Copper regulation of hypoxia-inducible factor-1 activity

Synergy effects of copper and silicon ions on stimulation of vascularization by copper-doped calcium silicate

Copper (Cu) has been reported to be able to stimulate vascularization/angiogenesis, which is critical for regeneration of vascularized tissue in tissue engineering. Silicate bioceramics have also been reported to have stimulatory effects on vascularization due to the silicon (Si) ions released from silicate biomaterials. Therefore, we hypothesize that a combination of Cu and Si ions may show synergy effects on vascularization. Therefore, a copper-doped calcium silicate bioceramic (Cu-CaSiO₃, Cu-CS) was designed and synthesized with the purpose to enhance the stimulatory effects of copper salts or pure silicate bioceramics on vascularization by combining the effects of Cu and Si ions. The cytocompatibility of Cu-CS was firstly assessed by testing the influence of Cu-CS ion extracts on proliferation of human umbilical vein endothelial cells (HUVECs). Thereafter, vascularization of HUVECs on ECMatrix™ gel or co-cultured with human dermal fibroblasts (HDFs) in Cu-CS extracts was evaluated and expression of angiogenic growth factors was analyzed. Results revealed that, as compared to CS extracts and media containing soluble CuSO₄, Cu-CS extracts possessed stronger stimulatory effects on upregulation of angiogenic growth factors, which finally resulted in better stimulatory effects on vascularization. During the vascularization process, paracrine effects dominated in the co-culture system. In addition, lower concentrations of Cu and Si ions released from Cu-CS than those released from pure CS or CuSO₄ were enough to stimulate vascularization, which indicated that there were synergy effects between Cu and Si ions during stimulation of vascularization by Cu-CS. Taken together, the designed Cu-CS may be suitable as a new biomaterial for regenerating blood vessels in tissue engineering.

The ginsenoside Rg1 prevents transverse aortic constriction-induced left ventricular hypertrophy and cardiac dysfunction by inhibiting fibrosis and enhancing angiogenesis

BACKGROUND

Ginsenoside Rg1, an important and active ingredient of Panax ginseng, has been shown to exert cardioprotective effects in vivo. The present study aimed to test the hypothesis that ginsenoside Rg1 attenuates cardiac dysfunction in a transverse aortic constriction (TAC)-induced left ventricular hypertrophy in vivo via proangiogenic and antifibrotic effects.

METHODS

This study investigated the effects of ginsenoside Rg1 in a rat model of TAC-induced left ventricular hypertrophy. Cardiac function was assessed by echocardiography. The antifibrotic and proangiogenic effects were assessed by histopathology and mRNA expression of procollagen I, III, and vascular endothelial growth factor (VEGF) through quantitative real-time PCR. The expression of phosphorylation of Akt, p38 mitogen-activated protein kinase (MAPK), hypoxia inducible factor-1 (HIF-1), and VEGF proteins were examined by Western blotting.

RESULTS

Ginsenoside Rg1 treatment significantly decreased TAC-induced myocardial fibrosis and left ventricular hypertrophy, and preserved cardiac function. Ginsenoside Rg1 administration enhanced angiogenesis by increasing the expression of HIF-1 and VEGF. These cardioprotective effects of ginsenoside Rg1 are partially related to the activation of phospho-Akt and inhibition of p38 MAPK.

CONCLUSIONS

Ginsenoside Rg1 exhibited protective effect against TAC-induced left ventricular hypertrophy and cardiac dysfunction, which is potentially associated with phospho-Akt activation and p38 MAPK inhibition.

