Cardioprotective Effects of a Selective c-Jun N-terminal Kinase Inhibitor in a Rat Model of Myocardial Infarction

Activation of c-Jun N-terminal kinases (JNKs) is involved in myocardial injury, left ventricular remodeling (LV), and heart failure (HF) after myocardial infarction (MI). The aim of this research was to evaluate the effects of a selective JNK inhibitor, 11H-indeno [1,2-b]quinoxalin-11-one oxime (IQ-1), on myocardial injury and acute myocardial ischemia/reperfusion (I/R) in adult male Wistar rats. Intraperitoneal administration of IQ-1 (25 mg/kg daily for 5 days) resulted in a significant decrease in myocardial infarct size on day 5 after MI. On day 60 after MI, a significant (2.6-fold) decrease in LV scar size, a 2.2-fold decrease in the size of the LV cavity, a 2.9-fold decrease in the area of mature connective tissue, and a 1.7-fold decrease in connective tissue in the interventricular septum were observed compared with the control group. The improved contractile function of the heart resulted in a significant (33%) increase in stroke size, a 40% increase in cardiac output, a 12% increase in LV systolic pressure, a 28% increase in the LV maximum rate of pressure rise, a 45% increase in the LV maximum rate of pressure drop, a 29% increase in the contractility index, a 14% increase in aortic pressure, a 2.7-fold decrease in LV end-diastolic pressure, and a 4.2-fold decrease in LV minimum pressure. We conclude that IQ-1 has cardioprotective activity and reduces the severity of HF after MI.

Copper promotes cardiac functional recovery via suppressing the transformation of fibroblasts to myofibroblasts in ischemia-infarcted monkey hearts

Myocardial ischemia leads to cardiac fibrosis along with copper (Cu) loss. Cu repletion diminishes myocardial fibrosis and improves cardiac function. The transformation of fibroblasts to myofibroblasts is highly responsible for the pathogenesis of cardiac fibrosis. This study was undertaken to test the hypothesis that Cu inhibition of cardiac fibrosis results from suppression of myofibroblasts. Rhesus monkeys 4-5 years old were subjected to coronary artery ligation to induce myocardial infarction (MI). At the end of the fourth week after the surgery, an ultrasound-directed Cu-albumin microbubble organ-specific Cu delivery technique was used to treat the ischemia-infarcted monkey hearts twice a week for 4 weeks. This treatment increased Cu concentrations in the infarct area, loosened the collagen cross-linking network, restored blood vessel density, and improved cardiac contractility. Total fibroblasts labeled with vimentin were increased in the infarct area, and Cu repletion did not alter this increase. Myofibroblasts, dually labeled with vimentin and α-smooth muscle actin (α-SMA), were also significantly increased in the infarct area but were significantly reduced by Cu repletion. Correspondingly, the products of myofibroblasts, type I and III collagens and inhibitors of collagenases were significantly reduced. In contrast, metalloproteinase-1 (MMP-1) and MMP-1 producing fibroblasts (vimentin⁺ and MMP-1⁺ cells) were significantly increased. These results suggest that Cu inhibits the transformation of fibroblasts to myofibroblasts, leading to a pro-fibrinolytic switch and an improvement in cardiac function.

Changes in Rats' Gut Microbiota Composition Caused by Induced Chronic Myocardial Infarction Lead to Depression-Like Behavior

Depression is common among patients who have chronic myocardial infarction (CMI). Despite their frequency, depression and CMI are bidirectional related conditions, each is a risk for the other, and they often co-exist, suggesting shared or interacting pathomechanisms. Accumulating data revealed the effects of gut microbiota in terms of regulating depression via the gut–brain axis. Thus, we investigated the role of gut microbial dysbiosis in CMI-induced depression-like behavior. Hierarchical cluster analysis of sucrose preference test (SPT) results was adopted to classify the CMI rats into depression-like behavior (CMI + Dep) or non-depression-like behavior (CMI + Non-Dep) phenotypes. First, 16S ribosomal RNA sequencing analysis showed both β-diversity and relative abundance of several gut bacteria significantly differed between the CMI + Dep and CMI + Non-Dep rats. Next, transplantation of fecal microbiota from CMI + Dep rats visibly altered the relative abundance of gut microbiota and also induced depression-like behavior in the antibiotics-treated pseudo-germ-free rats. In conclusion, these findings suggested that dysbiosis in gut microbial composition contributed to the onset of CMI-induced depression-like behavior and that exogenous regulation of gut microbiota composition could be a potential therapeutic strategy for CMI and related depression-like behavior.

