Acute cardiovascular protective effects of corticosteroids are mediated by non-transcriptional activation of endothelial nitric oxide synthase

Corticosteroids have been shown to exert beneficial effects in the treatment of acute myocardial infarction, but the precise mechanisms underlying their protective effects are unknown. Here we show that high-dose corticosteroids exert cardiovascular protection through a novel mechanism involving the rapid, non-transcriptional activation of endothelial nitric oxide synthase (eNOS). Binding of corticosteroids to the glucocorticoid receptor (GR) stimulated phosphatidylinositol 3-kinase and protein kinase Akt, leading to eNOS activation and nitric oxide dependent vasorelaxation. Acute administration of pharmacological concentrations of corticosteroids in mice led to decreased vascular inflammation and reduced myocardial infarct size following ischemia and reperfusion injury. These beneficial effects of corticosteroids were abolished by GR antagonists or eNOS inhibitors in wild-type mice and were completely absent in eNOS-deficient (Nos3(-/-)) mice. The rapid activation of eNOS by the non-nuclear actions of GR, therefore, represents an important cardiovascular protective effect of acute high-dose corticosteroid therapy.

Blood flow controls bone vascular function and osteogenesis

While blood vessels play important roles in bone homeostasis and repair, fundamental aspects of vascular function in the skeletal system remain poorly understood. Here we show that the long bone vasculature generates a peculiar flow pattern, which is important for proper angiogenesis. Intravital imaging reveals that vessel growth in murine long bone involves the extension and anastomotic fusion of endothelial buds. Impaired blood flow leads to defective angiogenesis and osteogenesis, and downregulation of Notch signalling in endothelial cells. In aged mice, skeletal blood flow and endothelial Notch activity are also reduced leading to decreased angiogenesis and osteogenesis, which is reverted by genetic reactivation of Notch. Blood flow and angiogenesis in aged mice are also enhanced on administration of bisphosphonate, a class of drugs frequently used for the treatment of osteoporosis. We propose that blood flow and endothelial Notch signalling are key factors controlling ageing processes in the skeletal system.

Formation of new blood vessels and bone is coupled. Here the authors show that blood flow represents a key regulator of angiogenesis and endothelial Notch signalling in the bone, and that reactivation of Notch signalling in the endothelium of aged mice rejuvenates the bone.

Essential role of endothelial Notch1 in angiogenesis

BACKGROUND

Notch signaling influences binary cell fate decisions in a variety of tissues. The Notch1 receptor is widely expressed during embryogenesis and is essential for embryonic development. Loss of global Notch1 function results in early embryonic lethality, but the cell type responsible for this defect is not known. Here, we identify the endothelium as the primary target tissue affected by Notch1 signaling.

METHODS AND RESULTS

We generated an endothelium-specific deletion of Notch1 using Tie2Cre and conditional Notch1(flox/flox) mice. Mutant embryos lacking endothelial Notch1 died at approximately embryonic day 10.5 with profound vascular defects in placenta, yolk sac, and embryo proper, whereas heterozygous deletion had no effect. In yolk sacs of mutant embryos, endothelial cells formed a primary vascular plexus indicative of intact vasculogenesis but failed to induce the secondary vascular remodeling required to form a mature network of well-organized large and small blood vessels, which demonstrates a defect in angiogenesis. These vascular defects were also evident in the placenta, where blood vessels failed to invade the placental labyrinth, and in the embryo proper, where defective blood vessel maturation led to pericardial and intersomitic hemorrhage. Enhanced activation of caspase-3 was detected in endothelial and neural cells of mutant mice, which resulted in enhanced apoptotic degeneration of somites and the neural tube.

CONCLUSIONS

These findings recapitulate the vascular phenotype of global Notch1-/- mutants and indicate an essential cell-autonomous role of Notch1 signaling in the endothelium during vascular development. These results may have important clinical implications with regard to Notch1 signaling in adult angiogenesis.