Rejuvenation: an integrated approach to regenerative medicine

The word "rejuvenate" found in the Merriam-Webster dictionary is (1) to make young or youthful again: give new vigor to, and (2) to restore to an original or new state. Regenerative medicine is the process of creating living, functional tissues to repair or replace tissue or organ function lost due to age, disease, damage, or congenital defects. To accomplish this, approaches including transplantation, tissue engineering, cell therapy, and gene therapy are brought into action. These all use exogenously prepared materials to forcefully mend the failed organ. The adaptation of the materials in the host and their integration into the organ are all uncertain. It is a common sense that tissue injury in the younger is easily repaired and the acute injury is healed better and faster. Why does the elder have a diminished capacity of self-repairing, or why does chronic injury cause the loss of the self-repairing capacity? There must be some critical elements that are involved in the repair process, but are suppressed in the elder or under the chronic injury condition. Rejuvenation of the self-repair mechanism would be an ideal solution for functional recovery of the failed organ. To achieve this, it would involve renewal of the injury signaling, reestablishment of the communication and transportation system, recruitment of the materials for repairing, regeneration of the failed organ, and rehabilitation of the renewed organ. It thus would require a comprehensive understanding of developmental biology and a development of new approaches to activate the critical players to rejuvenate the self-repair mechanism in the elder or under chronic injury condition. Efforts focusing on rejuvenation would expect an alternative, if not a better, accomplishment in the regenerative medicine.

Copper promotion of angiogenesis in isolated rat aortic ring: role of vascular endothelial growth factor

Copper stimulation of angiogenesis at the organ system level is vascular endothelial growth factor (VEGF) dependent, but copper stimulation of vascular endothelial cell proliferation in cultures is VEGF independent. The present study was undertaken to use isolated rat aortic rings to understand the seemly controversial observations between in vivo and in vitro studies. The thoracic aorta was isolated from Sprague Dawley rats (8-10 weeks) and sectioned into 1.0-mm thick vascular rings for culturing. Copper sulfide at a final concentration of 5, 25, 50 or 100 μM was added to the cultures and maintained for 8 days. A copper chelator, tetraethylenepentamine (TEPA) at a final concentration of 25 μM, was added to some cultures to block the effect of copper. An anti-VEGF antibody was used to determine the role of VEGF in copper promotion of angiogenesis. The data obtained showed that copper at 5 μM in cultures stimulated the vascular formation; an effect was blocked by TEPA. Copper at concentrations above 50 μM lost the proangiogenesis effect. However, copper at 5 μM did not enhance the production of VEGF, and concentrations above 50 μM significantly increased VEGF production. On the other hand, the treatment with anti-VEGF antibody completely blocked the proangiogenesis effect of 5-μM copper. This study thus demonstrates that VEGF is essential for angiogenesis but the proangiogenesis effect of copper does not act through enhanced production of VEGF.

Hepatocellular carcinoma in a young man with resting and postural tremors

A 25-year-old man who was normally fit and well, presented with a 2-year history of progressively worsening tremor. His tremor was generalised, affecting head, neck and all four limbs. One of the patient's brothers had suffered from similar problems, but never sought medical attention. Examination revealed a generalised tremor, of greater amplitude on the patient's left side, which increased in its amplitude upon exertion. Slit-lamp examination revealed bilateral Kayser-Fleischer rings and serum caeruloplasmin was found to be low, while 24 h urinary copper excretion was elevated. A diagnosis of Wilson's disease was made and an abdominal ultrasound was performed, revealing evidence of portal hypertension and a hyperechoic hepatic nodule, later confirmed to be hepatocellular carcinoma. The patient underwent partial hepatic resection and was started on D-penicillamine.

BS, Vuyyuru H, Muthuvel B, Konerirajapuram Natrajan S. CTR1 silencing inhibits angiogenesis by limiting copper entry into endothelial cells

Increased levels of intracellular copper stimulate angiogenesis in human umbilical vein endothelial cells (HUVECs). Copper transporter 1 (CTR1) is a copper importer present in the cell membrane and plays a major role in copper transport. In this study, three siRNAs targeting CTR1 mRNA were designed and screened for gene silencing. HUVECs when exposed to 100 µM copper showed 3 fold increased proliferation, migration by 1.8-fold and tube formation by 1.8-fold. One of the designed CTR1 siRNA (si 1) at 10 nM concentration decreased proliferation by 2.5-fold, migration by 4-fold and tube formation by 2.8-fold. Rabbit corneal packet assay also showed considerable decrease in matrigel induced blood vessel formation by si 1 when compared to untreated control. The designed si 1 when topically applied inhibited angiogenesis. This can be further developed for therapeutic application.

