Simvastatin treatment inhibits hypoxia inducible factor 1-alpha-(HIF-1alpha)-prolyl-4-hydroxylase 3 (PHD-3) and increases angiogenesis after myocardial infarction in streptozotocin-induced diabetic rat

Hypoxia-inducible factor-1: Regulatory mechanisms and drug therapy in myocardial infarction

Myocardial infarction (MI), an acute cardiovascular disease characterized by coronary artery blockage, inadequate blood supply, and subsequent ischemic necrosis of the myocardium, is one of the leading causes of death. The cellular, physiological, and pathological responses following MI are complex, involving multiple intertwined pathological mechanisms. Hypoxia-inducible factor-1 (HIF-1), a crucial regulator of hypoxia, plays a significant role in of the development of MI by modulating the behavior of various cells such as cardiomyocytes, endothelial cells, macrophages, and fibroblasts under hypoxic conditions. HIF-1 regulates various post-MI adaptive reactions to acute ischemia and hypoxia through various mechanisms. These mechanisms include angiogenesis, energy metabolism, oxidative stress, inflammatory response, and ventricular remodeling. With its crucial role in MI, HIF-1 is expected to significantly influence the treatment of MI. However, the drugs available for the treatment of MI targeting HIF-1 are currently limited, and most contain natural compounds. The development of precision-targeted drugs modulating HIF-1 has therapeutic potential for advancing MI treatment research and development. This study aimed to summarize the regulatory role of HIF-1 in the pathological responses of various cells following MI, the diverse mechanisms of action of HIF-1 in MI, and the potential drugs targeting HIF-1 for treating MI, thus providing the theoretical foundations for potential clinical therapeutic targets.

An intelligent phase transformation system based on lyotropic liquid crystals for sequential biomolecule delivery to enhance bone regeneration

Endogenous repair of critical bone defects is typically hampered by inadequate vascularization in the early stages and insufficient bone regeneration later on. Therefore, drug delivery systems with the ability to couple angiogenesis and osteogenesis in a spatiotemporal manner are highly desirable for vascularized bone formation. Herein, we devoted to develop a liquid crystal formulation system (LCFS) attaining a controlled temporal release of angiogenic and osteoinductive bioactive molecules that could orchestrate the coupling of angiogenesis and osteogenesis in an optimal way. It has been demonstrated that the release kinetics of biomolecules depend on the hydrophobicity of the loaded molecules, making the delivery profile programmable and controllable. The hydrophilic deferoxamine (DFO) could be released rapidly within 5 days to activate angiogenic signaling, while the lipophilic simvastatin (SIM) showed a slow and sustained release for continuous osteogenic induction. Apart from its good biocompatibility with mesenchymal stem cells derived from rat bone marrow (rBMSCs), the DFO/SIM loaded LCFS could stimulate the formation of a vascular morphology in human umbilical vein endothelial cells (HUVECs) and the osteogenic differentiation of rBMSCs in vitro. The in vivo rat femoral defect models have witnessed the prominent angiogenic and osteogenic effects induced by the sequential presentation of DFO and SIM. This study suggests that the sequential release of DFO and SIM from the LCFS results in enhanced bone formation, offering a facile and viable treatment option for bone defects by mimicking the physiological process of bone regeneration.

Statins and angiogenesis in non-cardiovascular diseases

Statins inhibit HMG-CoA reductase by competitively inhibiting the active site of the enzyme, thus preventing cholesterol synthesis and reducing the risk of developing cardiovascular disease. Many pleiotropic effects of statins have been demonstrated that can be either related or unrelated to their cholesterol-lowering ability. Among these effects are their proangiogenic and antiangiogenic properties that could offer new therapeutic applications. In this regard, pro- and anti-angiogenic properties of statins have been shown to be dose dependent. Statins also appear to have a variety of non-cardiovascular angiogenic effects in many diseases, some examples being ocular disease, brain disease, cancer, preeclampsia, diabetes and bone disease, which are discussed in this review using reports from in vitro and in vivo investigations.

