Fetal and perinatal stem cells in cardiac regeneration: Moving forward to the paracrine era

Applications of extraembryonic tissue-derived cells in vascular tissue regeneration

Vascular tissue engineering is a promising approach for regenerating damaged blood vessels and developing new therapeutic approaches for heart disease treatment. To date, different sources of cells have been recognized that offer assistance within the recovery of heart supply routes and veins with distinctive capacities and are compelling for heart regeneration. However, some challenges still remain that need to be overcome to establish the full potential application of these cells. In this paper, we review the different cell sources used for vascular tissue engineering, focusing on extraembryonic tissue-derived cells (ESCs), and elucidate their roles in cardiovascular disease. In addition, we highlight the intricate interplay between mechanical and biochemical factors in regulating mesenchymal stem cell (MSC) differentiation, offering insights into optimizing their application in vascular tissues.

Multipotent fetal stem cells in reproductive biology research

Due to the limited accessibility of the in vivo situation, the scarcity of the human tissue, legal constraints, and ethical considerations, the underlying molecular mechanisms of disorders, such as preeclampsia, the pathological consequences of fetomaternal microchimerism, or infertility, are still not fully understood. And although substantial progress has already been made, the therapeutic strategies for reproductive system diseases are still facing limitations. In the recent years, it became more and more evident that stem cells are powerful tools for basic research in human reproduction and stem cell-based approaches moved into the center of endeavors to establish new clinical concepts. Multipotent fetal stem cells derived from the amniotic fluid, amniotic membrane, chorion leave, Wharton´s jelly, or placenta came to the fore because they are easy to acquire, are not associated with ethical concerns or covered by strict legal restrictions, and can be banked for autologous utilization later in life. Compared to adult stem cells, they exhibit a significantly higher differentiation potential and are much easier to propagate in vitro. Compared to pluripotent stem cells, they harbor less mutations, are not tumorigenic, and exhibit low immunogenicity. Studies on multipotent fetal stem cells can be invaluable to gain knowledge on the development of dysfunctional fetal cell types, to characterize the fetal stem cells migrating into the body of a pregnant woman in the context of fetomaternal microchimerism, and to obtain a more comprehensive picture of germ cell development in the course of in vitro differentiation experiments. The in vivo transplantation of fetal stem cells or their paracrine factors can mediate therapeutic effects in preeclampsia and can restore reproductive organ functions. Together with the use of fetal stem cell-derived gametes, such strategies could once help individuals, who do not develop functional gametes, to conceive genetically related children. Although there is still a long way to go, these developments regarding the usage of multipotent fetal stem cells in the clinic should continuously be accompanied by a wide and detailed ethical discussion.

Mesenchymal stem cells in ischemic tissue regeneration

Diseases caused by ischemia are one of the leading causes of death in the world. Current therapies for treating acute myocardial infarction, ischemic stroke, and critical limb ischemia do not complete recovery. Regenerative therapies opens new therapeutic strategy in the treatment of ischemic disorders. Mesenchymal stem cells (MSCs) are the most promising option in the field of cell-based therapies, due to their secretory and immunomodulatory abilities, that contribute to ease inflammation and promote the regeneration of damaged tissues. This review presents the current knowledge of the mechanisms of action of MSCs and their therapeutic effects in the treatment of ischemic diseases, described on the basis of data from in vitro experiments and preclinical animal studies, and also summarize the effects of using these cells in clinical trial settings. Since the obtained therapeutic benefits are not always satisfactory, approaches aimed at enhancing the effect of MSCs in regenerative therapies are presented at the end.

Human Amniotic Membrane Mesenchymal Stem Cell-Synthesized PGE2 Exerts an Immunomodulatory Effect on Neutrophil Extracellular Trap in a PAD-4-Dependent Pathway through EP2 and EP4

Human amniotic membrane mesenchymal stem cells (hAM-MSC) secrete a myriad of components with immunosuppressive activities. In the present research, we aimed to describe the effect of prostaglandin E₂ (PGE₂) secreted by hAM-MSCs on neutrophil extracellular trap (NET) release and to characterize the role of its receptors (EP2/EP4) in PAD-4 and NFκB activity in neutrophils. Human peripheral blood neutrophils were ionomycin-stimulated in the presence of hAM-MSC conditioned medium (CM) treated or not with the selective PGE₂ inhibitor MF-63, PGE₂, EP2/EP4 agonists, and the selective PAD-4 inhibitor GSK-484. NET release, PAD-4, and NFκB activation were analyzed. Ionomycin induced NET release, which was inhibited in the presence of hAM-MSC-CM, while CM from hAM-MSCs treated with MF-63 prevented NET release inhibition. PGE₂ and EP2/EP4 agonists, and GSK-484 inhibited NET release. EP2/EP4 agonists and GSK-484 inhibited H3-citrullination but did not affect PAD-4 protein expression. Finally, PGE₂ and EP2/EP4 agonists and GSK-484 increased NFκB phosphorylation. Taken together, these results suggest that hAM-MSC exert their immunomodulatory activities through PGE_2, inhibiting NET release in a PAD-4-dependent pathway. This research proposes a new mechanism by which hAM-MSC exert their activities when modulating the innate immune response and inhibiting NET release.

