Saheli Samanta

MicroRNA: A new therapeutic strategy for cardiovascular diseases.

Myocardial infarction, atherosclerosis, and hypertension are the most common heart-related diseases that affect both the heart and the blood vessels. Multiple independent risk factors have been shown to be responsible for cardiovascular diseases. The combination of a healthy diet, exercise, and smoking cessation keeps these risk factors in check and helps maintain homeostasis. The dynamic monolayer endothelial cell integrity and cell-cell communication are the fundamental mechanisms in maintaining homeostasis. Recently, it has been revealed that small noncoding RNAs (ncRNAs) play a critical role in regulation of genes involved in either posttranscriptional or pretranslational modifications. They also control diverse biological functions like development, differentiation, growth, and metabolism. Among ncRNAs, the short interfering RNAs (siRNAs), and microRNAs (miRNAs) have been extensively studied, but their specific functions remain largely unknown. In recent years, miRNAs are efficiently studied as one of the important candidates for involvement in most biological processes and have been implicated in many human diseases. Thus, the identification and the respective targets of miRNAs may provide novel molecular insight and new therapeutic strategies to treat diseases. This review summarizes the recent developments and insight on the role of miRNAs in cardiovascular disease prognosis, diagnostic and clinical applications.

Epigenetic modifiers reduce inflammation and modulate macrophage phenotype during endotoxemia-induced acute lung injury

ABSTRACT Acute lung injury (ALI) during sepsis is characterized by bilateral alveolar infiltrates, lung edema and respiratory failure. Here, we examined the efficacy the DNA methyl transferase (DNMT) inhibitor 5-Aza 2-deoxycytidine (Aza), the histone deacetylase (HDAC) inhibitor Trichostatin A (TSA), as well as the combination therapy of Aza and TSA (Aza+TSA) provides in the protection of ALI. In LPS-induced mouse ALI, post-treatment with a single dose of Aza+TSA showed substantial attenuation of adverse lung histopathological changes and inflammation. Importantly, these protective effects were due to substantial macrophage phenotypic changes observed in LPS-stimulated macrophages treated with Aza+TSA as compared with untreated LPS-induced macrophages or LPS-stimulated macrophages treated with either drug alone. Further, we observed significantly lower levels of pro-inflammatory molecules and higher levels of anti-inflammatory molecules in LPS-induced macrophages treated with Aza+TSA than in LPS-induced macrophages treated with either drug alone. The protection was ascribed to dual effects by an inhibition of MAPK–HuR–TNF and activation of STAT3–Bcl2 pathways. Combinatorial treatment with Aza+TSA reduces inflammation and promotes an anti-inflammatory M2 macrophage phenotype in ALI, and has a therapeutic potential for patients with sepsis. Summary: Combinatorial treatment with Aza+TSA reduces inflammation and promotes an anti-inflammatory M2 macrophage phenotype in ALI, and has a therapeutic potential for patients with sepsis and ALI.

Macrophage polarization in response to epigenetic modifiers during infection and inflammation.

Macrophages are a heterogeneous population of phagocytic cells present in all tissues. Recently, several drugs that target the epigenetic machinery have emerged as attractive molecules for treating infection and inflammation by modulating macrophages. Treatment of lipopolysaccharide (LPS)-challenged macrophages with epigenetic modifiers leads to phenotype switching. This could provide stimulatory/destructive (M1) or suppressive/protective (M2) therapeutic strategies, which are crucial in the cytokine milieu in which the macrophages reside. In this review, we provide an overview of macrophage functional diversity during various diseases, including infection, as well as the current status in the development and clinical utility of epigenetic modifiers.