Roles of oxygen level and hypoxia-inducible factor signaling pathway in cartilage, bone and osteochondral tissue engineering

The repair and treatment of articular cartilage injury is a huge challenge of orthopedics. Currently, most of the clinical methods applied in treating cartilage injuries are mainly to relieve pains rather than to cure them, while the strategy of tissue engineering is highly expected to achieve the successful repair of osteochondral defects. Clear understandings of the physiological structures and mechanical properties of cartilage, bone and osteochondral tissues have been established, but the understanding of their physiological heterogeneity still needs further investigation. Apart from the gradients in the micromorphology and composition of cartilage-to-bone extracellular matrixes, an oxygen gradient also exists in natural osteochondral tissue. The response of hypoxia-inducible factor (HIF)-mediated cells to oxygen would affect the differentiation of stem cells and the maturation of osteochondral tissue. This article reviews the roles of oxygen level and HIF signaling pathway in the development of articular cartilage tissue, and their prospective applications in bone and cartilage tissue engineering. The strategies for regulating HIF signaling pathway and how these strategies finding their potential applications in the regeneration of integrated osteochondral tissue are also discussed.

Anti-inflammatory Effects of Statins in Lung Vascular Pathology: From Basic Science to Clinical Trials

HMG-CoA reductase inhibitors (or statins) are cholesterol-lowering drugs and are among the most widely prescribed medications in the United States. Statins exhibit pleiotropic effects that extend beyond cholesterol reduction including anti-atherosclerotic, antiproliferative, anti-inflammatory, and antithrombotic effects. Over the last 20 years, statins have been studied and examined in pulmonary vascular disorders, including both chronic pulmonary vascular disease such as pulmonary hypertension, and acute pulmonary vascular endothelial injury such as acute lung injury. In both research and clinical settings, statins have demonstrated promising vascular protection through modulation of the endothelium, attenuation of vascular leak, and promotion of endothelial repair following lung inflammation. This chapter provides a summary of the rapidly changing literature, summarizes the anti-inflammatory mechanism of statins on pulmonary vascular disorders, and explores clinical evidence for statins as a potential therapeutic approach to modulation of the endothelium as well as a means to broaden our understanding of pulmonary vasculopathy pathophysiology.

[Application status of hypoxia mimetic agents in bone tissue engineering]

Objective

To summarize the application status of hypoxia mimetic agents in bone tissue engineering.

Methods

The related literature about the hypoxia mimetic agents in bone tissue engineering was reviewed and analyzed. And the application status and progress of hypoxia mimetic agents in bone tissue engineering were retrospectively analyzed.

Results

Hypoxia mimetic agents have the same effect as hypoxia in up-regulating the level of hypoxia inducible factor 1α (HIF-1α). The combination of hypoxia mimetic agents and scaffolds can up-regulate the level of HIF-1α in bone tissue engineering, thus promoting early vascularization and bone regeneration of the bone defect area, which provides a new idea for using bone tissue engineering to repair bone defect. At present, the commonly used hypoxia mimetic agents include iron chelating agents, oxoglutarate competitive analogues, proline hydroxylase inhibitors, etc.

Conclusion

Hypoxia mimetic agents have a wide application prospect in bone tissue engineering, but they have been used in bone tissue engineering for a short time, more attention should be paid to their possible side effects. In the future research, the hypoxia mimetic agents should be developed in the direction of higher targeting specificity and safety, and the exact mechanism of hypoxia mimetic agents in promoting bone regeneration should be further explored.

SF-deferoxamine, a bone-seeking angiogenic drug, prevents bone loss in estrogen-deficient mice

Deferoxamine (DFO) possesses a good chelating capability and is therefore used for the clinical treatment of ion deposition diseases. Increasing evidence shows that DFO can inhibit the activity of proline hydroxylase (PHD) by chelating iron, resulting in hypoxia-induced factor (HIF) signaling activation and angiogenesis promotion. However, clinical evidence indicates that a high concentration of DFO could be biotoxic due to its enrichment in related organs. Thus, we established a new compound by conjugating DFO with the bone-seeking agent iminodiacetic acid (IDA); the new agent is called SF-DFO, and we verified its promotion of HIF activation and tube formation in vivo. After confirming the bone-seeking property of SF-DFO in the femur and vertebra of both male and female mice and comparing it to that of DFO, we analyzed the protective effect of DFO and SF-DFO in an ovariectomized (OVX) mouse model. The serum CTX-I level revealed no influence of DFO and SF-DFO on osteoclast activity, but the blood vessels and osteoblasts in the metaphysis were more abundant after SF-DFO treatment, which resulted in a greater protective effect against trabecular bone loss compared to the DFO group. Additionally, the cortical parameters and bone strength performance were identical between the DFO and SF-DFO groups. However, the diffuse inflammatory response in the liver and spleen that occurred after DFO injection was not observed in the SF-DFO group. Thus, with reduced biotoxicity and an equivalent bone-seeking capability, SF-DFO may be a better choice for the prevention of vascular degradation-induced osteoporosis.