Comparative Analysis of Co-Cultured Amniotic Cell-Conditioned Media with Cell-Free Amniotic Fluid Reveals Differential Effects on Epithelial–Mesenchymal Transition and Myofibroblast Activation

Myofibroblast activation is a cellular response elicited by a variety of physiological or pathological insults whereby cells initiate a coordinated response intended to eradicate the insult and then revert back to a basal state. However, an underlying theme in various disease states is persistent myofibroblast activation that fails to resolve. Based on multiple observations, we hypothesized that the secreted factors harvested from co-culturing amniotic stem cells might mimic the anti-inflammatory state that cell-free amniotic fluid (AF) elicits. We optimized an amnion epithelial and amniotic fluid cell co-culture system, and tested this hypothesis in the context of myofibroblast activation. However, we discovered that co-cultured amniotic cell conditioned media (coACCM) and AF have opposing effects on myofibroblast activation: coACCM activates the epithelial–mesenchymal transition (EMT) and stimulates gene expression patterns associated with myofibroblast activation, while AF does the opposite. Intriguingly, extracellular vesicles (EVs) purified from AF are necessary and sufficient to activate EMT and inflammatory gene expression patterns, while the EV-depleted AF potently represses these responses. In summary, these data indicate that coACCM stimulates myofibroblast activation, while AF represses it. We interpret these findings to suggest that coACCM, AF, and fractionated AF represent unique biologics that elicit different cellular responses that are correlated with a wide variety of pathological states, and therefore could have broad utility in the clinic and the lab.

Mesenchymal Stem/Stromal Cells Derived from Human and Animal Perinatal Tissues-Origins, Characteristics, Signaling Pathways, and Clinical Trials

Mesenchymal stem/stromal cells (MSCs) are currently one of the most extensively researched fields due to their promising opportunity for use in regenerative medicine. There are many sources of MSCs, of which cells of perinatal origin appear to be an invaluable pool. Compared to embryonic stem cells, they are devoid of ethical conflicts because they are derived from tissues surrounding the fetus and can be safely recovered from medical waste after delivery. Additionally, perinatal MSCs exhibit better self-renewal and differentiation properties than those derived from adult tissues. It is important to consider the anatomy of perinatal tissues and the general description of MSCs, including their isolation, differentiation, and characterization of different types of perinatal MSCs from both animals and humans (placenta, umbilical cord, amniotic fluid). Ultimately, signaling pathways are essential to consider regarding the clinical applications of MSCs. It is important to consider the origin of these cells, referring to the anatomical structure of the organs of origin, when describing the general and specific characteristics of the different types of MSCs as well as the pathways involved in differentiation.

NADPH Oxidases: Redox Regulators of Stem Cell Fate and Function

One of the major sources of reactive oxygen species (ROS) generated within stem cells is the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase family of enzymes (NOXs), which are critical determinants of the redox state beside antioxidant defense mechanisms. This balance is involved in another one that regulates stem cell fate: indeed, self-renewal, proliferation, and differentiation are decisive steps for stem cells during embryo development, adult tissue renovation, and cell therapy application. Ex vivo culture-expanded stem cells are being investigated for tissue repair and immune modulation, but events such as aging, senescence, and oxidative stress reduce their ex vivo proliferation, which is crucial for their clinical applications. Here, we review the role of NOX-derived ROS in stem cell biology and functions, focusing on positive and negative effects triggered by the activity of different NOX isoforms. We report recent findings on downstream molecular targets of NOX-ROS signaling that can modulate stem cell homeostasis and lineage commitment and discuss the implications in ex vivo expansion and in vivo engraftment, function, and longevity. This review highlights the role of NOX as a pivotal regulator of several stem cell populations, and we conclude that these aspects have important implications in the clinical utility of stem cells, but further studies on the effects of pharmacological modulation of NOX in human stem cells are imperative.

Comprehensive Profiling of Secretome Formulations from Fetal- and Perinatal Human Amniotic Fluid Stem Cells

