Skills and Expertise
NeuroimagingImagingNeurodegenerative DiseasesNeurophysiologyNeurodegenerationNeurological DiseasesMagnetic ResonanceClinical NeurologyNeuroprotectionBrain DiseasesNeurologyMovement DisordersHistologyBiomedical ImagingClinical ImagingPETStrokeMultiple SclerosisVeterinary MedicineAnesthesiaAdult NeurologyNeurologic ExaminationAnimal ModelsNeuroimmunologyStroke ImagingNeuromuscular DisordersDemyelinating DiseasesStroke ThrombolysisNeurosurgeryCerebrovascular CirculationCNS Demyelinating Autoimmune DiseasesCerebral IschemiaStereotactic SurgeryCaenorhabditis elegansPreclinical ImagingCerebrospinal FluidExperimental MicrosurgeryTranscranial UltrasonographyWMSBrain IschemiaAnimal ExperimentsNeuroprotective AgentsExperimental StrokeExperimental neurosurgery
- PostDoc Position
- Large (such as sheep) and small (rodents, rabbits) animal models of stroke including several image modalities (DCW-MRI, pASL,structuralMRI) processing, analysis,experimental neurosurgery, neuropathology (poststroke dementia), neurological deficits
Nov 2013 - Sep 2014
Feb 2012 - Oct 2013
Project aims include: I. The creation of standard references (template, TPM, atlas) enabling comprehensible image processing, statistical image analysis and reporting of findings in the sheep brain II. The volumetric and spatial determination of cerebral age and sexual dimorphism within a healthy population of sheep according to atlas space III. Specific adaptation of the references (see I) to enable observer independent automatic analysis of large lesioned brain tissue IV. Volumetric and spatial effects of infarct development on remaining cortical, subcortical, ventricular structures in subacute and chronic altered sheep brain after middle cerebral artery occlusion
Research Item (31)
As part of the neuronal cytoskeleton, neurofilaments are involved in maintaining cellular integrity. In the setting of ischemic stroke, the affection of the neurofilament network is considered to mediate the transition towards long-lasting tissue damage. Although peripheral levels of distinct neurofilament subunits are shown to correlate with the clinically observed severity of cerebral ischemia, neurofilaments have so far not been considered for neuroprotective approaches. Therefore, the present study systematically addresses ischemia-induced alterations of the neurofilament light (NF-L), medium (NF-M), and heavy (NF-H) subunits as well as of α-internexin (INA). For this purpose, we applied a multi-parametric approach including immunofluorescence labeling, western blotting, qRT-PCR and electron microscopy. Analyses comprised ischemia-affected tissue from three stroke models of middle cerebral artery occlusion (MCAO), including approaches of filament-based MCAO in mice, thromboembolic MCAO in rats, and electrosurgical MCAO in sheep, as well as human autoptic stroke tissue. As indicated by altered immunosignals, impairment of neurofilament subunits was consistently observed throughout the applied stroke models and in human tissue. Thereby, altered NF-L immunoreactivity was also found to reach penumbral areas, while protein analysis revealed consistent reductions for NF-L and INA in the ischemia-affected neocortex in mice. At the mRNA level, the ischemic neocortex and striatum exhibited reduced expressions of NF-L- and NF-H-associated genes, whereas an upregulation for Ina appeared in the striatum. Further, multiple fluorescence labeling of neurofilament proteins revealed spheroid and bead-like structural alterations in human and rodent tissue, correlating with a cellular edema and lost cytoskeletal order at the ultrastructural level. Thus, the consistent ischemia-induced affection of neurofilament subunits in animals and human tissue, as well as the involvement of potentially salvageable tissue qualify neurofilaments as promising targets for neuroprotective strategies. During ischemia formation, such approaches may focus on the maintenance of neurofilament integrity, and appear applicable as co-treatment to modern recanalizing strategies.