Sevoflurane postconditioning is not mediated by ferritin accumulation and cannot be rescued by simvastatin in isolated streptozotocin-induced diabetic rat hearts

Sevoflurane postconditioning (sevo postC) is an attractive and amenable approach that can protect the myocardium against ischemia/reperfusion (I/R)-injury. Unlike ischemic preconditioning (IPC), sevo postC does not require additional induced ischemic periods to a heart that is already at risk. IPC was previously shown to generate myocardial protection against I/R-injury through regulation of iron homeostasis and de novo ferritin synthesis, a process found to be impaired in the diabetic state. The current study investigated whether alterations in iron homeostasis and ferritin mRNA and protein accumulation are also involved in the cardioprotective effects generated by sevo postC. It was also investigated whether the protective effects of sevo postC in the diabetic state can be salvaged by simvastatin, through inducing nitric oxide (NO) bioavailability/activity, in isolated streptozotocin (STZ)-induced diabetic hearts (DH). Isolated rat hearts from healthy Controls and diabetic animals were retrogradely perfused using the Langendorff configuration and subjected to prolonged ischemia and reperfusion, with and without (2.4 and 3.6%) sevo postC and/or pre-treatment with simvastatin (0.5 mg/kg). Sevo postC significantly reduced infarct size and improved myocardial function in healthy Controls but not in isolated DH. The sevo postC mediated myocardial protection against I/R-injury was not associated with de novo ferrtin synthesis. Furthermore, simvastatin aggravated myocardial injury after sevo postC in STZ-induced DHs, likely due to increasing NO levels. Despite the known mechanistic overlaps between PC and postC stimuli, distinct differences underlie the cardioprotective interventions against myocardial I/R-injury and are impaired in the DH. Sevo postC mediated cardioprotection, unlike IPC, does not involve de novo ferritin accumulation and cannot be rescued by simvastatin in STZ-induced DHs.

Promoting vascularization for tissue engineering constructs: current strategies focusing on HIF-regulating scaffolds

INTRODUCTION

Vascularization remains one of the greatest yet unmet challenges in tissue engineering. When engineered tissues are scaled up to therapeutically relevant dimensions, their demand of oxygen and nutrients can no longer be met by diffusion. Thus, there is a need for perfusable vascular structures. Hypoxia-inducible factors (HIF) act as transcriptional oxygen sensors and regulate a multitude of genes involved in adaptive processes to hypoxia, including angiogenesis. Thus, targeting HIFs is a promising strategy to induce vascularization of engineered tissues.

AREAS COVERED

Here we review current vascularization strategies and summarize the present knowledge regarding activation of HIF signaling by ions, iron chelating agents, α-Ketoglutarate (αKG) analogues, and the lipid-lowering drug simvastatin to induce angiogenesis. Specifically, we focus on the incorporation of HIF-activating agents into biomaterials and scaffolds for controlled release.

EXPERT OPINION

Vascularization of tissue constructs through activation of upstream regulators of angiogenesis offers advantages but also suffers from drawbacks. HIFs can induce a complete angiogenic program; however, this program appears to be too slow to vascularize larger constructs before cell death occurs. It is therefore crucial that HIF-activation is combined with cell protective strategies and prevascularization techniques to obtain fully vascularized, vital tissues of therapeutically relevant dimensions.

Atorvastatin attenuates paraquat poisoning-induced epithelial-mesenchymal transition via downregulating hypoxia-inducible factor-1 alpha

AIM

This study investigated the effects of atorvastatin (ATS) on the paraquat (PQ)-induced epithelial-mesenchymal transition (EMT) and the potential mechanism through hypoxia-inducible factor-1 alpha (HIF-1α).