We previously reported that c-KIT+ human amniotic-fluid derived stem cells obtained from leftover samples of routine II trimester prenatal diagnosis (fetal hAFS) are endowed with regenerative paracrine potential driving pro-survival, anti-fibrotic and proliferative effects. hAFS may also be isolated from III trimester clinical waste samples during scheduled C-sections (perinatal hAFS), thus offering a more easily accessible alternative when compared to fetal hAFS. Nonetheless, little is known about the paracrine profile of perinatal hAFS. Here we provide a detailed characterization of the hAFS total secretome (i.e., the entirety of soluble paracrine factors released by cells in the conditioned medium, hAFS-CM) and the extracellular vesicles (hAFS-EVs) within it, from II trimester fetal- versus III trimester perinatal cells. Fetal- and perinatal hAFS were characterized and subject to hypoxic preconditioning to enhance their paracrine potential. hAFS-CM and hAFS-EV formulations were analyzed for protein and chemokine/cytokine content, and the EV cargo was further investigated by RNA sequencing. The phenotype of fetal- and perinatal hAFS, along with their corresponding secretome formulations, overlapped; yet, fetal hAFS showed immature oxidative phosphorylation activity when compared to perinatal ones. The profiling of their paracrine cargo revealed some differences according to gestational stage and hypoxic preconditioning. Both cell sources provided formulations enriched with neurotrophic, immunomodulatory, anti-fibrotic and endothelial stimulating factors, and the immature fetal hAFS secretome was defined by a more pronounced pro-vasculogenic, regenerative, pro-resolving and anti-aging profile. Small RNA profiling showed microRNA enrichment in both fetal- and perinatal hAFS-EV cargo, with a stably- expressed pro-resolving core as a reference molecular signature. Here we confirm that hAFS represents an appealing source of regenerative paracrine factors; the selection of either fetal or perinatal hAFS secretome formulations for future paracrine therapy should be evaluated considering the specific clinical scenario.

NGF nanoparticles enhance the potency of transplanted human umbilical cord mesenchymal stem cells for myocardial repair

In this study, we investigated whether human umbilical cord mesenchymal stem cell (hUCMSC) fibrin patches loaded with nerve growth factor (NGF) poly(lactic-co-glycolic acid) (PLGA) nanoparticles could enhance the therapeutic potency of hUCMSCs for myocardial infarction (MI). In vitro, NGF significantly improved the proliferation of hUCMSCs and mitigated cytotoxicity and apoptosis under hypoxic injury. NGF also promoted the paracrine effects of hUCMSCs on angiogenesis and cardiomyocyte protection. The tyrosine kinase A (TrkA) and phosphoinositide 3-kinase (PI3K)-serine/threonine protein kinase (Akt) signaling pathways in hUCMSCs were involved in the NGF-induced protection. NGF PLGA nanoparticles continued to release NGF for at least 1 mo and also exerted a protective effect on hUCMSCs, the same with free NGF. In vivo, we treated MI mice with nothing (MI group), a cell-free fibrin patch with blank PLGA nanoparticles (MI + OP group), a cell-free fibrin patch with NGF nanoparticles (MI + NGF group), and hUCMSC fibrin patches with blank PLGA nanoparticles (MI + MSC group) or NGF PLGA nanoparticles (MSC + NGF group). Among these groups, the MSC + NGF group exhibited the best cardiac contractile function, the smallest infarct size, and the thickest ventricular wall. The application of NGF PLGA nanoparticles significantly improved the retention of transplanted hUCMSCs and enhanced their ability to reduce myocardial apoptosis and promote angiogenesis in the mouse heart after MI. These findings demonstrate the promising therapeutic potential of hUCMSC fibrin cardiac patches loaded with NGF PLGA nanoparticles.NEW & NOTEWORTHY NGF PLGA nanoparticles can exert a protective effect on hUCMSCs and promote the paracrine effects of hUCMSCs on angiogenesis and cardiomyocyte protection through TrkA-PI3K/Akt signaling pathway, the same with free NGF. The application of NGF PLGA nanoparticles in the hUCMSC fibrin cardiac patches can significantly improve the retention of transplanted hUCMSCs and enhance their ability to reduce myocardial apoptosis and promote angiogenesis in the mouse heart after MI.

Neuroprotective effects of human amniotic fluid stem cells-derived secretome in an ischemia/reperfusion model

Stem cells offer the basis for the promotion of robust new therapeutic approaches for a variety of human disorders. There are still many limitations to be overcome before clinical therapeutic application, including a better understanding of the mechanism by which stem cell therapies may lead to enhanced recovery. In vitro investigations are necessary to dissect the mechanisms involved and to support the potential development in stem cell-based therapies. In spite of growing interest in human amniotic fluid stem cells, not much is known about the characteristics of their secretome and regarding the potential neuroprotective mechanism in different pathologies, including stroke. To get more insight on amniotic fluid cells therapeutic potential, signal transduction pathways activated by human amniotic fluid stem cells (hAFSCs)-derived secretome in a stroke in vitro model (ischemia/reperfusion [I/R] model) were investigated by Western blot. Moreover, miRNA expression in the exosomal fraction of the conditioned medium was analyzed. hAFSCs-derived secretome was able to activate pro-survival and anti-apoptotic pathways. MicroRNA analysis in the exosomal component revealed a panel of 16 overexpressed miRNAs involved in the regulation of coherent signaling pathways. In particular, the pathways of relevance in ischemia/reperfusion, such as neurotrophin signaling, and those related to neuroprotection and neuronal cell death, were analyzed. The results obtained strongly point toward the neuroprotective effects of the hAFSCs-conditioned medium in the in vitro stroke model here analyzed. This can be achieved by the modulation and activation of pro-survival processes, at least in part, due to the activity of secreted miRNAs.

