Heterotrimeric G Protein Subunit Gαq Is a Master Switch for Gßγ-Mediated Calcium Mobilization by Gi-Coupled GPCRs.

Mechanisms that control mobilization of cytosolic calcium [Ca2+]i are key for regulation of numerous eukaryotic cell functions. One such paradigmatic mechanism involves activation of phospholipase Cß (PLCß) enzymes by G protein ßγ subunits from activated Gαi-Gßγ heterotrimers. Here, we report identification of a master switch to enable this control for PLCß enzymes in living cells. We find that the Gαi-Gßγ-PLCß-Ca2+ signaling module is entirely dependent on the presence of active Gαq. If Gαq is pharmacologically inhibited or genetically ablated, Gßγ can bind to PLCß but does not elicit Ca2+ signals. Removal of an auto-inhibitory linker that occludes the active site of the enzyme is required and sufficient to empower "stand-alone control" of PLCß by Gßγ. This dependence of Gi-Gßγ-Ca2+ on Gαq places an entire signaling branch of G-protein-coupled receptors (GPCRs) under hierarchical control of Gq and changes our understanding of how Gi-GPCRs trigger [Ca2+]i via PLCß enzymes.

Inhibition of Vascular Growth by Modulation of the Anandamide/Fatty Acid Amide Hydrolase Axis.

OBJECTIVE: Pathological angiogenesis is a hallmark of various diseases characterized by local hypoxia and inflammation. These disorders can be treated with inhibitors of angiogenesis, but current compounds display a variety of side effects and lose efficacy over time. This makes the identification of novel signaling pathways and pharmacological targets involved in angiogenesis a top priority. Approach and Results: Here, we show that inactivation of FAAH (fatty acid amide hydrolase), the enzyme responsible for degradation of the endocannabinoid anandamide, strongly impairs angiogenesis in vitro and in vivo. Both, the pharmacological FAAH inhibitor URB597 and anandamide induce downregulation of gene sets for cell cycle progression and DNA replication in endothelial cells. This is underscored by cell biological experiments, in which both compounds inhibit proliferation and migration and evoke cell cycle exit of endothelial cells. This prominent antiangiogenic effect is also of pathophysiological relevance in vivo, as laser-induced choroidal neovascularization in the eye of FAAH-/- mice is strongly reduced. CONCLUSIONS: Thus, elevation of endogenous anandamide levels by FAAH inhibition represents a novel antiangiogenic mechanism.

Ultraviolet-radiation-induced inflammation promotes angiotropism and metastasis in melanoma.

Intermittent intense ultraviolet (UV) exposure represents an important aetiological factor in the development of malignant melanoma. The ability of UV radiation to cause tumour-initiating DNA mutations in melanocytes is now firmly established, but how the microenvironmental effects of UV radiation influence melanoma pathogenesis is not fully understood. Here we report that repetitive UV exposure of primary cutaneous melanomas in a genetically engineered mouse model promotes metastatic progression, independent of its tumour-initiating effects. UV irradiation enhanced the expansion of tumour cells along abluminal blood vessel surfaces and increased the number of lung metastases. This effect depended on the recruitment and activation of neutrophils, initiated by the release of high mobility group box 1 (HMGB1) from UV-damaged epidermal keratinocytes and driven by Toll-like receptor 4 (TLR4). The UV-induced neutrophilic inflammatory response stimulated angiogenesis and promoted the ability of melanoma cells to migrate towards endothelial cells and use selective motility cues on their surfaces. Our results not only reveal how UV irradiation of epidermal keratinocytes is sensed by the innate immune system, but also show that the resulting inflammatory response catalyses reciprocal melanoma-endothelial cell interactions leading to perivascular invasion, a phenomenon originally described as angiotropism in human melanomas by histopathologists. Angiotropism represents a hitherto underappreciated mechanism of metastasis that also increases the likelihood of intravasation and haematogenous dissemination. Consistent with our findings, ulcerated primary human melanomas with abundant neutrophils and reactive angiogenesis frequently show angiotropism and a high risk for metastases. Our work indicates that targeting the inflammation-induced phenotypic plasticity of melanoma cells and their association with endothelial cells represent rational strategies to specifically interfere with metastatic progression.