MAIN METHODS

Sprague-Dawley (SD) rats were randomly divided into a control group (n = 5), PQ group (n = 20), PQ + ATS L group (n = 20, ATS 20 mg/kg daily) and PQ + ATS H group (n = 20, ATS 40 mg/kg daily). All treated rats were given a 20% PQ solution (50 mg/kg) once by gavage and then sacrificed 12, 24, 72 and 168 h after PQ exposure. The A549 and RLE-6TN cell lines were treated with ATS, PQ or both for 24 h. Mesenchymal (α-SMA and vimentin) and epithelial (E-cadherin and ZO-1) cell marker expression was tested both in vivo and in vitro. The effects of ATS on HIF-1α and β‑catenin expression were also evaluated.

KEY FINDINGS

ATS alleviated PQ poisoning-induced lung injury and pulmonary fibrosis in vivo. This effect was dose-dependent. ATS treatment attenuated the EMT by increasing the levels of the epithelial markers E-cadherin and ZO-1 and by decreasing the expression of the mesenchymal markers α-SMA and vimentin in both lung tissues and in vitro cell culture. In addition, ATS treatment may decrease the HIF-1α and β‑catenin levels both in vivo and in vitro.

SIGNIFICANCE

In conclusion, ATS can attenuate PQ-induced pulmonary fibrosis. The mechanism may involve the downregulation of the HIF-1α/β‑catenin pathway and the inhibition of the PQ-induced EMT by ATS. ATS may be considered as a therapeutic agent for PQ poisoning-induced pulmonary fibrosis.

Increased survivability of ischemic skin flap tissue in Flk-1+/- mice by Pellino-1 intervention

OBJECTIVE

Reduced skin flap survival due to ischemia is a serious concern during reconstructive cosmetic surgery. The absence of VEGF and its receptors during ischemia may lead to flap failure. We identified Peli1, a 46-kDa protein, as a proangiogenic molecule and is directly regulated by VEGF. Therefore, we hypothesized that Peli1 acts downstream of Flk-1/VEGFR2 and aids in skin flap survival during ischemia.

METHODS

Scratch and matrigel assays were performed to observe cell proliferation, migration, and tube formation in vitro. Western blot analysis was carried out to detect the phosphorylation of Akt (p-Akt) and MAPKAPK2 (p-MK2) in HUVECs. The translational potential of Peli1 pretreatment in the rescue of skin flap tissue was studied in vivo using Flk-1^+/- mice. Animals underwent dorsal ischemic skin flap surgery, and the tissue was collected on day 12 for analysis.

RESULTS

Western blot analysis revealed a direct relationship between Peli1 and VEGF, as demonstrated by loss-of-function and gain-of-function studies. In addition, pretreatment with Ad.Peli1 restored the phosphorylation of Akt and MK2 and improved the migration potential of Flk-1-knockdown cells. Ad.Peli1 pretreatment salvaged the ischemic skin flap of Flk-1^+/- mice by increasing blood perfusion and reducing the inflammatory response and the extent of necrosis.

CONCLUSION

Our findings reveal that Peli1 is a proangiogenic molecule that acts downstream of VEGF-Flk-1 and restores angiogenesis and enhances skin flap survivability.

Enhanced osteogenesis and angiogenesis by mesoporous hydroxyapatite microspheres-derived simvastatin sustained release system for superior bone regeneration

Biomaterials with both excellent osteogenic and angiogenic activities are desirable to repair massive bone defects. In this study, simvastatin with both osteogenic and angiogenic activities was incorporated into the mesoporous hydroxyapatite microspheres (MHMs) synthesized through a microwave-assisted hydrothermal method using fructose 1,6-bisphosphate trisodium salt (FBP) as an organic phosphorous source. The effects of the simvastatin-loaded MHMs (S-MHMs) on the osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) and angiogenesis in EA.hy926 cells were investigated. The results showed that the S-MHMs not only enhanced the expression of osteogenic markers in rBMSCs but also promoted the migration and tube formation of EA.hy926 cells. Furthermore, the S-MHMs were incorporated into collagen matrix to construct a novel S-MHMs/collagen composite scaffold. With the aid of MHMs, the water-insoluble simvastatin was homogenously incorporated into the hydrophilic collagen matrix and presented a sustained release profile. In vivo experiments showed that the S-MHMs/collagen scaffolds enhanced the bone regeneration and neovascularization simultaneously. These results demonstrated that the water-insoluble simvastatin could be incorporated into the MHMs and maintained its biological activities, more importantly, the S-MHMs/collagen scaffolds fabricated in this study are of immense potential in bone defect repair by enhancing osteogenesis and angiogenesis simultaneously.