Hepatocellular carcinoma in a non-cirrhotic patient with Wilson's disease

We report the exceptional case of hepatocellular carcinoma in a non-cirrhotic patient, whose Wilson’s disease was diagnosed at the unusual age of 58 years. The liver histology revealed macrovesicular steatosis with fibrosis, but no cirrhosis. The disease was treated with D-penicillamine for 3 years until acute discomfort in the right upper quadrant led to detection of multifocal hepatocellular carcinoma, which was successfully resected. The histological examination confirmed the malignant nature of the 4 lesions, which were classified according to Edmondson and Steiner as poorly differentiated hepatocellular carcinoma grade 3. The non-tumoral parenchyma showed 80% steatosis with ballooned cells, lobular inflammation, septal fibrosis but no cirrhosis. Hepatocellular carcinoma is rare in Wilson’s disease, especially in the absence of cirrhosis. The literature’s 28 published cases are reviewed and the contributory role of copper in the hepatocarcinogenic process is discussed.

Copper deficiency leads to anemia, duodenal hypoxia, upregulation of HIF-2α and altered expression of iron absorption genes in mice

Iron and copper are essential trace metals, actively absorbed from the proximal gut in a regulated fashion. Depletion of either metal can lead to anemia. In the gut, copper deficiency can affect iron absorption through modulating the activity of hephaestin - a multi-copper oxidase required for optimal iron export from enterocytes. How systemic copper status regulates iron absorption is unknown. Mice were subjected to a nutritional copper deficiency-induced anemia regime from birth and injected with copper sulphate intraperitoneally to correct the anemia. Copper deficiency resulted in anemia, increased duodenal hypoxia and Hypoxia inducible factor 2α (HIF-2α) levels, a regulator of iron absorption. HIF-2α upregulation in copper deficiency appeared to be independent of duodenal iron or copper levels and correlated with the expression of iron transporters (Ferroportin - Fpn, Divalent Metal transporter - Dmt1) and ferric reductase - Dcytb. Alleviation of copper-dependent anemia with intraperitoneal copper injection resulted in down regulation of HIF-2α-regulated iron absorption genes in the gut. Our work identifies HIF-2α as an important regulator of iron transport machinery in copper deficiency.

Prion protein expression and functional importance in developmental angiogenesis: role in oxidative stress and copper homeostasis

AIM

It has been convincingly shown that oxidative stress and toxicity by deregulated metals, such as copper (Cu), are tightly linked to the development of pre-eclampsia and intrauterine growth retardation (IUGR), the most threatening pathologies of human pregnancy. However, mechanisms implemented to control these effects are far from being understood. Among proteins that bind Cu and insure cellular protection against oxidative stress is the cellular prion protein (PrP(C)), a glycosyl phosphatidyl inositol-anchored glycoprotein, which we reported to be highly expressed in human placenta. Herein, we investigated the pathophysiological role of PrP(C) in Cu and oxidative stress homeostasis in vitro using human placenta and trophoblast cells, and in vivo using three strains of mice (C57Bl6, PrP(C) knockout mice [PrP(-/-)], and PrP(C) overexpressing mice [Tga20]).

RESULTS

At the cellular level, PrP(C) protection against oxidative stress was established in multiple angiogenic processes: proliferation, migration, and tube-like organization. For the animal models, lack (PrP(-/-)) or overexpression (Tga20) of PrP(C) in gravid mice caused severe IUGR that was correlated with a decrease in litter size, changes in Cu homeostasis, increase in oxidative stress response, development of hypoxic environment, failure in placental function, and maintenance of growth defects of the offspring even 7.5 months after delivery.

INNOVATION

PrP(C) could serve as a marker for the idiopathic IUGR disease.