Fibrosis in Chronic Kidney Disease: Pathogenesis and Consequences

Fibrosis is a process characterized by an excessive accumulation of the extracellular matrix as a response to different types of tissue injuries, which leads to organ dysfunction. The process can be initiated by multiple and different stimuli and pathogenic factors which trigger the cascade of reparation converging in molecular signals responsible of initiating and driving fibrosis. Though fibrosis can play a defensive role, in several circumstances at a certain stage, it can progressively become an uncontrolled irreversible and self-maintained process, named pathological fibrosis. Several systems, molecules and responses involved in the pathogenesis of the pathological fibrosis of chronic kidney disease (CKD) will be discussed in this review, putting special attention on inflammation, renin-angiotensin system (RAS), parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), Klotho, microRNAs (miRs), and the vitamin D hormonal system. All of them are key factors of the core and regulatory pathways which drive fibrosis, having a great negative kidney and cardiac impact in CKD.

Biomaterial-based delivery systems of nucleic acid for regenerative research and regenerative therapy

Regenerative medicine is a new and promising medical method aiming at treating patients with defective or dysfunctional tissues by maintaining or enhancing the biological activity of cells. The development of biomaterial-based technologies, such as cell scaffolds and carriers for drug delivery system, are highly required to promote the regenerative research and regenerative therapy. Nucleic acids are one of the most feasible factors to efficiently modify the biological activity of cells. The effective and stable delivery of nucleic acids into cells is highly required to succeed in the modification. Biomaterials-based non-viral carriers or biological carriers, like exosomes, play an important role in the efficient delivery of nucleic acids. This review introduces the examples of regenerative research and regenerative therapy based on the delivery of nucleic acids with biomaterials technologies and emphasizes their importance to accomplish regenerative medicine.

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Modifying the activity of cells is important for regenerative medicine.

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Various nucleic acids regulate gene expression to modify the activity of cells.

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Intracellular delivery system is vital to the nucleic acids-based modification.

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Biomaterials are useful for the intracellular delivery of nucleic acids.

Recent development of synthetic nonviral systems for sustained gene delivery

Sustained gene delivery is of particular importance today because it circumvents the need for repeated therapeutic administration and provides spatial and temporal control of the release profile. Better understanding of the genetic basis of diseases and advances in gene therapy have propelled significant research on biocompatible gene carriers for therapeutic purposes. Varied biodegradable polymer-based architectures have been used to create new compositions with unique properties suitable for sustained gene delivery. This review presents the most recent advances in various polymeric systems: hydrogels, microspheres, nanospheres and scaffolds, having complex architectures to encapsulate and deliver functional genes. Through the recombination of different existing polymer systems, the multicomplex systems can be further endowed with new properties for better-targeted biomedical applications.

Micro- and Nanoparticles for Treating Cardiovascular Disease

Cardiovascular disease, including myocardial infarction (MI) and peripheral artery disease (PAD), afflicts millions of people in Unites States. Current therapies are insufficient to restore blood flow and repair the injured heart or skeletal muscle, respectively, which is subjected to ischemic damage following vessel occlusion. Micro- and nano-particles are being designed as delivery vehicles for growth factors, enzymes and/or small molecules to provide a sustained therapeutic stimulus at the injured tissue. Depending on the formulation, the particles can be injected directly into the heart or skeletal muscle, or accumulate at the site of injury following an intravenous injection. In this article we review existing particle based therapies for treating MI and PAD.

