间充质干细胞外泌体对海马星形胶质细胞活化的抑制作用研究

目的 探讨间充质干细胞外泌体(MSC-Exo)对海马星形胶质细胞活化的抑制作用.方法 实验通过超速离心法提取脐带MSC-Exo,并使用PKH-26染料标记;MSC-Exo预处理原代海马星形胶质细胞后使用脂多糖(LPS)诱导细胞活化,并分为对照组、LPS组和LPS+MSC-Exo组,进而行免疫细胞化学检测胶质纤维酸性蛋白...     

Mesenchymal stem cell-derived exosomes: Toward cell-free therapeutic strategies in regenerative medicine

Mesenchymal stem cells (MSCs) are multipotent stem cells with marked potential for regenerative medicine because of their strong immunosuppressive and regenerative abilities. The therapeutic effects of MSCs are based in part on their secretion of biologically active factors in extracellular vesicles known as exosomes. Exosomes have a diameter of 30-100 nm and mediate intercellular communication and material exchange. MSC-derived exosomes (MSC-Exos) have potential for cell-free therapy for diseases of, for instance, the kidney, liver, heart, nervous system, and musculoskeletal system. Hence, MSC-Exos are an alternative to MSC-based therapy for regenerative medicine. We review MSC-Exos and their therapeutic potential for a variety of diseases and injuries.     

Multifunctional role of microRNAs in mesenchymal stem cell-derived exosomes in treatment of diseases

Mesenchymal stem cells can be replaced by exosomes for the treatment of inflammatory diseases, injury repair, degenerative diseases, and tumors. Exosomes are small vesicles rich in a variety of nucleic acids [including messenger RNA, Long non-coding RNA, microRNA (miRNA), and circular RNA], proteins, and lipids. Exosomes can be secreted by most cells in the human body and are known to play a key role in the communication of information and material transport between cells. Like exosomes, miRNAs were neglected before their role in various activities of organisms was discovered. Several studies have confirmed that miRNAs play a vital role within exosomes. This review focuses on the specific role of miRNAs in MSC-derived exosomes (MSC-exosomes) and the methods commonly used by researchers to study miRNAs in exosomes. Taken together, miRNAs from MSC-exosomes display immense potential and practical value, both in basic medicine and future clinical applications, in treating several diseases.     

Immunomodulation by mesenchymal stem cells:Interplay between mesenchymal stem cells and regulatory lymphocytes

Mesenchymal stem cells(MSCs) possess immunomodulatory properties, which confer enormous potential for clinical application. Considerable evidence revealed their efficacy on various animal models of autoimmune diseases, such as multiple sclerosis, systemic lupus erythematosus and uveitis. MSCs elicit their immunomodulatory effects by inhibiting lymphocyte activation and proliferation, forbidding the secretion of proinflammatory cytokines, limiting the function of antigen presenting cells, and inducing regulatory T(Treg) and B(Breg) cells. The induction of Treg and Breg cells is of particular interest since Treg and Breg cells have significant roles in maintaining immune tolerance. Several mechanisms have been proposed regarding to the MSCs-mediated induction of Treg and Breg cells. Accordingly, MSCs induce regulatory lymphocytes through secretion of multiple pleiotropic cytokines, cell-to-cell contact with target cells and modulation of antigen-presenting cells. Here, we summarized how MSCs induce Treg and Breg cells to provoke immunosuppression.     

Neural stem cell transplantation therapy for brain ischemic stroke: Review and perspectives

Brain ischemic stroke is one of the most common causes of death and disability, currently has no efficient therapeutic strategy in clinic. Due to irreversible functional neurons loss and neural tissue injury, stem cell transplantation may be the most promising treatment approach. Neural stem cells (NSCs) as the special type of stem cells only exist in the nervous system, can differentiate into neurons, astrocytes, and oligodendrocytes, and have the abilities to compensate insufficient endogenous nerve cells and improve the inflammatory microenvironment of cell survival. In this review, we focused on the important role of NSCs therapy for brain ischemic stroke, mainly introduced the methods of optimizing the therapeutic efficacy of NSC transplantation, such as transfection and overexpression of specific genes, pretreatment of NSCs with inflammatory factors, and co-transplantation with cytokines. Next, we discussed the potential problems of NSC transplantation which seriously limited their rapid clinical transformation and application. Finally, we expected a new research topic in the field of stem cell research. Based on the bystander effect, exosomes derived from NSCs can overcome many of the risks and difficulties associated with cell therapy. Thus, as natural seed resource of nervous system, NSCs-based cell-free treatment is a newly therapy strategy, will play more important role in treating ischemic stroke in the future.     

