fractions. Restricting the geometrical model to the abdominal aorta did not influence the outcome of the CFD simulations. In conclusion, the presented reference dataset can be used to impose boundary conditions in the mouse aorta in future studies, keeping in mind that they represent a subsample of the total population, i.e., relatively old, non-diseased, male C57Bl/6 ApoE -/- mice.

PMID: 22206423 [PubMed - in process]