Unravelling Heterogeneity of Amplified Human Amniotic Fluid Stem Cells Sub-Populations

Human amniotic fluid stem cells (hAFSCs) are broadly multipotent immature progenitor cells with high self-renewal and no tumorigenic properties. These cells, even amplified, present very variable morphology, density, intracellular composition and stemness potential, and this heterogeneity can hinder their characterization and potential use in regenerative medicine. Celector^® (Stem Sel ltd.) is a new technology that exploits the Non-Equilibrium Earth Gravity Assisted Field Flow Fractionation principles to characterize and label-free sort stem cells based on their solely physical characteristics without any manipulation. Viable cells are collected and used for further studies or direct applications. In order to understand the intrapopulation heterogeneity, various fractions of hAFSCs were isolated using the Celector^® profile and live imaging feature. The gene expression profile of each fraction was analysed using whole-transcriptome sequencing (RNAseq). Gene Set Enrichment Analysis identified significant differential expression in pathways related to Stemness, DNA repair, E2F targets, G2M checkpoint, hypoxia, EM transition, mTORC1 signalling, Unfold Protein Response and p53 signalling. These differences were validated by RT-PCR, immunofluorescence and differentiation assays. Interestingly, the different fractions showed distinct and unique stemness properties. These results suggest the existence of deep intra-population differences that can influence the stemness profile of hAFSCs. This study represents a proof-of-concept of the importance of selecting certain cellular fractions with the highest potential to use in regenerative medicine.

Hypoxia-induced amniotic fluid stem cell secretome augments cardiomyocyte proliferation and enhances cardioprotective effects under hypoxic-ischemic conditions

Secretome derived from human amniotic fluid stem cells (AFSC-S) is rich in soluble bioactive factors (SBF) and offers untapped therapeutic potential for regenerative medicine while avoiding putative cell-related complications. Characterization and optimal generation of AFSC-S remains challenging. We hypothesized that modulation of oxygen conditions during AFSC-S generation enriches SBF and confers enhanced regenerative and cardioprotective effects on cardiovascular cells. We collected secretome at 6-hourly intervals up to 30 h following incubation of AFSC in normoxic (21%O₂, nAFSC-S) and hypoxic (1%O₂, hAFSC-S) conditions. Proliferation of human adult cardiomyocytes (hCM) and umbilical cord endothelial cells (HUVEC) incubated with nAFSC-S or hAFSC-S were examined following culture in normoxia or hypoxia. Lower AFSC counts and richer protein content in AFSC-S were observed in hypoxia. Characterization of AFSC-S by multiplex immunoassay showed higher concentrations of pro-angiogenic and anti-inflammatory SBF. hCM demonstrated highest proliferation with 30h-hAFSC-S in hypoxic culture. The cardioprotective potential of concentrated 30h-hAFSC-S treatment was demonstrated in a myocardial ischemia–reperfusion injury mouse model by infarct size and cell apoptosis reduction and cell proliferation increase when compared to saline treatment controls. Thus, we project that hypoxic-generated AFSC-S, with higher pro-angiogenic and anti-inflammatory SBF, can be harnessed and refined for tailored regenerative applications in ischemic cardiovascular disease.

Stem cell secretome derived from human amniotic fluid affords neuroprotection in an ischemic model

Human amniotic fluid stem cells (hAFSCs) are growing in interest; yet, little is understood about their secretome and neuroprotective actions in different diseases, including stroke. When stem cells are grown in vitro, they release an array of cytokines and growth factors that can stimulate neuroprotective processes. Furthermore, administering secretome rather than cells may be a safer route for patients who are at risk for rejection, promoting innate restorative processes. Current literature implicates that the miRNA contents of such secretome, more specifically exosomes, may regulate the effectiveness of secretome administration. In this review, we explore what factors may promote pro-survival and pro-apoptotic pathways after the administration of hAFSCs-derived secretome in ischemic models.

Targeted delivery of extracellular vesicles in heart injury

Extracellular vesicles (EVs) are nanoscale extracellular vesicles derived from endocytosis that are crucial to intercellular communication. EVs possess natural biocompatibility and stability that allow them to cross biological membranes and that protect them from degradation. Recent studies have shown that EVs-mediated crosstalk between different cell types in the heart could play important roles in the maintenance of cardiac homeostasis and the pathogenesis of heart diseases. In particular, EVs secreted by different types of stem cells exhibit cardioprotective effects. However, numerous studies have shown that intravenously injected EVs are quickly cleared by macrophages of the mononuclear phagocyte system (MPS) and preferentially accumulate in MPS organs such as the liver, spleen, and lung. In this review, we discuss exosome biogenesis, the role of EVs in heart diseases, and challenges in delivering EVs to the heart. Furthermore, we extensively discuss the targeted delivery of EVs for treating ischemic heart disease. These understandings will aid in the development of effective treatment strategies for heart diseases.