The ß2 agonist terbutaline specifically decreases pulmonary arterial pressure under normoxia and hypoxia via α adrenoceptor antagonism.

Pulmonary hypertension is a severe, incurable disease with a poor prognosis. Although treatment regimens have improved during the last 2 decades, current pharmacologic strategies are limited and focus on the modulation of only a few pathways related to endothelin, NO, and prostacyclin signaling. Therefore, the identification of novel molecular targets is urgently needed. We found that the ß2 adrenoceptor (AR) agonists terbutaline (TER) and salbutamol induced a dose-dependent vasorelaxation in large pulmonary arteries but not aortas of mouse. This effect was found to be independent of ß ARs and the endothelium but was determined by the type of the preconstrictor. Vasodilation by ß2 AR agonists occurred after pretreatment of pulmonary arteries with phenylephrine and serotonin, both agonists of α1 ARs, but was absent after preconstriction with the thromboxane analog U46619. These data indicated α-adrenolytic activity of ß2 AR agonists, which was confirmed by a right shift of the phenylephrine dose-response curve by TER. This effect was physiologically relevant because TER also relaxed small intrapulmonary arteries in lung slices and diminished pulmonary arterial pressure in an isolated perfused lung model under normoxia and hypoxia. Finally, TER applied as an aerosol also selectively decreased pulmonary arterial pressure without effects on systemic blood pressure and heart rate in mouse in vivo. Thus, ß2 AR agonists display α-adrenolytic activity in pulmonary arteries ex vivo and in vivo, and may provide a novel option to reduce pulmonary arterial pressure in pulmonary hypertension.-Neumann, V., Knies, R., Seidinger, A., Simon, A., Lorenz, K., Matthey, M., Breuer, J., Wenzel, D. The ß2 agonist terbutaline specifically decreases pulmonary arterial pressure under normoxia and hypoxia via α adrenoceptor antagonism.

The cochaperone BAG3 coordinates protein synthesis and autophagy under mechanical strain through spatial regulation of mTORC1.

The cochaperone BAG3 is a central protein homeostasis factor in mechanically strained mammalian cells. It mediates the degradation of unfolded and damaged forms of the actin-crosslinker filamin through chaperone-assisted selective autophagy (CASA). In addition, BAG3 stimulates filamin transcription in order to compensate autophagic disposal and to maintain the actin cytoskeleton under strain. Here we demonstrate that BAG3 coordinates protein synthesis and autophagy through spatial regulation of the mammalian target of rapamycin complex 1 (mTORC1). The cochaperone utilizes its WW domain to contact a proline-rich motif in the tuberous sclerosis protein TSC1 that functions as an mTORC1 inhibitor in association with TSC2. Interaction with BAG3 results in a recruitment of TSC complexes to actin stress fibers, where the complexes act on a subpopulation of mTOR-positive vesicles associated with the cytoskeleton. Local inhibition of mTORC1 is essential to initiate autophagy at sites of filamin unfolding and damage. At the same time, BAG3-mediated sequestration of TSC1/TSC2 relieves mTORC1 inhibition in the remaining cytoplasm, which stimulates protein translation. In human muscle, an exercise-induced association of TSC1 with the cytoskeleton coincides with mTORC1 activation in the cytoplasm. The spatial regulation of mTORC1 exerted by BAG3 apparently provides the basis for a simultaneous induction of autophagy and protein synthesis to maintain the proteome under mechanical strain.

Visualization of endothelial cell cycle dynamics in mouse using the Flt-1/eGFP-anillin system.

