Endothelial dysfunction--an obstacle of therapeutic angiogenesis

Role of platelet-derived growth factor c on endothelial dysfunction in cardiovascular diseases

Loss of endothelial function is a common feature to all cardiovascular diseases (CVDs). One of the risk factors associated with the development of CVDs is the hyperglycaemia that occurs in patients with metabolic disorders such as Type 1 and Type 2 diabetes mellitus. Hyperglycaemia causes endothelial dysfunction through increased production of reactive oxygen species (ROS) from different cellular sources leading to oxidative stress. Vascular endothelial growth factor (VEGF) is essential in the stimulation and maintenance of endothelial functional aspects and, although it can mitigate the impact of ROS, VEGF-mediated signalling is partially inhibited in diabetes mellitus. The search for therapeutic strategies that preserve, protect and improve the functions of the endothelium is of great relevance in the investigation of CVDs associated with hyperglycaemia. Platelet-derived growth factor C (PDGF-C) is a peptide with angiogenic properties, independent of VEGF, that stimulates angiogenesis and revascularization of ischemic tissue. In a diabetic mouse model, PDGF-C stimulates mature endothelial cell migration, angiogenesis, endothelial progenitor cell mobilization, and increased neovascularization, and protects blood vessels in a retinal degeneration model activating anti-apoptosis and proliferation signalling pathways in endothelial cells. This review summarizes the information on the damage that high d-glucose causes on endothelial function and the beneficial effects that PDGF-CC could exert in this condition.

CUL5-Mediated Visfatin (NAMPT) Degradation Blocks Endothelial Proliferation and Angiogenesis via the MAPK/PI3K-AKT Signaling

ABSTRACT

Endothelial dysfunction participates in the pathogenesis of various cardiovascular disorders, and dysregulated angiogenesis involves the vascular endothelial growth factor (VEGF)-matrix metalloproteinases (MMP) system. Nicotinamide phosphoribosyltransferase (NAMPT) is known to enhance endothelial function and angiogenesis. The study found that NAMPT overexpression protected human coronary artery endothelial cells (HCAECs) from H2O2-induced injury through promoting cell viability, inhibiting cell apoptosis, enhancing cell motility, and promoting tube formation. Through analyses based on 2 Protein-Protein Interaction databases, Mentha and BioGrid, we identified CUL5 as a protein that may interact with NAMPT, which was then validated by Co-IP experiments. Through interacting with NAMPT, CUL5 inhibited NAMPT expression. In contrast to NAMPT, CUL5 overexpression further aggravated H2O2-induced HCAEC dysfunction. In the meantime, CUL5 overexpression reduced, whereas NAMPT overexpression increased the phosphorylation of p38 and Akt and the protein levels of VEGF and MMP2. More importantly, NAMPT overexpression partially reversed the effects of CUL5 overexpression on H2O2-stimulated HCAECs and the MAPK/phosphatidylinositol 3-kinase-Akt/VEGF/MMP signaling. In conclusion, CUL5 interacts with NAMPT in H2O2-stimulated HCAECs, suppressing cell viability, promoting cell apoptosis, and inhibiting cell mobility and tube formation. NAMPT overexpression protects against H2O2-induced HCAEC dysfunction by promoting cell viability, inhibiting cell apoptosis, and enhancing cell mobility and tube formation.

MicroRNA sequence analysis of plasma exosomes in early Legg-Calvé-Perthes disease

The pathogenesis of Legg-Calvé-Perthes disease (LCPD) has not been fully elucidated, and studies on epigenetic changes that may contribute to the pathogenesis of LCPD are rare. MicroRNAs (miRNAs) are epigenetic modifications that play a critical role in gene regulation. This study aimed to determine the expression profiles of circulating exosomal miRNAs and examine the role of exosomal miRNAs in LCPD. Exosomes were extracted from the plasma of three patients with LCPD and three matched healthy volunteers. Total exosomal miRNAs were isolated, and next-generation sequencing and bioinformatic approaches were performed. The top 10 most differentially upregulated miRNAs were identified, and qRT-PCR validation was performed using additional 10 matches. In Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, plasma exosomes were used in verifying osteoclastogenesis and the endothelial dysfunction phenotypes involved. The elevated miRNAs in LCPD plasma exosomes were tested for osteoclastogenesis and endothelial dysfunction in vitro. Sequencing results revealed the expression profiles of plasma exosomal miRNAs with differential expression from the DESeq-identified miRNA profiles in LCPD versus controls in a pairwise comparison. Gene Ontology and KEGG pathway analyses indicated that the predicted target genes of different miRNAs were mainly enriched in the endothelial and osteoclast cells related to signaling pathways. Functional phenotype experiments showed that the plasma exosomes in the LCPD group promoted osteoclastogenesis and endothelial cell dysfunction. qRT-PCR experiments showed that nine miRNAs in circulating exosomes in LCPD patients were higher than those in the healthy controls. miR-3133, miR-4644, miR-4693-3p, and miR-4693-5p promoted endothelial dysfunction, and miR-3133, miR-4693-3p, miR-4693-5p, miR-141-3p and miR-30a promoted osteoclastogenesis in vitro. This study demonstrated that plasma exosomes from LCPD promote endothelial cell dysfunction and osteoclastogenesis likely through their miRNAs, which might contribute to the development of LCPD.