Oxidative Stress in Alzheimer's Disease: In Vitro Therapeutic Effect of Amniotic Fluid Stem Cells Extracellular Vesicles

Alzheimer's disease (AD) is characterized by abnormal protein aggregation, deposition of extracellular β-amyloid proteins (Aβ), besides an increase of oxidative stress. Amniotic fluid stem cells (AFSCs) should have a therapeutic potential for neurodegenerative disorders, mainly through a paracrine effect mediated by extracellular vesicles (EV). Here, we examined the effect of EV derived from human AFSCs (AFSC-EV) on the disease phenotypes in an AD neuron primary culture. We observed a positive effect of AFSC-EV on neuron morphology, viability, and Aβ and phospho-Tau levels. This could be due to the apoptotic and autophagic pathway modulation derived from the decrease in oxidative stress. Indeed, reactive oxygen species (ROS) were reduced, while GSH levels were enhanced. This modulation could be ascribed to the presence of ROS regulating enzymes, such as SOD1 present into the AFSC-EV themselves. This study describes the ROS-modulating effects of extracellular vesicles alone, apart from their deriving stem cell, in an AD in vitro model, proposing AFSC-EV as a therapeutic tool to stop the progression of AD.

An update on stem cell therapy for Asherman syndrome

The current treatment for Asherman syndrome is limited and not very effective. The aim of this review is to summarize the most recent evidence for stem cells in the treatment of Asherman syndrome. The advent of stem cell therapy has propagated experimentation on mice and humans as a novel treatment. The consensus is that the regenerative capacity of stem cells has demonstrated improved outcomes in terms of fertility and fibrosis in both mice and humans with Asherman syndrome. Stem cells have effects on tissue repair by homing to the injured site, recruiting other cells by secreting chemokines, modulating the immune system, differentiating into other types of cells, proliferating into daughter cells, and potentially having antimicrobial activity. The studies reviewed examine different origins and administration modalities of stem cells. In preclinical models, therapeutic systemic injection of stem cells is more effective than direct intrauterine injection in regenerating the endometrium. In conjunction, bone marrow-derived stem cells have a stronger effect on uterine regeneration than uterine-derived stem cells, likely due to their broader differentiation potency. Clinical trials have demonstrated the initial safety and effectiveness profiles of menstrual, bone marrow, umbilical cord, and adipose tissue-derived stem cells in resumption of menstruation, fertility outcomes, and endometrial regeneration.

Role of Mesenchymal Stem Cells in Counteracting Oxidative Stress-Related Neurodegeneration

Neurodegenerative diseases include a variety of pathologies such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis, and so forth, which share many common characteristics such as oxidative stress, glycation, abnormal protein deposition, inflammation, and progressive neuronal loss. The last century has witnessed significant research to identify mechanisms and risk factors contributing to the complex etiopathogenesis of neurodegenerative diseases, such as genetic, vascular/metabolic, and lifestyle-related factors, which often co-occur and interact with each other. Apart from several environmental or genetic factors, in recent years, much evidence hints that impairment in redox homeostasis is a common mechanism in different neurological diseases. However, from a pharmacological perspective, oxidative stress is a difficult target, and antioxidants, the only strategy used so far, have been ineffective or even provoked side effects. In this review, we report an analysis of the recent literature on the role of oxidative stress in Alzheimer’s and Parkinson’s diseases as well as in amyotrophic lateral sclerosis, retinal ganglion cells, and ataxia. Moreover, the contribution of stem cells has been widely explored, looking at their potential in neuronal differentiation and reporting findings on their application in fighting oxidative stress in different neurodegenerative diseases. In particular, the exposure to mesenchymal stem cells or their secretome can be considered as a promising therapeutic strategy to enhance antioxidant capacity and neurotrophin expression while inhibiting pro-inflammatory cytokine secretion, which are common aspects of neurodegenerative pathologies. Further studies are needed to identify a tailored approach for each neurodegenerative disease in order to design more effective stem cell therapeutic strategies to prevent a broad range of neurodegenerative disorders.

Small extracellular vesicles secreted from human amniotic fluid mesenchymal stromal cells possess cardioprotective and promigratory potential

Mesenchymal stromal cells (MSCs) exhibit antiapoptotic and proangiogenic functions in models of myocardial infarction which may be mediated by secreted small extracellular vesicles (sEVs). However, MSCs have frequently been harvested from aged or diseased patients, while the isolated sEVs often contain high levels of impurities. Here, we studied the cardioprotective and proangiogenic activities of size-exclusion chromatography-purified sEVs secreted from human foetal amniotic fluid stem cells (SS-hAFSCs), possessing superior functional potential to that of adult MSCs. We demonstrated for the first time that highly pure (up to 1.7 × 1010 particles/µg protein) and thoroughly characterised SS-hAFSC sEVs protect rat hearts from ischaemia-reperfusion injury in vivo when administered intravenously prior to reperfusion (38 ± 9% infarct size reduction, p < 0.05). SS-hAFSC sEVs did not protect isolated primary cardiomyocytes in models of simulated ischaemia-reperfusion injury in vitro, indicative of indirect cardioprotective effects. SS-hAFSC sEVs were not proangiogenic in vitro, although they markedly stimulated endothelial cell migration. Additionally, sEVs were entirely responsible for the promigratory effects of the medium conditioned by SS-hAFSC. Mechanistically, sEV-induced chemotaxis involved phosphatidylinositol 3-kinase (PI3K) signalling, as its pharmacological inhibition in treated endothelial cells reduced migration by 54 ± 7% (p < 0.001). Together, these data indicate that SS-hAFSC sEVs have multifactorial beneficial effects in a myocardial infarction setting.

