Platelet-derived Growth Factor-B Protects Rat Cardiac Allografts From Ischemia-reperfusion Injury

The current landscape of antifibrotic therapy across different organs: A systematic approach

Fibrosis is a common pathological process that can affect virtually all the organs, but there are hardly any effective therapeutic options. This has led to an intense search for antifibrotic therapies over the last decades, with a great number of clinical assays currently underway. We have systematically reviewed all current and recently finished clinical trials involved in the development of new antifibrotic drugs, and the preclinical studies analyzing the relevance of each of these pharmacological strategies in fibrotic processes affecting tissues beyond those being clinically studied. We analyze and discuss this information with the aim of determining the most promising options and the feasibility of extending their therapeutic value as antifibrotic agents to other fibrotic conditions.

Do platelets protect the heart against ischemia/reperfusion injury or exacerbate cardiac ischemia/reperfusion injury? The role of PDGF, VEGF, and PAF

BACKGROUND

Acute myocardial infarction (AMI) is one of the main causes of death. It is quite obvious that there is an urgent need to develop new approaches for treatment of AMI.

OBJECTIVE

This review analyzes data on the role of platelets in the regulation of cardiac tolerance to ischemia/reperfusion (I/R).

METHODS

It was performed a search of topical articles using PubMed databases.

FINDINGS

Platelets activated by a cholesterol-enriched diet, thrombin, and myocardial ischemia exacerbate I/R injury of the heart. The P2Y12 receptor antagonists, remote ischemic postconditioning and conditioning alter the properties of platelets. Platelets acquire the ability to increase cardiac tolerance to I/R. Platelet-derived growth factors (PDGFs) increase tolerance of cardiomyocytes and endothelial cells to I/R. PDGF receptors (PDGFRs) were found in cardiomyocytes and endothelial cells. PDGFs decrease infarct size and partially abrogate adverse postinfarction remodeling. Protein kinase C, phosphoinositide 3-kinase, and Akt involved in the cytoprotective effect of PDGFs. Vascular endothelial growth factor increased cardiac tolerance to I/R and alleviated adverse postinfarction remodeling. The platelet-activating factor (PAF) receptor inhibitors increase cardiac tolerance to I/R in vivo. PAF enhances cardiac tolerance to I/R in vitro. It is possible that PAF receptor inhibitors could protect the heart by blocking PAF receptor localized outside the heart. PAF protects the heart through activation of PAF receptor localized in cardiomyocytes or endothelial cells. Reactive oxygen species and kinases are involved in the cardioprotective effect of PAF.

CONCLUSION

Platelets play an important role in the regulation of cardiac tolerance to I/R.

Therapeutic implication of Sonic Hedgehog as a potential modulator in ischemic injury

Sonic Hedgehog (SHh) is a homology protein that is involved in the modeling and development of embryonic tissues. As SHh plays both protective and harmful roles in ischemia, any disruption in the transduction and regulation of the SHh signaling pathway causes ischemia to worsen. The SHh signal activation occurs when SHh binds to the receptor complex of Ptc-mediated Smoothened (Smo) (Ptc-smo), which initiates the downstream signaling cascade. This article will shed light on how pharmacological modifications to the SHh signaling pathway transduction mechanism alter ischemic conditions via canonical and non-canonical pathways by activating certain downstream signaling cascades with respect to protein kinase pathways, angiogenic cytokines, inflammatory mediators, oxidative parameters, and apoptotic pathways. The canonical pathway includes direct activation of interleukins (ILs), angiogenic cytokines like hepatocyte growth factor (HGF), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), and hypoxia-inducible factor alpha (HIF-), which modulate ischemia. The non-canonical pathway includes indirect activation of certain pathways like mTOR, PI3K/Akt, MAPK, RhoA/ROCK, Wnt/-catenin, NOTCH, Forkhead box protein (FOXF), Toll-like receptors (TLR), oxidative parameters such as GSH, SOD, and CAT, and some apoptotic parameters such as Bcl2. This review provides comprehensive insights that contribute to our knowledge of how SHh impacts the progression and outcomes of ischemic injuries.

Focal segmental glomerulosclerosis and concurrent glomerular microangiopathy after long-term imatinib administration

A 79-year-old Japanese man was admitted to our hospital because of proteinuria and kidney dysfunction. He was diagnosed with chronic myeloid leukemia 13 years before and was treated with imatinib. Deep molecular response was achieved but he developed 1+ proteinuria in the first year, which gradually worsened thereafter. Imatinib was discontinued 12 years later but proteinuria and kidney dysfunction were progressive. Percutaneous kidney biopsy revealed mild mesangial hyper-cellularity and matrix increase, swelling of endothelial cells, and partial double contours of glomerular tufts. Subendothelial edema in the interlobular artery was also noted. Immunofluorescence was not remarkable. Electron microscopy revealed endothelial injury with severe sub-endothelial edema. Since imatinib had already been discontinued, conservative therapy with maximal dose of azilsartan was administered. A second biopsy was performed 1 year later because of further deterioration of kidney function, which revealed markedly increased global glomerulosclerosis and severe interstitial fibrosis and tubular atrophy. Segmental glomerulosclerosis with podocyte hyperplasia was also observed. Electron microscopy revealed glomerulosclerotic changes and partially attenuated endothelial injury. Two and a half years later, proteinuria reduced, progression of kidney dysfunction slowed, and he was independent on dialysis therapy. Molecular response of chronic myeloid leukemia was also maintained. The clinical course suggested that endothelial and podocyte injuries were induced by imatinib, and that the nephrotoxic effects lasted for a few years after discontinuation.

