Imaging techniques to evaluate cell therapy in peripheral artery disease: state of the art and clinical trials

The recent advances in cell delivery approaches, biochemical and engineering procedures of cell therapy applied to coronary heart disease

Cell therapy is an important topic in the field of regeneration medicine that is gaining attention within the scientific community. However, its potential for treatment in coronary heart disease (CHD) has yet to be established. Several various strategies, types of cells, routes of distribution, and supporting procedures have been tried and refined to trigger heart rejuvenation in CHD. However, only a few of them result in a real considerable promise for clinical usage. In this review, we give an update on techniques and clinical studies of cell treatment as used to cure CHD that are now ongoing or have been completed in the previous five years. We also highlight the emerging efficacy of stem cell treatment for CHD. We specifically examine and comment on current breakthroughs in cell treatment applied to CHD, including the most effective types of cells, transport modalities, engineering, and biochemical approaches used in this context. We believe the current review will be helpful for the researcher to distill this information and design future studies to overcome the challenges faced by this revolutionary approach for CHD.

Epigenetic-sensitive pathways in personalized therapy of major cardiovascular diseases

The complex pathobiology underlying cardiovascular diseases (CVDs) has yet to be explained. Aberrant epigenetic changes may result from alterations in enzymatic activities, which are responsible for putting in and/or out the covalent groups, altering the epigenome and then modulating gene expression. The identification of novel individual epigenetic-sensitive trajectories at single cell level might provide additional opportunities to establish predictive, diagnostic and prognostic biomarkers as well as drug targets in CVDs. To date, most of studies investigated DNA methylation mechanism and miRNA regulation as epigenetics marks. During atherogenesis, big epigenetic changes in DNA methylation and different ncRNAs, such as miR-93, miR-340, miR-433, miR-765, CHROME, were identified into endothelial cells, smooth muscle cells, and macrophages. During man development, lipid metabolism, inflammation and homocysteine homeostasis, alter vascular transcriptional mechanism of fundamental genes such as ABCA1, SREBP2, NOS, HIF1. At histone level, increased HDAC9 was associated with matrix metalloproteinase 1 (MMP1) and MMP2 expression in pro-inflammatory macrophages of human carotid plaque other than to have a positive effect on toll like receptor signaling and innate immunity. HDAC9 deficiency promoted inflammation resolution and reverse cholesterol transport, which might block atherosclerosis progression and promote lesion regression. Here, we describe main human epigenetic mechanisms involved in atherosclerosis, coronary heart disease, ischemic stroke, peripheral artery disease; cardiomyopathy and heart failure. Different epigenetics mechanisms are activated, such as regulation by circular RNAs, as MICRA, and epitranscriptomics at RNA level. Moreover, in order to open new frontiers for precision medicine and personalized therapy, we offer a panoramic view on the most innovative bioinformatic tools designed to identify putative genes and molecular networks underlying CVDs in man.

Epigenetic Hallmarks of Fetal Early Atherosclerotic Lesions in Humans

Importance

Although increasingly strong evidence suggests a role of maternal total cholesterol and low-density lipoprotein cholesterol (LDLC) levels during pregnancy as a risk factor for atherosclerotic disease in the offspring, the underlying mechanisms need to be clarified for future clinical applications.

Objective

To test whether epigenetic signatures characterize early fetal atherogenesis associated with maternal hypercholesterolemia and to provide a quantitative estimate of the contribution of maternal cholesterol level to fetal lesion size.

Design, Setting, and Participants

This autopsy study analyzed 78 human fetal aorta autopsy samples from the Division of Human Pathology, Department of Advanced Biomedical Sciences, Federico II University of Naples, Naples, Italy. Maternal levels of total cholesterol, LDLC, high-density lipoprotein cholesterol (HDLC), triglycerides, and glucose and body mass index (BMI) were determined during hospitalization owing to spontaneous fetal death. Data were collected and immediately processed and analyzed to prevent degradation from January 1, 2011, through November 30, 2016.