CONCLUSION

These findings demonstrate the stress-protective role of PrP(C) during development, and propose PrP(C) dysregulation as a novel causative element of IUGR.

Copper(II) oxide nanoparticles penetrate into HepG2 cells, exert cytotoxicity via oxidative stress and induce pro-inflammatory response

The potential toxic effects of two types of copper(II) oxide (CuO) nanoparticles (NPs) with different specific surface areas, different shapes (rod or spheric), different sizes as raw materials and similar hydrodynamic diameter in suspension were studied on human hepatocarcinoma HepG2 cells. Both CuO NPs were shown to be able to enter into HepG2 cells and induce cellular toxicity by generating reactive oxygen species. CuO NPs increased the abundance of several transcripts coding for pro-inflammatory interleukins and chemokines. Transcriptomic data, siRNA knockdown and DNA binding activities suggested that Nrf2, NF-κB and AP-1 were implicated in the response of HepG2 cells to CuO NPs. CuO NP incubation also induced activation of MAPK pathways, ERKs and JNK/SAPK, playing a major role in the activation of AP-1. In addition, cytotoxicity, inflammatory and antioxidative responses and activation of intracellular transduction pathways induced by rod-shaped CuO NPs were more important than spherical CuO NPs. Measurement of Cu(2+) released in cell culture medium suggested that Cu(2+) cations released from CuO NPs were involved only to a small extent in the toxicity induced by these NPs on HepG2 cells.

Regression of pathological cardiac hypertrophy: signaling pathways and therapeutic targets

Pathological cardiac hypertrophy is a key risk factor for heart failure. It is associated with increased interstitial fibrosis, cell death and cardiac dysfunction. The progression of pathological cardiac hypertrophy has long been considered as irreversible. However, recent clinical observations and experimental studies have produced evidence showing the reversal of pathological cardiac hypertrophy. Left ventricle assist devices used in heart failure patients for bridging to transplantation not only improve peripheral circulation but also often cause reverse remodeling of the geometry and recovery of the function of the heart. Dietary supplementation with physiologically relevant levels of copper can reverse pathological cardiac hypertrophy in mice. Angiogenesis is essential and vascular endothelial growth factor (VEGF) is a constitutive factor for the regression. The action of VEGF is mediated by VEGF receptor-1, whose activation is linked to cyclic GMP-dependent protein kinase-1 (PKG-1) signaling pathways, and inhibition of cyclic GMP degradation leads to regression of pathological cardiac hypertrophy. Most of these pathways are regulated by hypoxia-inducible factor. Potential therapeutic targets for promoting the regression include: promotion of angiogenesis, selective enhancement of VEGF receptor-1 signaling pathways, stimulation of PKG-1 pathways, and sustention of hypoxia-inducible factor transcriptional activity. More exciting insights into the regression of pathological cardiac hypertrophy are emerging. The time of translating the concept of regression of pathological cardiac hypertrophy to clinical practice is coming.

Lactobacillus rhamnosus GG treatment potentiates intestinal hypoxia-inducible factor, promotes intestinal integrity and ameliorates alcohol-induced liver injury

Gut-derived endotoxin is a critical factor in the development and progression of alcoholic liver disease (ALD). Probiotics can treat alcohol-induced liver injury associated with gut leakiness and endotoxemia in animal models, as well as in human ALD; however, the mechanism or mechanisms of their beneficial action are not well defined. We hypothesized that alcohol impairs the adaptive response-induced hypoxia-inducible factor (HIF) and that probiotic supplementation could attenuate this impairment, restoring barrier function in a mouse model of ALD by increasing HIF-responsive proteins (eg, intestinal trefoil factor) and reversing established ALD. C57BJ/6N mice were fed the Lieber DeCarli diet containing 5% alcohol for 8 weeks. Animals received Lactobacillus rhamnosus GG (LGG) supplementation in the last 2 weeks. LGG supplementation significantly reduced alcohol-induced endotoxemia and hepatic steatosis and improved liver function. LGG restored alcohol-induced reduction of HIF-2α and intestinal trefoil factor levels. In vitro studies using the Caco-2 cell culture model showed that the addition of LGG supernatant prevented alcohol-induced epithelial monolayer barrier dysfunction. Furthermore, gene silencing of HIF-1α/2α abolished the LGG effects, indicating that the protective effect of LGG is HIF-dependent. The present study provides a mechanistic insight for utilization of probiotics for the treatment of ALD, and suggests a critical role for intestinal hypoxia and decreased trefoil factor in the development of ALD.

