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All Food and Drug Administration-approved noncoding RNA (ncRNA) drugs (n≈20) target known disease-causing molecular pathways by mechanisms such as antisense. In a fortuitous evolution of work on regenerative medicine, my coworkers and I inverted the RNA drug discovery process: first we identified natural disease-modifying ncRNAs, then used them as templates for new synthetic RNA drugs. Mechanism was probed only after bioactivity had been demonstrated. The journey began with the development of cardiosphere-derived cells (CDCs) for cardiac regeneration. While testing CDCs in a first-in-human trial, we discovered they worked indirectly: ncRNAs within CDC-secreted extracellular vesicles mediate the therapeutic benefits. The vast majority of such ncRNAs are fragments of unknown function. We chose several abundant ncRNA species from CDC-secreted extracellular vesicles, synthesized and screened each of them in vitro and in vivo. Those with exceptional disease-modifying bioactivity inspired new chemical entities that conform to the structural conventions of the Food and Drug Administration-approved ncRNA armamentarium. This discovery arc-Cell-Derived RNA from Extracellular vesicles for bioinspired Drug develOpment, or CREDO-has yielded various promising lead compounds, each of which works via a unique, and often novel, mechanism. The process relies on emergent insights to shape therapeutic development. The initial focus of our inquiry-CDCs-are now themselves in phase 3 testing for Duchenne muscular dystrophy and its associated cardiomyopathy. But the intravenous delivery strategy and the repetitive dosing protocol for CDCs, which have proven key to clinical success, both arose from systematic mechanistic inquiry. Meanwhile, emergent insights have led to multiple cell-free therapeutic candidates: CDC-secreted extracellular vesicles are in preclinical development for ventricular arrhythmias, while the CREDO-conceived RNA drugs are in translation for diseases ranging from myocarditis to scleroderma., Competing Interests: E. Marbán holds founder’s equity in Capricor, Inc.

Background and Aims: Extracellular vesicles (EVs) secreted by cardiosphere-derived cells exert immunomodulatory effects through the transmission of small non-coding RNAs., Methods: The mechanism and role of yREX3, a small Y RNA abundant in EVs in myocardial injury, was investigated., Results: yREX3 attenuates cardiac ischaemic injury by selective DNA methylation. Synthetic yREX3 encapsulated in lipid nanoparticles triggers broad transcriptomic changes in macrophages, localizes to the nucleus, and mediates epigenetic silencing of protein interacting with C kinase-1 (Pick1) through methylation of upstream CpG sites. Moreover, yREX3 interacts with polypyrimidine tract binding protein 3 (PTBP3) to methylate the Pick1 gene locus in a DNA methyltransferase-dependent manner. Suppression of Pick1 in macrophages potentiates Smad3 signalling and enhances efferocytosis, minimizing heart necrosis in rats with myocardial infarction. Adoptive transfer of Pick1-deficient macrophages recapitulates the cardioprotective effects of yREX3 in vivo., Conclusions: These findings highlight the role of a small Y RNA mined from EVs with a novel gene-methylating mechanism., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Despite improvements in clinical outcomes following acute myocardial infarction, mortality remains high, especially in patients with severely reduced left ventricular ejection fraction (LVEF <30%), emphasizing the need for effective cardioprotective strategies adjunctive to recanalization. Traditional cell therapy has shown equivocal success, shifting the focus to innovative cardioactive biologicals and cell mimetic therapies, particularly extracellular vesicles (EVs). EVs, as carriers of non-coding RNAs and other essential biomolecules, influence neighbouring and remote cell function in a paracrine manner. Compared to cell therapy, EVs possess several clinically advantageous traits, including stability, ease of storage (enabling off-the-shelf clinical readiness), and decreased immunogenicity. Allogeneic EVs from mesenchymal and/or cardiac stromal progenitor cells demonstrate safety and potential efficacy in preclinical settings. This review delves into the translational potential of EV-based therapeutic approaches, specifically highlighting findings from large-animal studies, and offers a synopsis of ongoing early-stage clinical trials in this domain., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Rejuvenation of an old organism was achieved in heterochronic parabiosis experiments, implicating different soluble factors in this effect. Extracellular vesicles (EVs) are the secretory effectors of many cells, including cardiosphere-derived cells (CDCs) with demonstrated anti-senescent effect. 1. To determine the role of EVs (versus other blood fractions) on the rejuvenating effect of the young blood. 2. To evaluate the anti-aging properties of therapeutically administered EVs secreted by young-CDCs in an old organism. Neonatal blood fractioned in 4 components (whole blood, serum, EV-depleted serum and purified EVs) was used to treat old human cardiac stromal cells (CSPCs). CDCs were generated from neonatal rat hearts and the secreted CDC-EVs were purified. CDC-EVs were then tested in naturally-aged rats, using monthly injections over 4-months period. For validation in human samples, pediatric CDC-EVs were tested in aged human CSPCs and progeric fibroblasts. While the purified EVs reproduced the rejuvenating effects of the whole blood, CSPCs treated with EV-depleted serum exhibited the highest degree of senescence. Treatment with young CDC-EVs induce structural and functional improvements in the heart, lungs, skeletal muscle, and kidneys of old rats, while favorably modulating glucose metabolism and anti-senescence pathways. Lifespan was prolonged. EVs secreted by young CDCs exert broad-ranging anti-aging effects in aged rodents and in cellular models of human senescence. Our work not only identifies CDC-EVs as possible therapeutic candidates for a wide range of age-related pathologies, but also raises the question of whether EVs function as endogenous modulators of senescence., (© 2023. The Author(s).)