Main Outcomes and Measurements

Results of DNA methylation and messenger RNA levels of the following genes involved in cholesterol metabolism were assessed: superoxide dismutase 2 (SOD2), low-density lipoprotein receptor (LDLR), sterol regulatory element binding protein 2 (SREBP2), liver X receptor α (LXRα), and adenosine triphosphate-binding cassette transporter 1 (ABCA1).

Results

Among the 78 fetal samples included in the analysis (59% male; mean [SD] fetal age, 25 [3] weeks), maternal cholesterol level explained a significant proportion of the fetal aortic lesion variance in multivariate analysis (61%; P = .001) independently by the effect of levels of HDLC, triglycerides, and glucose and BMI. Moreover, maternal total cholesterol and LDLC levels were positively associated with methylation of SREBP2 in fetal aortas (Pearson correlation, 0.488 and 0.503, respectively), whereas in univariate analysis, they were inversely correlated with SREBP2 messenger RNA levels in fetal aortas (Pearson correlation, -0.534 and -0.671, respectively). Epivariations of genes controlling cholesterol metabolism in cholesterol-treated human aortic endothelial cells were also observed.

Conclusions and Relevance

The present study provides a stringent quantitative estimate of the magnitude of the association of maternal cholesterol levels during pregnancy with fetal aortic lesions and reveals the epigenetic response of fetal aortic SREBP2 to maternal cholesterol level. The role of maternal cholesterol level during pregnancy and epigenetic signature in offspring in cardiovascular primary prevention warrants further long-term causal relationship studies.

Peripheral artery disease: the new frontiers of imaging techniques to evaluate the evolution of regenerative medicine

Introduction: Stem cells (ESC, iPSC, MSC) are known to have intrinsic regenerative properties. In the last decades numerous findings have favored the development of innovative therapeutic protocols based on the use of stem cells (Regenerative Medicine/Cell Therapy) for the treatment of numerous diseases including PAD, with promising results in preclinical studies. So far, several clinical studies have shown a general improvement of the patient's clinical outcome, however they possess many critical issues caused by the non-randomized design of the limited number of patients examined, the type cells to be used, their dosage, the short duration of treatment and also their delivery strategy. Areas covered: In this context, the use of the most advanced molecular imaging techniques will allow the visualization of very important physio-pathological processes otherwise invisible with conventional techniques, such as angiogenesis, also providing important structural and functional data. Expert opinion: The new frontier of cell therapy applied to PAD, potentially able to stop or even the process that causes the disease, with particular emphasis on the clinical aspects that different types of cells involve and on the use of more innovative molecular imaging techniques now available.

Transcutaneous oxygen pressure (TcPO2) and ulcer outcome in diabetic patients: Is there any correlation?

BACKGROUND

Due to poor blood circulation, the prevalence of foot ulcer is extensively reported among diabetic patients. Diabetic neuropathy is the critical factor of diabetes that can affect the nerves.

OBJECTIVE

To examine the outcomes and correlation between TcPO2 and ulcer outcomes among diabetic patients.

MATERIAL AND METHODS

A prospective cohort design has been employed to compare and correlate TcPO2 group with ulcer outcomes. A total of 192 patients were enrolled, who underwent diagnosis for ulcer outcome. Descriptive analysis and Pearson Correlation were used for data analysis via SPSS version 20.

RESULTS

The prevalence of minor amputation among diabetic patients in 25-40 mmHg 75 (85.22%) and >40 mmhG 73 (84.88%) group is reported for ulcer outcome. Mostly diabetic patients were healed with intact skin (male = 36, female = 73), and improved ulcer healing (male = 23, female = 43). Correlation between ulcer size (p = .016), ABI (p = .044), TBI (p = .000), Adiponectin (p = .009), HbA1c (p = .033), and S. creatinine (p = .025) was significant with TcpO2 group.

CONCLUSIONS

The study concluded that there is a positive and significant correlation between TcPO2 group and ulcer outcome. There is a positive association between TcPO2 baseline and degree of ulcer healing with intact skin.