Copper deficiency induced emphysema is associated with focal adhesion kinase inactivation

BACKGROUND

Copper is an important regulator of hypoxia inducible factor 1 alpha (HIF-1α) dependent vascular endothelial growth factor (VEGF) expression, and is also required for the activity of lysyl oxidase (LOX) to effect matrix protein cross-linking. Cell detachment from the extracellular matrix can induce apoptosis (anoikis) via inactivation of focal adhesion kinase (FAK).

METHODOLOGY

To examine the molecular mechanisms whereby copper depletion causes the destruction of the normal alveolar architecture via anoikis, Male Sprague-Dawley rats were fed a copper deficient diet for 6 weeks while being treated with the copper chelator, tetrathiomolybdate. Other groups of rats were treated with the inhibitor of auto-phosphorylation of FAK, 1,2,4,5-benzenetetraamine tetrahydrochloride (1,2,4,5-BT) or FAK small interfering RNA (siRNA).

PRINCIPAL FINDINGS

Copper depletion caused emphysematous changes, decreased HIF-1α activity, and downregulated VEGF expression in the rat lungs. Cleaved caspase-3, caspase-8 and Bcl-2 interacting mediator of cell death (Bim) expression was increased, and the phosphorylation of FAK was decreased in copper depleted rat lungs. Administration of 1,2,4,5-BT and FAK siRNA caused emphysematous lung destruction associated with increased expression of cleaved capase-3, caspase-8 and Bim.

CONCLUSIONS

These data indicate that copper-dependent mechanisms contribute to the pathogenesis of emphysema, which may be associated with decreased HIF-1α and FAK activity in the lung.

Copper stimulates growth of human umbilical vein endothelial cells in a vascular endothelial growth factor-independent pathway

Studies in vivo have shown that dietary copper (Cu) supplementation reverses pressure overload-induced cardiac hypertrophy in a mouse model, which is vascular endothelial growth factor (VEGF)-dependent and correlates with enhanced angiogenesis. Because Cu stimulation of endothelial cell growth and differentiation would play a critical role in angiogenesis, the present study was undertaken to examine the effect of Cu on growth of human umbilical vein endothelial cells (HUVECs) in cultures. The HUVECs were treated with CuSO4 at a final concentration of 5 μmol/L Cu element in cultures or with a Cu chelator, tetraethylenepentamine (TEPA), at a final concentration of 25 μmol/L in cultures. Cell growth and Cu effect on cell cycle were determined. In addition, the effect of Cu on VEGF and endothelial nitric oxide synthase (eNOS) mRNA levels was determined, and anti-VEGF antibody and siRNA targeting eNOS were applied to determine the role of VEGF or eNOS in the Cu effect on cell growth. Cu significantly stimulated and TEPA significantly inhibited cell growth, and the TEPA effect was blocked by excess Cu. Cu increased the number of cells in the S phase and correspondingly decreased the number in the G1 phase. Interestingly, Cu did not increase the level of VEGF mRNA, but significantly increased eNOS mRNA. Furthermore, neutralizing VEGF by anti-VEGF antibody did not suppress Cu stimulation of cell growth. However, siRNA targeting eNOS completely blocked Cu reversal of TEPA inhibition of cell growth. The data demonstrate that Cu stimulation of HUVEC cell growth is VEGF-independent, but eNOS-dependent.