Cationized gelatin hydrogels mixed with plasmid DNA induce stronger and more sustained gene expression than atelocollagen at calvarial bone defects in vivo

Gene transduction of exogenous factors at local sites in vivo is a promising approach to promote regeneration of tissue defects owing to its simplicity and capacity for expression of a variety of genes. Gene transduction by viral vectors is highly efficient; however, there are safety concerns associated with viruses. As a method for nonviral gene transduction, plasmid DNA delivery is safer and simpler, but requires an efficient carrier substance. Here, we aimed to develop a simple, efficient method for bone regeneration by gene transduction and to identify optimal conditions for plasmid DNA delivery at bone defect sites. We focused on carrier substances and compared the efficiencies of two collagen derivatives, atelocollagen, and gelatin hydrogel, as substrates for plasmid DNA delivery in vivo. To assess the efficiencies of these substrates, we examined exogenous expression of green fluorescence protein (GFP) by fluorescence microscopy, polymerase chain reaction, and immunohistochemistry. GFP expression at the bone defect site was higher when gelatin hydrogel was used as a substrate to deliver plasmids than when atelocollagen was used. Moreover, the gelatin hydrogel was almost completely absorbed at the defect site, whereas some atelocollagen remained. When a plasmid harboring bone morphogenic protein 2 was delivered with the substrate to bony defect sites, more new bone formation was observed in the gelatin group than in the atelocollagen group. These results suggested that the gelatin hydrogel was more efficient than atelocollagen as a substrate for local gene delivery and may be a superior material for induction of bone regeneration.

Biodegradable gelatin microspheres enhance the neuroprotective potency of osteopontin via quick and sustained release in the post-ischemic brain

Gelatin microspheres (GMSs) are widely used as drug carriers owing to their excellent biocompatibilities and toxicologically safe degradation products. The drug release profile is easily tailored by controlling the cross-linking density and surface-to-volume ratio, i.e. size, of the GMS. In this study, we employed GMSs which are 25 μm in diameter and cross-linked with 0.03125% glutaraldehyde, to enable rapid initial and a subsequent sustained release. Therapeutic potency of human recombinant osteopontin (rhOPN) with or without encapsulation into GMSs was investigated after administrating them to rat stroke model (Sprague-Dawley; middle cerebral artery occlusion, MCAO). The administration of rhOPN/GMS (100 ng/100 μg) at 1h post-MCAO reduced the mean infarct volume by 81.8% of that of the untreated MCAO control and extended the therapeutic window at least to 12h post-MCAO, demonstrating a markedly enhanced therapeutic potency for the use of OPN in the post-ischemic brain. Scanning electron microscopy micrographs revealed that GMSs maintained the three-dimensional shape for more than 5 days in normal brain but were degraded rapidly in the post-ischemic brain, presumably due to high levels of gelatinase induction. After encapsulation with GMS, the duration of OPN release was markedly extended; from the period of 2 days to 5 days in normal brain, and from 2 days to 4 days in the post-ischemic brain; these encompass the critical period for recovery processes, such as vascularization, and controlling inflammation. Together, these results indicate that GMS-mediated drug delivery has huge potential when it was used in the hyperacute period in the post-ischemic brain.

Vitamin D receptor activation, left ventricular hypertrophy and myocardial fibrosis

BACKGROUND

Left ventricular hypertrophy (LVH), a common complication in chronic kidney disease (CKD), is associated with high cardiovascular mortality. The aim of this experimental study was to analyze the effect of different vitamin D receptor activators (VDRAs) on both LVH and myocardial fibrosis in chronic renal failure (CRF).

METHODS

Male Wistar rats with CRF, carried out by 7/8 nephrectomy, were treated intraperitoneally with equivalent doses of VDRAs (calcitriol, paricalcitol and alfacalcidol, 5 days per week) during 4 weeks. A placebo group (CRF + vehicle) and a Sham group with normal renal function served as controls. Biochemical, morphological, functional and molecular parameters associated with LVH were evaluated, as well as cardiac fibrosis, collagen I, transforming growth factor β1 (TGFβ1) and matrix metalloproteinase-1 (MMP1) expression.

