Cardiac repair and the putative role of stem cells

Research progress on detachable microneedles for advanced applications

INTRODUCTION

Microneedles (MNs) have undergone great advances in transdermal drug delivery, and commercialized MN applications are currently available in vaccination and cosmetic products. Despite the development of MN technologies, common limitations of MN products still exist. Typical MN patches are applied to target tissues, where the substrate of an MN patch must remain until the drug is delivered, which reduces patients' compliance and hinders the applicability of the MN technique to many diseases in various tissues. MN research is ongoing to solve this issue.

AREAS COVERED

Most recent MNs developed by combining various biomaterials with appropriate fabrication processes are detachable MNs (DeMNs). Because of advances in biomaterials and fabrication techniques, various DeMNs have been rapidly developed. In this review, we discuss four types of DeMN: substrate-separable, multi-layered, crack-inducing, and shell DeMN. These DeMNs deliver various therapeutic agents ranging from small- and large-molecular-weight drugs to proteins and even stem cells for regeneration therapy. Furthermore, DeMNs are applied to skin as well as non-transdermal tissues.

EXPERT OPINION

It has become increasingly evident that novel MN technologies can be expected in terms of designs, fabrication methods, materials, and even possible application sites given the recent advances in DeMNs.

Extracellular Vesicles as a Cell-free Therapy for Cardiac Repair: a Systematic Review and Meta-analysis of Randomized Controlled Preclinical Trials in Animal Myocardial Infarction Models

Stem  cell therapy for cardiac regeneration has been gaining traction as a possible intervention for the reduction of the burden associated with MI and heart failure. However, stem cell therapies have several shortcomings, including poor engraftment, limited improvements in cardiac function, and possible teratogenicity. Recently, extracellular vesicles (EVs) from stem cell sources have been explored as a novel therapy to regenerate the injured myocardium in several animal MI trials. In this systematic review and meta-analysis, we investigate the use of stem cell-derived EVs for cardiac repair preclinical trials in animal MI models. Cochrane Library, Medline, Embase, PubMed, Scopus and Web of Science and grey literature (Canadian Agency for Drugs, Technologies in Health, and Google Scholar) were searched through August 20, 2020 and 37 articles were included in the final analysis. The overall effect size observed in EV-treated small animals after MI for ejection fraction (EF) was 10.85 [95 %CI: 8.79, 12.90] and for fractional shortening (FS) was 7.19 [95 %CI: 5.43, 8.96] compared to control-treated animals. The most abundant stem cell source used were mesenchymal stem cells which showed robust improvements in EF and FS (MD = 11.89 [95 % CI: 9.44, 14.34] and MD = 6.96 [95 % CI: 4.97, 8.96], respectively). Significant publication bias was detected for EF and FS outcomes. This study supports the use of EVs derived from stem cells as a novel therapy for cardiac repair after MI. Further investigation in larger animal studies may be necessary before clinical trials.PROSPERO registration number: CRD42019142218.

Autophagy stimulation delayed biological aging and decreased cardiac differentiation in rabbit mesenchymal stem cells

Introduction: Cardiovascular disease (CVD) is a type of disease that affects the function of cardiac-vascular tissues. This study aimed to consider the possible effects of autophagy, as an intrinsic catabolic pathway of cells, on the differentiation and aging process of mesenchymal stem cells (MSCs).

Methods: In this study, bone marrow-derived MSCs were obtained from rabbit bone marrow aspirates. The stemness feature was confirmed by using flow cytometry analysis Cells at passage three were treated with 50 μM Metformin and 15μM hydroxychloroquine (HCQ) for 72 hours. The intracellular accumulation of autophagolysosomes was imaged using LysoTracker staining. Protein levels of autophagy (LC3II/I ratio), aging (Klotho, PARP-1, and Sirt-1) effectors, and cardiomyocyte-like phenotype (α-actinin) were studied by western blotting.