Stereotaxic systems and automatic tissue segmentation routines enable neuronavigation as well as reproducible processing of neuroimage datasets. Such systems have been developed for humans, non-human-primates, sheep, and rodents, but not for dogs. Although dogs share important neurofunctional and -anatomical features with humans, and in spite of their importance in translational neuroscience, little is known about the variability of the canine brain morphology and, possibly related, function. Moreover, we lack templates, tissue probability maps (TPM), and stereotaxic brain labels for implementation in standard software utilities such as Statistical Parametric Mapping (SPM). Hence, objective and reproducible, image-based investigations are currently impeded in dogs. We have created a detailed stereotaxic reference frame for dogs including TPM and tissue labels, enabling inter-individual and cross-study neuroimage analysis. T2w datasets were acquired from 16 neurologically inconspicuous dogs of different breeds by 3T MRI. The datasets were averaged after initial preprocessing using linear and nonlinear registration algorithms as implemented in SPM8. TPM for gray (GM) and white matter (WM) as well as cerebrospinal fluid (CSF) were created. Different cortical, subcortical, medullary, and CSF regions were manually labeled to create a spatial binary atlas being aligned with the template. A proof-of-concept for automatic determination of morphological and volumetrical characteristics was performed using additional canine datasets (n = 64) including a subgroup of laboratory beagles (n = 24). Overall, 21 brain regions were labeled using the segmented tissue classes of the brain template. The proof-of-concept trial revealed excellent suitability of the created tools for image processing and subsequent analysis. There was high intra-breed variability in frontal lobe and hippocampus volumes, and noticeable inter-breed corpus callosum volume variation. The T2w brain template provides important, breed-averaged canine brain anatomy features in a spatial standard coordinate system. TPM allows automatic tissue segmentation using SPM and enables unbiased automatic image processing or morphological characterization in different canine breeds. The reported volumetric and morphometric results may serve as a starting point for further research aimed at in vivo analysis of canine brain anatomy and function. The data set is freely available at http://animal-brain-mapping.com/. Please do not forget to cite when using the data.
Background Disease models are useful for prospective studies of pathology, identification of molecular and cellular mechanisms, pre-clinical testing of interventions, and validation of clinical biomarkers. Here, we review animal models relevant to vascular cognitive impairment (VCI). A synopsis of each model was initially presented by expert practitioners. Synopses were refined by the authors, and subsequently by the scientific committee of a recent conference (International Conference on Vascular Dementia 2015). Only peer-reviewed sources were cited. Methods We included models that mimic VCI-related brain lesions (white matter hypoperfusion injury, focal ischaemia, cerebral amyloid angiopathy) or reproduce VCI risk factors (old age, hypertension, hyperhomocysteinemia, high-salt/high-fat diet) or reproduce genetic causes of VCI (CADASIL-causing Notch3 mutations). Conclusions We concluded that (1) translational models may reflect a VCI-relevant pathological process, while not fully replicating a human disease spectrum; (2) rodent models of VCI are limited by paucity of white matter; and (3) further translational models, and improved cognitive testing instruments, are required.
Question - How to segment an arbitary shape from an image using shape based template matching concept?
There are a lot of tools who can deal with that. Importantly, the input MRI should be cover the whole brain tissue. I prefer to work with SPM (http://www.fil.ion.ucl.ac.uk/spm/) since it allows to be modified by the user in a simply manner. In your case cerebellar tissue probability maps are required. Alternatively you can choose a atlas based segmentation approach. Both methods are described at the website.
