Mesenchymal stem cell exosomes

Post isolation modification of exosomes for nanomedicine applications

Exosomes are extracellular nanovesicles. They innately possess ideal structural and biocompatible nanocarrier properties. Exosome components can be engineered at the cellular level. Alternatively, when exosome source cells are unavailable for customized exosome production, exosomes derived from a variety of biological origins can be modified post isolation which is the focus of this article. Modification of exosome surface structures allows for exosome imaging and tracking in vivo. Exosome membranes can be loaded with hydrophobic therapeutics to increase drug stability and efficacy. Hydrophilic therapeutics such as RNA can be encapsulated in exosomes to improve cellular delivery. Despite advances in post isolation exosome modification strategies, many challenges to effectively harnessing their therapeutic potential remain. Future topics of exploration include: matching exosome subtypes with nanomedicine applications, optimizing exosomal nanocarrier formulation and investigating how modified exosomes interface with the immune system. Research into these areas will greatly facilitate personalized exosome-based nanomedicine endeavors.

In vitro models for assessing therapeutic angiogenesis

Arterial obstruction leading to ischemia causes a reduction of oxygen and nutrient supply to distal tissues. The physiological response to tissue ischemia triggers a cascade of events that results in the development of accessory vasculature to increase local tissue perfusion and to salvage tissue. However, this adaptive mechanism of repair is suboptimal in some patients. Therapeutic angiogenesis aims to stimulate new blood vessel formation via the local administration of proangiogenic agents or cell therapy products (CTPs). In this review, we provide a summary of the current understanding of in vitro models for assessing the angiogenic potential of a product.

Evidence-Based Clinical Use of Nanoscale Extracellular Vesicles in Nanomedicine

Recent research has demonstrated that all body fluids assessed contain substantial amounts of vesicles that range in size from 30 to 1000 nm and that are surrounded by phospholipid membranes containing different membrane microdomains such as lipid rafts and caveolae. The most prominent representatives of these so-called extracellular vesicles (EVs) are nanosized exosomes (70-150 nm), which are derivatives of the endosomal system, and microvesicles (100-1000 nm), which are produced by outward budding of the plasma membrane. Nanosized EVs are released by almost all cell types and mediate targeted intercellular communication under physiological and pathophysiological conditions. Containing cell-type-specific signatures, EVs have been proposed as biomarkers in a variety of diseases. Furthermore, according to their physical functions, EVs of selected cell types have been used as therapeutic agents in immune therapy, vaccination trials, regenerative medicine, and drug delivery. Undoubtedly, the rapidly emerging field of basic and applied EV research will significantly influence the biomedicinal landscape in the future. In this Perspective, we, a network of European scientists from clinical, academic, and industry settings collaborating through the H2020 European Cooperation in Science and Technology (COST) program European Network on Microvesicles and Exosomes in Health and Disease (ME-HAD), demonstrate the high potential of nanosized EVs for both diagnostic and therapeutic (i.e., theranostic) areas of nanomedicine.

Extracellular vesicles derived from mesenchymal stromal cells: a therapeutic option in respiratory diseases?

Extracellular vesicles (EVs) are plasma membrane-bound fragments released from several cell types, including mesenchymal stromal cells (MSCs), constitutively or under stimulation. EVs derived from MSCs and other cell types transfer molecules (such as DNA, proteins/peptides, mRNA, microRNA, and lipids) and/or organelles with reparative and anti-inflammatory properties to recipient cells. The paracrine anti-inflammatory effects promoted by MSC-derived EVs have attracted significant interest in the regenerative medicine field, including for potential use in lung injuries. In the present review, we describe the characteristics, biological activities, and mechanisms of action of MSC-derived EVs. We also review the therapeutic potential of EVs as reported in relevant preclinical models of acute and chronic respiratory diseases, such as pneumonia, acute respiratory distress syndrome, asthma, and pulmonary arterial hypertension. Finally, we discuss possible approaches for potentiating the therapeutic effects of MSC-derived EVs so as to enable use of this therapy in clinical practice.