Critical role of endothelial Notch1 signaling in postnatal angiogenesis

Notch receptors are important mediators of cell fate during embryogenesis, but their role in adult physiology, particularly in postnatal angiogenesis, remains unknown. Of the Notch receptors, only Notch1 and Notch4 are expressed in vascular endothelial cells. Here we show that blood flow recovery and postnatal neovascularization in response to hindlimb ischemia in haploinsufficient global or endothelial-specific Notch1(+/-) mice, but not Notch4(-/-) mice, were impaired compared with wild-type mice. The expression of vascular endothelial growth factor (VEGF) in response to ischemia was comparable between wild-type and Notch mutant mice, suggesting that Notch1 is downstream of VEGF signaling. Treatment of endothelial cells with VEGF increases presenilin proteolytic processing, gamma-secretase activity, Notch1 cleavage, and Hes-1 (hairy enhancer of split homolog-1) expression, all of which were blocked by treating endothelial cells with inhibitors of phosphatidylinositol 3-kinase/protein kinase Akt or infecting endothelial cells with a dominant-negative Akt mutant. Indeed, inhibition of gamma-secretase activity leads to decreased angiogenesis and inhibits VEGF-induced endothelial cell proliferation, migration, and survival. Overexpression of the active Notch1 intercellular domain rescued the inhibitory effects of gamma-secretase inhibitors on VEGF-induced angiogenesis. These findings indicate that the phosphatidylinositol 3-kinase/Akt pathway mediates gamma-secretase and Notch1 activation by VEGF and that Notch1 is critical for VEGF-induced postnatal angiogenesis. These results suggest that Notch1 may be a novel therapeutic target for improving angiogenic response and blood flow recovery in ischemic limbs.

Notch ligand Delta-like 1 is essential for postnatal arteriogenesis

Growth of functional arteries is essential for the restoration of blood flow to ischemic organs. Notch signaling regulates arterial differentiation upstream of ephrin-B2 during embryonic development, but its role during postnatal arteriogenesis is unknown. Here, we identify the Notch ligand Delta-like 1 (Dll1) as an essential regulator of postnatal arteriogenesis. Dll1 expression was specifically detected in arterial endothelial cells, but not in venous endothelial cells or capillaries. During ischemia-induced arteriogenesis endothelial Dll1 expression was strongly induced, Notch signaling activated and ephrin-B2 upregulated, whereas perivascular cells expressed proangiogenic vascular endothelial growth factor, and the ephrin-B2 activator EphB4. In heterozygous Dll1 mutant mice endothelial Notch activation and ephrin-B2 induction after hindlimb ischemia were absent, arterial collateral growth was abrogated and recovery of blood flow was severely impaired, but perivascular vascular endothelial growth factor and EphB4 expression was unaltered. In vitro, angiogenic growth factors synergistically activated Notch signaling by induction of Dll1, which was necessary and sufficient to regulate ephrin-B2 expression and to induce ephrin-B2 and EphB4-dependent branching morphogenesis in human arterial EC. Thus, Dll1-mediated Notch activation regulates ephrin-B2 expression and postnatal arteriogenesis.

Leptin enhances the potency of circulating angiogenic cells via src kinase and integrin (alpha)vbeta5: implications for angiogenesis in human obesity

OBJECTIVE

To investigate the capacity of the adipokine leptin to promote angiogenesis by modulating the function of circulating angiogenic cells (CACs).

METHODS AND RESULTS

In vitro, leptin specifically promoted CAC adhesion to tubular endothelial structures and migration along outgrowing sprouts of endothelial cells. In vivo, stimulation of CACs with leptin increased their capacity to promote new vessel formation in the chorioallantoic membrane of chicken embryos and to improve neovascularization of ischemic murine hind limbs. These effects required the phosphorylation of alphavbeta5 integrins, which depended on the interaction of leptin with its receptor ObR, and on Janus kinase (JAK) 2- and phospholipase C (PLC) gamma-mediated activation of Src kinase. Protein tyrosine phosphatase 1B, a negative regulator of leptin signaling, was overexpressed in CACs from obese, hyperleptinemic individuals, and this was associated with insensitivity of CACs to the angiogenic effects of leptin. Weight loss (by 30+/-15 kg) normalized protein tyrosine phosphatase 1B expression in CACs and restored their responsiveness to leptin. A similar dose-dependent response was found after incubation of CACs from obese subjects with a protein tyrosine phosphatase 1B inhibitor ex vivo.