As part of the extracellular matrix (ECM), perineuronal nets (PNs) are polyanionic, chondroitin sulfate proteoglycan (CSPG)-rich coatings of certain neurons, known to be affected in various neural diseases. Although these structures are considered as important parts of the neurovascular unit (NVU), their role during evolution of acute ischemic stroke and subsequent tissue damage is poorly understood and only a few preclinical studies analyzed PNs after acute ischemic stroke. By employing three models of experimental focal cerebral ischemia, this study was focused on histopathological alterations of PNs and concomitant vascular, glial and neuronal changes according to the NVU concept. We analyzed brain tissues obtained 1 day after ischemia onset from: (a) mice after filament-based permanent middle cerebral artery occlusion (pMCAO); (b) rats subjected to thromboembolic MACO; and (c) sheep at 14 days after electrosurgically induced focal cerebral ischemia. Multiple fluorescence labeling was applied to explore simultaneous alterations of NVU and ECM. Serial mouse sections labeled with the net marker Wisteria floribunda agglutinin (WFA) displayed largely decomposed and nearly erased PNs in infarcted neocortical areas that were demarcated by up-regulated immunoreactivity for vascular collagen IV (Coll IV). Subsequent semi-quantitative analyses in mice confirmed significantly decreased WFA-staining along the ischemic border zone and a relative decrease in the directly ischemia-affected neocortex. Triple fluorescence labeling throughout the three animal models revealed up-regulated Coll IV and decomposed PNs accompanied by activated astroglia and altered immunoreactivity for parvalbumin, a calcium-binding protein in fast-firing GABAergic neurons which are predominantly surrounded by neocortical PNs. Furthermore, ischemic neocortical areas in rodents simultaneously displayed less intense staining of WFA, aggrecan, the net components neurocan, versican and the cartilage link protein (CRTL) as well as markers in net-bearing neurons such as the potassium channel subunit Kv3.1b and neuronal nuclei (NeuN). In summary, theconsistent observations based on three different stroke models confirmed that PNs are highly sensitive constituents of the NVU along with impaired associated GABAergic neurons. These results suggest that PNs could be promising targets of future stroke treatment, and further studies should address their reorganization and plasticity in both stabilizing the acute stroke as well as supportive effects during the chronic phase of stroke.
- Feb 2017
Interspecies differences, anatomical and physiological aspects as wells as simplified study designs contribute to an overestimation of treatment effects and limit the transferability of experimental results into clinical applications. Confounders of cell therapies for cerebrovascular disorders (CVD) include common CVD comorbidities, frequent medications potentially affecting endogenous and transplanted stem cells, as well as age- and immune-system-related effects. All of those can contribute to a substantial modelling bias, ultimately limiting the prospective quality of preclinical research programs regarding the clinical value of a particular cell therapy. In this review, we discuss the nature and impact of most relevant confounders. We provide suggestions on how they can be considered in order to enhance the validity of CVD models in stem cell research. Acknowledging substantial and sometimes surprising effects of housing conditions, chronobiology and intersex-differences will further augment the translational value of animal models. We finally discuss options for the implementation of high-quality functional and imaging readout protocols. Altogether, this might help to gain a more holistic picture about the therapeutic impact of a particular cell therapy for CVD, but also on potential side and of-site effects of the intervention. This article is protected by copyright. All rights reserved.
- Jul 2016
- joint congress of EAVA (European Association of Veterinary Anatomists) and WAHVM (World Association for the History of Veterinary Medicine)
Anantomia Histologia Embryologia Supplements ISSN 1439-0264 joint congress of EAVA (European Association of Veterinary Anatomists) and WAHVM (World Association for the History of Veterinary Medicine) Introduction: Neuroscientific large animal models pose advantages over rodents including the application of complex imaging-based in vivo investigations using clinically relevant techniques. Here, the Statistical Parametric Mapping (SPM8) framework was used for automatic MR image processing in a recently developed intracerebral hemorrhage (ICH) ovine model to characterize the tissue and lesion pattern after ICH. Materials and Methods: The MRI data set (1.5T Philips MRI) include t1w 3D, t2w TSE, t2*, diffusion weighted imaging (DWI) and contrast enhanced perfusion weighed imaging (PWI) sequences from 14 sheep. After co-registration to the standard ovine template , segmentation procedure using SPM8 was applied to the structural data sets. Volumes of gray (GM) and white (WM) matter, lateral ventricle and lesion were calculated. PWI and DWI deficit volume were computed followed by comparing the DICES’s similarity between t2w TSE, PWI and DWI deficit volumes. Finally, voxel-based-morphometry (VBM) determined statistical differences between lateral ventricle before and after bleeding. Results: SPM8 reproduced high-contrast tissue masks without substantial voxel misclassification. After ICH, GM and WM volumes were decreased. The volume ratio between ventricle:brain was significantly higher in the contralateral hemisphere after ICH as compared to baseline. VBM displayed a significant compression of the lateral aspect of the ipsilateral ventricle in comparison to baseline (p<0.01). DICE’s similarity between structural lesion and diffusion deficit volume were highest (0.54), while a DWI and PWI deficit mismatch revealed a perihematomal penumbra. Conclusion: SPM8 avoids subjective manual image processing procedures and enables objective analysis according to the recommendations for statistical image processing. Moreover, the perihematomal penumbra point to the potential of our ovine ICH model for a translational stroke research of further therapeutic and/or diagnostic options. (1) Nitzsche et al. (2015). A stereotaxic, population-averaged T1w ovine brain atlas including cerebral morphology and tissue volumes. Front Neuroanat. 9.