Neuroprotection against cerebral ischemia/reperfusion by dietary phytochemical extracts from Tibetan turnip (Brassica rapa L.)

ETHNOPHARMACOLOGICAL RELEVANCE

The Tibetan turnip (Brassica rapa L.) has a wide array of medicine properties including heat-clearing, detoxifying and anti-hypoxia as listed in the famous centuries-old Tibetan medicine classic "The Four Medical Tantras". Evidence-based medicine also indicated the anti-hypoxic effect of turnips, suggesting a potential link to neuroprotective effect on ischemic stroke. This thereby enables turnips to serve as a novel nontoxic agent in related treatment.

AIM OF THE STUDY

This study aimed to investigate the neuroprotective effect and elucidate the mechanism of aqueous extract of turnip (AET) on cerebral ischemia/reperfusion.

MATERIALS AND METHODS

The experimental models of cerebral ischemia included transient middle cerebral artery occlusion/reperfusion (MCAO) in C57BL/6J mice and oxygen-glucose deprivation/reoxygenation (OGD/R) in HT-22 cells. Long-term effect of AET on infarct volume was evaluated by microtubule-associated protein 2 (MAP2) immunofluorescence 28 days after MCAO, and on neurofunctional outcomes determined by rotarod, grid walking, and cylinder tests in the meantime. Efficacy of AET was determined by the cell viability, the release of lactate dehydrogenase (LDH) and reactive oxygen species (ROS) in neurons. The underlying mechanism of AET rescued OGD/R cells were characterized by PI3K, Akt and mTOR expressions, which were further used to validate AET's role in the pathway.

RESULTS

AET can reduce cerebral infarct volume and ameliorate behavioral deficits of MCAO/R mice dose-dependently. In vitro experiment further demonstrated that suitable concentrations of AET inhibited ROS, LDH production and restored mitochondrial expression induced by OGD/R. AET pretreatment can reverse the OGD/R-induced decreased level of phosphorylation of PI3K, Akt, mTOR, whereas this effect was blocked in the LY294002 (PI3K inhibitor) treatment group.

CONCLUSIONS

AET improved the survival of OGD/R-injured HT-22 cells by activating the PI3K/Akt/mTOR pathway. Based on the results above, aqueous extract of turnip has a protective effect on focal cerebral ischemic injury.

Increased circulating CD31+/CD42b-EMPs in Perthes disease and inhibit HUVECs angiogenesis via endothelial dysfunction

AIMS

Endothelial microparticles (EMPs) are extracellular vesicles secreted by endothelial cells. The purpose of this research is to explore that the clinical significance and roles in angiogenesis and endothelial dysfunction of circulating microparticles in Perthes disease.

MAIN METHODS

We collected platelet-poor plasma (PPP) from patients and controls, then microparticles (MPs) were extracted. Flow cytometry was performed to calculate the concentrations of CD31+/CD42b-, CD62E+ and CD31+/CD42b+ MPs. ELISA was performed to detect the expression level of biomarkers of endothelial dysfunction and inflammatory factors in plasma. In vitro experiments to evaluate the effect of circulating MPs and EMPs derived from IL-6-stimulated human umbilical vein endothelial cells (HUVECs) on angiogenesis and endothelial dysfunction.