Newts have the extraordinary ability to fully regenerate lost or damaged cardiac, neural and retinal tissues, and even amputated limbs. In contrast, mammals lack these broad regenerative capabilities. While the molecular basis of newts' regenerative ability is the subject of active study, the underlying paracrine signaling factors involved remain largely uncharacterized. Extracellular vesicles (EVs) play an important role in cell-to-cell communication via EV cargo-mediated regulation of gene expression patterns within the recipient cells. Here, we report that newt myogenic precursor (A1) cells secrete EVs (A1EVs) that contain messenger RNAs associated with early embryonic development, neuronal differentiation, and cell survival. Exposure of rat primary superior cervical ganglion (SCG) neurons to A1EVs increased neurite outgrowth, facilitated by increases in mitochondrial respiration. Canonical pathway analysis pinpointed activation of NGF/ERK5 signaling in SCG neurons exposed to A1EV, which was validated experimentally. Thus, newt EVs drive neurite growth and complexity in mammalian primary neurons., (© 2023. The Author(s).)

Extracellular vesicles (EVs) carry diverse bioactive components including nucleic acids, proteins, lipids and metabolites that play versatile roles in intercellular and interorgan communication. The capability to modulate their stability, tissue-specific targeting and cargo render EVs as promising nanotherapeutics for treating heart, lung, blood and sleep (HLBS) diseases. However, current limitations in large-scale manufacturing of therapeutic-grade EVs, and knowledge gaps in EV biogenesis and heterogeneity pose significant challenges in their clinical application as diagnostics or therapeutics for HLBS diseases. To address these challenges, a strategic workshop with multidisciplinary experts in EV biology and U.S. Food and Drug Administration (USFDA) officials was convened by the National Heart, Lung and Blood Institute. The presentations and discussions were focused on summarizing the current state of science and technology for engineering therapeutic EVs for HLBS diseases, identifying critical knowledge gaps and regulatory challenges and suggesting potential solutions to promulgate translation of therapeutic EVs to the clinic. Benchmarks to meet the critical quality attributes set by the USFDA for other cell-based therapeutics were discussed. Development of novel strategies and approaches for scaling-up EV production and the quality control/quality analysis (QC/QA) of EV-based therapeutics were recognized as the necessary milestones for future investigations., (© 2023 The Authors. Journal of Extracellular Vesicles published by Wiley Periodicals, LLC on behalf of the International Society for Extracellular Vesicles.)