Results: Based on our findings, flow cytometry analysis showed that the obtained cells expressed CD44 and CD133 strongly, and CD31 and CD34 dimly, showing a typical characteristic of MSCs. Our data confirmed an increased LC3II/I ratio in the metformin-received group compared to the untreated and HCQ-treated cells (P < 0.05). Besides, we showed that the incubation of rabbit MSCs with HCQ increased cellular aging by induction of PARP-1 while Metformin increased rejuvenating factor Sirt-1 comparing with the normal group (P < 0.05). Western blotting data showed that the autophagy stimulation response in rabbit MSCs postponed the biological aging and decreased the differentiation potential to the cardiac cells by diminishing α-actinin comparing with control cells (P < 0.05).

Conclusion: In summary, for the informants in this study, it could be noted that autophagy inhibition/stimulation could alter rabbit MSCs aging and differentiation capacity.

The Potential Properties of Natural Compounds in Cardiac Stem Cell Activation: Their Role in Myocardial Regeneration

Cardiovascular diseases (CVDs), which include congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, and many other cardiac disorders, cause about 30% of deaths globally; representing one of the main health problems worldwide. Among CVDs, ischemic heart diseases (IHDs) are one of the major causes of morbidity and mortality in the world. The onset of IHDs is essentially due to an unbalance between the metabolic demands of the myocardium and its supply of oxygen and nutrients, coupled with a low regenerative capacity of the heart, which leads to great cardiomyocyte (CM) loss; promoting heart failure (HF) and myocardial infarction (MI). To date, the first strategy recommended to avoid IHDs is prevention in order to reduce the underlying risk factors. In the management of IHDs, traditional therapeutic options are widely used to improve symptoms, attenuate adverse cardiac remodeling, and reduce early mortality rate. However, there are no available treatments that aim to improve cardiac performance by replacing the irreversible damaged cardiomyocytes (CMs). Currently, heart transplantation is the only treatment being carried out for irreversibly damaged CMs. Hence, the discovery of new therapeutic options seems to be necessary. Interestingly, recent experimental evidence suggests that regenerative stem cell medicine could be a useful therapeutic approach to counteract cardiac damage and promote tissue regeneration. To this end, researchers are tasked with answering one main question: how can myocardial regeneration be stimulated? In this regard, natural compounds from plant extracts seem to play a particularly promising role. The present review will summarize the recent advances in our knowledge of stem cell therapy in the management of CVDs; focusing on the main properties and potential mechanisms of natural compounds in stimulating and activating stem cells for myocardial regeneration.

Fluorescent PSC-Derived Cardiomyocyte Reporter Lines: Generation Approaches and Their Applications in Cardiovascular Medicine

Recent advances have made pluripotent stem cell (PSC)-derived cardiomyocytes an attractive option to model both normal and diseased cardiac function at the single-cell level. However, in vitro differentiation yields heterogeneous populations of cardiomyocytes and other cell types, potentially confounding phenotypic analyses. Fluorescent PSC-derived cardiomyocyte reporter systems allow specific cell lineages to be labelled, facilitating cell isolation for downstream applications including drug testing, disease modelling and cardiac regeneration. In this review, the different genetic strategies used to generate such reporter lines are presented with an emphasis on their relative technical advantages and disadvantages. Next, we explore how the fluorescent reporter lines have provided insights into cardiac development and cardiomyocyte physiology. Finally, we discuss how exciting new approaches using PSC-derived cardiomyocyte reporter lines are contributing to progress in cardiac cell therapy with respect to both graft adaptation and clinical safety.

Rab27a deletion impairs the therapeutic potential of endothelial progenitor cells for myocardial infarction

Endothelial progenitor cell (EPC) transplantation has shown advantages in the treatment of myocardial infarction (MI) in animal models and clinical trials through mechanisms of direct intercellular contacts, autocrine, and paracrine. However, the effects of EPC transplantation for MI treatment remain controversial and the underlying mechanisms have not been fully elucidated. Here, we explored the role of Rab27a in the therapeutic potential of EPC transplantation in MI. We found that Rab27a knockout impaired the viability, and reduced the proliferation and tube formation function of ECPs. The recovery of cardiac function and improvement of ventricular remodeling from EPCs transplantation were significantly damaged by Rab27a deletion in vivo. Rab27a deletion inhibited the protein expression of phosphoinositide 3-kinase (PI3K) and cyclin D1 and the phosphorylation levels of Akt and FoxO3a. Therefore, Rab27a knockout suppressed the PI3K-Akt-FoxO3a/cyclin D1 signaling pathway. Furthermore, Rab27a ablation dramatically reduced exosome release in EPCs. These results demonstrated that Rab27a plays an essential role in EPC functions. The elucidation of this mechanism provides novel insights into EPC transplantation as a promising treatment for post-MI injuries.