- Jul 2016
Anantomia Histologia Embryologia Supplements Proceeding of joint congress of EAVA (European Association of Veterinary Anatomists) and WAHVM (World Association for the History of Veterinary Medicine) ISSN 1439-0264 Introduction: Stereotaxic references and brain atlases play a key role in neuroscientific research enabling objective and comparable reporting of morphological and functional aspects. Stereotaxic coordinate systems have been developed for human, non-human-primates, dogs and rodents but still lacking for other important species such as sheep. Here, a spatial, unbiased, population-averaged MRI template including cerebral a-priori-probabilities (TPM) for grey (GM) and white matter (WM) as well as cerebrospinal fluid (CSF) is presented including the application of automatic segmentation procedures to determine cerebral morphological characteristics in an adult sheep population. Materials and Methods: Fourteen t1w MRI datasets (1.5T Phillips) of healthy Merino sheep were assigned to create a non-linearly transformed MR brain template and corresponding cerebral TPM using MINC toolkit. Further 24 healthy neutered-male and female sheep t1w datasets were included and cerebral tissue volumes (GM, WM, CSF) using automatic image preprocessing of SPM8 (Statistical Parametric Mapping version 8) were analyzed considering sex and age differences. Results: The t1w brain template provides an appropriate population-averaged ovine brain anatomy in a spatial standard coordinate system. The implementation of the TPM into the SPM framework created highly-contrast tissue mask without remarkable misclassified voxels. Cerebral GM, WM and CSF volumes were calculated with 50.3, 42.8 and 33.9 mL, respectively. In healthy, unaltered sheep a positive correlation of GM volume and body weight explained about 15% of the variance of GM while a positive correlation between WM and age was found. Absolute tissue volume differences were not detected, indeed females showed significantly more GM per bodyweight as compared to neutered males. Conclusion: The spatial brain template and cerebral TPM enable unbiased automatic image preprocessing and morphological characterization in sheep. Moreover, the freely available framework (http://www.bic.mni.mcgill.ca/ServicesAtlases/Ovine) may serve as a starting point for further experimental and/or translational research including group wise image analysis or stereotaxic approaches.
- Jun 2016
- Experimental Neurosurgery in Animal Models
According to the recommendation of international expert committees, large animal stroke models are demanded for preclinical research. Based on a brief introduction to the ovine cranial anatomy, a sheep model of permanent middle cerebral artery occlusion (MCAO) will be described in this chapter. The model was particularly designed to verify several therapeutic strategies during both, acute and long-term studies, but is also feasible for development of diagnostic procedures. Further, exemplary application of imaging procedures and imaging data analyses using magnetic resonance imaging (MRI) and positron emission tomography (PET) are described. The chapter also includes recommendations for appropriate animal housing and medication.