Mesenchymal stem cells from different sources and their derived exosomes: A pre-clinical perspective

Since the introduction of cell therapy as a strategy for the treatment of many diseases, mesenchymal stem cells have emerged as ideal candidates, yet the underlying mechanisms of their beneficial effects are only partially understood.At the start of the 21 st century, a paracrine effect was proposed as a mechanism of tissue repair by these cells. In addition, a role was suggested for a heterogeneous population of extracellular vesicles in cell-to-cell communication.Some of these vesicles including exosomes have been isolated from most fluids and cells, as well as from supernatants of in vitro cell cultures. Recent research in the field of regenerative medicine suggests that exosomes derived from mesenchymal stem cells could be a powerful new therapeutic tool. This review examines the therapeutic potential of these exosomes obtained from the sources most used in cell therapy: bone marrow, adipose tissue, and umbilical cord.     

Disagreements in the therapeutic use of mesenchymal stem cell-derived secretome

In a recent article, the authors provide a detailed summary of the characteristics and biological functions of mesenchymal stem cells (MSCs), as well as a discussion on the potential mechanisms of action of MSC-based therapies. They describe the morphology, biogenesis, and current isolation techniques of exosomes, one of the most important fractions of the MSC-derived secretome. They also summarize the characteristics of MSC-derived exosomes and highlight their functions and therapeutic potential for tissue/organ regeneration and for kidney, liver, cardiovascular, neurological, and musculoskeletal diseases, as well as cutaneous wound healing. Despite the fact that MSCs are regarded as an important pillar of regenerative medicine, their regenerative potential has been demonstrated to be limited in a number of pathological conditions. The negative effects of MSC-based cell therapy have heightened interest in the therapeutic use of MSC-derived secretome. On the other hand, MSC-derived exosomes and microvesicles possess the potential to have a significant impact on disease development, including cancer. MSCs can interact with tumor cells and promote mutual exchange and induction of cellular markers by exchanging secretome. Furthermore, enzymes secreted into and activated within exosomes can result in tumor cells acquiring new properties. As a result, therapeutic applications of MSC-derived secretomes must be approached with extreme caution.     

Mesenchymal stem cell-derived exosomes: A novel and potential remedy for cutaneous wound healing and regeneration

Poor healing of cutaneous wounds is a common medical problem in the field of traumatology. Due to the intricate pathophysiological processes of wound healing, the use of conventional treatment methods, such as chemical molecule drugs and traditional dressings, have been unable to achieve satisfactory outcomes. Within recent years, explicit evidence suggests that mesenchymal stem cells (MSCs) have great therapeutic potentials on skin wound healing and regeneration. However, the direct application of MSCs still faces many challenges and difficulties. Intriguingly, exosomes as cell-secreted granular vesicles with a lipid bilayer membrane structure and containing specific components from the source cells may emerge to be excellent substitutes for MSCs. Exosomes derived from MSCs (MSC-exosomes) have been demonstrated to be beneficial for cutaneous wound healing and accelerate the process through a variety of mechanisms. These mechanisms include alleviating inflammation, promoting vascularization, and promoting proliferation and migration of epithelial cells and fibroblasts. Therefore, the application of MSC-exosomes may be a promising alternative to cell therapy in the treatment of cutaneous wounds and could promote wound healing through multiple mechanisms simultaneously. This review will provide an overview of the role and the mechanisms of MSC-derived exosomes in cutaneous wound healing, and elaborate the potentials and future perspectives of MSC-exosomes application in clinical practice.     