KEY FINDINGS

Our results revealed that the CD31+/CD42b- EMPs were significantly higher in Perthes disease group than in the control group. The Perthes-MPs being taken up by HUVECs promoted endothelial cell apoptosis, endothelial dysfunction and inhibited angiogenesis in vitro. Moreover, the level of IL-6 in plasma significantly increased in patients with Perthes, which was tightly correlated with the elevated level of circulating CD31+/CD42b- EMPs. IL-6 promoted HUVECs to secrete CD31+/CD42b- MPs, and EMPs derived from high concentration IL-6-stimulated (100 and 1000 pg/mL) HUVECs promoted endothelial cell apoptosis, endothelial dysfunction and inhibited angiogenesis.

SIGNIFICANCE

In summary, our study suggests that circulating EMPs in the phenotypic spectrum revealed unique phenotypes of endothelial dysfunction, showing close correlation with the secretion of IL-6. These circulating EMPs may give rise to endothelial cell apoptosis, endothelial dysfunction and angiogenesis in Perthes disease.

Sirtuins family as a target in endothelial cell dysfunction: implications for vascular ageing

The vascular endothelium is a protective barrier between the bloodstream and the vasculature that may be disrupted by different factors such as the presence of diseased states. Diseases like diabetes and obesity pose a great risk toward endothelial cell inflammation and oxidative stress, leading to endothelial cell dysfunction and thereby cardiovascular complications such as atherosclerosis. Sirtuins are NAD⁺-dependent histone deacetylases that are implicated in the pathophysiology of cardiovascular diseases, and they have been identified to be important regulators of endothelial cell function. A handful of recent studies suggest that disbalance in the regulation of endothelial sirtuins, mainly sirtuin 1 (SIRT1), contributes to endothelial cell dysfunction. Herein, we summarize how SIRT1 and other sirtuins may contribute to endothelial cell function and how presence of diseased conditions may alter their expressions to cause endothelial dysfunction. Moreover, we discuss how the beneficial effects of exercise on the endothelium are dependent on SIRT1. These mainly include regulation of signaling pathways related to endothelial nitric oxide synthase phosphorylation and nitric oxide production, mitochondrial biogenesis and mitochondria-mediated apoptotic pathways, oxidative stress and inflammatory pathways. Sirtuins as modulators of the adverse conditions in the endothelium hold a promising therapeutic potential for health conditions related to endothelial dysfunction and vascular ageing.

MiR-4674 regulates angiogenesis in tissue injury by targeting p38K signaling in endothelial cells

Neoangiogenesis is critical for tissue repair in response to injury such as myocardial ischemia or dermal wound healing. MicroRNAs are small noncoding RNAs and important regulators of angiogenesis under physiological and pathological disease states. Therefore, identification of microRNAs that may restore impaired angiogenesis in response to tissue injury may provide new targets for therapy. Using a microRNA microarray profiling approach, we identified a human-specific microRNA, miR-4674, that was significantly decreased in patients after myocardial tissue injury and had an endothelial cell (EC)-enriched expression pattern. Functionally, overexpression of miR-4674 markedly attenuated EC proliferation, migration, network tube formation, and spheroid sprouting, whereas blockade of miR-4674 had the opposite effects. Transcriptomic profiling, gene set enrichment analyses, bioinformatics, 3'-untranslated region (3'-UTR) reporter and microribonucleoprotein immunoprecipitation (miRNP-IP) assays, and small interfering RNA dependency studies revealed that miR-4674 regulates VEGF stimulated-p38 mitogen-activated protein kinase (MAPK) signaling and targets interleukin 1 receptor-associated kinase 1 (Irak1) and BICD cargo adaptor 2 (Bicd2) in ECs. Furthermore, Irak1 and Bicd2 were necessary for miR-4674-driven EC proliferation and migration. Finally, neutralization of miR-4674 increased angiogenesis, Irak1 and Bicd2 expression, and p38 phosphorylation in human skin organoids as a model of tissue injury. Collectively, targeting miR-4674 may provide a novel therapeutic target for tissue repair in pathological disease states associated with impaired angiogenesis.

Organ-level vascularization: The Mars mission of bioengineering

Organ-level vascularization has been a long-standing challenge in the field of tissue engineering. Recent advances, particularly in the use of projection stereolithography and food colors as photoabsorbers are highlighted, as are several recent studies on the clinical translation of engineered vasculature.