International academic and industrial expert consortia (STAIR, STEPS) suggest stringent preclinical research strategies for stroke including validation of novel treatment strategies in gyrencephalic animal models. However, many existing gyrencephalic animal models are expensive, constrained by ethical considerations or limited by species-specific anatomical restrictions. Importantly, many large animal models do not allow long term investigations, being crucial for robust safety and efficacy assessments. To overcome these limitations, an ovine model of cerebral ischemia by permanent middle cerebral artery occlusion (MCAO) in sheep was established. After detailed characterization of the model itself, it was utilized in acute stroke treatment studies, for example using nitrogen monoxide, but also in long term experiments such as assessment of autologous bone marrow cell therapy. Additionally, frameless stereotaxic methods were established that enable local administration of cells and/or substances for different purposes. Moreover, the ovine model is routinely used for state-of-the-art imaging studies (MRI, PET and combined PET/MRI) including automatic image processing and analysis using ovine stereotaxic atlas. Major strengths of the ovine MCAO model comprise reproducible lesion size, capability for long term studies and suitability for clinical imaging procedures, as well as relatively low costs. The transcranial approach avoids enucleation, enabling testing of neurological functions without modelling effects, but at the cost of artificial intracranial pressure profiles. The model has also been adopted for transient MCAO. Keywords: sheep, MCAO, ischemia, translational studies, Nitric Oxide, Bone Marrow, brain atlas
Standard stereotaxic reference systems play a key role in human brain studies. Stereotaxic coordinate systems have also been developed for experimental animals including non-human primates, dogs and rodents. However, they are lacking for other species being relevant in experimental neuroscience including sheep. Here, we present a spatial, unbiased ovine brain template with tissue probability maps (TPM) that offer a detailed stereotaxic reference frame for anatomical features and localization of brain areas, thereby enabling inter-individual and cross-study comparability. Three-dimensional data sets from healthy adult Merino sheep (Ovis orientalis aries, 12 ewes and 26 neutered rams) were acquired on a 1.5T Philips MRI using a T1w sequence. Data were averaged by linear and non-linear registration algorithms. Moreover, animals were subjected to detailed brain volume analysis including examinations with respect to body weight, age and sex. The created T1w brain template provides an appropriate population-averaged ovine brain anatomy in a spatial standard coordinate system. Additionally, TPM for gray (GM) and white (WM) matter as well as cerebrospinal fluid (CSF) classification enabled automatic prior-based tissue segmentation using statistical parametric mapping (SPM). Overall, a positive correlation of GM volume and body weight explained about 15% of the variance of GM while a positive correlation between WM and age was found. Absolute tissue volume differences were not detected, indeed ewes showed significantly more GM per bodyweight as compared to neutered rams. The created framework including spatial brain template and TPM represent a useful tool for unbiased automatic image preprocessing and morphological characterization in sheep. Therefore, the reported results may serve as a starting point for further experimental and/or translational research aiming at in vivo analysis in this species.
Objective: Sheep play an important role in studies of neuroscience including imaging procedures, neuronavigation and electrophysiology due to the large brain size and body weight of this gyrencephalic species. The anatomical and vascular comparability to human being emphasizes the importance for ovine models of cerebrovascular diseases such as ischemic or hemorrhagic stroke including MRI analysis. Stereotaxic references or brain atlases enable objective and comparable studies but still lacking for the ovine species. Here, a spatial, unbiased, population-averaged MRI template including cerebral a-priori-probabilities (TPM) for grey (GM) and white matter (WM) as well as cerebrospinal fluid (CSF) is presented. Methods: 14 t1w MRI datasets of healthy Merino sheep (6 – 28 months) were assigned to create a non-linearly transformed MR template and corresponding cerebral TPM. Further 24 healthy neutered-male and female sheep were included and cerebral tissue volumes using automatic image preprocessing of SPM8 (Statistical Parametric Mapping) were analyzed considering sex and age differences. Result: In healthy, unaltered sheep a positive correlation of GM volume and body weight explained about 15% of the variance of GM while a positive correlation between WM and age was found. Absolute tissue volume differences were not detected, indeed females showed significantly more GM per bodyweight as compared to neutered males. Discussion: The created framework including spatial brain template and cerebral TPM represent a useful tool for unbiased automatic image preprocessing and morphological characterization in sheep. Therefore, the reported results may serve as a starting point for further experimental and/or translational research.