Nanodiamond-based injectable hydrogel for sustained growth factor release: Preparation, characterization and in vitro analysis

Nanodiamonds (NDs) represent an emerging class of carbon nanomaterials that possess favorable physical and chemical properties to be used as multifunctional carriers for a variety of bioactive molecules. Here we report the synthesis and characterization of a new injectable ND-based nanocomposite hydrogel which facilitates a controlled release of therapeutic molecules for regenerative applications. In particular, we have formulated a thermosensitive hydrogel using gelatin, chitosan and NDs that provides a sustained release of exogenous human vascular endothelial growth factor (VEGF) for wound healing applications. Addition of NDs improved the mechanical properties of the injectable hydrogels without affecting its thermosensitive gelation properties. Biocompatibility of the generated hydrogel was verified by in vitro assessment of apoptotic gene expressions and anti-inflammatory interleukin productions. NDs were complexed with VEGF and the inclusion of this complex in the hydrogel network enabled the sustained release of the angiogenic growth factor. These results suggest for the first time that NDs can be used to formulate a biocompatible, thermosensitive and multifunctional hydrogel platform that can function both as a filling agent to modulate hydrogel properties, as well as a delivery platform for the controlled release of bioactive molecules and growth factors. STATEMENT OF SIGNIFICANCE One of the major drawbacks associated with the use of conventional hydrogels as carriers of growth factors is their inability to control the release kinetics of the loaded molecules. In fact, in most cases, a burst release is inevitable leading to diminished therapeutic effects and unsuccessful therapies. As a potential solution to this issue, we hereby propose a strategy of incorporating ND complexes within an injectable hydrogel matrix. The functional groups on the surface of the NDs can establish interactions with the model growth factor VEGF and promote a prolonged release from the polymer network, therefore, providing a longer therapeutic effect. Our strategy demonstrates the efficacy of using NDs as an essential component for the design of a novel injectable nanocomposite system with improved release capabilities.

Generation of Functional Cardiomyocytes from Efficiently Generated Human iPSCs and a Novel Method of Measuring Contractility.

Human induced pluripotent stem cells (iPSCs) derived cardiomyocytes (iCMCs) would provide an unlimited cell source for regenerative medicine and drug discoveries. The objective of our study is to generate functional cardiomyocytes from human iPSCs and to develop a novel method of measuring contractility of CMCs. In a series of experiments, adult human skin fibroblasts (HSF) and human umbilical vein endothelial cells (HUVECs) were treated with a combination of pluripotent gene DNA and mRNA under specific conditions. The iPSC colonies were identified and differentiated into various cell lineages, including CMCs. The contractile activity of CMCs was measured by a novel method of frame-by-frame cross correlation (particle image velocimetry-PIV) analysis. Our treatment regimen transformed 4% of HSFs into iPSC colonies at passage 0, a significantly improved efficiency compared with use of either DNA or mRNA alone. The iPSCs were capable of differentiating both in vitro and in vivo into endodermal, ectodermal and mesodermal cells, including CMCs with >88% of cells being positive for troponin T (CTT) and Gata4 by flow cytometry. We report a highly efficient combination of DNA and mRNA to generate iPSCs and functional iCMCs from adult human cells. We also report a novel approach to measure contractility of iCMCs.

Exosomes: new molecular targets of diseases

Extracellular vesicles (EVs) comprise apoptotic bodies, microvesicles and exosomes, and they perform as key regulators in cell-to-cell communication in normal as well as diseased states. EVs contain natural cargo molecules, such as miRNA, mRNA and proteins, and transfer these functional cargos to neighboring cells or more distant cells through circulation. These functionally active molecules then affect distinct signaling cascades. The message conveyed to the recipient cells is dependent upon the composition of the EV, which is determined by the parent cell and the EV biogenesis. Because of their properties such as increased stability in circulation, biocompatibility, low immunogenicity and toxicity, EVs have drawn attention as attractive delivery systems for therapeutics. This review focuses on the functional use of exosomes in therapy and the potential advantages and challenges in using exosomes for therapeutic purposes.

Biology and clinical relevance of noncoding sno/scaRNAs

Small nucleolar RNAs (snoRNAs) are a group of noncoding RNAs that perform various biological functions, including biochemical modifications of other RNAs, precursors of miRNA, splicing, and telomerase activity. The small Cajal body-associated RNAs (scaRNAs) are a subset of the snoRNA family and collect in the Cajal body where they perform their canonical function to biochemically modify spliceosomal RNAs prior to maturation. Failure of sno/scaRNAs have been implicated in pathology such as congenital heart anomalies, neuromuscular disorders, and various malignancies. Thus, understanding of sno/scaRNAs demonstrates the clinical value.