CONCLUSIONS

Our results point to the ObR-Src kinase-alphavbeta5 cross talk as a distinct novel component of the network of specific interactions between integrins and cytokine receptors in angiogenesis.

Nontranscriptional actions of the glucocorticoid receptor

Many cellular responses to corticosteroids involve the transcriptional modulation of target genes by a prototypical nuclear receptor, the glucocorticoid receptor (GR). In the classic model of steroid hormone action GR acts as ligand-dependent transcription factor by either activating or repressing gene expression through direct interactions with DNA or other transcription factors. Recent evidence suggests an important role for nontranscriptional effects of GR in the vascular system. The nontranscriptional actions of GR involve the rapid activation of protein kinases, such as phosphatidylinositol-3 kinase and Akt, leading to the activation of endothelial nitric oxide synthase. This novel pathway of steroid hormone action protects against ischemic injury by augmenting blood flow and decreasing vascular inflammation.

Rapid nontranscriptional activation of endothelial nitric oxide synthase mediates increased cerebral blood flow and stroke protection by corticosteroids

Many cellular responses to corticosteroids involve the transcriptional modulation of target genes by the glucocorticoid receptor (GR). A rapid, non-nuclear effect of GR was found to mediate neuroprotection. High-dose corticosteroids (20 mg/kg intraperitoneally), given within 2 hours of transient cerebral ischemia, acutely increased endothelial nitric oxide synthase (eNOS) activity, augmented regional cerebral blood flow (CBF) by 40% to 50%, and reduced cerebral infarct size by 32%. These neuroprotective effects of corticosteroids were abolished by the GR antagonist RU486 and by inhibition of phosphatidylinositol 3-kinase (PI3K), and were absent in eNOS(-/-) mice. To determine the mechanism by which GR activated eNOS, we measured the effect of corticosteroids on PI3K and the protein kinase Akt. In a ligand-dependent manner, GR activated PI3K and Akt in vitro and in vivo caused NO-dependent vasodilation, which was blocked by cotreatment with RU486 or the PI3K inhibitor LY294002 but not by transcriptional inhibitors. Indeed, a mutant GR, which cannot dimerize and bind to DNA, still activated PI3K and Akt in response to corticosteroids. These findings indicate that non-nuclear GR rapidly activates eNOS through the PI3K/Akt pathway and suggest that this mechanism mediates the acute neuroprotective effects of corticosteroids through augmentation of CBF.

Notch and TLR signaling coordinate monocyte cell fate and inflammation

Conventional Ly6C^hi monocytes have developmental plasticity for a spectrum of differentiated phagocytes. Here we show, using conditional deletion strategies in a mouse model of Toll-like receptor (TLR) 7-induced inflammation, that the spectrum of developmental cell fates of Ly6C^hi monocytes, and the resultant inflammation, is coordinately regulated by TLR and Notch signaling. Cell-intrinsic Notch2 and TLR7-Myd88 pathways independently and synergistically promote Ly6C^lo patrolling monocyte development from Ly6C^hi monocytes under inflammatory conditions, while impairment in either signaling axis impairs Ly6C^lo monocyte development. At the same time, TLR7 stimulation in the absence of functional Notch2 signaling promotes resident tissue macrophage gene expression signatures in monocytes in the blood and ectopic differentiation of Ly6C^hi monocytes into macrophages and dendritic cells, which infiltrate the spleen and major blood vessels and are accompanied by aberrant systemic inflammation. Thus, Notch2 is a master regulator of Ly6C^hi monocyte cell fate and inflammation in response to TLR signaling.