Harnessing the Angiogenic Potential of Stem Cell-Derived Exosomes for Vascular Regeneration

Mesenchymal stem cells (MSCs) are known to display important regenerative properties through the secretion of proangiogenic factors. Recent evidence pointed at the key role played by exosomes released from MSCs in this paracrine mechanism. Exosomes are key mediators of intercellular communication and contain a cargo that includes a modifiable content of microRNA (miRNA), mRNA, and proteins. Since the biogenesis of the MSCs-derived exosomes is regulated by the cross talk between MSCs and their niche, the content of the exosomes and consequently their biological function are dependent on the cell of origin and the physiologic or pathologic status of their microenvironment. Recent preclinical studies revealed that MSCs-derived exosomes have a critical implication in the angiogenic process since the use of exosomes-depleted conditioned medium impaired the MSCs angiogenesis response. In this review, we discuss the current knowledge related to the angiogenic potential of MSCs-exosomes and methods to enhance their biological activities for improved vascular regeneration. The current gain of insight in exosomes studies highlights the power of combining cell based therapies and their secreted products in therapeutic angiogenesis.

Development and regulation of exosome-based therapy products

Recently, various innovative therapies involving the ex vivo manipulation and subsequent reintroduction of exosome-based therapeutics into humans have been developed and validated, although no exosome-based therapeutics have yet to be brought into the clinic. Exosomes are nanosized vesicles secreted by many cells that utilize them for cell-to-cell communications to facilitate transport of proteins and genetic material. Comprised of cellular membranes with multiple adhesive proteins on their surface, exosomes offer distinct advantages that exceptionally position them as highly effective drug carriers. Additionally, exosomes can exert unique biological activity reflective of their origin that may be used for therapy of various diseases. In fact, exosomes have benefits of both synthetic nanocarriers and cell-mediated drug delivery systems, and avoid their limitations. This concise review highlights the recent developments in exosome-based drug delivery systems and the main regulatory considerations for using this type of therapeutic in clinic. WIREs Nanomed Nanobiotechnol 2016, 8:744-757. doi: 10.1002/wnan.1395 For further resources related to this article, please visit the WIREs website.

Mesenchymal Stem Cell-Derived Extracellular Vesicles Promote Angiogenesis: Potencial Clinical Application

Mesenchymal stem cells (MSCs) are adult multipotent stem cells that are able to differentiate into multiple specialized cell types including osteocytes, adipocytes, and chondrocytes. MSCs exert different functions in the body and have recently been predicted to have a major clinical/therapeutic potential. However, the mechanisms of self-renewal and tissue regeneration are not completely understood. It has been shown that the biological effect depends mainly on its paracrine action. Furthermore, it has been reported that the secretion of soluble factors and the release of extracellular vesicles, such as exosomes, could mediate the cellular communication to induce cell-differentiation/self-renewal. This review provides an overview of MSC-derived exosomes in promoting angiogenicity and of the clinical relevance in a therapeutic approach.

Mesenchymal stem cell-derived exosomes from different sources selectively promote neuritic outgrowth