Morphine Prevents Ischemia/Reperfusion-Induced Myocardial Mitochondrial Damage by Activating δ-opioid Receptor/EGFR/ROS Pathway

OBJECTIVE

The purpose of this study was to determine whether the epidermal growth factor receptor (EGFR), which is a classical receptor tyrosine kinase, is involved in the protective effect of morphine against ischemia/reperfusion (I/R)-induced myocardial mitochondrial damage.

METHODS

Isolated rats hearts were subjected to global ischemia followed by reperfusion. Cardiac H9c2 cells were exposed to a simulated ischemia solution followed by Tyrode's solution to induce hypoxia/reoxygenation (H/R) injury. Triphenyltetrazolium chloride (TTC) was used to measure infarct size. The mitochondrial morphological and functional changes were determined using transmission election microscopy (TEM), mitochondrial stress assay, and mitochondrial swelling, respectively. Mitochondrial fluorescence indicator JC-1, DCFH-DA, and Mitosox Red were used to determine mitochondrial membrane potential (△Ψm), intracellular reactive oxygen species (ROS) and mitochondrial superoxide. A TUNUL assay kit was used to detect the level of apoptosis. Western blotting analysis was used to measure the expression of proteins.

RESULTS

Treatment of isolated rat hearts with morphine prevented I/R-induced myocardial mitochondrial injury, which was inhibited by the selective EGFR inhibitor AG1478, suggesting that EGFR is involved in the mitochondrial protective effect of morphine under I/R conditions. In support of this hypothesis, the selective EGFR agonist epidermal growth factor (EGF) reduced mitochondrial morphological and functional damage similarly to morphine. Further study demonstrated that morphine may alleviate I/R-induced cardiac damage by inhibiting autophagy but not apoptosis. Morphine increased protein kinase B (Akt), extracellular regulated protein kinases (ERK) and signal transducer and activator of transcription-3 (STAT-3) phosphorylation, which was inhibited by AG1478, and EGF had similar effects, indicating that morphine may activate Akt, ERK, and STAT-3 via EGFR. Morphine and EGF increased intracellular reactive oxygen species (ROS) generation. This effect of morphine was inhibited by AG1478, indicating that morphine promotes intracellular ROS generation by activating EGFR. However, morphine did not increase ROS generation when cells were transfected with siRNA against EGFR. In addition, EGFR activity was markedly increased by morphine, but the effect of morphine was reversed by naltrindole. These results suggest that morphine may activate EGFR via δ-opioid receptor activation.

CONCLUSIONS

Morphine may prevent I/R-induced myocardial mitochondrial damage by activating EGFR through δ-opioid receptors, in turn increasing RISK and SAFE pathway activity via intracellular ROS. Moreover, morphine may reduce myocardial injury by regulating autophagy but not apoptosis.

Biologics and their delivery systems: Trends in myocardial infarction

Cardiovascular disease is the leading cause of death around the world, in which myocardial infarction (MI) is a precipitating event. However, current therapies do not adequately address the multiple dysregulated systems following MI. Consequently, recent studies have developed novel biologic delivery systems to more effectively address these maladies. This review utilizes a scientometric summary of the recent literature to identify trends among biologic delivery systems designed to treat MI. Emphasis is placed on sustained or targeted release of biologics (e.g. growth factors, nucleic acids, stem cells, chemokines) from common delivery systems (e.g. microparticles, nanocarriers, injectable hydrogels, implantable patches). We also evaluate biologic delivery system trends in the entire regenerative medicine field to identify emerging approaches that may translate to the treatment of MI. Future developments include immune system targeting through soluble factor or chemokine delivery, and the development of advanced delivery systems that facilitate the synergistic delivery of biologics.

Overexpression of MiR-29b-3p Inhibits Atrial Remodeling in Rats by Targeting PDGF-B Signaling Pathway

Purpose

Studies have found that microRNAs (miRNAs) are closely associated with atrial fibrillation, but their specific mechanism remains unclear. The purpose of this experiment is to explore the function of miR-29b-3p in regulating atrial remodeling by targeting PDGF-B signaling pathway and thereby also explore the potential mechanisms.