MicroRNA-615-5p Regulates Angiogenesis and Tissue Repair by Targeting AKT/eNOS (Protein Kinase B/Endothelial Nitric Oxide Synthase) Signaling in Endothelial Cells

Objective- In response to tissue injury, the appropriate progression of events in angiogenesis is controlled by a careful balance between pro and antiangiogenic factors. We aimed to identify and characterize microRNAs that regulate angiogenesis in response to tissue injury. Approach and Results- We show that in response to tissue injury, microRNA-615-5p (miR-615-5p) is rapidly induced and serves as an antiangiogenic microRNA by targeting endothelial cell VEGF (vascular endothelial growth factor)-AKT (protein kinase B)/eNOS (endothelial nitric oxide synthase) signaling in vitro and in vivo. MiR-615-5p expression is increased in wounds of diabetic db/db mice, in plasma of human subjects with acute coronary syndromes, and in plasma and skin of human subjects with diabetes mellitus. Ectopic expression of miR-615-5p markedly inhibited endothelial cell proliferation, migration, network tube formation in Matrigel, and the release of nitric oxide, whereas miR-615-5p neutralization had the opposite effects. Mechanistic studies using transcriptomic profiling, bioinformatics, 3' untranslated region reporter and microribonucleoprotein immunoprecipitation assays, and small interfering RNA dependency studies demonstrate that miR-615-5p inhibits the VEGF-AKT/eNOS signaling pathway in endothelial cells by targeting IGF2 (insulin-like growth factor 2) and RASSF2 (Ras-associating domain family member 2). Local delivery of miR-615-5p inhibitors, markedly increased angiogenesis, granulation tissue thickness, and wound closure rates in db/db mice, whereas miR-615-5p mimics impaired these effects. Systemic miR-615-5p neutralization improved skeletal muscle perfusion and angiogenesis after hindlimb ischemia in db/db mice. Finally, modulation of miR-615-5p expression dynamically regulated VEGF-induced AKT signaling and angiogenesis in human skin organoids as a model of tissue injury. Conclusions- These findings establish miR-615-5p as an inhibitor of VEGF-AKT/eNOS-mediated endothelial cell angiogenic responses and that manipulating miR-615-5p expression could provide a new target for angiogenic therapy in response to tissue injury. Visual Overview- An online visual overview is available for this article.

Effects of direct high sodium exposure at endothelial cell migration

The present study aimed to test the hypothesis that high sodium affects the migratory phenotype of endothelial cells (EC) and investigates mechanisms involved independently of hemodynamic factors. Cell migration was evaluated by Wound-Healing at conditions: High Sodium (HS; 160 mM) and Control (CT; 140 mM). O₂^- production was evaluated by DHE. NADPH oxidase activity was determined by chemiluminescence assay. Expression of adhesion molecules was analyzed by RT-PCR. Shear Stress was performed using a rhythmic shake. Nitric oxide production was measured by Griess reaction. HS-induced impairment in EC migration while both Candesartan and DPI prevented it. HS increased NADPH oxidase activity, which was blocked by Candesartan. Also, HS increased O₂^- production that was inhibited by Candesartan. HS decreased adhesion molecules expression via ROS (Integrin Alpha 5, Integrin Beta 1, Integrin Beta 3, VE-Cadherin and PECAM) and via AT1R (PECAM). The nitric oxide production induced by shear stress was decreased after EC exposure to HS while both Candesartan and DPI prevented it. Conclusion: This study demonstrated that HS reduced EC migration by AT1R and ROS derived from NADPH Oxidase and mitochondria. The HS reduction in adhesion molecules expression modulated by ROS and AT1R may help to explain the impairment in migration capacity. Also, HS affected EC functionality by reducing their nitric oxide production in response to shear stress.

MicroRNA-135a-3p regulates angiogenesis and tissue repair by targeting p38 signaling in endothelial cells