Simvastatin prevents and reverses chronic pulmonary hypertension in newborn rats via pleiotropic inhibition of RhoA signaling

Chronic neonatal pulmonary hypertension (PHT) frequently results in early death. Systemically administered Rho-kinase (ROCK) inhibitors prevent and reverse chronic PHT in neonatal rats, but at the cost of severe adverse effects, including systemic hypotension and growth restriction. Simvastatin has pleiotropic inhibitory effects on isoprenoid intermediates that may limit activity of RhoA, which signals upstream of ROCK. We therefore hypothesized that statin treatment would safely limit pulmonary vascular RhoA activity and prevent and reverse experimental chronic neonatal PHT via downstream inhibitory effects on pathological ROCK activity. Sprague-Dawley rats in normoxia (room air) or moderate normobaric hypoxia (13% O2) received simvastatin (2 mg·kg−1·day−1 ip) or vehicle from postnatal days 1–14 (prevention protocol) or from days 14–21 (rescue protocol). Chronic hypoxia increased RhoA and ROCK activity in lung tissue. Simvastatin reduced lung content of the isoprenoid intermediate farnesyl pyrophosphate and decreased RhoA/ROCK signaling in the hypoxia-exposed lung. Preventive or rescue treatment of chronic hypoxia-exposed animals with simvastatin decreased pulmonary vascular resistance, right ventricular hypertrophy, and pulmonary arterial remodeling. Preventive simvastatin treatment improved weight gain, did not lower systemic blood pressure, and did not cause apparent toxic effects on skeletal muscle, liver or brain. Rescue therapy with simvastatin improved exercise capacity. We conclude that simvastatin limits RhoA/ROCK activity in the chronic hypoxia-exposed lung, thus preventing or ameliorating hemodynamic and structural markers of chronic PHT and improving long-term outcome, without causing adverse effects.

Influence of Statin Pretreatment on Initial Neurological Severity and Short-Term Functional Outcome in Acute Ischemic Stroke Patients: The Fukuoka Stroke Registry

Background: Statins have neuroprotective effects against ischemic stroke. However, associations between pre-stroke statin treatment and initial stroke severity and between the treatment and functional outcome remain controversial. This study aimed at determining these associations in ischemic stroke patients. Methods: Among patients registered in the Fukuoka Stroke Registry from June 2007 to October 2014, 3,848 patients with ischemic stroke within 24 h of onset, who had been functionally independent before onset, were enrolled in this study. Ischemic stroke was classified as cardioembolic or non-cardioembolic infarction. Primary and secondary study outcomes were mild neurological symptoms defined as a National Institutes of Health Stroke Scale score of ≤4 on admission and favorable functional outcome defined as a modified Rankin Scale score of ≤2 at discharge, respectively. Multivariable logistic regression models were used to quantify associations between pre-stroke statin treatment and study outcomes. Results: Of all 3,848 participants, 697 (18.1%) were taking statins prior to the stroke. The frequency of mild neurological symptoms was significantly higher in patients with pre-stroke statin treatment (64.1%) than in those without the treatment (58.3%, p < 0.01). Multivariable analysis showed that pre-stroke statin treatment was significantly associated with mild neurological symptoms (OR 1.31; 95% CI 1.04-1.65; p < 0.01). Sensitivity analysis in patients with dyslipidemia (n = 1,998) also showed the same trend between pre-stroke statin treatment and mild neurological symptoms (multivariable-adjusted OR 1.26; 95% CI 0.99-1.62; p = 0.06). In contrast, the frequency of favorable functional outcome was not different between patients with (67.0%) and without (65.3%) the treatment (p = 0.40). Multivariable analysis also showed no significant association between pre-stroke statin treatment and favorable functional outcome (OR 1.21; 95% CI 0.91-1.60; p = 0.19). Continuation of statin treatment, however, was significantly associated with favorable functional outcome among patients with pre-stroke statin treatment (multivariable-adjusted OR 2.17; 95% CI 1.16-4.00; p = 0.02). Conclusions: Pre-stroke statin treatment in ischemic stroke patients was significantly associated with mild neurological symptoms within 24 h of onset. Pre-stroke statin treatment per se did not significantly influence the short-term functional outcome; however, continuation of statin treatment during the acute stage of stroke seems to relate with favorable functional outcome for patients with pre-stroke statin treatment.