Cerebrovascular diseases are significant causes of death and disability in humans. Improvements in diagnostic and therapeutic approaches strongly rely on adequate gyrencephalic, large animal models being demanded for translational research. Ovine stroke models may represent a promising approach but are currently limited by insufficient knowledge regarding the venous system of the cerebral angioarchitecture. The present study was intended to provide a comprehensive anatomical analysis of the intracranial venous system in sheep as a reliable basis for the interpretation of experimental results in such ovine models. We used corrosion casts as well as contrast-enhanced magnetic resonance venography to scrutinize blood drainage from the brain. This combined approach yielded detailed and, to some extent, novel findings. In particular, we provide evidence for chordae Willisii and lateral venous lacunae, and report on connections between the dorsal and ventral sinuses in this species. For the first time, we also describe venous confluences in the deep cerebral venous system and an 'anterior condylar confluent' as seen in humans. This report provides a detailed reference for the interpretation of venous diagnostic imaging findings in sheep, including an assessment of structure detectability by in vivo (imaging) versus ex vivo (corrosion cast) visualization methods. Moreover, it features a comprehensive interspecies-comparison of the venous cerebral angioarchitecture in man, rodents, canines and sheep as a relevant large animal model species, and describes possible implications for translational cerebrovascular research.
Question - Is there any anaesthetic that can be used in place of ketamine on mice?
thiopental worked also i.p but has limited analgesic effects. Combine with diazepam should be usefull to increase analgesia (but need to applicate in lower dose). Phenobabital and diazepam may also a good solution. Overall anesthesia depend on kind of approach
Assessment of biodistribution and monitoring of cell migration processes in vivo are essential for the safety of novel cell-based therapies for ischemic stroke and early-stage clinical trials, but are mainly lacking investigation in large animal models which are closer to the situation found in human patients. This chapter reports a series of experiments which establish a MRI-sensitive labeling procedure for autologous ovine mesenchymal stem cells (MSC) and the assessment of in vivo and in vitro detection limits of the cells at 3.0 T. Cell migration was monitored after intravenous transplantation following experimental stroke in sheep. Cell detection was feasible at 3.0 T with detection limits defined at 500 cells in vitro and 1,000 cells after local stereotaxic administration in vivo. No signs for MSC homing toward the ischemic lesion were observed after systemic cell delivery. Iron-containing cells were identified in the lung and skin wounds, but not in brain parenchyma after intravenous cell delivery. These findings are in contrast to results obtained in small animal models and may indicate significant differences of MSC behavior in large organisms. They also revealed the necessity for sensitivity-enhanced MRI sequences for improved cell detection in large animals.
- Dec 2011
Stroke is the third most common cause of death in industrialized countries. The main therapeutic target is the ischemic penumbra, potentially salvageable brain tissue that dies within the first few hours after blood flow cessation. Hence, strategies to keep the penumbra alive until reperfusion occurs are needed. To study the effect of inhaled nitric oxide on cerebral vessels and cerebral perfusion under physiological conditions and in different models of cerebral ischemia. This experimental study demonstrates that inhaled nitric oxide (applied in 30% oxygen/70% air mixture) leads to the formation of nitric oxide carriers in blood that distribute throughout the body. This was ascertained by in vivo microscopy in adult mice. Although under normal conditions inhaled nitric oxide does not affect cerebral blood flow, after experimental cerebral ischemia induced by transient middle cerebral artery occlusion it selectively dilates arterioles in the ischemic penumbra, thereby increasing collateral blood flow and significantly reducing ischemic brain damage. This translates into significantly improved neurological outcome. These findings were validated in independent laboratories using two different mouse models of cerebral ischemia and in a clinically relevant large animal model of stroke. Inhaled nitric oxide thus may provide a completely novel strategy to improve penumbral blood flow and neuronal survival in stroke or other ischemic conditions.
