Placenta Stem/Stromal Cell–Derived Extracellular Vesicles for Potential Use in Lung Repair

Many acute and chronic lung injuries are incurable and rank as the fourth leading cause of death globally. While stem cell treatment for lung injuries is a promising approach, there is growing evidence that the therapeutic efficacy of stem cells originates from secreted extracellular vesicles (EVs). Consequently, EVs are emerging as next‐generation therapeutics. While EVs are extensively researched for diagnostic applications, their therapeutic potential to promote tissue repair is not fully elucidated. By housing and delivering tissue‐repairing cargo, EVs refine the cellular microenvironment, modulate inflammation, and ultimately repair injury. Here, the potential use of EVs derived from two placental mesenchymal stem/stromal cell (MSC) lines is presented; a chorionic MSC line (CMSC29) and a decidual MSC cell line (DMSC23) for applications in lung diseases. Functional analyses using in vitro models of injury demonstrate that these EVs have a role in ameliorating injuries caused to lung cells. It is also shown that EVs promote repair of lung epithelial cells. This study is fundamental to advancing the field of EVs and to unlock the full potential of EVs in regenerative medicine.     

Calcium channels and their role in regenerative medicine

Stem cells hold indefinite self-renewable capability that can be differentiated into all desired cell types.Based on their plasticity potential,they are divided into totipotent(morula stage cells),pluripotent(embryonic stem cells),multipotent(hematopoietic stem cells,multipotent adult progenitor stem cells,and mesenchymal stem cells[MSCs]),and unipotent(progenitor cells that differentiate into a single lineage)cells.Though bone marrow is the primary source of multipotent stem cells in adults,other tissues such as adipose tissues,placenta,amniotic fluid,umbilical cord blood,periodontal ligament,and dental pulp also harbor stem cells that can be used for regenerative therapy.In addition,induced pluripotent stem cells also exhibit fundamental properties of self-renewal and differentiation into specialized cells,and thus could be another source for regenerative medicine.Several diseases including neurodegenerative diseases,cardiovascular diseases,autoimmune diseases,virus infection(also coronavirus disease 2019)have limited success with conventional medicine,and stem cell transplantation is assumed to be the best therapy to treat these disorders.Importantly,MSCs,are by far the best for regenerative medicine due to their limited immune modulation and adequate tissue repair.Moreover,MSCs have the potential to migrate towards the damaged area,which is regulated by various factors and signaling processes.Recent studies have shown that extracellular calcium(Ca²⁺)promotes the proliferation of MSCs,and thus can assist in transplantation therapy.Ca²⁺signaling is a highly adaptable intracellular signal that contains several components such as cell-surface receptors,Ca²⁺channels/pumps/exchangers,Ca²⁺buffers,and Ca²⁺sensors,which together are essential for the appropriate functioning of stem cells and thus modulate their proliferative and regenerative capacity,which will be discussed in this review.     

Autophagy in fate determination of mesenchymal stem cells and bone remodeling

Mesenchymal stem cells (MSCs) have been widely exploited as promising candidates in clinical settings for bone repair and regeneration in view of their self-renewal capacity and multipotentiality. However, little is known about the mechanisms underlying their fate determination, which would illustrate their effectiveness in regenerative medicine. Recent evidence has shed light on a fundamental biological role of autophagy in the maintenance of the regenerative capability of MSCs and bone homeostasis. Autophagy has been implicated in provoking an immediately available cytoprotective mechanism in MSCs against stress, while dysfunction of autophagy impairs the function of MSCs, leading to imbalances of bone remodeling and a wide range of aging and degenerative bone diseases. This review aims to summarize the up-to-date knowledge about the effects of autophagy on MSC fate determination and its role as a stress adaptation response. Meanwhile, we highlight autophagy as a dynamic process and a double-edged sword to account for some discrepancies in the current research. We also discuss the contribution of autophagy to the regulation of bone cells and bone remodeling and emphasize its potential involvement in bone disease.     