间充质干细胞外泌体在阿尔兹海默症治疗中的研究进展

阿尔兹海默症（AD）是一种病理机制复杂,以进行性认知功能障碍为主的中枢神经系统疾病,目前仍缺乏有效的治疗方法。多项研究结果显示,间充质干细胞（MSCs）外泌体能够促进抗炎、调节免疫功能、加强Aβ降解、促进神经细胞轴突生长等,能很好地针对AD的核心病理机制发挥效果从而达到治疗效果。本文主要介绍MSCs外泌体在各项AD病理机制治疗中的研究进展。     

间充质干细胞来源的外泌体在炎症性肠病治疗中的作用机制及应用前景

炎症性肠病(IBD)是一种原因不明的非特异性肠道疾病,其发病率逐年提高,目前治疗药物疗效有限。间充质干细胞(MSCs)具有免疫调节、抗炎等功能,有望成为IBD的新兴治疗手段。然而MSCs因归巢能力有限,目前认为其可能通过旁分泌发挥治疗作用。MSCs分泌的外泌体(MSCs-Exo)具有MSCs的大部分功能,无恶性分化且在体内稳定存在,在干细胞治疗领域具有重要研究价值,但其在IBD中的作用机制尚不明确。本文将就MSCs-Exo对IBD的作用机制以及在IBD中的应用前景进行综述。     

Methods to produce induced pluripotent stem cell-derived mesenchymal stem cells: Mesenchymal stem cells from induced pluripotent stem cells

Mesenchymal stem cells (MSCs) have received significant attention in recent years due to their large potential for cell therapy. Indeed, they secrete a wide variety of immunomodulatory factors of interest for the treatment of immune-related disorders and inflammatory diseases. MSCs can be extracted from multiple tissues of the human body. However, several factors may restrict their use for clinical applications: the requirement of invasive procedures for their isolation, their limited numbers, and their heterogeneity according to the tissue of origin or donor. In addition, MSCs often present early signs of replicative senescence limiting their expansion in vitro, and their therapeutic capacity in vivo. Due to the clinical potential of MSCs, a considerable number of methods to differentiate induced pluripotent stem cells (iPSCs) into MSCs have emerged. iPSCs represent a new reliable, unlimited source to generate MSCs (MSCs derived from iPSC, iMSCs) from homogeneous and well-characterized cell lines, which would relieve many of the above mentioned technical and biological limitations. Additionally, the use of iPSCs prevents some of the ethical concerns surrounding the use of human embryonic stem cells. In this review, we analyze the main current protocols used to differentiate human iPSCs into MSCs, which we classify into five different categories: MSC Switch, Embryoid Body Formation, Specific Differentiation, Pathway Inhibitor, and Platelet Lysate. We also evaluate common and method-specific culture components and provide a list of positive and negative markers for MSC characterization. Further guidance on material requirements to produce iMSCs with these methods and on the phenotypic features of the iMSCs obtained is added. The information may help researchers identify protocol options to design and/or refine standardized procedures for large-scale production of iMSCs fitting clinical demands.     

Stem cell-derived exosomes as a therapeutic tool for cardiovascular disease

Mesenchymal stem cells(MSCs) have been used to treat patients suffering from acute myocardial infarction(AMI) and subsequent heart failure. Although it was originally assumed that MSCs differentiated into heart cells such as cardiomyocytes, recent evidence suggests that the differentiation capacity of MSCs is minimal and that injected MSCs restore cardiac function via the secretion of paracrine factors. MSCs secrete paracrine factors in not only naked forms but also membrane vesicles including exosomes containing bioactive substances such as proteins, messenger RNAs, and microR NAs. Although the details remain unclear, these bioactive molecules are selectively sorted in exosomes that are then released from donor cells in a regulated manner. Furthermore, exosomes are specifically internalized by recipient cells via ligand-receptor interactions. Thus, exosomes are promising natural vehicles that stably and specifically transport bioactive molecules to recipient cells. Indeed, stem cell-derived exosomes have been successfully used to treat cardiovascular disease(CVD), such as AMI, stroke, and pulmonary hypertension, in animal models, and their efficacy has been demonstrated. Therefore, exosome administration may be a promising strategy for the treatment of CVD. Furthermore, modifications of exosomal contents may enhance their therapeutic effects. Future clinical studies are required to confirm the efficacy of exosome treatment for CVD.     