Translational researchers and clinicians recommend the use of large animal models in preclinical stroke research. This represents an important part of a strategy aiming to prevent past translational failures in future therapeutic developments. Thirty-five Merino rams were subjected to sham surgery (n = 3), one-branch middle cerebral artery occlusion (MCAO, n = 8) or total MCAO (n = 24). Twelve animals from the latter group received intravenous administration of 4 × 10(6) autologous mononuclear bone marrow cells (BM MNC) per kilogram 24 h after total MCAO. Animals were sacrificed at day 49 post MCAO. Histological investigations were performed to reveal (1) the impact of different MCAO modalities on a cellular level and (2) the influence of BM MNC therapy following stroke. Clear differences between one-branch and total MCAO were observed histologically with results being comparable to those seen in human patients. BM MNC treatment reduced final lesion extension, lymphocytic infiltration and axonal degeneration after MCAO. The sheep model may represent a feasible tool for translational stroke research as pathohistological findings mimic the situation in humans. Histological evidence was found for beneficial impact of autologous BM MNC therapy. Further studies are needed to assess the neurofunctional impact of the approach in the gyrencephalic brain.
We aimed to evaluate the feasibility and efficacy of autologous umbilical cord blood mononuclear cell (UCMNC) transplantation on right ventricular (RV) function in a novel model of chronic RV volume overload. Four-month-old sheep (n = 20) were randomized into cell (n = 10) and control groups (n = 10). After assessment of baseline RV function by the conductance catheter method, a transannular patch (TAP) was sutured to the right ventricular outflow tract (RVOT). Following infundibulotomy the ring of the pulmonary valve was transected without cardiopulmonary bypass. UCMNC implantation (8.22 ± 6.28 × 10⁷) in the cell group and medium injection in the control group were performed into the RV myocardium around the TAP. UCMNCs were cultured for 2 weeks after fluorescence-activated cell sorting (FACS) analysis for CD34 antigen. Transthoracic echocardiography (TTE) and computed tomography were performed after 6 weeks and 3 months, respectively. RV function was assessed 3 months postoperatively before the hearts were excised for immunohistological examinations. FACS analysis revealed 1.2 ± 0.22% CD34⁺ cells within the isolated UCMNCs from which AcLDL⁺ endothelial cells were cultured in vitro. All animals survived surgery. TTE revealed grade II‐III pulmonary regurgitation in both groups. Pressure‐volume loops under dobutamine stress showed significantly improved RV diastolic function in the cell group (dP/dtmin: p = 0.043; Eed: p = 0.009). CD31 staining indicated a significantly enhanced number of microvessels in the region of UCMNC implantation in the cell group (p
As effective stroke treatment by thrombolysis is bound to a narrow time window excluding most patients, numerous experimental treatment strategies have been developed to gain new options for stroke treatment. However, all approaches using neuroprotective agents that have been successfully evaluated in rodents have subsequently failed in clinical trials. Existing large animal models are of significant scientific value, but sometimes limited by ethical drawbacks and mostly do not allow for long-term observation. In this study, we are introducing a simple, but reliable stroke model using permanent middle cerebral artery occlusion in sheep. This model allows for control of ischemic lesion size and subsequent neurofunctional impact, and it is monitored by behavioral phenotyping, magnetic resonance imaging, and positron emission tomography. Neuropathologic and (immuno)histologic investigations showed typical ischemic lesion patterns whereas commercially available antibodies against vascular, neuronal, astroglial, and microglial antigens were feasible for ovine brain specimens. Based on absent mortality in this study and uncomplicated species-appropriate housing, long-term studies can be realized with comparatively low expenditures. This model could be used as an alternative to existing large animal models, especially for longitudinal analyses of the safety and therapeutic impact of novel therapies in the field of translational stroke research.
A key challenge of functional genomics today is to generate well-annotated data sets that can be interpreted across different platforms and technologies. Large-scale functional genomics data often fail to connect to standard experimental approaches of gene characterization in individual laboratories. Furthermore, a lack of universal annotation standards for phenotypic data sets makes it difficult to compare different screening approaches. Here we address this problem in a screen designed to identify all genes required for the first two rounds of cell division in the Caenorhabditis elegans embryo. We used RNA-mediated interference to target 98% of all genes predicted in the C. elegans genome in combination with differential interference contrast time-lapse microscopy. Through systematic annotation of the resulting movies, we developed a phenotypic profiling system, which shows high correlation with cellular processes and biochemical pathways, thus enabling us to predict new functions for previously uncharacterized genes.