The Texas Society of Pathologists: molded by the legacy of pathology and focused on excellence in medicine for 100 years and beyond

In 1921, 16 Texas pathologists gathered in Dallas, Texas, to found the Texas Society of Pathologists (TSP). The TSP is now the oldest state pathology society in the USA with continuity traced back to its founding 100 years ago. This article aims to both commemorate the TSP centennial and to provide context for the remarkable success of the society. The article takes a look back and a look forward from 1921. The look back focuses on the development of the field of pathology and the maturation of medicine and pathology in the USA and Texas. The look forward encompasses developments in science, technology, American health care policy, and medicine that have impacted Texas pathologists and influenced proactive initiatives of the TSP. The review of the life and times of the TSP highlights the importance of leaders and leadership in shaping outcomes. Complexities and uncertainties of the contemporary health care scene point to the need for continued strong leadership. The successful past century and hopeful future of the TSP are inextricably linked to the guiding principle of the TSP, which is a focus on continual striving for excellence in medicine.

Umbilical cord mesenchymal stromal cells engraft and transdifferentiate into cardiomyocyte-like cells following acute myocardial ischemia⋆

OBJECTIVE

Human umbilical cord-derived mesenchymal stromal cells (hUC-MSCs) gained importance in acute/chronic ischemic cardiomyopathy because of their outstanding regenerative potential in various pathologic conditions. The present study was designed to determine to what extent hUC-MSCs contribute to myocardial regeneration in acute experimental myocardial infarction (MI) in rats.

METHODS

Animals were assigned into two groups; the control group received intramyocardial PBS injections, while the hUC-MSC group received calcein-AM-labeled 8.8 × 10⁶/kg hUC-MSCs. Three weeks following the acute MI induction, rats were sacrificed after assessing the left ventricular (LV) function using echocardiography. For the assessment of infarct size, the triphenyl tetrazolium chloride (TTC) test was used in isolated hearts. Collagen-rich scar tissue was demonstrated using Masson's trichrome staining, followed by the detection of cardiac troponin I (cTnI), α-sarcomeric actin (α-SA), von Willebrand factor (vWF), CD68 and CD206 expressions in control and cell-injected sections.

RESULTS

Echocardiography revealed a significant difference (P = 0.037) in the LV ejection fraction between groups. TTC assays demonstrated a significant difference (P = 0.006) between the groups regarding the ratio of the infarcted LV area. Calcein-AM-loaded cells were identified mostly in ischemic myocardium. Transplanted cells also expressed human-specific cTnI, providing concrete proof of transdifferentiation into cardiomyocytes, and α-SA. vWF⁺ cells verified the neovascularization in the ischemic myocardium. Finally, a slight shift from pro-inflammatory to anti-inflammatory macrophages (CD68⁺/CD206⁺) was noted in both groups.

CONCLUSIONS

We found that the intramyocardial transplanted hUC-MSCs engrafted and partially transdifferentiated into cardiomyocytes, reduced scar formation, and induced angiogenesis through the association of pro/anti-inflammatory macrophages.

Prevention of heart failure with preserved ejection fraction (HFpEF): reexamining microRNA-21 inhibition in the era of oligonucleotide-based therapeutics