Alpinate Oxyphyllae extracts enhance the longevity and homing of mesenchymal stem cells and augment their protection against senescence in H9c2 cells

Adipose-derived mesenchymal stem cells (ADMSCs) are easily accessible and are attractive mesenchymal stem cells for use in regenerative medicine; however their application is frequently restricted due to various challenges present in the environment they are administered. Therefore ADMSCs are preferably preconditioned with various stimulating factors to overcome the barriers developed in any pathological conditions. Here we used ADMSCs from rat adipose based on the abundance of positive markers and preconditioned the cells with extracts from Alpinate Oxyphyllae Fructus (AOF), a traditional Chinese herb used for antiaging, associated various health benefits. The preconditioned stem cells were tested for their potential to drive H9c2 from doxorubicin (Dox)-induced aging. The AOF-treated stem cells enriched stemness in ADMSCs with respect to their stem cells' positive marker, and enhanced their longevity mechanism and elevated the stem cell homing-associated C-X-C chemokine receptor type 7 (CXCR7). The AOF preconditioned stem cells, when cocultured with H9c2 cells, showed effective protection to Dox-induced senescence and stem cell homing to damaged H9c2 cells. The presence of AOF provided greater protective effects in the Dox environment. In addition, AOF-pretreated ADMSCs showed enhanced migration than those treated with AOF in Dox environment. Therefore, our results show that administration of AOF preconditioned stem cells is potentially an effective strategy in the management of aging-associated cardiac disorders.     

Multiplexed targeting of microRNA in stem cell-derived extracellular vesicles for regenerative medicine

Regenerative medicine is a research field that develops methods to restore damaged cell or tissue function by regeneration, repair or replacement. Stem cells are the raw material of the body that is ultimately used from the point of view of regenerative medicine, and stem cell therapy uses cells themselves or their derivatives to promote responses to diseases and dysfunctions, the ultimate goal of regenerative medicine. Stem cell-derived extracellular vesicles (EVs) are recognized as an attractive source because they can enrich exogenous microRNAs (miRNAs) by targeting pathological recipient cells for disease therapy and can overcome the obstacles faced by current cell therapy agents. However, there are some limitations that need to be addressed before using miRNA-enriched EVs derived from stem cells for multiplexed therapeutic targeting in many diseases. Here, we review various roles on miRNA-based stem cell EVs that can induce effective and stable functional improvement of stem cell-derived EVs. In addition, we introduce and review the implications of several miRNA-enriched EV therapies improved by multiplexed targeting in diseases involving the circulatory system and nervous system. This systemic review may offer potential roles for stem cell-derived therapeutics with multiplexed targeting.     

Insulin-like growth factor binding proteins 4 and 7 released by senescent cells promote premature senescence in mesenchymal stem cells

Cellular senescence is the permanent arrest of cell cycle, physiologically related to aging and aging-associated diseases. Senescence is also recognized as a mechanism for limiting the regenerative potential of stem cells and to protect cells from cancer development. The senescence program is realized through autocrine/paracrine pathways based on the activation of a peculiar senescence-associated secretory phenotype (SASP). We show here that conditioned media (CM) of senescent mesenchymal stem cells (MSCs) contain a set of secreted factors that are able to induce a full senescence response in young cells. To delineate a hallmark of stem cells SASP, we have characterized the factors secreted by senescent MSC identifying insulin-like growth factor binding proteins 4 and 7 (IGFBP4 and IGFBP7) as key components needed for triggering senescence in young MSC. The pro-senescent effects of IGFBP4 and IGFBP7 are reversed by single or simultaneous immunodepletion of either proteins from senescent-CM. The blocking of IGFBP4/7 also reduces apoptosis and promotes cell growth, suggesting that they may have a pleiotropic effect on MSC biology. Furthermore, the simultaneous addition of rIGFBP4/7 increased senescence and induced apoptosis in young MSC. Collectively, these results suggest the occurrence of novel-secreted factors regulating MSC cellular senescence of potential importance for regenerative medicine and cancer therapy.     

Obesity and weight loss could alter the properties of adipose stem cells?

The discovery that adipose tissue represents an interesting source of multipotent stem cells has led to many studies exploring the clinical potential of these cells in cell-based therapies. Recent advances in understanding the secretory capacity of adipose tissue and the role of adipokines in the development of obesity and associated disorders have added a new dimension to the study of adipose tissue biology in normal and diseased states. Subcutaneous adipose tissue forms the interface between the clinical application of regenerative medicine and the establishment of the pathological condition of obesity. These two facets of adipose tissue should be understood as potentially related phenomena. Because of the functional characteristics of adipose stem cells, these cells represent a fundamental tool for understanding how these two facets are interconnected and could be important for therapeutic applications. In fact, adipose tissue stem cells have multiple functions in obesity related to adipogenic, angiogenic and secretory capacities. In addition, we have also previously described a predominance of larger blood vessels and an adipogenic memory in the subcutaneous adipose tissue after massive weight loss subsequent to bariatric surgery(ex-obese patients). Understanding the reversibility of the behavior of adipose stem cells in obeses and in weight loss is relevant to both physiological studies and the potential use of these cells in regenerative medicine.     

