NADPH oxidase 4 protects against development of endothelial dysfunction and atherosclerosis in LDL receptor deficient mice

AIMS Endothelial dysfunction is an early step in the development of atherosclerosis. Increased formation of superoxide anions by NADPH oxidase Nox1, 2, and 5 reduces nitric oxide availability and can promote endothelial dysfunction. In contrast, recent evidence supports a vasoprotective role of H2O2 produced by main endothelial isoform Nox4. Therefore, we analysed the impact of genetic deletion of Nox4 on endothelial dysfunction and atherosclerosis in the low-density lipoprotein receptor (Ldlr) knockout model. METHODS AND RESULTS Ex vivo analysis of endothelial function by Mulvany myograph showed impaired endothelial function in thoracic aorta of Nox4(-/-)/Ldlr(-/-) mice. Further progression of endothelial dysfunction due to high-fat diet increased atherosclerotic plaque burden and galectin-3 staining in Nox4(-/-)/Ldlr(-/-) mice compared with Ldlr(-/-) mice. Under physiological conditions, loss of Nox4 does not influence aortic vascular function. In this setting, loss of Nox4-derived H2O2 production could be partially compensated for by nNOS upregulation. Using an innovative optical coherence tomography approach, we were able to analyse endothelial function by flow-mediated vasodilation in the murine saphenous artery in vivo. This new approach revealed an altered flow-mediated dilation in Nox4(-/-) mice, indicating a role for Nox4 under physiological conditions in peripheral arteries in vivo. CONCLUSIONS Nox4 plays an important role in maintaining endothelial function under physiological and pathological conditions. Loss of Nox4-derived H2O2 could be partially compensated for by nNOS upregulation, but severe endothelial dysfunction is not reversible. This leads to increased atherosclerosis under atherosclerotic prone conditions

Conception of an implantable RF-transmitter with self-sufficient power supply for intraocular pressure monitoring

Für die Glaukomfrühdiagnostik sollte der intraokulare Druck (IOP) bei Risikogruppen regelmäßig erfasst werden. Es soll ein intraokularer Mikrodrucksensor konzipiert werden, welcher eine periodische Aufzeichnung ermöglicht. Insbesondere bei Organen wie dem Auge ist die Implantatgröße stark limitiert. Mit Verzicht auf eine perkutane Verbindung durch einen Sensor mit RF-Transmitter (Frequenzmodulation) kann das Infektionsrisiko deutlich verringert werden. Vorbereitende Untersuchungen an repräsentativen Gewebetypen gaben Aufschluss über das Dämpfungsverhalten für die RF-Strecke. Neben der Signalübertragung stellt auch die autonome Energiegewinnung und Energiespeicherung zur dauerhaften Versorgung des Implantats eine der Hauptaufgaben dar. Auf Basis mikromechanischer Resonatorstrukturen (Biegewandler) sollen Mikrogeneratoren entwickelt werden, mit denen im menschlichen Körper vorhandene mechanische Energie (Vibrationen) in elektrische Energie umgesetzt werden kann. Für die Energiewandlung wurden piezoaktive (c-Achsen orientierte) Aluminiumnitrid (AlN)-Dünnschichten (d = 200 nm) in einem RF-Magnetron Sputterprozess abgeschieden und mittels Röntgen-Diffraktometrie charakterisiert. Zudem erfolgte eine Untersuchung der Resonanzfrequenzen von Mikrostrukturen. Die Anwendung piezoelektrischer AlN-Cantilever für das „Energy Harvesting“ zeigte dabei vielversprechende Ergebnisse

Optical Imaging

Optical Coherence Tomography (OCT)We describe the fundamental concept of optical coherence tomography (OCT) and discuss the two main working principles time domain OCT and frequency domain OCT. Then, we review extended functionalities including spectrally and polarization-resolved OCT as well as Doppler-OCT and show concepts for contrast enhancement. Based on these fundamentals, we demonstrate the potential of OCT for small animal imaging on the basis of exemplary studies on retinal imaging and lung imaging.Optoacoustic ImagingThis chapter deals with the fascinating topic of optoacoustic imaging, a recent powerful addition to the arsenal of in vivo functional and molecular small animal imaging. Due to its hybrid nature, involving optical excitation and ultrasonic detection, optoacoustics overcomes the imaging depth limitations of optical microscopy related to light scattering in living tissues while further benefiting from the compelling advantages of optical contrast. To this end, optoacoustic imaging has been shown capable of delivering multiple types of imaging contrast (structural, functional, kinetic, molecular) within a single imaging modality. It can further deliver images with high spatiotemporal resolution that rivals performance of other well-established whole-body imaging modalities. As such, optoacoustics can play a vital role in biomedical research, from early disease detection and monitoring of dynamic phenomena noninvasively to accelerating drug discovery.Optical ProbesThis chapter is devoted to the properties and application of fluorescence dyes as probes for optical imaging. A variety of agents have been described to date, including nontargeting dyes, vascular agents, targeted conjugates, activatable dyes, and sensing probes. The major classes encompass polymethine dyes and xanthenes dyes, both of which are commercially available in broad variations. Addressing the purpose of optical animal imaging, the most relevant parameters to apply such probes are discussed, thereby supporting the reader in choosing reasonable imaging probes and in preparing bioconjugates for his studies