Angiogenesis is a critical process in repair of tissue injury that is regulated by a delicate balance between pro- and antiangiogenic factors. In disease states associated with impaired angiogenesis, we identified that miR-135a-3p is rapidly induced and serves as an antiangiogenic microRNA (miRNA) by targeting endothelial cell (EC) p38 signaling in vitro and in vivo. MiR-135a-3p overexpression significantly inhibited EC proliferation, migration, and network tube formation in matrigel, whereas miR-135-3p neutralization had the opposite effects. Mechanistic studies using transcriptomic profiling, bioinformatics, 3'-UTR reporter and miRNA ribonucleoprotein complex -immunoprecipitation assays, and small interfering RNA dependency studies revealed that miR-135a-3p inhibits the p38 signaling pathway in ECs by targeting huntingtin-interacting protein 1 (HIP1). Local delivery of miR-135a-3p inhibitors to wounds of diabetic db/db mice markedly increased angiogenesis, granulation tissue thickness, and wound closure rates, whereas local delivery of miR-135a-3p mimics impaired these effects. Finally, through gain- and loss-of-function studies in human skin organoids as a model of tissue injury, we demonstrated that miR-135a-3p potently modulated p38 signaling and angiogenesis in response to VEGF stimulation by targeting HIP1. These findings establish miR-135a-3p as a pivotal regulator of pathophysiological angiogenesis and tissue repair by targeting a VEGF-HIP1-p38K signaling axis, providing new targets for angiogenic therapy to promote tissue repair.-Icli, B., Wu, W., Ozdemir, D., Li, H., Haemmig, S., Liu, X., Giatsidis, G., Cheng, H. S., Avci, S. N., Kurt, M., Lee, N., Guimaraes, R. B., Manica, A., Marchini, J. F., Rynning, S. E., Risnes, I., Hollan, I., Croce, K., Orgill, D. P., Feinberg, M. W. MicroRNA-135a-3p regulates angiogenesis and tissue repair by targeting p38 signaling in endothelial cells.

Effect of Diallyl Trisulfide on Ischemic Tissue Injury and Revascularization in a Diabetic Mouse Model

BACKGROUND AND OBJECTIVE

Allitridin [diallyl trisulfide (DATS)] is an extract from garlic (Allium sativum) that putatively improves endothelial function and is protective against cardiovascular diseases. Endothelial dysfunction after tissue ischemia in diabetic patients is partially due to poor angiogenic response. This study investigated whether DATS may improve angiogenesis in a diabetic mouse model with hind limb ischemia.

METHODS

Streptozotocin was administered by intraperitoneal injection to establish the model of diabetes in male C57BL/6 mice. After 14 days, nondiabetic and diabetic mice (n = 24, each) underwent unilateral hind limb ischemia by femoral artery ligation. The mice were apportioned to 4 groups: nondiabetic treated (or not) with DATS and diabetic treated (or not) with DATS. DATS treatment consisted of a single daily intraperitoneal injection of 500 μg·kg·d for 14 days, beginning on the day of induced ischemia. Ischemia was scored by standard criteria. Blood perfusion was determined using thermal infrared imaging. Tissue capillary density and oxidative stress levels were measured by immunohistochemistry and immunofluorescence, respectively. Serum lipids were measured by enzymatic colorimetric assay. Fasting serum insulin was detected using an insulin enzyme-linked immunosorbent assay kit. Nitric oxide (NO) metabolites and protein carbonyls in tissues were determined by enzyme-linked immunosorbent assay. Targeted protein concentrations were measured by western blotting.

RESULTS

At 14 days after ligation, the ischemic skeletal muscle of the streptozotocin-induced diabetic mice had lower levels of endothelial NO synthase, phosphorylated endothelial NO synthase, and vascular endothelial growth factor compared with nondiabetic group. In addition, the hind limb blood perfusion, capillary density, and NO bioactivity were lower in the diabetic group, whereas oxidative stress and protein carbonyl levels were higher. These changes were ameliorated by DATS treatment.

CONCLUSIONS

DATS treatment of diabetic mice promoted revascularization in ischemic tissue.

Minimising failure in critical lower limb ischaemia intervention: Adjuvant capillary bed recruitment is the missed opportunity

Critical limb ischaemia is the end stage of peripheral arterial disease before limb loss. Contemporary interventions to restore blood flow have high morbidity and mortality and fail to provide sustained restoration of peripheral circulation. Cell-based therapies designed to promote neovascularisation or angiogenesis have been shown in trials to be safe but clinically ineffective. Notwithstanding endless research in the area, no headway has been made in identifying a successful therapy designed specifically to target muscle disease in critical lower limb ischaemia. Thus, the quest to find an effective, lasting solution for critical lower limb ischaemia continues and requires more innovative therapeutic tactics. Our aim is to highlight the crucially interlinked role of the capillary bed, skeletal muscle mass and mitochondria in critical lower limb ischaemia patients and to identify novel therapeutic mechanisms that the vascular interventionalist can add to their armamentarium.