Endothelial cell proliferation is a key process during vascular growth but its kinetics could only be assessed in vitro or ex vivo so far. To enable the monitoring and quantification of cell cycle kinetics in vivo, we have generated transgenic mice expressing an eGFP-anillin construct under control of the endothelial-specific Flt-1 promoter. This construct labels the nuclei of endothelial cells in late G1, S and G2 phase and changes its localization during the different stages of M phase, thereby enabling the monitoring of EC proliferation and cytokinesis. In Flt-1/eGFP-anillin mice, we found eGFP+ signals specifically in Ki67+/PECAM+ endothelial cells during vascular development. Quantification using this cell cycle reporter in embryos revealed a decline in endothelial cell proliferation between E9.5 to E12.5. By time-lapse microscopy, we determined the length of different cell cycle phases in embryonic endothelial cells in vivo and found a M phase duration of about 80 min with 2/3 covering karyokinesis and 1/3 cytokinesis. Thus, we have generated a versatile transgenic system for the accurate assessment of endothelial cell cycle dynamics in vitro and in vivo.

Heterologous Expression, Biosynthetic Studies, and Ecological Function of the Selective Gq-Signaling Inhibitor FR900359.

The cyclic depsipeptide FR900359 (FR), isolated from the tropical plant Ardisia crenata, is a strong and selective inhibitor of Gq proteins, making it an indispensable pharmacological tool to study Gq-related processes, as well as a promising drug candidate. Gq inhibition is a novel mode of action for defense chemicals and crucial for the ecological function of FR, as shown by in vivo experiments in mice, its affinity to insect Gq proteins, and insect toxicity studies. The uncultured endosymbiont of A. crenata was sequenced, revealing the FR nonribosomal peptide synthetase (frs) gene cluster. We here provide a detailed model of FR biosynthesis, supported by in vitro enzymatic and bioinformatic studies, and the novel analogue AC-1, which demonstrates the flexibility of the FR starter condensation domains. Finally, expression of the frs genes in E. coli led to heterologous FR production in a cultivable, bacterial host for the first time.

Intercellular transfer of miR-126-3p by endothelial microparticles reduces vascular smooth muscle cell proliferation and limits neointima formation by inhibiting LRP6.

BACKGROUND: Vascular smooth muscle cell (VSMC) proliferation is of importance in the pathogenesis of vascular diseases such as restenosis or atherosclerosis. Endothelial microparticles (EMPs) regulate function and phenotype of target endothelial cells (ECs), but their influence on VSMC biology is unknown. We aim to investigate the role of EMPs in the regulation of vascular smooth muscle cell (VSMC) proliferation and vascular remodeling. METHODS AND RESULTS: Systemic treatment of mice with EMPs after vascular injury reduced neointima formation in vivo. In vitro, EMP uptake in VSMCs diminished VSMC proliferation and migration, both pivotal steps in neointima formation. To explore the underlying mechanisms, Taqman microRNA-array was performed and miR-126-3p was identified as the predominantly expressed miR in EMPs. Confocal microscopy revealed an EMP-mediated miR-126 transfer into recipient VSMCs. Expression of miR-126 target protein LRP6, regulating VSMC proliferation, was reduced in VSMCs after EMP treatment. Importantly, genetic regulation of miR-126 in EMPs showed a miR-126-dependent inhibition of LRP6 expression, VSMC proliferation and neointima formation in vitro and in vivo, suggesting a crucial role of miR-126 in EMP-mediated neointima formation reduction. Finally, analysis of miR-126 expression in circulating MPs in 176 patients with coronary artery disease revealed a reduced PCI rate in patients with high miR-126 expression level, supporting a central role for MP-incorporated miR-126 in vascular remodelling. CONCLUSION: EMPs reduce VSMC proliferation, migration and subsequent neointima formation by delivering functional miR-126 into recipient VSMCs.

Engineered Context-Sensitive Agonism: Tissue-Selective Drug Signaling through a G Protein-Coupled Receptor.