Extracellular vesicles (EVs) are potent signalling mediators. Although interest in EV translation is ever-increasing, development efforts are hampered by the inability to reliably assess the uptake of EVs and their RNA cargo. Here, we establish a novel qPCR-based method for the detection of unmodified EVS using an RNA Tracer (DUST). In this proof-of-concept study we use a human-specific Y RNA-derived small RNA (YsRNA) we dub "NT4" that is enriched in cardiosphere-derived cell small EVs (CDC-sEVs). The assay is robust, sensitive, and reproducible. Intravenously administered CDC-sEVs accumulated primarily in the heart on a per mg basis. Cardiac injury enhanced EV uptake in the heart, liver, and brain. Inhibition of EV docking by heparin suppressed uptake variably, while inhibition of endocytosis attenuated uptake in all organs. In vitro, EVs were uptaken more efficiently by macrophages, endothelial cells, and cardiac fibroblasts compared to cardiomyocytes. These findings demonstrate the utility of DUST to assess uptake of EVs in vivo and in vitro., (© 2021 The Authors. Journal of Extracellular Vesicles published by Wiley Periodicals, LLC on behalf of the International Society for Extracellular Vesicles.)

Background: Extracellular vesicles (EVs) from heart stromal/progenitor cells modulate innate immunity, with salutary effects in a variety of cardiac disease models. Little is known, however, about the effects of these EVs on adaptive immunity., Methods: Ex vivo differentiation of naïve CD4 + T cells was conducted to assess the effect of EVs on cytokine production and proliferation of Th1, Th2, Th17, and regulatory T (T reg ) cells. These effects were further tested in vivo using the experimental autoimmune myocarditis (EAM) model., Results: Using differentiated CD4 + T cells, we show that EVs secreted by human-derived heart stromal/progenitor cells selectively influence the phenotype, activity, and proliferation of regulatory T (T reg ) cells. Exposure of T reg cells to EVs results in faster proliferation, augmented production of IL-10, and polarization toward an intermediate FOXP3 + RORγt + phenotype. In experimental autoimmune myocarditis, EVs attenuate cardiac inflammation and functional decline, in association with increased numbers of splenic IL10 + -T reg cells., Conclusions: T cell modulation by EVs represents a novel therapeutic approach to inflammation, harnessing endogenous immunosuppressive mechanisms that may be applied in solid organ transplantation, graft-versus-host disease, and autoimmune disorders., Competing Interests: Disclosure A. Akhmerov was supported by the National Institutes of Health (NIH) T32 HL116273-07. The work was supported by NIH R01 HL 124074. E. Marbán holds the Mark S. Siegel Family Distinguished Chair of the Cedars-Sinai Medical Center. E. Marbán owns founder's equity in Capricor Therapeutics. The other authors report no conflicts., (Copyright © 2021 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

Aims: Arrhythmogenic cardiomyopathy (ACM) is characterized by progressive loss of cardiomyocytes, and fibrofatty tissue replacement. Extracellular vesicles (EVs) secreted by cardiosphere-derived cells, immortalized, and engineered to express high levels of β-catenin, exert anti-inflammatory, and anti-fibrotic effects. The aim of the current study was to assess efficacy of EVs in an ACM murine model., Methods and Results: Four-week-old homozygous knock-in mutant desmoglein-2 (Dsg2mt/mt) were randomized to receive weekly EVs or vehicle for 4 weeks. After 4 weeks, DSG2mt/mt mice receiving EVs showed improved biventricular function (left, P < 0.0001; right, P = 0.0037) and less left ventricular dilation (P < 0.0179). Electrocardiography revealed abbreviated QRS duration (P = 0.0003) and QTc interval (P = 0.0006) in EV-treated DSG2mt/mt mice. Further electrophysiology testing in the EV group showed decreased burden (P = 0.0042) and inducibility of ventricular arrhythmias (P = 0.0037). Optical mapping demonstrated accelerated repolarization (P = 0.0290) and faster conduction (P = 0.0274) in Dsg2mt/mt mice receiving EVs. DSG2mt/mt hearts exhibited reduced fibrosis, less cell death, and preserved connexin 43 expression after EV treatment. Hearts of Dsg2mt/mt mice expressed markedly increased levels of inflammatory cytokines that were, in part, attenuated by EV therapy. The pan-inflammatory transcription factor nuclear factor-κB (NF-κB), the inflammasome sensor NLRP3, and the macrophage marker CD68 were all reduced in EV-treated animals. Blocking EV hsa-miR-4488 in vitro and in vivo reactivates NF-κB and blunts the beneficial effects of EVs., Conclusions: Extracellular vesicle treatment improved cardiac function, reduced cardiac inflammation, and suppressed arrhythmogenesis in ACM. Further studies are needed prior to translating the present findings to human forms of this heterogenous disease., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