RESULTS

All VDRAs treatment prevented LVH, with values of cardiomyocyte size, LV wall and septum thickness and heart-body weight ratio similar to those observed in the Sham group. At molecular levels, all VDRAs attenuated atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) expression compared with CRF + vehicle. The phosphorylation of ERK1/2, a signal for activating growth, was stimulated in the CRF + vehicle group; VDRAs use prevented this activation. Paricalcitol was the only VDRA used that maintained in the normal range all parameters associated with myocardial fibrosis (total collagen, collagen I, TGFβ1 and MMP1).

CONCLUSIONS

Our findings demonstrated that the three VDRAs used induced similar changes in bone metabolic parameters and LVH. In addition, paricalcitol was the only VDRA which showed a relevant beneficial effect in the reduction of myocardial fibrosis, a key factor in the myocardial dysfunction in CKD patients.

Recent advances in polymeric microspheres for parenteral drug delivery--part 2

INTRODUCTION

Currently marketed microsphere products are manufactured with the use of organic solvents which have a negative impact on the environment and stability of biological molecules. With recent advances in fabrication technologies, solvent free methods have demonstrated potential for the preparation of microspheres.

AREAS COVERED

New technical advances recently achieved in solvent based microsphere manufacturing processes have allowed for major improvement in product quality and properties. Novel solvent free fabrication methods combined with newly functionalized biodegradable polymers have been explored for their application in the preparation of microspheres containing biological molecules.

EXPERT OPINION

Novel fabrication methods for microspheres have been recently reported but technical challenges and development risks remain high for scale up from bench to industrial commercialization. While the applications of microspheres for delivery of proteins, genes and vaccines have shown promise for clinical use, the approval of newly functionalized polymers as carriers may still face scrutiny on safety and biocompatibility, which can be key factors in securing the regulatory approval of the product.

Transplantation of elastin-secreting myoblast sheets improves cardiac function in infarcted rat heart

Myoblast sheet transplantation for cardiac failure is a promising therapy to enhance cardiac function via paracrine mechanism. However, their efficacies of treatment showed a gradual decline. The gene modification of the implanted myoblast is important in improving the long-term results of the treatment. Elastin fiber enhances the extensibility of the infarcted wall and can prevent left ventricular dilation. We therefore hypothesized that the elastin gene modification of the implanted myoblast could strengthen and maintain the long-term improvement effects of cardiac function. In this study, we evaluated long-term follow-up benefits of functional myoblast sheets that secrete elastin in an infarcted model. The animal models were divided into three groups: a group transplanted with nontransfected, wild-type, skeletal myoblast-type sheets (WT-rSkM); group transplanted with myoblast sheets that secreted elastin fragments (ELN-rSkM); and a control group (ligation only). Cardiac function was examined by echocardiography, and cardiac remodeling after infarction was evaluated by histological examination. The cardiac function was significantly improved and the left ventricle end-diastolic dimensions were significantly reduced in the ELN-rSkM group. Histological analysis showed that left ventricular remodeling was attenuated in the ELN-rSkM group and that elastic fiber was formed in the epicardial area of ELN-rSkM group. The functionalization of myoblast sheet by elastin gene transfer showed the long-term improvement of cardiac function. Expressed recombinant elastin fiber prevented the dilation of the left ventricular chamber after myocardial infarction. The functional myoblast sheet transplantation maintained the treatment effect by the paracrine effect of myoblast and the formed recombinant elastin.

KMUP-3 attenuates ventricular remodelling after myocardial infarction through eNOS enhancement and restoration of MMP-9/TIMP-1 balance

BACKGROUND AND PURPOSE

Previously, 7-[2-[4-(4-nitrobenzene)piperazinyl]ethyl]-1, 3-dimethylxanthine (KMUP-3) has been shown to induce aortic smooth muscle relaxation through K(ATP) channel opening and endothelial nitric oxide synthase (eNOS) enhancement. We further investigated whether KMUP-3 protects against myocardial remodelling after myocardial infarction (MI), and whether KMUP-3 increases the expression of eNOS in MI rats.