Drug discovery strives for selective ligands to achieve targeted modulation of tissue function. Here we introduce engineered context-sensitive agonism as a postreceptor mechanism for tissue-selective drug action through a G protein-coupled receptor. Acetylcholine M2-receptor activation is known to mediate, among other actions, potentially dangerous slowing of the heart rate. This unwanted side effect is one of the main reasons that limit clinical application of muscarinic agonists. Herein we show that dualsteric (orthosteric/allosteric) agonists induce less cardiac depression ex vivo and in vivo than conventional full agonists. Exploration of the underlying mechanism in living cells employing cellular dynamic mass redistribution identified context-sensitive agonism of these dualsteric agonists. They translate elevation of intracellular cAMP into a switch from full to partial agonism. Designed context-sensitive agonism opens an avenue toward postreceptor pharmacologic selectivity, which even works in target tissues operated by the same subtype of pharmacologic receptor.

Endocannabinoid anandamide mediates hypoxic pulmonary vasoconstriction.

Endocannabinoids are important regulators of organ homeostasis. Although their role in systemic vasculature has been extensively studied, their impact on pulmonary vessels remains less clear. Herein, we show that the endocannabinoid anandamide (AEA) is a key mediator of hypoxic pulmonary vasoconstriction (HPV) via fatty acid amide hydrolase (FAAH)-dependent metabolites. This is underscored by the prominent vasoconstrictive effect of AEA on pulmonary arteries and strongly reduced HPV in FAAH(-/-) mice and wild-type mice upon pharmacological treatment with FAAH inhibitor URB597. In addition, mass spectrometry measurements revealed a clear increase of AEA and the FAAH-dependent metabolite arachidonic acid in hypoxic lungs of wild-type mice. We have identified pulmonary vascular smooth muscle cells as the source responsible for hypoxia-induced AEA generation. Moreover, either FAAH(-/-) mice or wild-type mice treated with FAAH inhibitor URB597 are protected against hypoxia-induced pulmonary hypertension and the concomitant vascular remodeling in the lung. Thus, the AEA/FAAH pathway is an important mediator of HPV and is involved in the generation of pulmonary hypertension.

Reliability and validity of measurements on digital study models and plaster models.

OBJECTIVE: To compare manual plaster cast and digitized model analysis for accuracy and efficiency. MATERIAL AND METHODS: Nineteen plaster models of orthodontic patients in permanent dentition were analyzed by two calibrated examiners. Analyses were performed with a diagnostic calliper and computer-assisted analysis after digitization of the plaster models. The reliability and efficiency of different examiners and methods were compared statistically using a mixed model. RESULTS: Statistically significant differences were found for comparisons of all 28 teeth (P < 0.001), mandibular intermolar width (IMW, P = 0.0453), and overjet (P < 0.001 to P = 0.0329). Single-tooth measurements tended to have larger values when measured manually and the SD was between 0.06 and 1.33mm. Digital analyses gave significantly higher values for mandibular IMW and overjet. Less time was needed for digital measurements. CONCLUSION: Clinical significance of the differences between the methods compared did not appear significant. 3D laser-scanned plaster model analysis appears to be an adequate, reliable, and time saving alternative to analogue model analysis using a calliper.

The toxic effect of R350P mutant desmin in striated muscle of man and mouse.

Mutations of the human desmin gene on chromosome 2q35 cause autosomal dominant, autosomal recessive and sporadic forms of protein aggregation myopathies and cardiomyopathies. We generated R349P desmin knock-in mice, which harbor the ortholog of the most frequently occurring human desmin missense mutation R350P. These mice develop age-dependent desmin-positive protein aggregation pathology, skeletal muscle weakness, dilated cardiomyopathy, as well as cardiac arrhythmias and conduction defects. For the first time, we report the expression level and subcellular distribution of mutant versus wild-type desmin in our mouse model as well as in skeletal muscle specimens derived from human R350P desminopathies. Furthermore, we demonstrate that the missense-mutant desmin inflicts changes of the subcellular localization and turnover of desmin itself and of direct desmin-binding partners. Our findings unveil a novel principle of pathogenesis, in which not the presence of protein aggregates, but disruption of the extrasarcomeric intermediate filament network leads to increased mechanical vulnerability of muscle fibers. These structural defects elicited at the myofiber level finally impact the entire organ and subsequently cause myopathy and cardiomyopathy.