Human CardioChimeras: Creation of a Novel "Next-Generation" Cardiac Cell

Background

CardioChimeras produced by fusion of murine c‐kit⁺ cardiac interstitial cells with mesenchymal stem cells promote superior structural and functional recovery in a mouse model of myocardial infarction compared with either precursor cell alone or in combination. Creation of human CardioChimeras (hCCs) represents the next step in translational development of this novel cell type, but new challenges arise when working with c‐kit⁺ cardiac interstitial cells isolated and expanded from human heart tissue samples. The objective of the study was to establish a reliable cell fusion protocol for consistent optimized creation of hCCs and characterize fundamental hCC properties.

Methods and Results

Cell fusion was induced by incubating human c‐kit⁺ cardiac interstitial cells and mesenchymal stem cells at a 2:1 ratio with inactivated Sendai virus. Hybrid cells were sorted into 96‐well microplates for clonal expansion to derive unique cloned hCCs, which were then characterized for various cellular and molecular properties. hCCs exhibited enhanced survival relative to the parent cells and promoted cardiomyocyte survival in response to serum deprivation in vitro.

Conclusions

The generation of hCC is demonstrated and validated in this study, representing the next step toward implementation of a novel cell product for therapeutic development. Feasibility of creating human hybrid cells prompts consideration of multiple possibilities to create novel chimeric cells derived from cells with desirable traits to promote healing in pathologically damaged myocardium.

On-site fabrication of Bi-layered adhesive mesenchymal stromal cell-dressings for the treatment of heart failure

Mesenchymal stromal/stem cell (MSC)-based therapy is a promising approach for the treatment of heart failure. However, current MSC-delivery methods result in poor donor cell engraftment, limiting the therapeutic efficacy. To address this issue, we introduce here a novel technique, epicardial placement of bi-layered, adhesive dressings incorporating MSCs (MSC-dressing), which can be easily fabricated from a fibrin sealant film and MSC suspension at the site of treatment. The inner layer of the MSC dressing, an MSC-fibrin complex, promptly and firmly adheres to the heart surface without sutures or extra glues. We revealed that fibrin improves the potential of integrated MSCs through amplifying their tissue-repair abilities and activating the Akt/PI3K self-protection pathway. Outer collagen-sheets protect the MSC-fibrin complex from abrasion by surrounding tissues and also facilitates easy handling. As such, the MSC-dressing technique not only improves initial retention and subsequent maintenance of donor MSCs but also augment MSC's reparative functions. As a result, this technique results in enhanced cardiac function recovery with improved myocardial tissue repair in a rat ischemic cardiomyopathy model, compared to the current method. Dose-dependent therapeutic effects by this therapy is also exhibited. This user-friendly, highly-effective bioengineering technique will contribute to future success of MSC-based therapy.

Amniotic Fluid Cells, Stem Cells, and p53: Can We Stereotype p53 Functions?

In recent years, great interest has been devoted to finding alternative sources for human stem cells which can be easily isolated, ideally without raising ethical objections. These stem cells should furthermore have a high proliferation rate and the ability to differentiate into all three germ layers. Amniotic fluid, ordinarily discarded as medical waste, is potentially such a novel source of stem cells, and these amniotic fluid derived stem cells are currently gaining a lot of attention. However, further information will be required about the properties of these cells before they can be used for therapeutic purposes. For example, the risk of tumor formation after cell transplantation needs to be explored. The tumor suppressor protein p53, well known for its activity in controlling Cell Prolif.eration and cell death in differentiated cells, has more recently been found to be also active in amniotic fluid stem cells. In this review, we summarize the major findings about human amniotic fluid stem cells since their discovery, followed by a brief overview of the important role played by p53 in embryonic and adult stem cells. In addition, we explore what is known about p53 in amniotic fluid stem cells to date, and emphasize the need to investigate its role, particularly in the context of cell tumorigenicity.