The dual effect of adenovirus type 5 E1A 13S protein on NF-kappaB activation is antagonized by E1B 19K

The genomes of human adenoviruses encode several regulatory proteins, including the two differentially spliced gene products E1A and E1B. Here, we show that the 13S but not the 12S splice variant of E1A of adenovirus type 5 can activate the human transcription factor NF-kappaB in a bimodal fashion. One mode is the activation of NF-kappaB containing the p65 subunit from the cytoplasmic NF-kappaB-IkappaB complex. This activation required reactive oxygen intermediates and the phosphorylation of IkappaBalpha at serines 32 and 36, followed by IkappaBalpha degradation and the nuclear uptake of NF-kappaB. In addition, 13S E1A stimulated the transcriptional activity of the C-terminal 80 amino acids of p65 at a core promoter with either a TATA box or an initiator (INR) element. The C-terminal 80 amino acids of p65 were found to associate with E1A in vitro. The activation of NF-kappaB-dependent reporter gene transcription by E1A was potently suppressed upon coexpression of the E1B 19-kDa protein (19K). E1B 19K prevented both the activation of NF-kappaB and the E1A-mediated transcriptional enhancement of p65. These inhibitory effects were not found for the 55-kDa splice variant of the E1B protein. We suggest that the inductive effect of E1A 13S on the host factor NF-kappaB, whose activation is important for the transcription of various adenovirus genes, must be counteracted by the suppressive effect of E1B 19K so that the adenovirus-infected cell can escape the immune-stimulatory and apoptotic effects of NF-kappaB.

Haematopoietic stem cells improve cardiac function after infarction without permanent cardiac engraftment

BACKGROUND

Transplantation of bone marrow derived adult stem cells (BMC) improves cardiac function after acute myocardial infarction (MI). However, the cell population mediating myocardial recovery and the fate of the transplanted cells are still controversial.

AIMS

We determined the effects of Sca-1+ c-kit+ lin- haematopoietic BMC on cardiac function after MI and the cell fate after transplantation.

METHODS

Sca-1+ c-kit+ lin- BMC of male donor C57BL/6 mice were transplanted by intravenous injection into syngenic females after permanent MI. LV dimensions and function were determined by echocardiography and cardiac magnetic resonance imaging, transplanted BMC were identified by Y chromosome DNA in situ hybridization.

RESULTS

BMC treatment completely prevented LV dilation (LV end-diastolic volume BMC 70 +/- 16 microl vs. control 122 +/- 41 microl; p < 0.05) and improved fractional shortening (BMC 22.9 +/- 8% vs. control 15.4 +/- 8.4%; p < 0.05) and ejection fraction BMC 68.2 +/- 6.6% vs. control 52 +/- 14.3%; p < 0.05) as early as 3 days after transplantation, but did not decrease infarct size (BMC 27 +/- 6% vs. control 28 +/- 7%, p = n.s.). After 4 weeks, only sporadic cells of male origin were identified in infarcted hearts (< 0.01% of periinfarct cells).

CONCLUSION

Intravenous injection of Sca-1+ c-kit+ lin- in BMC after MI improves LV dimensions and function without evidence for long term engraftment.

Extrinsic Notch ligand Delta-like 1 regulates tip cell selection and vascular branching morphogenesis

RATIONALE

In developing blood vessels, single endothelial cells (ECs) specialize into tip cells that sense vascular endothelial growth factor (VEGF) and contribute to vessel sprouting and branch formation. Tip cell differentiation is inhibited through lateral Notch signaling between ECs, which is controlled by Notch ligands expressed in vessel sprouts. The contribution of the Notch ligand Delta-like (Dll) 1 herein is unknown.

OBJECTIVE

To investigate the role of Dll1 in vascular morphogenesis and tip cell formation in the mouse retina.

METHODS AND RESULTS

Mice with heterozygous deletion of Dll1 had fewer tip cells during angiogenic sprouting of the superficial vascular plexus but also showed impaired vessel branching into deeper retinal layers and impaired deep plexus angiogenesis. Interestingly, the formation of vertical branches was also guided by filopodia-extending ECs located at the tip of branches, consistent with tip cells, which emerged from established vessels to form a secondary plexus within the deeper neuronal cell layers. During both phases of vascular patterning, Dll1 was not expressed in ECs but in the superficial neuronal layer in close contact with expanding vessels, where Dll1 expression coincided with tip cell formation in a spatiotemporal manner. In vitro, culture of ECs on DLL1 induced essential tip cell genes, including Dll4, VEGF receptor 3, and ephrin-B2, and stimulated VEGF responsiveness and vascular network formation.