Stem Cell-Derived Photoreceptor Transplants Differentially Integrate Into Mouse Models of Cone-Rod Dystrophy

Citation: Santos-Ferreira T, Völkner M, Borsch O, et al. Stem cell-derived photoreceptor transplants differentially integrate into mouse models of cone-rod dystrophy. Invest Ophthalmol Vis Sci. 2016;57:3509-3520. DOI:10.1167/iovs.16-19087 PURPOSE. Preclinical studies on photoreceptor transplantation provided evidence for restoration of visual function with pluripotent stem cells considered as a potential source for sufficient amounts of donor material. Adequate preclinical models representing retinal disease conditions of potential future patients are needed for translation research. Here we compared transplant integration in mouse models with mild (prominin1-deficient; Prom1 METHODS. For photoreceptor transplant production, we combined the mouse embryonic stem cell retinal organoid system with rhodopsin-driven GFP cell labeling by recombinant adenoassociated virus (AAV). Organoid-derived photoreceptors were enriched by CD73-based magnetic-activated cell sorting (MACS) and transplanted subretinally into wild-type, Prom1 and Cpfl1/Rho À/À hosts. The survival, maturation, and synapse formation of donor cells was analyzed by immunohistochemistry. RESULTS. Retinal organoids yielded high photoreceptor numbers that were further MACSenriched to 85% purity. Grafted photoreceptors survived in the subretinal space of all mouse models. Some cells integrated into wild-type as well as Prom1 À/À mouse retinas and acquired a mature morphology, expressing rod and synaptic markers in close proximity to secondorder neurons. In contrast, in the novel Cpfl1/Rho À/À model with complete photoreceptor degeneration, transplants remained confined to the subretinal space, expressed rod-specific but only reduced synaptic markers, and did not acquire mature morphology. CONCLUSIONS. Comparison of photoreceptor grafts in preclinical models with incomplete or complete photoreceptor loss, showed differential transplant success with effective and impaired integration, respectively. Thus, Cpfl1/Rho À/À mice represent a potential benchmark model resembling patients with severe retinal degeneration to optimize photoreceptor replacement therapies

Imaging of nanoparticle-labeled stem cells using magnetomotive optical coherence tomography, laser speckle reflectometry, and light microscopy

Cell transplantation and stem cell therapy are promising approaches for regenerative medicine and are of interest to researchers and clinicians worldwide. However, currently, no imaging technique that allows three-dimensional in vivo inspection of therapeutically administered cells in host tissues is available. Therefore, we investigate magnetomotive optical coherence tomography (MM-OCT) of cells labeled with magnetic particles as a potential noninvasive cell tracking method. We develop magnetomotive imaging of mesenchymal stem cells for future cell therapy monitoring. Cells were labeled with fluorescent iron oxide nanoparticles, embedded in tissue-mimicking agar scaffolds, and imaged using a microscope setup with an integrated MM-OCT probe. Magnetic particle-induced motion in response to a pulsed magnetic field of 0.2 T was successfully detected by OCT speckle variance analysis, and cross-sectional and volumetric OCT scans with highlighted labeled cells were obtained. In parallel, fluorescence microscopy and laser speckle reflectometry were applied as two-dimensional reference modalities to image particle distribution and magnetically induced motion inside the sample, respectively. All three optical imaging modalities were in good agreement with each other. Thus, magnetomotive imaging using iron oxide nanoparticles as cellular contrast agents is a potential technique for enhanced visualization of selected cells in OCT

Stem Cell-Derived Photoreceptor Transplants Differentially Integrate Into Mouse Models of Cone-Rod Dystrophy

Preclinical studies on photoreceptor transplantation provided evidence for restoration of visual function with pluripotent stem cells considered as a potential source for sufficient amounts of donor material. Adequate preclinical models representing retinal disease conditions of potential future patients are needed for translation research. Here we compared transplant integration in mouse models with mild (prominin1-deficient; Prom1-/-) or severe (cone photoreceptor function loss 1/rhodopsin-deficient double-mutant; Cpfl1/Rho-/-) cone-rod degeneration.status: publishe

Characterization of light lesion paradigms and optical coherence tomography as tools to study adult retina regeneration in zebrafish

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