Potential therapeutic roles of stem cells in ischemia-reperfusion injury

Ischemia-reperfusion injury (I/RI), produced by an initial interruption of organ blood flow and its subsequent restoration, contributes significantly to the pathophysiologies of stroke, myocardial infarction, renal I/RI, intestinal I/RI and liver I/RI, which are major causes of disability (including transplant failure) and even mortality. While the restoration of blood flow is required to restore oxygen and nutrient requirements, reperfusion often triggers local and systemic inflammatory responses and subsequently elevate the ischemic insult where the duration of ischemia determines the magnitude of I/RI damage. I/RI increases vascular leakage, changes transcriptional and cell death programs, drives leukocyte entrapment and inflammation and oxidative stress in tissues. Therapeutic approaches which reduce complications associated with I/RI are desperately needed to address the clinical and economic burden created by I/RI. Stem cells (SC) represent ubiquitous and uncommitted cell populations with the ability to self-renew and differentiate into one or more developmental 'fates'. Like immune cells, stem cells can home to and penetrate I/R-injured tissues, where they can differentiate into target tissues and induce trophic paracrine signaling which suppress injury and maintain tissue functions perturbed by ischemia-reperfusion. This review article summarizes the present use and possible protective mechanisms underlying stem cell protection in diverse forms of ischemia-reperfusion.

Mesenchymal stem cells from human amniotic membrane differentiate into cardiomyocytes and endothelial-like cells without improving cardiac function after surgical administration in rat model of chronic heart failure

Introduction: Human amnion-derived mesenchymal stem cells (hAMSCs) have been used in the treatment of acute myocardial infarction. In the current study, we investigated the efficacy of hAMSCs for the treatment of chronic model of myocardial ischemia and heart failure (HF) in rats. Methods: Male Wistar rats weighing between 250 to 350 g were randomized into three groups: sham, HF control and HF+hAMSCs. For HF induction, animals were anesthetized and underwent left anterior descending artery ligation. In HF+hAMSCs group, 2×106 cells were injected into the left ventricular muscle four weeks post ischemia in the border zone of the ischemic area. Cardiac function was studied using echocardiography. Masson's trichrome staining was used for studying tissue fibrosis. Cells were transduced with green fluorescent protein (GFP) coding lentiviral vector. Immunohistochemistry was used for detecting GFP, vascular-endothelial growth factor (VEGF) and troponin T markers in the tissue sections. Results: Assessment of the cardiac function revealed no improvement in the myocardial function compared to the control HF group. Moreover, tissue fibrosis was similar in two groups. Immunohistochemical study revealed the homing of the injected hAMSCs to the myocardium. Cells were stained positive for VEGF and troponin T markers. Conclusion: injection of hAMSCs 4 weeks after ischemia does not improve cardiac function and cardiac muscle fibrosis, although the cells show markers of differentiation into vascular endothelial cells and cardiomyocytes. In sum, it appears that hAMSCs are effective in the early phases of myocardial ischemia and does not offer a significant advantage in patients with chronic HF.

The Ability of Conditioned Media From Stem Cells to Repair Vocal Fold Injuries

OBJECTIVE

This study investigated the ability of hypoxia-induced 25-fold concentrated conditioned media (hCM) from human nasal inferior turbinate-derived mesenchymal stem cells (hTMSC) to repair injured vocal folds during the early phase of the wound-healing process.

METHODS

The vocal fold was injured in Sprague-Dawley rats. Next, hCM from hTMSC (the hCM group) or hTMSC (the hTMSC group) were injected into the injured vocal folds. As a control, saline (the phosphate-buffered saline group) or 25-fold concentrated media (the media group) was injected in the same manner. The vocal folds were harvested for quantitative real-time polymerase chain reaction (PCR) at 1 week and 2 weeks after injury. Histologic evaluation was performed at 3 weeks postinjury.

RESULTS

In the hCM group at 1 week after injury, PCR showed that the genes encoding hyaluronan synthase (HAS), HAS 1, and HAS 2 were significantly upregulated compared to the media and normal groups. The gene encoding procollagen III was significantly downregulated compared to the media group. Nearly identical results were obtained for the hTMSC group at 1 week after injury. Histological examination showed that the hCM group was similar to or better than the hTMSC group in collagen deposition and hyaluronic acid production.

CONCLUSION

The injection of hCM into injured vocal folds produced antifibrotic effects in the early phase of wound healing. These effects were equivalent to those produced by the injection of hTMSC. These results provide a foundation for the future clinical use of hCM for vocal fold regeneration.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:1867-1875, 2019.

Stem Cell Extracellular Vesicles in Skin Repair

Stem cell extracellular vesicles (EVs) have been widely studied because of their excellent therapeutic potential. EVs from different types of stem cell can improve vascularization as well as aid in the treatment of cancer and neurodegenerative diseases. The skin is a complex organ that is susceptible to various types of injury. Strategies designed to restore epithelial tissues’ integrity with stem cell EVs have shown promising results. Different populations of stem cell EVs are able to control inflammation, accelerate skin cell migration and proliferation, control wound scarring, improve angiogenesis, and even ameliorate signs of skin aging. However, large-scale production of such stem cell EVs for human therapy is still a challenge. This review focuses on recent studies that explore the potential of stem cell EVs in skin wound healing and skin rejuvenation, as well as challenges of their use in therapy.