Cell therapy limits ischemic injury following myocardial infarction (MI) by preventing cell death, modulating the immune response, and promoting tissue regeneration. The therapeutic efficacy of cardiosphere-derived cells (CDCs) and mesenchymal stem cells (MSCs) is associated with extracellular vesicle (EV) release. Prior head-to-head comparisons have shown CDCs to be more effective than MSCs in MI models. Despite differences in cell origin, it is unclear why EVs from different adult stem cell populations elicit differences in therapeutic efficacy. Here, we compare EVs derived from multiple human MSC and CDC donors using diverse in vitro and in vivo assays. EV membrane protein and non-coding RNA composition are highly specific to the parent cell type; for example, miR-10b is enriched in MSC-EVs relative to CDC-EVs, while Y RNA fragments follow the opposite pattern. CDC-EVs enhance the Arg1/Nos2 ratio in macrophages in vitro and reduce MI size more than MSC-EVs and suppress inflammation during acute peritonitis in vivo. Thus, CDC-EVs are distinct from MSC-EVs, confer immunomodulation, and protect the host against ischemic myocardial injury and acute inflammation.

Extracellular vesicles (EVs) from cardiac stromal cells, developed as therapeutic candidates, improve dystrophic muscle function when administered parenterally, but oral delivery remains untested. We find that casein, the dominant protein in breast milk, enhances the uptake and bioactivity of ingested heart-derived EVs, altering gene expression in blood cells and enhancing muscle function in mdx mice with muscular dystrophy. Thus, EVs, administered orally, are absorbed and exert disease-modifying bioactivity in vivo . Formulating EVs with casein enhances uptake and markedly expands the range of potential therapeutic applications., Competing Interests: EM declares ownership of founder's equity in Capricor Therapeutics. Other authors declare no conflict of interest., (© 2021 The Authors. Journal of Extracellular Vesicles published by Wiley Periodicals, LLC on behalf of the International Society for Extracellular Vesicles.)

Acute ischemic stroke is devastating to patients and their families because of few viable therapeutic options to promote recovery after reperfusion windows close. Recent breakthroughs in biotechnology have resulted in a reproducible patented process for the purification of extracellular vesicles (EVs) from human cardiosphere-derived cells (CDCs). Because CDC-EVs have many features potentially beneficial to treat acute ischemic stroke, CDC-EVs were evaluated in an established small-clot rabbit embolic stroke model, where clinically relevant end points were used to assess recovery in a more translational large animal model. Biodistribution studies with fluorescent DiD-labeled CDC-EVs showed intense uptake in the ischemic region of the brain. In this report, we show that intravenous (IV) CDC-EVs (0.75 mg/kg) administered 1-hour post-embolization significantly attenuate behavioral deficits following an embolic stroke in rabbits. In CDC-EV-treated rabbits, P 50 (3.63 ± 1.27 mg, n = 24) was increased by 245% over vehicle control (1.05 ± 0.15 mg, n = 24); by comparison, rt-PA increased P 50 by 91% (2.01 ± 0.24 mg, n = 23). Importantly, the therapy was also without adverse effects on intracerebral hemorrhage or survival rate of embolized rabbits. Thus, as a first step toward widespread use, CDC-EVs, given adjunctively to routine reperfusion therapy, merit further investigation as a therapeutic candidate for stroke., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Extracellular vesicles (EVs) and exosomes are nano-sized, membrane-bound vesicles shed by most eukaryotic cells studied to date. EVs play key signaling roles in cellular development, cancer metastasis, immune modulation and tissue regeneration. Attempts to modify exosomes to increase their targeting efficiency to specific tissue types are still in their infancy. Here we describe an EV membrane anchoring platform termed "cloaking" to directly embed tissue-specific antibodies or homing peptides on EV membrane surfaces ex vivo for enhanced vesicle uptake in cells of interest. The cloaking system consists of three components: DMPE phospholipid membrane anchor, polyethylene glycol spacer and a conjugated streptavidin platform molecule, to which any biotinylated molecule can be coupled for EV decoration., Results: We demonstrate the utility of membrane surface engineering and biodistribution tracking with this technology along with targeting EVs for enhanced uptake in cardiac fibroblasts, myoblasts and ischemic myocardium using combinations of fluorescent tags, tissue-targeting antibodies and homing peptide surface cloaks. We compare cloaking to a complementary approach, surface display, in which parental cells are engineered to secrete EVs with fusion surface targeting proteins., Conclusions: EV targeting can be enhanced both by cloaking and by surface display; the former entails chemical modification of preformed EVs, while the latter requires genetic modification of the parent cells. Reduction to practice of the cloaking approach, using several different EV surface modifications to target distinct cells and tissues, supports the notion of cloaking as a platform technology.