Methods

We randomly divided twenty-four rats into four groups. Caudal intravenous injections of angiotensin-II (Ang-II) were administered to establish atrial fibrosis models. Expressions of miR-29b-3p and PDGF-B were then tested via RT-PCR, western blot, and immunohistochemistry. Binding sites were then analyzed via the bioinformatics online software TargetScan and verified by Luciferase Reporter. We used Masson staining to detect the degree of atrial fibrosis, while immunofluorescence and western blot were used to detect the expressions of Collagen-I and a-SMA. We used immunohistochemistry and western blot to detect the expression of connexin 43 (Cx43).

Results

In comparison with the Ang-II group, miR-29b-3p was seen to lower the degree of atrial fibrosis, decrease the expression of fibrosis markers such as Collagen-I and a-SMA, and increase the protein expression of Cx43. MiR-29b-3p can lower the expression of PDGF-B, while the Luciferase Reporter showed that PDGF-B is the verified target gene of miR-29b-3p.

Conclusions

MiR-29b-3p was able to reduce atrial structural and electrical remodeling in the study's rat fibrosis model. This biological function may be expressed through the targeted regulation of the PDGF-B signaling pathway.

Multiple Progressive Thermopreconditioning Improves Cardiac Ischemia/Reperfusion-induced Left Ventricular Contractile Dysfunction and Structural Abnormality in Rat

BACKGROUND

Triple progressive thermopreconditioning (3PTP) may induce high Hsp-70 expression to maintain cardiac function. We suggest that 3PTP may reduce myocardial ischemia/reperfusion (I/R) injury during organ transplantation through Bag3/Hsp-70 mediated defense mechanisms.

METHODS

Male Wistar rats were divided into sham control group and 72 h after 3PTP in a 42°C water bath (3PTP) group. Rats underwent 60 min of ischemia by occlusion of the left anterior descending coronary artery followed by 240 min reperfusion. Hemodynamic parameters, including the electrocardiogram, microcirculation, heart rate, left ventricular end-diastolic pressure, maximal rate of rise (+dp/dt), and fall (-dp/dt) in the left ventricular pressure for index of contraction and relaxation were determined. Myocardial infarct size was evaluated by the Evans blue-2,3,5-triphenyltetrazolium chloride method. 3PTP-induced protective mechanisms were determined by Western blot and immunohistochemistry.

RESULTS

Cardiac I/R depressed cardiac microcirculation, induced S-T segment elevation, and R-R and P-R interval elongation increased infarct size associated with erythrocyte extravasation, leukocytes and macrophage/monocyte infiltration, granulocyte colony-stimulating factor, poly(ADP-ribose) polymerase 1 stain, and transferase-mediated dUTP-biotin nick end labeling positive cells. However, 3PTP evoked significant cardioprotection against I/R injury, characterized by the increased +dp/dt value and the decreased elevated left ventricular end-diastolic pressure, erythrocyte extravasation, leukocyte and macrophage/monocyte infiltration, granulocyte colony-stimulating factor expression, poly(ADP-ribose) polymerase 1 expression, transferase-mediated dUTP-biotin nick end labeling positive cells, and fragmentation and infarct area. In addition, 3PTP increased Hsp-70 and Bag3 expression and decreased Bax/Bcl-2 ratio, but did not affect the Beclin-1 and LC3-II/LC3-I ratio in the heart with I/R injury.

CONCLUSIONS

3PTP therapies may through Bag3 upregulation alleviate I/R injury-induced left ventricular structural deterioration and dysfunction.

A PDGF/VEGF homologue provides new insights into the nucleus grafting operation and immune response in the pearl oyster Pinctada fucata

The platelet-derived growth factor/vascular endothelial growth factor (PDGF/VEGF, PVF) family of proteins have been implicated in a wide range of biological functions in vertebrates, including cell proliferation, cell differentiation, cell migration, neural development and especially angiogenesis/vasculogenesis. In this study, a PVF gene, belonging to the PDGF/VEGF family, was cloned and characterized from Pinctada fucata. It contained an ORF of 1110bp encoding a putative protein of 369 amino acids. The deduced amino acid sequence presented the typical structural features of PDGF family members and the N-terminal signal peptide for secretion. Comparative phylogenetic analysis revealed that PfPVF shows relatively high identity with other invertebrate PVF homologues. Furthermore, gene expression analysis revealed that PfPVF is involved in not only the nucleus grafting operation and but also the response to immune stimulation. The study may help to increase understanding of the functions of molluscan PVF.

Platelet-Derived Growth Factor in Heart Failure

Defective vascular and cardiomyocyte function are implicated in the development and progression of both heart failure with reduced and preserved ejection fraction. Any treatment option that augments these myocardial processes may therefore be of significant value. The platelet-derived growth factor (PDGF) family is involved in a wide range of growth processes and plays a key role in both regulating angiogenesis and mesenchymal cell development. Thus, PDGF may serve as a potent therapy for heart failure. While numerous animal studies have demonstrated beneficial cardiovascular effects of growth factor therapy, promising laboratory data has not yet translated to effective therapies. In this review, we outline the biological role of PDGF and summarize previous studies that have focused on the cardiovascular effects of normal PDGF signaling, administration of PDGF, and the effects of PDGF on stem cell therapy.