Recent trends in stem cell-based therapies and applications of artificial intelligence in regenerative medicine

Stem cells are undifferentiated cells that can self-renew and differentiate into diverse types of mature and functional cells while maintaining their original identity. This profound potential of stem cells has been thoroughly investigated for its significance in regenerative medicine and has laid the foundation for cell-based therapies. Regenerative medicine is rapidly progressing in healthcare with the prospect of repair and restoration of specific organs or tissue injuries or chronic disease conditions where the body’s regenerative process is not sufficient to heal. In this review, the recent advances in stem cell-based therapies in regenerative medicine are discussed, emphasizing mesenchymal stem cell-based therapies as these cells have been extensively studied for clinical use. Recent applications of artificial intelligence algorithms in stem cell-based therapies, their limitation, and future prospects are highlighted.     

Regenerating cardiac cells: insights from the bench and the clinic

A major challenge in cardiovascular regenerative medicine is the development of novel therapeutic strategies to restore the function of cardiac muscle in the failing heart. The heart has historically been regarded as a terminally differentiated organ that does not have the potential to regenerate. This concept has been updated by the discovery of cardiac stem and progenitor cells that reside in the adult mammalian heart. Whereas diverse types of adult cardiac stem or progenitor cells have been described, we still do not know whether these cells share a common origin. A better understanding of the physiology of cardiac stem and progenitor cells should advance the successful use of regenerative medicine as a viable therapy for heart disease. In this review, we summarize current knowledge of the various adult cardiac stem and progenitor cell types that have been discovered. We also review clinical trials presently being undertaken with adult stem cells to repair the injured myocardium in patients with coronary artery disease.     

Mesenchymal stem cell–derived extracellular vesicles: a new impetus of promoting angiogenesis in tissue regeneration

Over the past few decades, extracellular vesicles (EVs) have emerged as crucial mediators of intercellular communication. EVs encapsulate and convey information to surrounding cells or distant cells, where they mediate cellular biological responses. Among their multifaceted roles in the modulation of biological responses, the involvement of EVs in vascular development, growth and maturation has been widely documented and their potential therapeutic application in regenerative medicine or in the treatment of angiogenesis-related diseases is drawing increasing interest. In this review, we have summarized the details about the current knowledge on biogenesis of EVs and conventional isolation methods. Evidence supporting the use of EVs derived from mesenchymal stromal cells (MSCs) to enhance angiogenesis in the development of insufficient angiogenesis, such as chronic wounds, stroke and myocardial infarction, will also be discussed critically. Finally, the main challenges and prerequisites for their therapeutic applications will be evaluated.     

Generation of mesenchymal stem-like cells for producing extracellular vesicles

Mesenchymal stem cells (MSCs) are multipotent progenitor cells with therapeutic potential against autoimmune diseases, inflammation, ischemia, and metabolic disorders. Contrary to the previous conceptions, recent studies have revealed that the tissue repair and immunomodulatory functions of MSCs are largely attributed to their secretome, rather than their potential to differentiate into desired cell types. The composition of MSC secretome encompasses cytokines and growth factors, in addition to the cell-derived structures known as extracellular vesicles (EVs). EVs are membrane-enclosed nanoparticles that are capable of delivering biomolecules, and it is now believed that MSC-derived EVs are the major players that induce biological changes in the target tissues. Based on these EVs’ characteristics, the potential of EVs derived from MSC (MSC-EV) in terms of tissue regeneration and immune modulation has grown during the last decade. However, the use of MSCs for producing sufficient amount of EVs has not been satisfactory due to limitations in the cell growth and large variations among the donor cell types. In this regard, pluripotent stem cells (PSCs)-derived MSC-like cells, which can be robustly induced and expanded in vitro, have emerged as more accessible cell source that can overcome current limitations of using MSCs for EV production. In this review, we have highlighted the methods of generating MSC-like cells from PSCs and their therapeutic outcome in preclinical studies. Finally, we have also discussed future requirements for making this cell-free therapy clinically feasible.     