CONCLUSIONS

Dll1 acts as an extrinsic cue involved in tip cell selection, which directs vessel sprouting and branch formation.

The chemokine receptor CX3CR1 coordinates monocyte recruitment and endothelial regeneration after arterial injury

Regeneration of arterial endothelium after injury is critical for the maintenance of normal blood flow, cell trafficking, and vascular function. Using mouse models of carotid injury, we show that the transition from a static to a dynamic phase of endothelial regeneration is marked by a strong increase in endothelial proliferation, which is accompanied by induction of the chemokine CX3CL1 in endothelial cells near the wound edge, leading to progressive recruitment of Ly6Clo monocytes expressing high levels of the cognate CX3CR1 chemokine receptor. In Cx3cr1-deficient mice recruitment of Ly6Clo monocytes, endothelial proliferation and regeneration of the endothelial monolayer after carotid injury are impaired, which is rescued by acute transfer of normal Ly6Clo monocytes. Furthermore, human non-classical monocytes induce proliferation of endothelial cells in co-culture experiments in a VEGFA-dependent manner, and monocyte transfer following carotid injury promotes endothelial wound closure in a hybrid mouse model in vivo Thus, CX3CR1 coordinates recruitment of specific monocyte subsets to sites of endothelial regeneration, which promote endothelial proliferation and arterial regeneration.

Urokinase receptor associates with myocardin to control vascular smooth muscle cells phenotype in vascular disease

OBJECTIVE

The urokinase-type plasminogen activator (uPA) and its specific receptor (uPAR) are a potent multifunctional system involved in vascular remodeling. The goal of the study was to unravel the mechanisms of uPA/uPAR-directed vascular smooth muscle cell (VSMC) differentiation.

METHODS AND RESULTS

Using cultured human primary VSMCs, we identified a new molecular mechanism controlling phenotypic modulation in vitro and in vivo. We found that the urokinase-type plasminogen activator receptor (uPAR) acts together with the transcriptional coactivator myocardin to regulate the VSMC phenotype. uPAR, a glycosylphosphatidylinositol-anchored cell-surface receptor family member, undergoes ligand-induced internalization and nuclear transport in VSMCs. Platelet-derived growth factor receptor β and SUMOylated RanGAP1 mediate this trafficking. Nuclear uPAR associates with myocardin, which is then recruited from the promoters of serum response factor target genes and undergoes proteasomal degradation. This chain of events initiates the synthetic VSMC phenotype. Using mouse carotid artery ligation model, we show that this mechanism contributes to adverse vascular remodeling after injury in vivo. We then cultured cells on a microstructured biomaterial and found that substrate topography induced uPAR-mediated VSMC differentiation.

CONCLUSIONS

These findings reveal the transcriptional activity of uPAR, controlling the differentiation of VSMCs in a vascular disease model. They also suggest a new role for uPAR as a therapeutic target and as a marker for VSMC phenotyping on prosthetic biomaterials.

Transcoronary delivery of bone marrow cells to the infarcted murine myocardium

Efficient strategies for labelling and delivery of bone marrow derived stem cells (BMCs) are required to elucidate the cellular kinetics and therapeutic effects after BMC transfer for myocardial infarction (MI). Lineage negative (lin-) BMCs, labelled ex vivo in a simple procedure with the cell tracker dye tetramethyl-rhodamine (TAMRA), were reliably detected by fluorescence microscopy with higher specificity than retroviral enhanced green fluorescence protein (EGFP) marking and detection. Only few cells entered the ischemic myocardium after intravenous (i.v.) application, but this number increased more than 18-fold after transcoronary delivery. Time course and kinetic analysis over 12 h revealed that myocardial colonization seems to be a biphasic process of first order decay with different elimination half-lives. Most cells are eliminated rapidly during the first 2 h (t1/2 40 min), but the remaining cells are retained significantly longer in the ischemic heart (t1/2 5.2 h). In contrast, BMC colonization of the spleen increased rather in a linear fashion. Although transcoronary BMC transfusion did not alter infarct size, it increased capillary density in the infarct border zone and improved LV function 4 weeks after MI. In conclusion, BMCs delivered by transcoronary injection increase capillary density and improve LV function after MI although homing to the ischemic heart is only transient.