Ghrelin ameliorates impaired angiogenesis of ischemic myocardium through GHSR1a-mediated AMPK/eNOS signal pathway in diabetic rats

OBJECTIVES

Ghrelin, an endogenous ligand of the growth hormone secretagogue receptor (GHSR), has been found to stimulate angiogenesis in vivo and in vitro. However, the effect and the corresponding mechanisms of ghrelin on impaired myocardial angiogenesis in diabetic and myocardial infarction (MI) rat model are still unknown.

METHODS

In the present study, adult SD rats were randomly divided into 4 groups: control, DM, DM+ghrelin, DM+ghrelin+[D-Lys3]-GHRP-6 groups. DM was induced by streptozotocin (STZ) 60 mg/kg body weight. 12 weeks post STZ injection all groups were subjected to MI, which was induced by ligation left anterior descending artery (LAD). Ghrelin and [D-Lys3]-GHRP-6 were administered via intraperitoneal injection at the doses 200 μg/kg and 50mg/kg for 4 weeks, respectively. Left ventricular function, microvascular density (MVD), myocardial infarct size, the expression of hypoxia-inducible factor (HIF1α), vascular endothelial growth factor (VEGF), fetal liver kinase-1 (Flk-1) and fms-like tyrosine kinase-1 (Flt-1), AMPK and endothelial nitric oxide synthase (eNOS) phosphorylation were examined.

RESULTS

Compared with the DM group, left ventricular ejection fraction (LVEF), fractional shortening (FS), and MVD were increased, whereas myocardial infarct size decreased remarkably in DM+ghrelin group. For the mechanism study, we found that ghrelin promoted the HIF1α, VEGF, Flk-1 and Flt-1 expression, AMPK and eNOS phosphorylation in diabetic rats. However, the above biochemical events in ghrelin treated diabetic rats were completely inhibited by GHSR-1a blocker [D-Lys3]-GHRP-6.

CONCLUSIONS

These results suggest that administration of ghrelin ameliorates impaired angiogenesis in diabetic MI rats. And these beneficial effects derive from regulating GHSR1a-mediated AMPK/eNOS signal pathway by upregulating of HIF1α, VEGF and its receptors Flk-1, Flt-1 expressions.

Thioredoxin-1 (Trx1) engineered mesenchymal stem cell therapy increased pro-angiogenic factors, reduced fibrosis and improved heart function in the infarcted rat myocardium

INTRODUCTION

Engraftment of mesenchymal stem cells (MSCs) has emerged as a powerful candidate for mediating myocardial repair. In this study, we genetically modified MSCs with an adenovector encoding thioredoxin-1 (Ad.Trx1). Trx1 has been described as a growth regulator, a transcription factor regulator, a cofactor, and a powerful antioxidant. We explored whether engineered MSCs, when transplanted, are capable of improving cardiac function and angiogenesis in a rat model of myocardial infarction (MI).

METHODS

Rat MSCs were cultured and divided into MSC, MSC+Ad.LacZ, and MSC+Ad.Trx1 groups. The cells were assayed for proliferation, and differentiation potential. In addition, rats were divided into control-sham (CS), control-MI (CMI), MSC+Ad.LacZ-MI (MLZMI), and MSC+Ad.Trx1-MI (MTrxMI) groups. MI was induced by left anterior descending coronary artery (LAD) ligation, and MSCs preconditioned with either Ad.LacZ or Ad.Trx1 were immediately administered to four sites in the peri-infarct zone.