Heart failure with preserved ejection fraction (HFpEF) accounts for 50% of cases of heart failure, which is the most common cause of hospitalization in US patients over the age of 65. HFpEF pathogenesis is increasingly believed to be due to pathological hypertrophy and fibrosis of the myocardium that may be a result of systemic inflammation from comorbid conditions such as hypertension, diabetes mellitus, chronic obstructive pulmonary disease, anemia, chronic kidney disease and others. It is believed that oxidative stress triggers a process of pathological hypertrophy and fibrosis in cardiac endothelial cells, which leads to increased left ventricle filling pressures and, eventually, symptoms of heart failure. Numerous recent major clinical trials that have examined various therapies aimed at improving mortality in HFpEF have emerged empty-handed and thus the search for effective management strategies continues. Over the last several years, there have been many new developments in the field of antisense oligonucleotide-based therapeutics, which involves using noncoding nucleic acid particles such as microRNA and small interfering RNA to repress the expression of specific messenger RNA. In this article, we review the concept of using oligonucleotide-based therapeutics to prevent or treat HFpEF by targeting a specific microRNA that has been implicated in the pathogenesis of myocardial fibrosis and hypertrophy, microRNA-21 (miR-21). We review the various evidence that implicates miR-21 in the process of myocardial fibrosis and discuss recent attempts to use antimiR-21 compounds to prevent fibrosis. We also discuss proposed methods for screening patients at high risk for HFpEF for diastolic dysfunction in order to determine which patients.

Phlpp1 is associated with human intervertebral disc degeneration and its deficiency promotes healing after needle puncture injury in mice

Back pain is a leading cause of global disability and is strongly associated with intervertebral disc (IVD) degeneration (IDD). Hallmarks of IDD include progressive cell loss and matrix degradation. The Akt signaling pathway regulates cellularity and matrix production in IVDs and its inactivation is known to contribute to a catabolic shift and increased cell loss via apoptosis. The PH domain leucine-rich repeat protein phosphatase (Phlpp1) directly regulates Akt signaling and therefore may play a role in regulating IDD, yet this has not been investigated. The aim of this study was to investigate if Phlpp1 has a role in Akt dysregulation during IDD. In human IVDs, Phlpp1 expression was positively correlated with IDD and the apoptosis marker cleaved Caspase-3, suggesting a key role of Phlpp1 in the progression of IDD. In mice, 3 days after IVD needle puncture injury, Phlpp1 knockout (KO) promoted Akt phosphorylation and cell proliferation, with less apoptosis. At 2 and 8 months after injury, Phlpp1 deficiency also had protective effects on IVD cellularity, matrix production, and collagen structure as measured with histological and immunohistochemical analyses. Specifically, Phlpp1-deletion resulted in enhanced nucleus pulposus matrix production and more chondrocytic cells at 2 months, and increased IVD height, nucleus pulposus cellularity, and extracellular matrix deposition 8 months after injury. In conclusion, Phlpp1 has a role in limiting cell survival and matrix degradation in IDD and research targeting its suppression could identify a potential therapeutic target for IDD.

Molecular Mechanisms of Cardiac Remodeling and Regeneration in Physical Exercise

Regular physical activity with aerobic and muscle-strengthening training protects against the occurrence and progression of cardiovascular disease and can improve cardiac function in heart failure patients. In the past decade significant advances have been made in identifying mechanisms of cardiomyocyte re-programming and renewal including an enhanced exercise-induced proliferational capacity of cardiomyocytes and its progenitor cells. Various intracellular mechanisms mediating these positive effects on cardiac function have been found in animal models of exercise and will be highlighted in this review. 1) activation of extracellular and intracellular signaling pathways including phosphatidylinositol 3 phosphate kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR), EGFR/JNK/SP-1, nitric oxide (NO)-signaling, and extracellular vesicles; 2) gene expression modulation via microRNAs (miR), in particular via miR-17-3p and miR-222; and 3) modulation of cardiac cellular metabolism and mitochondrial adaption. Understanding the cellular mechanisms, which generate an exercise-induced cardioprotective cellular phenotype with physiological hypertrophy and enhanced proliferational capacity may give rise to novel therapeutic targets. These may open up innovative strategies to preserve cardiac function after myocardial injury as well as in aged cardiac tissue.

Pathobiology of cardiovascular diseases: an update

This article introduces the Second Special Issue of Cardiovascular Pathology (CVP), the official journal of the Society for Cardiovascular Pathology (SCVP). This CVP Special Issue showcases a series of commemorative review articles in celebration of the 25th anniversary of CVP originally published in 2016 and now compiled into a virtual collection with online access for the cardiovascular pathology community. This overview also provides updates on the major categories of cardiovascular diseases from the perspective of cardiovascular pathologists, highlighting publications from CVP, as well as additional important review articles and clinicopathologic references.