Overexpression of integrin beta 5 enhances the paracrine properties of circulating angiogenic cells via Src kinase-mediated activation of STAT3

OBJECTIVE

To determine the intracellular mechanisms mediating the angiogenic effects of integrin alpha v beta 5 overexpression in circulating angiogenic cells (CACs).

METHODS AND RESULTS

Integrin alpha v beta 5 is expressed on angiogenic endothelial cells, and integrin alpha v beta 5 activation was shown to improve the reparative functions of endothelial progenitors within the cardiovascular system. CACs were transiently transfected with the full-length cDNA of human integrin beta 5 (CAC-ITGB5) or control-vector (CAC-vector). Integrin beta 5 overexpression was confirmed using flow cytometry, Western blot, and PCR analysis; it enhanced the angiogenic capacities of CACs in vitro (spheroid and Matrigel angiogenesis assay) and stimulated new vessel formation in vivo (murine hind limb ischemia model). Overexpression of ITGB5 resulted in integrin alpha v beta 5 phosphorylation and activation of Src kinase and signal transducer and activator of transcription (STAT) 3. Furthermore, elevated mRNA and protein expression of the CXC chemokine CXCL8 and the CC chemokine CCL2 was detected in CAC-ITGB5, and conditioned medium from CAC-ITGB5 enhanced the sprouting of coincubated human endothelial cells in a STAT3-, CXCL8-, and CCL2-dependent manner.

CONCLUSIONS

Src kinase-mediated activation of STAT3 and subsequent angiogenic gene expression mediate the effects of integrin alpha v beta 5 and may be exploited to enhance the paracrine activities of CACs.

Monocyte Subsets and Related Chemokines in Carotid Artery Stenosis and Ischemic Stroke

Carotid stenosis (CS) is an important cause of ischemic stroke. However, reliable markers for the purpose of identification of high-risk, so-called vulnerable carotid plaques, are still lacking. Monocyte subsets are crucial players in atherosclerosis and might also contribute to plaque rupture. In this study we, therefore, aimed to investigate the potential role of monocyte subsets and associated chemokines as clinical biomarkers for vulnerability of CS. Patients with symptomatic and asymptomatic CS (n = 21), patients with cardioembolic ischemic strokes (n = 11), and controls without any cardiovascular disorder (n = 11) were examined. Cardiovascular risk was quantified using the Essen Stroke Risk Score (ESRS). Monocyte subsets in peripheral blood were measured by quantitative flow cytometry. Plaque specimens were histologically analyzed. Furthermore, plasma levels of monocyte chemotactic protein 1 (MCP-1) and fractalkine were measured. Intermediate monocytes (Mon2) were significantly elevated in symptomatic and asymptomatic CS-patients compared to controls. Mon2 counts positively correlated with the ESRS. Moreover, stroke patients showed an elevation of Mon2 compared to controls, independent of the ESRS. MCP-1 levels were significantly higher in patients with symptomatic than in those with asymptomatic CS. Several histological criteria significantly differed between symptomatic and asymptomatic plaques. However, there was no association of monocyte subsets or chemokines with histological features of plaque vulnerability. Due to the multifactorial influence on monocyte subsets, the usability as clinical markers for plaque vulnerability seems to be limited. However, monocyte subsets may be critically involved in the pathology of CS.