Metallic ions as therapeutic agents in tissue engineering scaffolds: an overview of their biological applications and strategies for new developments

This article provides an overview on the application of metallic ions in the fields of regenerative medicine and tissue engineering, focusing on their therapeutic applications and the need to design strategies for controlling the release of loaded ions from biomaterial scaffolds. A detailed summary of relevant metallic ions with potential use in tissue engineering approaches is presented. Remaining challenges in the field and directions for future research efforts with focus on the key variables needed to be taken into account when considering the controlled release of metallic ions in tissue engineering therapeutics are also highlighted.

Complex N-acetylation of triethylenetetramine

Triethylenetetramine (TETA) is an efficient copper chelator that has versatile clinical potential. We have recently shown that spermidine/spermine-N(1)-acetyltransferase (SSAT1), the key polyamine catabolic enzyme, acetylates TETA in vitro. Here, we studied the metabolism of TETA in three different mouse lines: syngenic, SSAT1-overexpressing, and SSAT1-deficient (SSAT1-KO) mice. The mice were sacrificed at 1, 2, or 4 h after TETA injection (300 mg/kg i.p.). We found only N(1)-acetyltriethylenetetramine (N(1)AcTETA) and/or TETA in the liver, kidney, and plasma samples. As expected, SSAT1-overexpressing mice acetylated TETA at an accelerated rate compared with syngenic and SSAT1-KO mice. It is noteworthy that SSAT1-KO mice metabolized TETA as syngenic mice did, probably by thialysine acetyltransferase, which had a K(m) value of 2.5 ± 0.3 mM and a k(cat) value of 1.3 s(-1) for TETA when tested in vitro with the human recombinant enzyme. Thus, the present results suggest that there are at least two N-acetylases potentially metabolizing TETA. However, their physiological significance for TETA acetylation requires further studies. Furthermore, we detected chemical intramolecular N-acetyl migration from the N(1) to N(3) position of N(1)AcTETA and N(1),N(8)-diacetyltriethylenetetramine in an acidified high-performance liquid chromatography sample matrix. The complex metabolism of TETA together with the intramolecular N-acetyl migration may explain the huge individual variations in the acetylation rate of TETA reported earlier.

Copper and homocysteine in cardiovascular diseases

High blood copper (Cu) and homocysteine (Hcy) concentrations have been independently reported as risk factors for cardiovascular diseases. When they are simultaneously measured, a concomitant increase in both parameters in association with vascular dysfunction has been observed. Cu chelator penicillamine can significantly diminish the inhibitory effect of Hcy on endothelial function, which has led to the interpretation that Cu mediates the deleterious effect of Hcy. However, Cu itself has been shown to be beneficial to the cardiovascular system. In particular, Cu promotion of angiogenesis has been well documented. Cu stimulates endothelial cell proliferation and differentiation and promotes microtubule formation in cultured saphenous veins. High levels of Hcy do not affect the process of microtubule formation, but the combination of Cu and Hcy leads to a significant inhibitory effect. Under other conditions, Cu does not affect, but Hcy inhibits, the endothelium-dependent relaxation of blood vessels and the combination of both augments the inhibition. Why does Cu produce adverse effects when it co-exists with Hcy? Cu forms complexes with Hcy and the Cu-Hcy complexes possess a deleterious potential due to their redox properties. Cu chelation can remove Cu from the Cu-Hcy complexes, but leaves behind high levels of Hcy and produces Cu deficiency. An alternative approach should focus on the reduction of Hcy, but maintenance of Cu, making detrimental Cu beneficial. A comprehensive understanding of Cu speciation and a development of selective modulation of Cu coordination to Cu-binding molecules to avoid Cu-Hcy complex formation would effectively improve the condition of cardiovascular disease.