Novel epigenetic-sensitive clinical challenges both in type 1 and type 2 diabetes

BACKGROUND

Epigenetics modulated tissue-specific gene expression during the onset of type 1 and type 2 diabetes and their complications.

METHODS

We searched the PubMed recent studies about the main epigenetic tags involved in type 1 and type 2 diabetes onset and their clinical complications. PubMed studies about the epigenetic tags involved in type 1 and 2 diabetes onset was searched.

RESULTS

The epigenetic methylation maps of cord blood samples highlighted differences in the methylation status of CpG sites within the MHC genes between carriers of diabetes type 1 DR3-DQ2 and DR4-DQ8 risk haplotypes. β cell-derived unmethylated INS DNA showed the decline of β-cell mass preserving insulin secretion. Differentially methylated regions in pancreatic islets from type 2 diabetes covered PDX1, TCF7L2, and ADCY5 promoters during islet dysfunction. The recruitment of SET7 and SUV39H1 histone methyltransferases and LSD-1 lysine-specific demethylase-1 at NF-kβ-p65 promoter in vascular cells was involved in coronary heart disease. Neutrophil extracellular trap, activated by protein arginine deiminase-4, impaired wound healing from diabetic foot ulcers. MiR-199a-3p over-expression induced coagulative cascade, swelling and pain by a down-regulation of SERPIN-E2 in diabetic peripheral neuropathy. A DNA hypo-methylation and histone hyper-acetylation at MIOX promoter led an overexpression of ROS, fibronectin, HIF-1α, and NOX-4 associated with diabetic tubulopathy. A hypo-methylation of H3K4 at SOD2 promoter by LSD-1 increased ROS causing diabetic retinopathy.

CONCLUSIONS

Epigenetics played a relevant role in prevention, diagnosis, and treatment of diabetes.

Compromised nutritional status in patients with end-stage liver disease: Role of gut microbiota

BACKGROUND

Patients with end-stage liver disease (ESLD) have a compromised nutritional status because of the liver crucial role in regulating metabolic homeostasis and energy balance.

DATA SOURCES

A systematic review of literature based on extensive relevant articles published from 2001 to 2017 in English in PubMed database was performed by searching keywords such as liver disease, non-alcoholic liver disease, alcoholic liver disease, malnutrition, epigenetics, gut microbiota, and probiotics.

RESULTS

Liver transplantation would be one eligible therapy for ESLD patients, even if, the clinical outcome is negatively influenced by malnutrition and/or infections. The malnutrition is a condition of nutrient imbalance with a high incidence in ESLD patients. An accurate evaluation of nutritional status could be fundamental for reducing complications and prolonging the survival of ESLD patients including those undergoing liver transplantation. In addition, the interaction among nutrients, diet and genes via epigenetics has emerged as a potential target to reduce the morbidity and mortality in ESLD patients. The malnutrition induces changes in gut microbiota causing dysbiosis with a probable translocation of bacteria and/or pathogen-derived factors from the intestine to the liver. Gut microbiota contribute to the progression of chronic liver diseases as well as hepatocellular carcinoma. The administration of probiotics modulating gut microbiota could improve all chronic liver diseases.

CONCLUSIONS

This review provides an update on malnutrition status linked to epigenetics and the potential benefit of some probiotics on the management of ESLD patients. In support of this view and to reveal the constant and growing interest in this field, some clinical trials are reported.

Potential clinical benefits of cell therapy in coronary heart disease: an update

Cell therapy is a central issue of regenerative medicine and is raising a growing interest in the scientific community, but its full therapeutic potential in coronary heart disease (CHD) has not been reached yet. Several different methods, cell types, delivery routes, and supporting techniques have been attempted and improved to elicit cardiac regeneration in CHD, but only some of them showed a really convincing potential for the use in clinical practice. Here we provide an update on approaches and clinical trials of cell therapy applied to CHD, which are ongoing or that have been realized in the last 5 years. Moreover, we discuss the evidence collected so far in favor or against the validity of stem cell therapy for CHD. In particular, we review and comment the recent advances in cell therapy applied to CHD, the most promising cell types, delivery strategies, biochemical and engineering techniques that have been adopted in this context.