RGD peptides induce relaxation of pulmonary arteries and airways via ß3-integrins.

Novel relaxants of pulmonary arteries and airways are of special interest to obtain insights into pulmonary signaling pathways and to develop treatment strategies for lung diseases. Herein, we demonstrate that Arg-Gly-Asp (RGD) peptides induce a dose-dependent relaxation of pulmonary arteries and airways in mouse. The relaxing effect was specific because it was strongly reduced using the control peptides RGE or RAD (P<0.001). Longer peptide sequences containing RGD and its flanking amino acids found in fibronectin showed a similar effect even at a 10-fold lower concentration. The relevance of RGD-induced pulmonary vasorelaxation was demonstrated in isometric force measurements, lung slices, and the isolated perfused lung model under normoxia and hypoxia and in vivo. As cell surface receptor we identified ß3- but not ß1-integrin subunits. Moreover, vasorelaxation by RGD peptides was strongly diminished after removal of the endothelium in endothelial nitric oxide synthase-deficient (eNOS(-/-) mice; P<0.01) and after pharmacological inhibition of the NO/sGC pathway (P<0.05). Additionally, several potassium channels like Kv, Kir, and KATP played a role. In airways the response was mediated by Kv and KCa channels. Thus, RGD peptides are relaxants of pulmonary arteries and airways. These findings may help to establish novel therapeutic approaches for pulmonary hypertension and obstructive lung disease.

Endothelial microparticle-mediated transfer of MicroRNA-126 promotes vascular endothelial cell repair via SPRED1 and is abrogated in glucose-damaged endothelial microparticles.

BACKGROUND: Repair of the endothelium after vascular injury is crucial for preserving endothelial integrity and preventing the development of vascular disease. The underlying mechanisms of endothelial cell repair are largely unknown. We sought to investigate whether endothelial microparticles (EMPs), released from apoptotic endothelial cells (ECs), influence EC repair. METHODS AND RESULTS: Systemic treatment of mice with EMPs after electric denudation of the endothelium accelerated reendothelialization in vivo. In vitro experiments revealed that EMP uptake in ECs promotes EC migration and proliferation, both critical steps in endothelial repair. To dissect the underlying mechanisms, Taqman microRNA array was performed, and microRNA (miR)-126 was identified as the predominantly expressed miR in EMPs. The following experiments demonstrated that miR-126 was transported into recipient human coronary artery endothelial cells by EMPs and functionally regulated the target protein sprouty-related, EVH1 domain-containing protein 1 (SPRED1). Knockdown of miR-126 in EMPs abrogated EMP-mediated effects on human coronary artery endothelial cell migration and proliferation in vitro and reendothelialization in vivo. Interestingly, after simulating diabetic conditions, EMPs derived from glucose-treated ECs contained significantly lower amounts of miR-126 and showed reduced endothelial repair capacity in vitro and in vivo. Finally, expression analysis of miR-126 in circulating microparticles from 176 patients with stable coronary artery disease with and without diabetes mellitus revealed a significantly reduced miR-126 expression in circulating microparticles from diabetic patients. CONCLUSIONS: Endothelial microparticles promote vascular endothelial repair by delivering functional miR-126 into recipient cells. In pathological hyperglycemic conditions, EMP-mediated miR-126-induced EC repair is altered.

The endocannabinoid-CB2 receptor axis protects the ischemic heart at the early stage of cardiomyopathy.