Cardiac-specific overexpression of HIF-1{alpha} prevents deterioration of glycolytic pathway and cardiac remodeling in streptozotocin-induced diabetic mice

Defective glycolysis and angiogenesis in the heart of diabetic patients and in experimental diabetic animal models have been reported. The aim of this study was to determine whether overexpression of hypoxia-inducible factor (HIF)-1alpha protects from myocardial injury in diabetic mice by increasing myocardial glycolysis and angiogenesis. Cardiac-specific HIF-1alpha-overexpressing transgenic and age-matched wild-type control mice were treated with streptozotocin to induce diabetes. Changes in glucose transporters, glycolytic enzymes, angiogenic factors and cardiac morphology were examined in the hearts by real-time RT-PCR, Western blotting, enzymatic assay, and histological assays. HIF-1alpha overexpression elevated hexokinase II (HK-II) protein level and total HK activity in nondiabetic heart and prevented the decreases in HK-II mRNA, protein, and total HK activity in diabetic heart. In addition, the reduction of glucose transporter I, but not glucose transporter 4, was restored in HIF transgenic mouse heart along with a recovery of myocardium ATP production. HIF-1alpha overexpression also normalized diabetes-reduced vascular endothelial growth factor concentration along with a sustained myocardial capillary density and an inhibition of cardiomyocyte hypertrophy and cardiac fibrosis. Therefore, elevation of HIF-1alpha provides a cardiac protection from diabetic-induced impairment in glucose metabolism and angiogenesis via up-regulation of HIF-1 target genes.

Metabolic crossroads of iron and copper

Interactions between the essential dietary metals, iron and copper, have been known for many years. This review highlights recent advances in iron-copper interactions with a focus on tissues and cell types important for regulating whole-body iron and copper homeostasis. Cells that mediate dietary assimilation (enterocytes) and storage and distribution (hepatocytes) of iron and copper are considered, along with the principal users (erythroid cells) and recyclers of red cell iron (reticuloendothelial macrophages). Interactions between iron and copper in the brain are also discussed. Many unanswered questions regarding the role of these metals and their interactions in health and disease emerge from this synopsis, highlighting extensive future research opportunities.

The stimulation of angiogenesis and collagen deposition by copper

Copper is known to trigger endothelial cells towards angiogenesis. Different approaches have been investigated to develop vascularisation in biomaterials. The angiogenic and healing potential of copper ions in combination with two major angiogenic factors was examined. A 3D culture system in which, under stimulation by FGF-2 and to a lesser degree with VEGF, endothelial cells assembled into structures resembling to an angiogenic process was used. The combination of CuSO(4) with increasing doses of VEGF or FGF-2 enhanced the complexity of angiogenic networks in a significant manner. In vivo studies were also conducted by incorporating FGF-2 with CuSO(4) in a cylindrical collagen-based scaffold. CuSO(4) enhanced significantly the invasion of microvessel compared to control implants and to 20ng FGF-2+/-CuSO(4). Vascular infiltration was also significantly improved by combination of CuSO(4) with FGF-2, compared to FGF-2 alone (0.2 and 1microg). Nevertheless, in comparison with CuSO(4) alone, there was a significant increase only with 1microg of FGF-2 combined with CuSO(4). Significantly, collagen fiber deposition was enhanced following the combinatory loading in comparison to that with FGF-2 alone but not with CuSO(4) only. Thus, copper associated with growth factors may have synergistic effects which are highly attractive in the fields of tissue engineering (e.g., bone) and biomaterials.

Why is effective treatment of asthma so difficult? An integrated systems biology hypothesis of asthma

A hypothesis is presented that asthma is not only an airway disease, but that the disease involves the entire lung, and that the chronicity of asthma and asthma exacerbations can perhaps be explained if one considers asthma as a systemic disease. Increased lung-not only airway-vascularity may be the result of the action of angiogenesis factors, such as vascular endothelial growth factor (VEGF) and sphingosine-1-phosphate (S1P). A bone-marrow lung axis can be postulated as one element of the systemic nature of the asthma syndrome, in which the inflamed lung emits chemotactic signals, which the bone marrow responds to by releasing cells that contribute to lung angiogenesis. A molecular model of the pathobiology of asthma can be built by connecting hypoxia-inducible transcription factor-1 alpha, VEGF S1P, and bone-marrow precursor cell mobilization and acknowledging that angiogenesis is part of the inflammatory response.