Genetic and Epigenetic Control of CDKN1C Expression: Importance in Cell Commitment and Differentiation, Tissue Homeostasis and Human Diseases

The CDKN1C gene encodes the p57^Kip2 protein which has been identified as the third member of the CIP/Kip family, also including p27^Kip1 and p21^Cip1. In analogy with these proteins, p57^Kip2 is able to bind tightly and inhibit cyclin/cyclin-dependent kinase complexes and, in turn, modulate cell division cycle progression. For a long time, the main function of p57^Kip2 has been associated only to correct embryogenesis, since CDKN1C-ablated mice are not vital. Accordingly, it has been demonstrated that CDKN1C alterations cause three human hereditary syndromes, characterized by altered growth rate. Subsequently, the p57^Kip2 role in several cell phenotypes has been clearly assessed as well as its down-regulation in human cancers. CDKN1C lies in a genetic locus, 11p15.5, characterized by a remarkable regional imprinting that results in the transcription of only the maternal allele. The control of CDKN1C transcription is also linked to additional mechanisms, including DNA methylation and specific histone methylation/acetylation. Finally, long non-coding RNAs and miRNAs appear to play important roles in controlling p57^Kip2 levels. This review mostly represents an appraisal of the available data regarding the control of CDKN1C gene expression. In addition, the structure and function of p57^Kip2 protein are briefly described and correlated to human physiology and diseases.

Effect of nutrient deprivation on the expression and the epigenetic signature of sirtuin genes

BACKGROUND AND AIM

Over the last decades advances in understanding the molecular bases of the close relationship between nutrition, metabolism, and diseases have been impressive. However, there are always novel frontiers coming up and epigenetics is one of these. Sirtuins, are pivotal factors in the control of metabolic pathways according to nutrient availability. In the present study we evaluated the effect of nutrient deprivation on expression, DNA methylation and chromatin status of the sirtuin genes.

METHODS AND RESULTS

We performed these studies in mouse hepatoma cells, that were grown in standard medium, or in media containing low glucose concentration, or no glucose, or no amino acids. We applied quantitative real-time PCR to cDNA, methylation-enriched DNA and nuclease-treated DNA in order to evaluate gene expression, DNA methylation, and chromatin condensation, respectively. This study shows that the expression of sirtuin genes varies following nutrient deprivation. Moreover, we observed that changes of DNA methylation and chromatin condensation occur at the transcription start site of sirtuin genes following nutrient deprivation.

CONCLUSIONS

Epigenetic mechanisms may have a role in the sirtuin response to nutrient deprivations in cultured hepatoma cells. Replicating these results in vivo to achieve a comprehensive understanding of the epigenetic control of sirtuin expression following nutrient deprivations might open up novel therapeutic possibilities to cure metabolic diseases and promote human health.

Sirtuins as Mediator of the Anti-Ageing Effects of Calorie Restriction in Skeletal and Cardiac Muscle

Fighting diseases and controlling the signs of ageing are the major goals of biomedicine. Sirtuins, enzymes with mainly deacetylating activity, could be pivotal targets of novel preventive and therapeutic strategies to reach such aims. Scientific proofs are accumulating in experimental models, but, to a minor extent, also in humans, that the ancient practice of calorie restriction could prove an effective way to prevent several degenerative diseases and to postpone the detrimental signs of ageing. In the present review, we summarize the evidence about the central role of sirtuins in mediating the beneficial effects of calorie restriction in skeletal and cardiac muscle since these tissues are greatly damaged by diseases and advancing years. Moreover, we entertain the possibility that the identification of sirtuin activators that mimic calorie restriction could provide the benefits without the inconvenience of this dietary style.