DNMT and HDAC inhibitors together abrogate endotoxemia mediated macrophage death by STAT3-JMJD3 signaling

Acute lung injury (ALI) is a common complication of sepsis that often leads to fatal lung disease without effective therapies. It is known that bone marrow derived macrophages are important in resolving the inflammation and maintaining tissue homeostasis. Here, we hypothesize that treatment in combination of DNA methyl transferase inhibitor (DNMTi) 5-Aza 2-deoxycytidine (Aza) and histone deacetylase inhibitor (HDACi) Trichostatin A (TSA) mitigates the inflammation induced pyroptosis and apoptosis during endotoxemia induced ALI. To test this hypothesis, the mice challenged with a sublethal dose of LPS followed by one-hour post-treatment with a single dose of Aza and TSA intraperitoneally showed a substantial attenuation of apoptosis and inflammation. Importantly, we observed significant changes in the mitochondrial membrane structure, and lower levels of DNA fragmentation, reduced expression of apoptotic and pyroptotic genes both transcriptionally and translationally in LPS induced BMDMs treated by a combination of Aza and TSA than in LPS-induced BMDMs treated with either drug alone. The protection was mediated by an inhibition of JNK-ERK and STAT3-JMJD3 activated pathways. Thus, targeting these important signaling pathways with the combination of Aza and TSA would be a good treatment modality for ALI.

Therapy of Infectious Diseases Using Epigenetic Approaches

Abstract Epigenetic modifications are the heritable changes in gene expression patterns that are independent of primary DNA sequence changes and affect the outcome of a locus or chromosome without altering the underlying DNA sequence. Exposures to environmental factors such as nutrients, pollution, toxicants, and inflammation can induce epigenetic alterations. These epigenetic changes may be the cause of many diseases, including cancers, autoimmune disorders, and diabetes. Recently, it has been shown that epigenetic modifications, including DNA methylation, histone modifications, and noncoding RNAs, play an important role in viral infection and also in sepsis. These modifications affect a spectrum of immune functions in limiting or preventing the development of specific cells that affect the immune responses. In this review, we provide a brief overview of relationships between epigenetic regulations and innate/adaptive immunity during the progress of infection, pathogenesis, especially sepsis, and discuss the epigenetic-based drug therapy.

Manipulation-free cultures of human iPSC-derived cardiomyocytes offer a novel screening method for cardiotoxicity

Induced pluripotent stem cell (iPSC)-based cardiac regenerative medicine requires the efficient generation, structural soundness and proper functioning of mature cardiomyocytes, derived from the patients somatic cells. The most important functional property of cardiomyocytes is the ability to contract. Currently available methods routinely used to test and quantify cardiomyocyte function involve techniques that are labor-intensive, invasive, require sophisticated instruments or can adversely affect cell vitality. We recently developed optical flow imaging method analyses and quantified cardiomyocyte contractile kinetics from video microscopic recordings without compromising cell quality. Specifically, our automated particle image velocimetry (PIV) analysis of phase-contrast video images captured at a high frame rate yields statistical measures characterizing the beating frequency, amplitude, average waveform and beat-to-beat variations. Thus, it can be a powerful assessment tool to monitor cardiomyocyte quality and maturity. Here we demonstrate the ability of our analysis to characterize the chronotropic responses of human iPSC-derived cardiomyocytes to a panel of ion channel modulators and also to doxorubicin, a chemotherapy agent with known cardiotoxic side effects. We conclude that the PIV-derived beat patterns can identify the elongation or shortening of specific phases in the contractility cycle, and the obtained chronotropic responses are in accord with known clinical outcomes. Hence, this system can serve as a powerful tool to screen the new and currently available pharmacological compounds for cardiotoxic effects.