EXPERIMENTAL APPROACH

Wistar rats were randomly allocated into three groups: MI (n= 10), MI + KMUP-3 group (n= 10) and sham group (n= 10). MI was induced by ligation of the left anterior descending coronary artery. After recovery, the MI + KMUP-3 group received KMUP-3 (0.3 mg·kg(-1) ·day(-1) ) infusion for 4 weeks, while the MI and sham group received vehicle only. To further confirm that the effect of KMUP-3 is dependent on eNOS, KMUP-3 was applied in the culture of transforming growth factor-β-stimulated human cardiac fibroblasts.

KEY RESULTS

KMUP-3 treatment attenuated cardiac hypertrophy post-MI and improved cardiac function. The fibrotic area was reduced by KMUP-3 both in central-, peri- and non-infarction areas. KMUP-3 enhanced the expression of eNOS and tissue inhibitor of metalloproteinase-1 (TIMP-1), but reduced matrix metalloproteinase-9 (MMP-9) expression. In vitro, the activities of KMUP-3 were blocked by pretreatment with the eNOS inhibitor N(ω) -nitro-L-arginine methyl ester.

CONCLUSIONS AND IMPLICATIONS

The K(ATP) channel opener KMUP-3 preserved cardiac function after MI by enhancing the expression of eNOS. In addition, KMUP-3 restored the myocardial MMP-9/TIMP-1 balance and attenuated ventricular remodelling by an eNOS-dependent mechanism.

Delivering regenerative cues to the heart: cardiac drug delivery by microspheres and peptide nanofibers

Our understanding of signaling pathways and cues vital for cardiac regeneration is being refined by laboratories worldwide. As various mechanisms enabling cardiac regeneration are becoming elucidated, delivery vehicles suited for these potential therapeutics must also be developed. This review focuses on advances in two technologies, novel degradable microspheres for controlled release systems and self-assembling peptide nanofibers for cell and factor delivery. Polyketals, a new class of resorbable polymers, are well suited for treating inflammatory diseases due to biocompatible degradation products. Polyketals have been used to deliver small molecule inhibitors and antioxidant proteins to rat models of myocardial infarction with notable improvements in cardiac function. Self-assembling peptide nanofibers are a class of hydrogels that are well-defined scaffolds made up of 99% water and amenable to incorporation of a variety of bioactive cues. Work done by our laboratory and others have demonstrated functional improvements using these hydrogels as both a drug delivery vehicle for proteins as well as a defined microenvironment for transplanted cells. Combining non-inflammatory polymer microspheres for sustained release of drugs with self-assembling nanofibers yields multifunctional scaffolds that may soon drive the body's healing response following myocardial infarction towards cardiac regeneration.

Is structural remodeling of fibrillated atria the consequence of tissue hypoxia?

BACKGROUND

Matrix metalloproteinases (MMPs) play an important role in degradation of the extracellular matrix of injured tissue. MMP-9 expression increases in fibrillating atrial tissue; however, the mechanism for this increase has not been clarified.

METHODS AND RESULTS

Changes in the expression of vascular endothelial growth factor (VEGF), VEGF receptors, and hypoxia-induced transcription factor-1alpha (HIF-1alpha) in fibrillating atrial tissue were investigated. Atrial tissue samples were obtained from 13 patients with atrial fibrillation (AF) and 25 patients without a history of AF (regular sinus rhythm, RSR) undergoing cardiac operations. Western blot, real-time polymerase chain reaction, and immunofluorescence analyses of the expression of VEGF, VEGF receptors, and HIF-1alpha were performed. The VEGF mRNA and protein levels increased significantly in the AF group compared with the RSR group (P<0.05), and the expression of HIF-1alpha protein was also significantly higher in the AF group. VEGF receptor-1 mRNA, a high-affinity receptor for VEGF, but not VEGF receptor-2 mRNA, was upregulated in the atria of the AF group (P<0.05). Immunofluorescence staining revealed excess production and co-localization of HIF-1alpha, VEGF and MMP-9 in the endothelium of the atrial arteries in the AF group.

CONCLUSIONS

It is possible that upregulation of HIF-1/VEGF is involved in the enhancement of MMP-9 expression under hypoxic conditions.