Mechanistic exploration has pinpointed nanosized extracellular vesicles, known as exosomes, as key mediators of the benefits of cell therapy. Exosomes appear to recapitulate the benefits of cells and more. As durable azoic entities, exosomes have numerous practical and conceptual advantages over cells. Will cells end up just being used to manufacture exosomes, or will they find lasting value as primary therapeutic agents? Here, a venerable natural process-the generation of honey-serves as an instructive parable. Flowers make nectar, which bees collect and process into honey. Cells make conditioned medium, which laboratory workers collect and process into exosomes. Unlike flowers, honey is durable, compact, and nutritious, but these facts do not negate the value of flowers themselves. The parallels suggest new ways of thinking about next-generation therapeutics., (Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Cardiosphere-derived cells (CDCs) reduce myocardial infarct size via secreted extracellular vesicles (CDC-EVs), including exosomes, which alter macrophage polarization. We questioned whether short non-coding RNA species of unknown function within CDC-EVs contribute to cardioprotection. The most abundant RNA species in CDC-EVs is a Y RNA fragment (EV-YF1); its relative abundance in CDC-EVs correlates with CDC potency in vivo Fluorescently labeled EV-YF1 is actively transferred from CDCs to target macrophages via CDC-EVs. Direct transfection of macrophages with EV-YF1 induced transcription and secretion of IL-10. When cocultured with rat cardiomyocytes, EV-YF1-primed macrophages were potently cytoprotective toward oxidatively stressed cardiomyocytes through induction of IL-10. In vivo, intracoronary injection of EV-YF1 following ischemia/reperfusion reduced infarct size. A fragment of Y RNA, highly enriched in CDC-EVs, alters Il10 gene expression and enhances IL-10 protein secretion. The demonstration that EV-YF1 confers cardioprotection highlights the potential importance of diverse exosomal contents of unknown function, above and beyond the usual suspects (e.g., microRNAs and proteins)., (© 2017 The Authors. Published under the terms of the CC BY 4.0 license.)