Loss of vascular endothelial notch signaling promotes spontaneous formation of tertiary lymphoid structures

Tertiary lymphoid structures (TLS) are lymph node-like immune cell clusters that emerge during chronic inflammation in non-lymphoid organs like the kidney, but their origin remains not well understood. Here we show, using conditional deletion strategies of the canonical Notch signaling mediator Rbpj, that loss of endothelial Notch signaling in adult mice induces the spontaneous formation of bona fide TLS in the kidney, liver and lung, based on molecular, cellular and structural criteria. These TLS form in a stereotypical manner around parenchymal arteries, while secondary lymphoid structures remained largely unchanged. This effect is mediated by endothelium of blood vessels, but not lymphatics, since a lymphatic endothelial-specific targeting strategy did not result in TLS formation, and involves loss of arterial specification and concomitant acquisition of a high endothelial cell phenotype, as shown by transcriptional analysis of kidney endothelial cells. This indicates a so far unrecognized role for vascular endothelial cells and Notch signaling in TLS initiation.

Loss of canonical Notch signaling in vascular endothelial cells induces spontaneous formation of proto-typical tertiary lymphoid structures in mouse kidney, liver and lungs, which form around central arteries that acquire a high endothelial cell signature

Ex vivo expanded hematopoietic progenitor cells improve cardiac function after myocardial infarction: role of beta-catenin transduction and cell dose

Cell-based therapy after myocardial infarction (MI) is a promising therapeutic option but the relevant cell subsets and dosage requirements are poorly defined. We hypothesized that cell therapy for myocardial infarction is improved by ex vivo expansion and high-dose transplantation of defined hematopoietic progenitor cells (HPCs). Since beta-catenin promotes self-renewal of stem cells we evaluated the therapeutic efficacy of beta-catenin-mediated ex vivo expansion of mouse HPCs in a mouse model of myocardial ischemia/reperfusion followed by intraarterial cell delivery. The impact of cell dose was determined by comparing a low-dose (LD, 5 x 10(5) cells) vs. a high-dose (HD, 1 x 10(7) cells) cell transplantation regimen of beta-catenin-HPCs. The impact of beta-catenin modification of HPCs was determined by comparing control-transduced HPCs (GFP-HPCs) vs. transgenic beta-catenin-HPCs. HD beta-catenin-HPCs significantly improved LV function and end-systolic and end-diastolic dimensions as compared to saline and LD beta-catenin-HPCs. Furthermore, while treatment with HD GFP-HPC resulted in a modest cardiac improvement the application of beta-catenin-HPCs was superior, resulting in a significant improvement in EF, FS and LVESD over saline and control GFP-HPC treatment. Although myocardial engraftment of HPCs was only transient, as determined by cell quantification after dye labeling, beta-catenin-HPC treatment significantly decreased infarct size, reduced cardiomyocyte apoptosis and increased capillary angiogenesis in vitro and in vivo. Ex vivo expanded HPCs improve cardiac function and remodeling post MI in a cell number- and beta-catenin-dependent manner.

Spontaneous Formation of Extensive Vessel-Like Structures in Murine Engineered Heart Tissue

Engineered heart tissue (EHT) from primary heart cells contains endothelial cells (ECs), but the extent to which ECs organize into vessel-like structures or even functional vessels remains unknown and is difficult to study by conventional methods. In this study, we generated fibrin-based mini-EHTs from a transgenic mouse line (Cdh5-CreERT2 × Rosa26-LacZ), in which ECs were specifically and inducibly labeled by applying tamoxifen (EC(iLacZ)). EHTs were generated from an unpurified cell mix of newborn mouse hearts and were cultured under standard serum-containing conditions. Cre expression in 15-day-old EHTs was induced by addition of o-hydroxytamoxifen to the culture medium for 48 h, and ECs were visualized by X-gal staining. EC(iLacZ) EHTs showed a dense X-gal-positive vessel-like network with distinct tubular structures. Immunofluorescence revealed that ECs were mainly associated with cardiomyocytes within the EHT. EC(iLacZ) EHT developed spontaneous and regular contractility with forces up to 0.1 mN. Coherent contractility and the presence of an extensive vessel-like network were both dependent on the presence of animal sera in the culture medium. Contractile EC(iLacZ) EHTs successfully served as grafts in implantation studies onto the hearts of immunodeficient mice. Four weeks after implantation, EHTs showed X-gal-positive lumen-forming vessel structures connected to the host myocardium circulation as they contained erythrocytes on a regular basis. Taken together, genetic labeling of ECs revealed the extensive formation of vessel-like structures in EHTs in vitro. The EC(iLacZ) EHT model could help simultaneously study biological effects of compounds on cardiomyocyte function and tissue vascularization.