Recovery of neurological function of ischemic stroke by application of conditioned medium of bone marrow mesenchymal stem cells derived from normal and cerebral ischemia rats

Background

Several lines of evidence have demonstrated that bone marrow-derived mesenchymal stem cells (BM-MSC) release bioactive factors and provide neuroprotection for CNS injury. However, it remains elusive whether BM-MSC derived from healthy donors or stroke patients provides equal therapeutic potential. The present work aims to characterize BM-MSC prepared from normal healthy rats (NormBM-MSC) and cerebral ischemia rats (IschBM-MSC), and examine the effects of their conditioned medium (Cm) on ischemic stroke animal model.

Results

Isolated NormBM-MSC or IschBM-MSC formed fibroblastic like morphology and expressed CD29, CD90 and CD44 but failed to express the hematopoietic marker CD34. The number of colony formation of BM-MSC was more abundant in IschBM-MSC than in NormBM-MSC. This is in contrast to the amount of Ficoll-fractionated mononuclear cells from normal donor and ischemic rats. The effect of cm of BM-MSC was further examined in cultures and in middle cerebral artery occlusion (MCAo) animal model. Both NormBM-MSC Cm and IschBM-MSC Cm effectively increased neuronal connection and survival in mixed neuron-glial cultures. In vivo, intravenous infusion of NormBM-MSC Cm and IschBM-MSC Cm after stroke onset remarkably improved functional recovery. Furthermore, NormBM-MSC Cm and IschBM-MSC Cm increased neurogenesis and attenuated microglia/ macrophage infiltration in MCAo rat brains.

Conclusions

Our data suggest equal effectiveness of BM-MSC Cm derived from ischemic animals or from a normal population. Our results thus revealed the potential of BM-MSC Cm on treatment of ischemic stroke.     

The bad and the good of mesenchymal stem cells in cancer: Boosters of tumor growth and vehicles for targeted delivery of anticancer agents

In cancer biology, mesenchymal stem cells (MSCs) display aspects that can appear contradictory. On one hand, these cells possess several features which give them the ability to specifically target and then sustain cancer cells in their ability to survive the multifaceted host response against cancer. On the other hand, due to this excellent aptitude to home-in on tumor tissues, regardless their location in the host's body, MSCs are considered to be extremely selective vehicles to reach cancer cells specifically. Recently, MSC sustainment of cancer cell growth is a hot research topic. Indeed, these cells are known to sustain tumor angiogenesis and metastasis formation, to create a microenvironment favorable for cancer cell growth and to down-modulate the immune system capabilities in the host organism. On the other hand, since scientists became able to take advantage of their extremely selective capability to target cancer cells, MSCs are now also thought of in a different light. Indeed, MSCs are now considered a promising vehicle for local expression or delivery of even particularly toxic anticancer agents, ranging from Herpes Simplex Virus to locally-acting antineoplastic drugs. On this basis, investigation is now focused on how to impair the pro-neoplastic features of MSCs on one hand whilst taking advantage of their specific tropism toward cancer cells, on the other. As with the two faces of Janus, this review will concisely explore the research activity in these two apparently conflicting fields.     

Exosomes for drug delivery — a novel application for the mesenchymal stem cell

Exosomes are the most extensively characterized class of secreted membrane vesicles that carry proteins and RNAs for intercellular communication. They are increasingly seen as possible alternatives to liposomes as drug delivery vehicles. Like liposomes, they could deliver their cargo across the plasma membrane and provide a barrier against premature transformation and elimination. In addition, these naturally-occurring secreted membrane vesicles are less toxic and better tolerated in the body as evidenced by their ubiquitous presence in biological fluids, and have an intrinsic homing ability. They are also amenable to in vivo and in vitro loading of therapeutic agents, and membrane modifications to enhance tissue-specific homing. Here we propose human mesenchymal stem cells as the ideal cell source of exosomes for drug delivery. Mesenchymal stem cell transplantation for various disease indications has been extensively tested and shown to be safe in numerous clinical trials. These cells are also prolific producers of immunologically inert exosomes. Immortalization of these cells does not compromise the quantity or quality of exosome production, thus enabling infinite and reproducible exosome production from a single cell clone.