Therapeutic abortion and ectopic pregnancy: alternative sources for fetal stem cell research and therapy in Iran as an Islamic country

Regenerative medicine as a background of stem cell research and therapy has a long history. A wide variety of diseases including Parkinson's disease, heart diseases, multiple sclerosis, spinal cord injury, diabetes mellitus and etc. are candidate to be treated using different types of stem cells. There are several sources of stem cells such as bone marrow, umbilical cord, peripheral blood, germ cells and the embryo/fetus tissues. Fetal stem cells (FSCs) and embryonic stem cells (ESCs) have been described as the most potent stem cell source. Although their pluri- or multipotent properties leads to promising reports for their clinical applications, owning to some ethical and legal obstacles in different communities such as Muslim countries, care should be taken for therapeutic applications of FSCs and ESCs. Derivation of these cell types needs termination of pregnancy and embryo or fetus life that is prohibited according to almost all rules and teaches in Muslim communities. Abortion and termination of pregnancy under a normal condition for the procurement of stem cell materials is forbidden by nearly all the major world religions such as Islam. Legislated laws in the most of Muslim countries permit termination of pregnancy and abortion only when the life of the mother is severely threatened or when continuing pregnancy may lead to the birth of a mentally retarded, genetically or anatomically malformed child. Based on the rules and conditions in Islamic countries, finding an alternative and biologically normal source for embryonic or fetal stem cell isolation will be too difficult. On the one hand, Muslim scientists have the feasibility for finding of genetically and anatomically normal embryonic or fetal stem cell sources for research or therapy, but on the other hand they should adhere to the law and related regional and local rules in all parts of their investigation. The authors suggest that the utilization of ectopic pregnancy (EP) conceptus, extra-embryonic tissues, and therapeutic abortion materials as a valuable source of stem cells for research and medical purposes can overcome limitations associated with finding the appropriate stem cell source. Pregnancy termination because of the mentioned subjects is accepted by almost all Islamic laws because of maternal lifesaving. Also, there are no ethical or legal obstacles in the use of extra-embryonic or EP derived tissues which lead to candidate FSCs as a valuable source for stem cell researches and therapeutic applications.

Cardiac Restoration Stemming From the Placenta Tree: Insights From Fetal and Perinatal Cell Biology

Efficient cardiac repair and ultimate regeneration still represents one of the main challenges of modern medicine. Indeed, cardiovascular disease can derive from independent conditions upsetting heart structure and performance: myocardial ischemia and infarction (MI), pharmacological cardiotoxicity, and congenital heart defects, just to name a few. All these disorders have profound consequences on cardiac tissue, inducing the onset of heart failure over time. Since the cure is currently represented by heart transplantation, which is extremely difficult due to the shortage of donors, much effort is being dedicated to developing innovative therapeutic strategies based on stem cell exploitation. Among the broad scenario of stem/progenitor cell subpopulations, fetal and perinatal sources, namely amniotic fluid and term placenta, have gained interest due to their peculiar regenerative capacity, high self-renewal capability, and ease of collection from clinical waste material. In this review, we will provide the state-of-the-art on fetal perinatal stem cells for cardiac repair and regeneration. We will discuss different pathological conditions and the main therapeutic strategies proposed, including cell transplantation, putative paracrine therapy, reprogramming, and tissue engineering approaches.

The Ability of Human Nasal Inferior Turbinate-Derived Mesenchymal Stem Cells to Repair Vocal Fold Injuries

Objective This study investigated the ability of implanted human nasal inferior turbinate-derived mesenchymal stem cells (hTMSCs) to repair injured vocal folds. To this end, we used quantitative real-time polymerase chain reaction (PCR) to analyze the early phase of wound healing and histopathological analysis to explore the late phase of wound healing in xenograft animal models. Study Design Prospective animal study. Setting Research laboratory. Subjects and Methods The right-side lamina propria of the vocal fold was injured in 20 rabbits and 30 rats. Next, hTMSCs were implanted into half of the injured vocal folds (hTMSC groups). As a control, phosphate-buffered saline (PBS) was injected into the other half of the injured vocal folds (PBS groups). Rat vocal folds were harvested for polymerase chain reaction (PCR) at 1 week after injury. Rabbit vocal folds were evaluated endoscopically and the larynges harvested for histological and immunohistochemical examination at 2 and 8 weeks after injury. Results In the hTMSC group, PCR showed that hyaluronan synthase ( HAS) 1, HAS 2, and transforming growth factor ( TGF)-β1 were significantly upregulated compared with the PBS group. Procollagen type III ( COL III) messenger RNA expression was significantly upregulated in the PBS group compared with the normal group. Histological analyses showed that hTMSC administration afforded more favorable collagen and hyaluronic acid deposition than was evident in the controls. Implanted hTMSCs were observed in injured vocal folds 2 weeks after implantation. Conclusions Our results show that hTMSCs implantation into injured vocal folds facilitated vocal fold regeneration, with presenting antifibrotic effects.