Effectiveness of a Fixed-Dose, Single-Pill Combination of Perindopril and Amlodipine in Patients with Hypertension: A Non-Interventional Study

INTRODUCTION

We conducted a prospective, non-interventional, multicenter study to examine the effect of a fixed-dose combination of perindopril/amlodipine in patients with arterial hypertension.

METHODS

Patients who were previously untreated or required a change in medication were treated with a fixed combination of perindopril/amlodipine (3.5/2.5 or 7.0/5.0 mg) for 12 weeks. Changes in office, home and ambulatory blood pressure (BP) were recorded. Adherence was assessed by the Hill-Bone medication adherence scale.

RESULTS

Overall, 1814 patients (mean age 60.0 ± 13.4 years) were included in 614 German practices, and data of 1770 patients were analyzed. At study entry, 97.7% of patients received perindopril/amlodipine at a daily dose of 3.5 mg/2.5 mg, and 47.9% of patients remained on this dose during the study period. Treatment with perindopril/amlodipine decreased mean office BP from 163.7/95.4 to 133.6/80.3 mmHg (p < 0.0001), resulting in a hypertension control rate of 69.1%. Blood pressure control was comparable in previously untreated and treated patients (70.3 vs. 68.1%), and in younger and older patients (70.6 < 65 vs. 66.3% ≥ 65 years). Ambulatory BP measurements were available in a subgroup of patients (n = 167), and mean 24 h ambulatory BP decreased from 150.6 ± 12.6/88.9 ± 8.8 to 132.4 ± 11.9/79.4 ± 8.5 mmHg (p < 0.0001). Furthermore, the proportion of patients with severe hypertension European Society of Hypertension/European Society of Cardiology (ESH/ESC) grade II or III decreased from 64.4 to 3.9%, and patients with pre-existing isolated systolic hypertension (n = 284) converted to normal BP in 67.6% of cases. Nearly half of the patients (47.2%) were perfectly adherent during the study. In previously treated patients, the percentage of patients with perfect adherence increased from 20.6% prior to study to 43.5% at final visit (p < 0.0001). Adverse drug reactions were documented for 4.9% of patients.

CONCLUSION

A fixed-dose combination of perindopril/amlodipine shows significant blood pressure reduction and improvement in medication adherence in a primary care setting.

TRIAL REGISTRATION

ISRCTN26323538.

FUNDING

Servier Deutschland GmbH.

Current practice of blood pressure measurement in Germany: a nationwide questionnaire-based survey in medical practices

PURPOSE

Discrepancies exist between guideline recommendations and real-world practice of blood pressure (BP) measurements. The aim of this study was to assess, with a nationwide, questionnaire-based survey, the current practice of BP measurement and associated BP values in German medical practices.

MATERIAL AND METHODS

A nationwide survey in German medical practices was performed in the period from 10 May 2021 to 15 August 2021. The questionnaire was divided into five sections. The current office BP (OBP) values as well as the current drug therapy were recorded. In addition, the implementation of office BP (OBP) and home BP monitoring (HBPM) was queried. For analysis, questionnaires were scanned and automatically digitised.

RESULTS

A total of 7049 questionnaires were analysed, the majority of which came from general practitioners (66%) and internal medicine practices (34%). The average OBP (SD) was 140.0 (18)/82.7 (11) mmHg. 40.8% of treated patients had OBP in the controlled range, with monotherapy (34.7%) or dual combination therapy (38.2%) prescribed in most cases. OBP was taken from a single measurement in 66.3% of cases, and in 21.8% from 23 measurements. OBP was mostly measured after a rest period (87.1%) and in a separate room (80.4%). HBPM was performed in 62.3% of patients; however, in 24.9% of the participants HBP measurements were recorded once a week or less.

CONCLUSION

In this nationwide survey in German medical practices, BP control remains at below 50%, while monotherapy is prescribed in around one third of patients. Moreover, office measurements and HBPM are often not performed according to current guideline recommendations.