RESULTS

The MSC+Ad.Trx1 cells increased the proliferation capacity and maintained pluripotency, allowing them to divide into cardiomyocytes, smooth muscle, and endothelial cells. Western blot analysis, 4 days after treatment showed increased vascular endothelial growth factor (VEGF), heme oxygenase-1 (HO-1), and C-X-C chemokine receptor type 4 (CXCR4). Also capillary density along with myocardial function as examined by echocardiography was found to be increased. Fibrosis was reduced in the MTrxMI group compared to MLZMI and CMI. Visualization of Connexin-43 by immunohistochemistry confirmed increased intercellular connections in the MTrxMI rats compared to MLZMI.

CONCLUSION

Engineering MSCs to express Trx1 may prove to be a strategic therapeutic modality in the treatment of cardiac failure.

Inhibition of prolyl hydroxylase 3 ameliorates cardiac dysfunction in diabetic cardiomyopathy

Prolyl hydroxylase 3 (PHD3) is a member of the prolyl hydroxylases (PHDs) family and is induced by hypoxia. It plays a critical role in regulating the abundance of hypoxia-inducible factor (HIF). Its expression is increased in diabetic rat hearts; however, its role remains unclear. We investigated the potential role and mechanism of action of PHD3 in the setting of diabetes-induced myocardial dysfunction in rats. In vivo, type 2 diabetic rat model was induced via a high-fat diet and intraperitoneal injection of streptozotocin. PHD3 expression was knocked down using lentivirus-mediated short-hairpin RNA (shRNA). In vitro, primary neonatal cardiomyocytes and H9c2 cardiomyoblasts were cultured in 33.3 mM glucose (high glucose, HG) and 5.5 mM glucose (normal glucose, NG), the latter of which was used as a control. PHD3-siRNA was used to inhibit the expression of PHD3 and to investigate the role of PHD3 in HG-induced apoptosis in H9c2 cardiomyoblasts. Rats with diabetic cardiomyopathy (DCM) exhibited severe left ventricular dysfunction as well as myocardial apoptosis and fibrosis. PHD3 expression was increased in the myocardial tissues of diabetic rats, and inhibition of PHD3 ameliorated the disease. Additionally, the inhibition of PHD3 significantly decreased HG-induced apoptosis and MAPK activation in H9c2 cardiomyoblasts. Our results suggest that PHD3 inhibition ameliorates myocardial dysfunction in the setting of diabetic cardiomyopathy.

Deletion of prolyl hydroxylase domain proteins (PHD1, PHD3) stabilizes hypoxia inducible factor-1 alpha, promotes neovascularization, and improves perfusion in a murine model of hind-limb ischemia

BACKGROUND

There is an emerging focus on investigating innovative therapeutic molecules that can potentially augment neovascularization in order to treat peripheral arterial disease (PAD). Although prolyl hydroxylase domain proteins 1 and 3 (PHD1 and PHD3) may modulate angiogenesis via regulation of hypoxia inducible factor-1α (HIF-1α), there has been no study directly addressing their roles in ischemia-induced vascular growth. We hypothesize that PHD1(-/-) or PHD3(-/-) deficiency might promote angiogenesis in the murine hind-limb ischemia (HLI) model.

STUDY DESIGN

Wild type (WT), PHD1(-/-) and PHD3(-/-) male mice aged 8-12weeks underwent right femoral artery ligation. Post-procedurally, motor function assessment and laser Doppler imaging were periodically performed. The mice were euthanized after 28days and muscles were harvested. Immunohistochemical analysis was performed to determine the extent of angiogenesis by measuring capillary and arteriolar density. VEGF expression was quantified by enzyme-linked immunosorbent assay (ELISA). Bcl-2 and HIF-1α were analyzed by immunofluorescence. Fibrosis was measured by picrosirius red staining.

RESULTS

PHD1(-/-) and PHD3(-/-) mice showed significantly improved recovery of perfusion and motor function score when compared to WT after femoral artery ligation. These mice also exhibited increased capillary and arteriolar density, capillary/myocyte ratio along with decreased fibrosis compared to WT. VEGF, Bcl-2 and HIF-1α expression increased in PHD1(-/-) and PHD3(-/-) mice compared to WT.