Serum from differently exercised subjects induces myogenic differentiation in LHCN-M2 human myoblasts

Myogenesis is the formation of muscle tissue from muscle precursor cells. Physical exercise induces satellite cell activation in muscle. Currently, C2C12 murine myoblast cells are used to study myogenic differentiation. Herein, we evaluated whether human LHCN-M2 myoblasts can differentiate into mature myotubes and express early (myotube formation, creatine kinase activity and myogenin) and late (MyHC-β) muscle-specific markers when cultured in differentiation medium (DM) for 2, 4 and 7 days. We demonstrate that treatment of LHCN-M2 cells with DM supplemented with 0.5% serum from long-term (3 years) differently exercised subjects for 4 days induced myotube formation and significantly increased the early (creatine kinase activity and myogenin) and late (MyHC-β expression) differentiation markers versus cells treated with serum from untrained subjects. Interestingly, serum from aerobic exercised subjects (swimming) had a greater positive effect on late-differentiation marker (MyHC-β) expression than serum from anaerobic (body building) or from mixed exercised (soccer and volleyball) subjects. Moreover, p62and anti-apoptotic Bcl-2 protein expression was lower in LHCN-M2 cells cultured with human sera from differently exercised subjectst han in cells cultured with DM. In conclusion, LHCN-M2 human myoblasts represent a species-specific system with which to study human myogenic differentiation induced by serum from differently exercised subjects.

Possible Muscle Repair in the Human Cardiovascular System

The regenerative potential of tissues and organs could promote survival, extended lifespan and healthy life in multicellular organisms. Niches of adult stemness are widely distributed and lead to the anatomical and functional regeneration of the damaged organ. Conversely, muscular regeneration in mammals, and humans in particular, is very limited and not a single piece of muscle can fully regrow after a severe injury. Therefore, muscle repair after myocardial infarction is still a chimera. Recently, it has been recognized that epigenetics could play a role in tissue regrowth since it guarantees the maintenance of cellular identity in differentiated cells and, therefore, the stability of organs and tissues. The removal of these locks can shift a specific cell identity back to the stem-like one. Given the gradual loss of tissue renewal potential in the course of evolution, in the last few years many different attempts to retrieve such potential by means of cell therapy approaches have been performed in experimental models. Here we review pathways and mechanisms involved in the in vivo repair of cardiovascular muscle tissues in humans. Moreover, we address the ongoing research on mammalian cardiac muscle repair based on adult stem cell transplantation and pro-regenerative factor delivery. This latter issue, involving genetic manipulations of adult cells, paves the way for developing possible therapeutic strategies in the field of cardiovascular muscle repair.

Splicing regulators in endothelial cell differentiation

AIMS

Alternative splicing represents a key mechanism of gene regulation. Despite its role in regulating cell pluripotency and differentiation being well known, the underlining mechanisms are still poorly studied. Here, we investigated the possible involvement of splicing regulators during the different steps of endothelial cell differentiation through expression studies on human circulating progenitors.

METHODS

Total RNAs were extracted from all cells and reverse-transcribed. Semiquantitative and real-time RT-PCR was performed using selective oligonucleotides. Differences between group means were considered significant at P value less than 0.05 and more significant at P value less than 0.01. Protein extracts were incubated with an antibody directed against MED23. Immunoprecipitation of supernatants and pellets was probed with both anti-Muscleblind-like splicing regulator (MBNL)1 and anti-MBNL2 antibodies.

RESULTS

Several clinical trials demonstrated the safety and efficacy of progenitor cells in regenerative therapy of the cardiovascular system. Particularly, we analyzed the expression of genes belonging to muscleblind family members and MED complex subunits, which are known to be involved during differentiation in other models. This study shows that MED23, MBNL1 and MBNL2 were all expressed at high levels only in differentiated cells. Moreover, immunoprecipitation assays indicated that MED23 is able to bind MBNLs in endothelial cells.

CONCLUSION

Our data suggest that MED23, MBNL1 and MBNL2 could regulate alternative splicing events activated during differentiation through a common mechanism. Hence, these observations corroborate previous evidence that splicing regulators may have an essential role in the basic apparatus required for cell pluripotency and reprogramming, allowing identification of novel biomarkers to use for early diagnosis in cardiovascular diseases.