Aims Cardiomyopathy patients are prone to ventricular arrhythmias (VA) and sudden cardiac death. Current therapies to prevent VA include radiofrequency ablation to destroy slowly conducting pathways of viable myocardium which support re-entry. Here, we tested the reverse concept, namely that boosting local tissue viability in zones of slow conduction might eliminate slow conduction and suppress VA in ischaemic cardiomyopathy. Methods and results Exosomes are extracellular vesicles laden with bioactive cargo. Exosomes secreted by cardiosphere-derived cells (CDCEXO) reduce scar and improve heart function after intramyocardial delivery. In a VA-prone porcine model of ischaemic cardiomyopathy, we injected CDCEXO or vehicle into zones of delayed conduction defined by electroanatomic mapping. Up to 1-month post-injection, CDCEXO, but not the vehicle, decreased myocardial scar, suppressed slowly conducting electrical pathways, and inhibited VA induction by programmed electrical stimulation. In silico reconstruction of electrical activity based on magnetic resonance images accurately reproduced the suppression of VA inducibility by CDCEXO. Strong anti-fibrotic effects of CDCEXO, evident histologically and by proteomic analysis from pig hearts, were confirmed in a co-culture assay of cardiomyocytes and fibroblasts. Conclusion Biological substrate modification by exosome injection may be worth developing as a non-destructive alternative to conventional ablation for the prevention of recurrent ventricular tachyarrhythmias. [ABSTRACT FROM AUTHOR]

Context: The identification and biological actions of pituitary-derived exosomes remain elusive. Objective: This work aimed to validate production of exosomes derived from human and rat pituitary and elucidate their actions. Methods: Isolated extracellular vesicles (EVs) were analyzed by Nanoparticle Tracking Analysis (NTA) and expressed exosomal markers detected by Western blot, using nonpituitary fibroblast FR and myoblast H9C2 cells as controls. Exosome inhibitor GW4869 was employed to detect attenuated EV release. Exosomal RNA contents were characterized by RNA sequencing. In vitro and in vivo hepatocyte signaling alterations responding to GH1-derived exosomes (GH1-exo) were delineated by mRNA sequencing. GH1-exo actions on protein synthesis, cAMP (3′,5′-cyclic adenosine 5′-monophosphate) response, cell motility, and metastases were assessed. Results: NTA, exosomal marker detection, and GW4869 attenuated EV release, confirming the exosomal identity of pituitary EVs. Hydrocortisone increased exosome secretion in GH1 and GH3 cells, suggesting a stress-associated response. Exosomal RNA contents showed profiles distinct for pituitary cells, and rat primary hepatocytes exposed to GH1-exo exhibited transcriptomic alterations distinct from those elicited by growth hormone or prolactin. Intravenous GH1-exo injection into rats attenuated hepatic Eif2ak2 and Atf4 mRNA expression, both involved in cAMP responses and amino acid biosynthesis. GH1-exo suppressed protein synthesis and forskolin-induced cAMP levels in hepatocytes. GH1-exo–treated HCT116 cells showed dysregulated p53 and mitogenactivated protein kinase (MAPK) pathways and attenuated motility of malignant HCT116 cells, and decreased tumor metastases in nude mice harboring splenic HCT116 implants. Conclusion: Our findings elucidate biological actions of somatotroph-derived exosomes and implicate exosomes as nonhormonal pituitary-derived messengers. [ABSTRACT FROM AUTHOR]

Heart disease remains an increasing major public health challenge in the United States and worldwide. A common end-organ feature in diseased hearts is myocardial fibrosis, which stiffens the heart and interferes with normal pump function, leading to pump failure. The development of cells for regenerative therapy has been met with many pitfalls on its path to clinical translation. Recognizing that regenerative cells secrete therapeutically bioactive vesicles has paved the way to circumvent many failures of cell therapy. In this review, we provide an overview of extracellular vesicles (EVs), with a focus on their utility as therapeutic agents for cardiac regeneration. We also highlight the engineering potential of EVs to enhance their therapeutic application. [ABSTRACT FROM AUTHOR]

Exosomes are nanosized membrane particles that are secreted by cells that transmit information from cell to cell. The information within exosomes prominently includes their protein and RNA payloads. Exosomal microRNAs in particular can potently and fundamentally alter the transcriptome of recipient cells. Here we summarize what is known about exosome biogenesis, content, and transmission, with a focus on cardiovascular physiology and pathophysiology. We also highlight some of the questions currently under active investigation regarding these extracellular membrane vesicles and their potential in diagnostic and therapeutic applications. [ABSTRACT FROM AUTHOR]