MicroRNA-185 inhibits angiogenesis in human microvascular endothelial cells through targeting stromal interaction molecule 1

Angiogenesis is a vital biological mechanism representing the adaptive response to a variety of pathological stimuli such as hypoxia. It is regulated by several pro-angiogenic and anti-angiogenic microRNAs. Studies have demonstrated an altered microRNA-185 (miR-185) expression in endothelial cells under hypoxic conditions; however, its role in angiogenesis has not been elucidated. We investigated the role of miR-185 in angiogenesis and found that miR-185 had an inhibitory effect on cell proliferation, migration, and tube formation. Stromal interaction molecule 1 (STIM1) appeared to be a direct target of miR-185 by computational prediction; this was confirmed by luciferase reporter assay. Silencing of the STIM1 gene was found to mimic miR-185-mediated inhibition of angiogenesis. STIM1 overexpression eliminated the anti-angiogenic effect of miR-185. Our study results suggest a direct interaction between miR-185 and STIM1 mRNA in microvascular endothelial cells. MicroRNA-185 acted as a negative regulator of angiogenesis in microvascular endothelial cells through downregulation of the STIM1 protein.

Cardiovascular risk factors cause premature rarefaction of the collateral circulation and greater ischemic tissue injury

RATIONALE

Collaterals lessen tissue injury in occlusive disease. However, aging causes progressive decline in their number and smaller diameters in those that remain (collateral rarefaction), beginning at 16 months of age in mice (i.e., middle age), and worse ischemic injury-effects that are accelerated in even 3-month-old eNOS(-/-) mice. These findings have found indirect support in recent human studies.

OBJECTIVE

We sought to determine whether other cardiovascular risk factors (CVRFs) associated with endothelial dysfunction cause collateral rarefaction, investigate possible mechanisms, and test strategies for prevention.

METHODS AND RESULTS

Mice with nine different models of CVRFs of 4-12 months of age were assessed for number and diameter of native collaterals in skeletal muscle and brain and for collateral-dependent perfusion and ischemic injury after arterial occlusion. Hypertension caused collateral rarefaction whose severity increased with duration and level of hypertension, accompanied by greater hindlimb ischemia and cerebral infarct volume. Chronic treatment of wild-type mice with L-N (G)-nitro-arginine methylester caused similar rarefaction and worse ischemic injury which were not prevented by lowering arterial pressure with hydralazine. Metabolic syndrome, hypercholesterolemia, diabetes mellitus, and obesity also caused collateral rarefaction. Neither chronic statin treatment nor exercise training lessened hypertension-induced rarefaction.

CONCLUSION

Chronic CVRF presence caused collateral rarefaction and worse ischemic injury, even at relatively young ages. Rarefaction was associated with increased proliferation rate of collateral endothelial cells, effects that may promote accelerated endothelial cell senescence.

The role of tissue engineering and biomaterials in cardiac regenerative medicine

In recent years, the development of 3-dimensional engineered heart tissue (EHT) has made large strides forward because of advances in stem cell biology, materials science, prevascularization strategies, and nanotechnology. As a result, the role of tissue engineering in cardiac regenerative medicine has become multifaceted as new applications become feasible. Cardiac tissue engineering has long been established to have the potential to partially or fully restore cardiac function after cardiac injury. However, EHTs may also serve as surrogate human cardiac tissue for drug-related toxicity screening. Cardiotoxicity remains a major cause of drug withdrawal in the pharmaceutical industry. Unsafe drugs reach the market because preclinical evaluation is insufficient to weed out cardiotoxic drugs in all their forms. Bioengineering methods could provide functional and mature human myocardial tissues, ie, physiologically relevant platforms, for screening the cardiotoxic effects of pharmaceutical agents and facilitate the discovery of new therapeutic agents. Finally, advances in induced pluripotent stem cells have made patient-specific EHTs possible, which opens up the possibility of personalized medicine. Herein, we give an overview of the present state of the art in cardiac tissue engineering, the challenges to the field, and future perspectives.

Cardiac Tissue Vascularization: From Angiogenesis to Microfluidic Blood Vessels

Myocardial infarction results from a blockage of a major coronary artery that shuts the delivery of oxygen and nutrients to a region of the myocardium, leading to massive cardiomyocytes death and regression of microvasculature. Growth factor and cell delivery methods have been attempted to revascularize the ischemic myocardium and prevent further cell death. Implantable cardiac tissue patches were engineered to directly revascularize as well as remuscularize the affected muscle. However, inadequate vascularization in vitro and in vivo limits the efficacy of these new treatment options. Breakthroughs in cardiac tissue vascularization will profoundly impact ischemic heart therapies. In this review, we discuss the full spectrum of vascularization approaches ranging from biological angiogenesis to microfluidic blood vessels as related to cardiac tissue engineering.