脐带血干细胞的基础与应用研究

作为造血干/祖细胞(hematopoieticstemcells/hematopoieticprogenitorcells,HSCs/HPCs)的另一来源,脐带血已经应用于临床治疗多种恶性和非恶性疾病。脐带血中HSCs/HPCs的质与量是决定其临床应用效果的最重要因素。同时,脐带血中还存在多种非造血的干细胞和前体细胞,如间充质干细胞(mesenchymalstemcells,MSCs)、内皮前体细胞(endothelialprogenitorcells,EPCs)和非限制性体干细胞(unrestrictedsomaticstemcells,USSCs)等,这些细胞可能会在未来的细胞治疗和再生医学中发挥重要作用。本综述还讨论了脐带血的临床应用及HSCs/HPCs的体外扩增、增加HSCs归巢和再植能力等提高其临床应用能力的相关研究。     

Stem-cell-based approaches for regenerative medicine

Recent success in transplantation of islets raises the hopes of diabetic patients that replacement therapies may be a feasible treatment of their disease. Although several lines of evidence suggest that stem cells exist in the pancreas, it is still technically hard for us to isolate or maintain the stem cells in vitro. The establishment of human embryonic stem (ES) cells has excited scientists regarding their potential medical use in tissue replacement therapy. When applied with appropriate signals, ES cells can be directed to differentiate into a specific cell lineage. Therefore, ES cells are no doubt an excellent source not only for regenerative medicine but also for studies of early events of pancreatic development, and to portray the pancreatic progenitor cells. Despite many attempts that have been tried, the efficiency of differentiation of ES cells into islets is still very low. This low efficiency reflects our lack of understanding of the intrinsic and extrinsic signals which regulate the developmental processes of the pancreas. In this review, I present a summary of recent works on ES cells, the identification of pancreatic progenitor cells from the adult pancreas, and refer to the possibilities of transdifferentiation from adult stem cells derived from other tissues.     

Extracellular vesicles: Emerged as a promising strategy for regenerative medicine

Cell transplantation therapy has certain limitations including immune rejection and limited cell viability, which seriously hinder the transformation of stem cell-based tissue regeneration into clinical practice. Extracellular vesicles (EVs) not only possess the advantages of its derived cells, but also can avoid the risks of cell transplantation. EVs are intelligent and controllable biomaterials that can participate in a variety of physiological and pathological activities, tissue repair and regeneration by transmitting a variety of biological signals, showing great potential in cell-free tissue regeneration. In this review, we summarized the origins and characteristics of EVs, introduced the pivotal role of EVs in diverse tissues regeneration, discussed the underlying mechanisms, prospects, and challenges of EVs. We also pointed out the problems that need to be solved, application directions, and prospects of EVs in the future and shed new light on the novel cell-free strategy for using EVs in the field of regenerative medicine.     

From cellular to chemical approach for acute neural and alternative options for age-induced functional diseases

Endogenous “stem cell niche” (SCN) accompanying vessels contains immune system components which in vivo determine differentiation of multi potent stem cells toward proper cell types in given tissue. Combinations of sex steroids may represent novel chemical approach for neuronal areas of regenerative medicine, since they cause transformation of vascular smooth muscle stem cells into differentiating neuronal cells. Circulating sex steroids are present during pregnancy and can be utilized where needed, when various embryonic/fetal tissues develop from their stem cells. Utilization of induced regeneration of tissues (regenerative medicine) is expected being more effective in sudden failures of younger individuals carrying intact SCN, as compared to established chronic disorders caused by SCN alteration. An essential component of SCN are monocyte-derived cells exhibiting tissue-specific “stop effect” (SE) preventing, for instance, an aging of neuronal cells. Its alteration causes that implantation of neuronal stem cells will also result in their differentiation toward aging cells. When we repair the SE by supply of circulating mononuclear cells from young healthy individuals, we may be able to provide novel regenerative treatments of age-induced neural diseases by sex steroid combinations. Questions regarding some age-induced body alterations are also addressed.     