Ischemic heart disease is associated with inflammation, interstitial fibrosis and ventricular dysfunction prior to the development of heart failure. Endocannabinoids and the cannabinoid receptor CB2 have been claimed to be involved, but their potential role in cardioprotection is not well understood. We therefore explored the role of the cannabinoid receptor CB2 during the initial phase of ischemic cardiomyopathy development prior to the onset of ventricular dysfunction or infarction. Wild type and CB2-deficient mice underwent daily brief, repetitive ischemia and reperfusion (I/R) episodes leading to ischemic cardiomyopathy. The relevance of the endocannabinoid-CB2 receptor axis was underscored by the finding that CB2 was upregulated in ischemic wild type cardiomyocytes and that anandamide level was transiently increased during I/R. CB2-deficient mice showed an increased rate of apoptosis, irreversible loss of cardiomyocytes and persistent left ventricular dysfunction 60 days after the injury, whereas wild type mice presented neither morphological nor functional defects. These defects were due to lack of cardiomyocyte protection mechanisms, as CB2-deficient hearts were in contrast to controls unable to induce switch in myosin heavy chain isoforms, antioxidative enzymes and chemokine CCL2 during repetitive I/R. In addition, a prolonged inflammatory response and adverse myocardial remodeling were found in CB2-deficient hearts because of postponed activation of the M2a macrophage subpopulation. Therefore, the endocannabinoid-CB2 receptor axis plays a key role in cardioprotection during the initial phase of ischemic cardiomyopathy development.

Nonradiological method for 3-dimensional implant position assessment using an intraoral scan: new method for postoperative implant control.

INTRODUCTION: This study presents a method to verify the position of dental implants after insertion without the repeated x-ray exposure. MATERIAL AND METHODS: An implant was inserted into the natural gap between the canines and premolars of 8 domestic pigs and 1 human patient. A scanbody was then connected to the implants and a digital intraoral impression of the jaw segment was acquired using a handheld scanner. In addition, the implant position was radiologically detected by cone beam computed tomography. The position of the implant based on both techniques was compared by digital matching. RESULTS: The position of the dental implants determined by the scanner accurately represents the position in the radiograph in the pigs and also in the human patient. CONCLUSION: Evaluating the position of implants using intraoral scans is a straightforward, accurate, and radiation-free method of 3-dimensional implant position determination.

Endothelial beta1 integrins regulate sprouting and network formation during vascular development.

beta1 integrins are important regulators of vascular differentiation and development, as their endothelial-specific deletion results in embryonic lethality. In the present study, we investigated the molecular mechanisms underlying the prominent vascular abnormalities that occur in the absence of beta1 integrins. Because of the early embryonic lethality of knockout mice, we studied endothelial cell and vessel development in beta1-integrin-deficient murine embryonic stem cells to gain novel insights into the role of beta1 integrins in vasculo-angiogenesis. We found that vessel development was strongly defective in the mutant embryoid bodies (EBs), as only primitive and short sprouts developed from clusters of vascular precursors in beta1 integrin(-/-) EBs, whereas complex network formation of endothelial tubes was observed in wild-type EBs. The vascular defect was due to deficient beta1 integrin expression in endothelial cells, as its endothelial-specific re-expression rescued the phenotype entirely. The mechanism responsible for defective vessel formation was found to be reduced endothelial cell maturation, migration and elongation. Moreover, the lower number of endothelial cells in beta1 integrin(-/-) EBs was due to an increased apoptosis versus proliferation rate. The enhanced apoptosis and proliferation of beta1 integrin(-/-) endothelial cells was related to the elevation of peNOS and pAKT signaling molecules, respectively. Our data demonstrate that endothelial beta1 integrins are determinants of vessel formation and that this effect is mediated via different signaling pathways.

Preeclampsia and long-term risk of cardiovascular disease: what do obstetrician-gynecologists know?