[The effect of amlodipine, bisoprolol on the myocardial ultrastructure of the hypertensive rats]

Calcium channel blockers and beta1-adrenoblockers are effective antihypertensive agents, but their cell protective properties are not investigated well. Spontaneously hypertensive rats received a 10 mg/kg/day amlodipine dose and 25 mg/kg/day bisoprolol dose via an orogastric tube during three months. We performed examination of the myocardium's fragments under a scanning electron microscope. Morphometric investigation of mitochondrions we performed using special program what is named "ORGANELLE". Amlodipine significantly normalizes the ultrastructure of the myocardium. This antihypertensive drug prevented the signs of over-contractility of myofibrils. Amlodipine causes the fusion mitochondrions which has compensatory character on the background of good safety of mitochondrial ultrastructures. Another feature of amlodipine is a significant increase in the number of capillaries. Bisoprolol significantly reduced over-contractility of the myofibrils, but the signs of dystrophic-destructive processes in myofibrils and mitochondrions of cardiomyocytes remained. Bisoprolol improved the condition of the endothelial cells, but the activation of the functional activity of these cells has not been observed. The combined use of two antihypertensive drugs amlodipine and bisoprolol led to a better recovery of myofibrils than their separate use, whereas the effect on mitochondrions noted similar as in the group of rats received bisoprolol and that effect was worse than during amlodipine's monotherapy. Also we didn't reveal a reason to combine these drugs after analysis of the effect of the drug combination on the conditions of blood microvessels, which number was increased compared with hypertensive rats, but significantly less than when rats received only amlodipine. These essential cell-protective effects of amlodipine and bisoprolol in spontaneously hypertensive rats could be a significant additional factor in the treatment of hypertension complicated with pathological changes in the heart.

Promoting blood vessel growth in ischemic diseases: challenges in translating preclinical potential into clinical success

Angiogenic therapy, which involves the use of an exogenous stimulus to promote blood vessel growth, is an attractive approach for the treatment of ischemic diseases. It has been shown in animal models that the stimulation of blood vessel growth leads to the growth of the whole vascular tree, improvement of ischemic tissue perfusion and improved muscle aerobic energy metabolism. However, very few positive results have been gained from Phase 2 and 3 clinical angiogenesis trials. Many reasons have been given for the failures of clinical trials, including poor transgene expression (in gene-therapy trials) and instability of the vessels induced by therapy. In this Review, we discuss the selection of preclinical models as one of the main reasons why clinical translation has been unsuccessful thus far. This issue has received little attention, but could have had dramatic implications on the expectations of clinical trials. We highlight crucial differences between human patients and animal models with regards to blood flow and pressure, as well as issues concerning the chronic nature of ischemic diseases in humans. We use these as examples to demonstrate why the results from preclinical trials might have overestimated the efficacy of angiogenic therapies developed to date. We also suggest ways in which currently available animal models of ischemic disease could be improved to better mimic human disease conditions, and offer advice on how to work with existing models to avoid overestimating the efficacy of new angiogenic therapies.

Myocardial therapeutic angiogenesis: a review of the state of development and future obstacles

A significant percentage of patients have coronary artery disease that is too advanced or diffuse for percutaneous or surgical intervention. Therapeutic angiogenesis is a treatment modality to induce vessel formation that is being developed for patients with advanced coronary disease not amenable to currently available interventions. A number of approaches to induce coronary collateralization are being developed. These include gene, protein, cellular and miRNA modalities, each of which have advantages and disadvantages. At this time, no modality has emerged as the single clear choice, and combination therapies may provide synergistic benefits. However, there have been a number of recent studies advancing our knowledge as to how we can refine procollateralizing treatments. In this article, we will examine some recent successes and future obstacles in the effort to bring therapeutic angiogenesis to patients.