CONCLUSIONS

Taken together these results suggest that PHD1 and PHD3 deletions promote angiogenesis in ischemia-injured tissue, and may present a promising therapeutic strategy in treating PAD.

Enhanced in vitro osteoblast differentiation on TiO2 scaffold coated with alginate hydrogel containing simvastatin

The aim of this study was to develop a three-dimensional porous bone graft material as vehicle for simvastatin delivery and to investigate its effect on primary human osteoblasts from three donors. Highly porous titanium dioxide (TiO₂) scaffolds were submerged into simvastatin containing alginate solution. Microstructure of scaffolds, visualized by scanning electron microscopy and micro-computed tomography, revealed an evenly distributed alginate layer covering the surface of TiO₂ scaffold struts. Progressive and sustained simvastatin release was observed for up to 19 days. No cytotoxic effects on osteoblasts were observed by scaffolds with simvastatin when compared to scaffolds without simvastatin. Expression of osteoblast markers (collagen type I alpha 1, alkaline phosphatase, bone morphogenetic protein 2, osteoprotegerin, vascular endothelial growth factor A and osteocalcin) was quantified using real-time reverse transcriptase–polymerase chain reaction. Secretion of osteoprotegerin, vascular endothelial growth factor A and osteocalcin was analysed by multiplex immunoassay (Luminex). The relative expression and secretion of osteocalcin was significantly increased by cells cultured on scaffolds with 10 µM simvastatin when compared to scaffolds without simvastatin after 21 days. In addition, secretion of vascular endothelial growth factor A was significantly enhanced from cells cultured on scaffolds with both 10 nM and 10 µM simvastatin when compared to scaffolds without simvastatin at day 21. In conclusion, the results indicate that simvastatin-coated TiO₂ scaffolds can support a sustained release of simvastatin and induce osteoblast differentiation. The combination of the physical properties of TiO₂ scaffolds with the osteogenic effect of simvastatin may represent a new strategy for bone regeneration in defects where immediate load is wanted or unavailable.

Fluvastatin-induced reduction of oxidative stress ameliorates diabetic cardiomyopathy in association with improving coronary microvasculature

Diabetic cardiomyopathy is associated with increased oxidative stress and vascular endothelial dysfunction, which lead to coronary microangiopathy. We tested whether statin-induced redox imbalance improvements could ameliorate diabetic cardiomyopathy and improve coronary microvasculature in streptozotocin-induced diabetes mellitus (DM). Fluvastatin (10 mg/kg/day) or vehicle was orally administered for 12 weeks to rats with or without DM. Myocardial oxidative stress was assessed by NADPH (nicotinamide adenine dinucleotide phosphate) oxidase subunit p22(phox) and gp91(phox) mRNA expression, and myocardial 8-iso-prostaglandin F(2α) (PGF(2α)) levels. Myocardial vascular densities were assessed using anti-CD31 and anti-α-smooth muscle actin (SMA) antibodies. Fluvastatin did not affect blood pressure or plasma cholesterol, but attenuated increased left ventricular (LV) minimum pressure and ameliorated LV systolic dysfunction in DM rats in comparison with vehicle (LV dP/dt, 8.9 ± 1.8 vs 5.4 ± 1.0 × 10(3) mmHg/s, P < 0.05). Myocardial oxidative stress increased in DM, but fluvastatin significantly reduced p22(phox) and gp91(phox) mRNA expression and myocardial PGF(2α) levels. Fluvastatin enhanced myocardial endothelial nitric oxide synthase (eNOS) protein levels and increased eNOS, vascular endothelial growth factor, and hypoxia-inducible factor-1α mRNA expression. CD31-positive cell densities were lower in DM rats than in non-DM rats (28.4 ± 13.2 vs 48.6 ± 4.3/field, P < 0.05) and fluvastatin restored the number (57.8 ± 18.3/field), although there were no significant differences in SMA-positive cell densities between groups. Fluvastatin did not affect cardiac function, oxidative stress, or vessel densities in non-DM rats. These results suggest that beneficial effects of fluvastatin on diabetic cardiomyopathy might result, at least in part, from improving coronary microvasculature through reduction in myocardial oxidative stress and upregulation of angiogenic factor.