BACKGROUND: Preeclampsia (PE), a hypertensive disorder of pregnancy affects 2-8% of women and is associated with increased cardiovascular disease (CVD) risk later in life. There is little information about the knowledge of obstetrician-gynecologists in German outpatient care setting regarding the future health risk of PE and knowledge of the current guidelines on treatment and counseling patients post PE. This study aimed to assess whether obstetrician-gynecologists are aware of PE's association with maternal long-term adverse outcomes and providing appropriate counseling. METHODS: A random sample of 500 obstetrician-gynecologists in the federal state of Lower Saxony was mailed a survey and a reminder with a second copy of the survey. The questionnaire elicited both personal information, and knowledge on future disease risks, e.g. cardiovascular disease (CVD) and current guidelines as well as on counseling practice. Descriptive analysis was used to analyze the responses. RESULTS: A total of 212 obstetrician-gynecologists (42.4%) responded to the questionnaire. A large proportion of physicians stated that PE was associated with a higher risk for the development for hypertension (86.6%), stroke (78.5%) and kidney disease (78.0%). Of the participants 75.8% reported that women after PE have a shorter life expectancy. Respondents with knowledge of the current guidelines of the German Association of Obstetrics and Gynecology concerning follow up and risk management of PE (45.2%) were more often aware of the development of CVD and stroke and counseled patients on self -blood-pressure measurement, meaning and long-term-risks of PE and attached importance to family history of PE compared to physicians with no knowledge of the guidelines. CONCLUSION: Although the majority of obstetrician-gynecologists were aware of higher CVD risk after PE, weaknesses exist in the follow up care and counseling of these patients. These deficiencies would be amendable to directed educational activities to improve the implementation of current guidelines.

Difference of two dependent sensitivities and specificities: Comparison of various approaches.

In diagnostic studies, a new diagnostic test is often compared with a standard test and both tests are applied on the same patients, called paired design. The true disease state is in general given by the so-called gold standard (most reliable method for classification), which has to be known for all patients. The benefit of the new diagnostic test can be evaluated by sensitivity and specificity, which are in fact proportions. This means, for the comparison of two diagnostic tests, confidence intervals for the difference of the dependent estimated sensitivities and specificities are calculated. In the literature, many comparisons of different approaches can be found, but none explicitly for diagnostic studies. For this reason we compare 13 approaches for a set of scenarios that represent data of diagnostic studies (e.g., with sensitivity and specificity ≥0.8). With simulation studies, we show that the nonparametric interval with normal approximation can be recommended for the difference of two dependent sensitivities or specificities without restriction, the Wald interval with the limitation of slightly anti-conservative results for small sample sizes, and the nonparametric intervals with t-approximation, and the Tango interval with the limitation of conservative results for high correlations.

Combined use of magnetic microbeads for endothelial cell isolation and enhanced cell engraftment in myocardial repair.

Background: The regenerative potential of the heart after injury is limited. Therefore, cell replacement strategies have been developed. However, the engraftment of transplanted cells in the myocardium is very inefficient. In addition, the use of heterogeneous cell populations precludes the reproducibility of the outcome. Methods: To address both issues, in this proof of principle study, we applied magnetic microbeads for combined isolation of eGFP+ embryonic cardiac endothelial cells (CECs) by antigen-specific magnet-associated cell sorting (MACS) and improved engraftment of these cells in myocardial infarction by magnetic fields. Results: MACS provided CECs of high purity decorated with magnetic microbeads. In vitro experiments revealed that the angiogenic potential of microbead-labeled CECs was preserved and the magnetic moment of the cells was strong enough for site-specific positioning by a magnetic field. After myocardial infarction in mice, intramyocardial CEC injection in the presence of a magnet resulted in a strong improvement of cell engraftment and eGFP+ vascular network formation in the hearts. Hemodynamic and morphometric analysis demonstrated augmented heart function and reduced infarct size only when a magnetic field was applied. Conclusion: Thus, the combined use of magnetic microbeads for cell isolation and enhanced cell engraftment in the presence of a magnetic field is a powerful approach to improve cell transplantation strategies in the heart.