Identification of a mechanism underlying regulation of the anti-angiogenic forkhead transcription factor FoxO1 in cultured endothelial cells and ischemic muscle

Chronic limb ischemia, a complication commonly observed in conjunction with cardiovascular disease, is characterized by insufficient neovascularization despite the up-regulation of pro-angiogenic mediators. One hypothesis is that ischemia induces inhibitory signals that circumvent the normal capillary growth response. FoxO transcription factors exert anti-proliferative and pro-apoptotic effects on many cell types. We studied the regulation of FoxO1 protein in ischemic rat skeletal muscle following iliac artery ligation and in cultured endothelial cells. We found that FoxO1 expression was increased in capillaries within ischemic muscles compared with those from rats that underwent a sham operation. This finding correlated with increased expression of p27(Kip1) and reduced expression of Cyclin D1. Phosphorylated Akt was reduced concurrently with the increase in FoxO1 protein. In skeletal muscle endothelial cells, nutrient stress as well as lack of shear stress stabilized FoxO1 protein, whereas shear stress induced FoxO1 degradation. Endogenous FoxO1 co-precipitated with the E3 ubiquitin ligase murine double minute-2 (Mdm2) in endothelial cells, and this interaction varied in direct relation to the extent of Akt and Mdm2 phosphorylation. Moreover, ischemic muscles had a decreased level of Mdm2 phosphorylation and a reduced interaction between Mdm2 and FoxO1. Our results provide novel evidence that the Akt-Mdm2 pathway acts to regulate endothelial cell FoxO1 expression and illustrate a potential mechanism underlying the pathophysiological up-regulation of FoxO1 under ischemic conditions.

Age, gender and diabetic status are associated with effects of bone marrow cell therapy on recovery of left ventricular function after acute myocardial infarction: a systematic review and meta-analysis

Clinical studies on intracoronary bone marrow cell (BMCs) infusion in patients with acute myocardial infarction (AMI) revealed mixed results. Recently, meta-analysis on this topic have been conducted and found that there was marked heterogeneity between trials. The objective of this systematic review is to have a retrospection of the efficacy of cell therapy and explore whether the study design or characteristics of subjects may have influenced the effects of cell therapy on recovery of left ventricular function after AMI. Trials were identified in ClinicalTrial, mRCT, Cochrane Library, EMBASE, and PubMed databases, reviews, and reference lists of relevant papers. The weighted mean difference (WMD) was calculated for net changes in left ventricular ejection fraction (LVEF) by using random-effect models. Meta-regression analyses were performed to explore the influence of study characteristics. Ten randomized controlled trials (12 comparisons) with a total of 814 participants were included. In an overall pooled estimate, compared with the control group, BMCs therapy significantly improved the LVEF change from baseline to follow-up (WMD: 3.79%, 95% CI: 2.4-5.7%, P<0.001; heterogeneity test: I(2)=82.7%, P<0.001). A multivariate meta-regression analysis was conducted to investigate the potential sources of heterogeneity. The model including age (coefficient=21%, P=0.04), male proportion (coefficient=-14%, P=0.001) and diabetic patients' proportion (coefficient=17%, P=0.002) explained most of the identified heterogeneity. The present systematic review and meta-analysis suggest that (1) BMCs therapy is effective at improving the LVEF; (2) BMCs therapy is more effective in ageing and diabetic individuals, whereas less effective in males.

Engineering more than a cell: vascularization strategies in tissue engineering

Host integration and performance of engineered tissues have been severely limited by the lack of robust strategies to generate patent vascularization and tissue perfusion. This review highlights a selection of exciting developments in vascularization approaches for tissue engineering research. Current strategies for vascularization in tissue engineering are related to growth factor signaling and delivery, cell transplantation, bioactive smart matrix materials, and directed fabrication. Application of these techniques to in vivo models has resulted in a number of robust host vascular responses, especially with synergistic and engineered bioactive systems. The future outlook of the field includes refinement and development of new technologies for vascularization and combining these techniques with functional repair models for metabolically active tissues and relevant disease states.

The role of resistin as a regulator of inflammation: Implications for various human pathologies

Resistin was originally described as an adipocyte-secreted peptide that induced insulin resistance in rodents. Increasing evidence indicates its important regulatory roles in various biological processes, including several inflammatory diseases. Further studies have shown that resistin in humans, in contrast to its production by adipocytes in mice, is synthesized predominantly by mononuclear cells both within and outside adipose tissue. Possible roles for resistin in obesity-related subclinical inflammation, atherosclerosis and cardiovascular disease, non-alcoholic fatty liver disease, rheumatic diseases, malignant tumors, asthma, inflammatory bowel disease, and chronic kidney disease have already been demonstrated. In addition, resistin can modulate several molecular pathways involved in metabolic, inflammatory, and autoimmune diseases. In this review, current knowledge about the functions and pathophysiological implications of resistin in different human pathologies is summarized, although there is a significant lack of firm evidence regarding the specific role resistin plays in the "orchestra" of the numerous mediators of inflammation.