Primary cell therapy continues to face significant hurdles to therapeutic translation including the inherent variations that exist from donor to donor, batch to batch, and scale-up driven modifications to the manufacturing process. Cardiosphere-derived cells (CDCs) are stromal/progenitor cells with clinically demonstrated tissue reparative capabilities. Mechanistic investigations have identified canonical Wnt/β-catenin signaling as a therapeutic potency marker, and THY1 (CD90) expression as inversely correlated with potency. Here we demonstrate that the cardiosphere formation process increases β-catenin levels and enriches for therapeutic miR content in the extracellular vesicles of these cells, namely miR-146a and miR-22. We further find that loss of potency is correlated with impaired cardiosphere formation. Finally, our data show that small GSK3β inhibitors including CHIR, and BIO and "pro-canonical Wnt" culturing conditions can rescue β-catenin signaling and reduce CD90 expression. These findings identify strategies that could be used to maintain CDC potency and therapeutic consistency. CD90 and beta catenin expression are negative and positive markers of cardiosphere-derived cell therapeutic potency (respectively). Factors like cell stress and immortalization using SV40 small and large T-antigen reduce CDC potency while cardiosphere-formation, gsk3β inhibition, and wnt3a-fibronectin exposure reduce CD90 expression and increase beta catenin levels. Potent CDCs secrete extracellular vesicles (EVs) enriched in miR-146a and miR-22. [Display omitted] [ABSTRACT FROM AUTHOR]

Newts can regenerate amputated limbs and cardiac tissue, unlike mammals which lack broad regenerative capacity. Several signaling pathways involved in cell proliferation, differentiation and survival during newt tissue regeneration have been elucidated, however the factors that coordinate signaling between cells, as well as the conservation of these factors in other animals, are not well defined. Here we report that media conditioned by newt limb explant cells (A1 cells) protect mammalian cardiomyocytes from oxidative stress-induced apoptosis. The cytoprotective effect of A1-conditioned media was negated by exposing A1 cells to GW4869, which suppresses the generation of extracellular vesicles (EVs). A1-EVs are similar in diameter (~100-150 nm), structure, and share several membrane surface and cargo proteins with mammalian exosomes. However, isolated A1-EVs contain significantly higher levels of both RNA and protein per particle than mammalian EVs. Additionally, numerous cargo RNAs and proteins are unique to A1-EVs. Of particular note, A1-EVs contain numerous mRNAs encoding nuclear receptors, membrane ligands, as well as transcription factors. Mammalian cardiomyocytes treated with A1-EVs showed increased expression of genes in the PI3K/AKT pathway, a pivotal player in survival signaling. We conclude that newt cells secrete EVs with diverse, distinctive RNA and protein contents. Despite ~300 million years of evolutionary divergence between newts and mammals, newt EVs confer cytoprotective effects on mammalian cardiomyocytes. [ABSTRACT FROM AUTHOR]

Reverse transcription–quantitative polymerase chain reaction (RT-qPCR) is one of the most sensitive, economical and widely used methods for evaluating gene expression. However, the utility of this method continues to be undermined by a number of challenges including normalization using appropriate reference genes. The need to develop tailored and effective strategies is further underscored by the burgeoning field of extracellular vesicle (EV) biology. EVs contain unique signatures of small RNAs including microRNAs (miRs). In this study we develop and validate a comprehensive strategy for identifying highly stable reference genes in a therapeutically relevant cell type, cardiosphere-derived cells. Data were analysed using the four major approaches for reference gene evaluation: NormFinder, GeNorm, BestKeeper and the Delta Ct method. The weighted geometric mean of all of these methods was obtained for the final ranking. Analysis of RNA sequencing identified miR-101-3p, miR-23a-3p and a previously identified EV reference gene, miR-26a-5p. Analysis of a chip-based method (NanoString) identified miR-23a, miR-217 and miR-379 as stable candidates. RT-qPCR validation revealed that the mean of miR-23a-3p, miR-101-3p and miR-26a-5p was the most stable normalization strategy. Here, we demonstrate that a comprehensive approach of a diverse data set of conditions using multiple algorithms reliably identifies stable reference genes which will increase the utility of gene expression evaluation of therapeutically relevant EVs. [ABSTRACT FROM PUBLISHER]