The epigenetic promise to improve prognosis of heart failure and heart transplantation

Heart transplantation is still the only possible life-saving treatment for end-stage heart failure, the critical epilogue of several cardiac diseases. Epigenetic mechanisms are being intensively investigated because they could contribute to establishing innovative diagnostic and predictive biomarkers, as well as ground-breaking therapies both for heart failure and heart transplantation rejection. DNA methylation and histone modifications can modulate the innate and adaptive immune response by acting on the expression of immune-related genes that, in turn, are crucial determinants of transplantation outcome. Epigenetic drugs acting on methylation and histone-modification pathways may modulate Treg activity by acting as immunosuppressive agents. Moreover, the identification of non-invasive and reliable epigenetic biomarkers for the prediction of allograft rejection and for monitoring immunosuppressive therapies represents an attractive perspective in the management of transplanted patients. MiRNAs seem to fit particularly well to this purpose because they are differently expressed in patients at high and low risk of rejection and are detectable in biological fluids besides biopsies. Although increasing evidence supports the involvement of epigenetic tags in heart failure and transplantation, further short and long-term clinical studies are needed to translate the possible available findings into clinical setting.

Epigenetics and type 1 diabetes: mechanisms and translational applications

Type 1 diabetes (T1D) is an irreversible degenerative disease with severe complications such as heart disease, nephropathy, neuropathy, and retinopathy. Although exogenous insulin administration is a life-saving therapy, it does not cure the disease. This review addresses the epigenetic mechanisms responsible for the development of T1D and discusses epigenetic-based strategies for prevention and treatment of the disease. We describe novel epigenetic biomarkers for the identification of susceptible individuals and the establishment of innovative therapies with epidrugs and cell therapy to regenerate the lost β-cells. Despite the wealth of promising data regarding the potential benefits of epigenetic tools to reduce the burden of T1D, clinical trials are still very few, and this issue needs to be resolved in the near future.

Clinical relevance of epigenetics in the onset and management of type 2 diabetes mellitus

Epigenetics is involved in the altered expression of gene networks that underlie insulin resistance and insufficiency. Major genes controlling β-cell differentiation and function, such as PAX4, PDX1, and GLP1 receptor, are epigenetically controlled. Epigenetics can cause insulin resistance through immunomediated pro-inflammatory actions related to several factors, such as NF-kB, osteopontin, and Toll-like receptors. Hereafter, we provide a critical and comprehensive summary on this topic with a particular emphasis on translational and clinical aspects. We discuss the effect of epigenetics on β-cell regeneration for cell replacement therapy, the emerging bioinformatics approaches for analyzing the epigenetic contribution to type 2 diabetes mellitus (T2DM), the epigenetic core of the transgenerational inheritance hypothesis in T2DM, and the epigenetic clinical trials on T2DM. Therefore, prevention or reversion of the epigenetic changes occurring during T2DM development may reduce the individual and societal burden of the disease.

Imaging of small animal peripheral artery disease models: recent advancements and translational potential

Peripheral artery disease (PAD) is a broad disorder encompassing multiple forms of arterial disease outside of the heart. As such, PAD development is a multifactorial process with a variety of manifestations. For example, aneurysms are pathological expansions of an artery that can lead to rupture, while ischemic atherosclerosis reduces blood flow, increasing the risk of claudication, poor wound healing, limb amputation, and stroke. Current PAD treatment is often ineffective or associated with serious risks, largely because these disorders are commonly undiagnosed or misdiagnosed. Active areas of research are focused on detecting and characterizing deleterious arterial changes at early stages using non-invasive imaging strategies, such as ultrasound, as well as emerging technologies like photoacoustic imaging. Earlier disease detection and characterization could improve interventional strategies, leading to better prognosis in PAD patients. While rodents are being used to investigate PAD pathophysiology, imaging of these animal models has been underutilized. This review focuses on structural and molecular information and disease progression revealed by recent imaging efforts of aortic, cerebral, and peripheral vascular disease models in mice, rats, and rabbits. Effective translation to humans involves better understanding of underlying PAD pathophysiology to develop novel therapeutics and apply non-invasive imaging techniques in the clinic.