Small extracellular vesicles from mesenchymal stromal cells: the next therapeutic paradigm for musculoskeletal disorders

Musculoskeletal disorders are one of the biggest contributors to morbidity and place an enormous burden on the health care system in an aging population. Owing to their immunomodulatory and regenerative properties, mesenchymal stromal/stem cells (MSCs) have demonstrated therapeutic efficacy for treatment of a wide variety of conditions, including musculoskeletal disorders. Although MSCs were originally thought to differentiate and replace injured/diseased tissues, it is now accepted that MSCs mediate tissue repair through secretion of trophic factors, particularly extracellular vesicles (EVs). Endowed with a diverse cargo of bioactive lipids, proteins, nucleic acids and metabolites, MSC-EVs have been shown to elicit diverse cellular responses and interact with many cell types needed in tissue repair. The present review aims to summarize the latest advances in the use of native MSC-EVs for musculoskeletal regeneration, examine the cargo molecules and mechanisms underlying their therapeutic effects, and discuss the progress and challenges in their translation to the clinic.     

干细胞来源的胞外囊泡对T细胞的免疫调控作用

胞外囊泡（EVs）是细胞旁分泌产生的一种亚细胞成分,实质上是一组纳米级颗粒。它是双层膜结合型囊泡,内含蛋白质、核酸等活性成分。EVs在细胞间通过转移携带的信号分子而获得重要的地位。目前关于EVs在体外和体内的研究中对T细胞的调控能力引起了人们广泛的兴趣。在大多数研究中干细胞被报道能够抑制T细胞的增殖、活化和分化,在极少数研究中也发现干细胞具有增强T细胞免疫反应的作用。事实上所有的细胞类型均能释放EVs,包括干/祖/前体细胞。EVs被认为是细胞间交流的一种新机制,具有与干/祖细胞等亲代细胞相似的免疫调控作用。本综述是概述干/祖细胞来源的EVs对T细胞调控作用及可能的机制。     

皮毛之道：以表皮器官为研究模型探讨再生生物学与再生医学的基础概念

再生医学是一个具有巨大潜力的新兴医学领域。该文以此为方向讨论了再生医学研究中的三个关键问题,并以非神经外胚层器官的干细胞行为为例做进一步的探讨。第一,如何获取干细胞,介绍了包括胚胎干细胞、组织干细胞和诱导性多能干细胞的获得途径,以及若干组织细胞重编程的成功范例;第二,如何将干细胞转化为组织和器官,这需要了解干细胞分化以及形态发生的机制,并以羽毛的形态发生为模型,引入了千细胞拓扑生物学的概念以及干细胞微环境调控塑造器官形态的机制;第三,如何将干细胞及其转化产物置于患者体内,并以鼠毛生长周期波为例,阐明了宏观环境因素如何调控干细胞的活性：最后,还分析了在器官发生中干细胞的自组织对于新生毛发组织工程的重要意义。该文的许多原则不仅限于皮肤,同时也适用于其它体内器官。通过对生物再生的过程的基础研究,我们可以受到生物再生之道的启发,逐渐理解组织修复及再生的机制,并提高分子和细胞水平上的干细胞操作技术,希望在不久的将来将干细胞研究成果应用于临床医学。     

Surface functionalization of inorganic nano-crystals with fibronectin and E-cadherin chimera synergistically accelerates trans-gene delivery into embryonic stem cells

Stem cells holding great promises in regenerative medicine have the potential to be differentiated to a specific cell type through genetic manipulation. However, conventional ways of gene transfer to such progenitor cells suffer from a number of disadvantages particularly involving safety and efficacy issues. Here, we report on the development of a bio-functionalized inorganic nano-carrier of DNA by embedding fibronectin and E-cadherin chimera on the carrier, leading to its high affinity interactions with embryonic stem cell surface and accelerated trans-gene delivery for subsequent expression. While only apatite nano-particles were very inefficient in transfecting embryonic stem cells, fibronectin-anchored particles and to a more significant extent, fibronectin and E-cadherin-Fc-associated particles dramatically enhanced trans-gene delivery with a value notably higher than that of commercially available lipofection system. The involvement of both cell surface integrin and E-cadherin in mediating intracellular localization of the hybrid carrier was verified by blocking integrin binding site with excess free fibronectin and up-regulating both integrin and E-cadherin through PKC activation. Thus, the new establishment of a bio-functional hybrid gene-carrier would promote and facilitate development of stem cell-based therapy in regenerative medicine.