Mesenchymal stem cells (MSCs) obtained from bone marrow (BM) have been shown to promote neuronal growth and survival. However, the comparative effects of MSCs of different sources, including menstrual MSCs (MenSCs), BM, umbilical cord and chorion stem cells on neurite outgrowth have not yet been explored. Moreover, the modulatory effects of MSCs may be mediated by paracrine mechanisms, i.e. by molecules contained in the MSC secretome that includes soluble factors and extracellular vesicles such as microvesicles and/or exosomes. The biogenesis of microvesicles, characterized by a vesicle diameter of 50 to 1000 nm, involves membrane shedding while exosomes, of 30 to 100 nm in diameter, originate in the multivesicular bodies within cells. Both vesicle types, which can be harvested from the conditioned media of cell cultures by differential centrifugation steps, regulate the function of target cells due to their molecular content of microRNA, mRNA, proteins and lipids. Here, we compared the effect of human menstrual MSCs (MenSCs) mediated by cell-cell contact, by their total secretome or by secretome-derived extracellular vesicles on neuritic outgrowth in primary neuronal cultures. The contact of MenSCs with cortical neurons inhibited neurite outgrowth while their total secretome enhanced it. The extracellular vesicle fractions showed a distinctive effect: while the exosome-enriched fraction enhanced neurite outgrowth, the microvesicle-enriched fraction displayed an inhibitory effect. When we compared exosome fractions of different human MSC sources, MenSC exosomes showed superior effects on the growth of the longest neurite in cortical neurons and had a comparable effect to BM-SC exosomes on neurite outgrowth in dorsal root ganglia neurons. Thus, the growth-stimulating effects of exosomes derived from MenSCs as well as the opposing effects of both extracellular vesicle fractions provide important information regarding the potential use of MenSCs as therapeutic conveyors in neurodegenerative pathologies.

Human urinary exosome proteome unveils its aerobic respiratory ability

Exosomes are 40-100-nm vesicles released by most cell types after fusion of multivesicular endosomes with the plasma membrane. Exosomes, ubiquitary in body fluids including urines, contain proteins and RNA species specific of the tissue of origin. Exosomes from urine have been extensively studied as a promising reservoir for disease biomarkers. Here, we report the proteome analysis of urinary exosomes compared to urinoma, studied by Orbitrap mass spectrometry. A discovery approach was utilized on the sample. 3429 proteins were present, with minimal overlapping among exosome and urinoma. 959 proteins (28%) in exosome and 1478 proteins (43%) in urinoma were exclusively present in only one group. By cytoscape analysis, the biological process gene ontology was correlated to their probability (P ≤ 0.05) to be functional. This was never studied before and showed a significant clustering around metabolic functions, in particular to aerobic ATP production. Urinary exosomes carry out oxidative phosphorylation, being able to synthesize ATP and consume oxygen. A previously unsuspected function emerges for human urinary exosomes as bioactive vesicles that consume oxygen to aerobically synthesize ATP. Determination of normal human urine proteome can help generate the healthy urinary protein database for comparison, useful for various renal diseases.

BIOLOGICAL SIGNIFICANCE

The findings reported represent a significant advance in the understanding of the healthy human urinary proteome. The methodology utilized to analyze the collection of proteomic data allowed the assessment of the unique composition of urinary exosomes with respect to urinoma and to elucidate the presence in the former of molecular pathways previously unknown. The paper has the potential to impact its field of research, due to the biological relevance of the metabolic capacity of urinary exosomes, which may represent their important general feature.

Exosomes as Novel Regulators of Adult Neurogenic Niches

Adult neurogenesis has been convincingly demonstrated in two regions of the mammalian brain: the sub-granular zone (SGZ) of the dentate gyrus (DG) in the hippocampus, and the sub-ventricular zone (SVZ) of the lateral ventricles (LV). SGZ newborn neurons are destined to the granular cell layer (GCL) of the DG, while new neurons from the SVZ neurons migrate rostrally into the olfactory bulb (OB). The process of adult neurogenesis persists throughout life and is supported by a pool of neural stem cells (NSCs), which reside in a unique and specialized microenvironment known as "neurogenic niche". Neurogenic niches are structured by a complex organization of different cell types, including the NSC-neuron lineage, glial cells and vascular cells. Thus, cell-to-cell communication plays a key role in the dynamic modulation of homeostasis and plasticity of the adult neurogenic process. Specific cell-cell contacts and extracellular signals originated locally provide the necessary support and regulate the balance between self-renewal and differentiation of NSCs. Furthermore, extracellular signals originated at distant locations, including other brain regions or systemic organs, may reach the niche through the cerebrospinal fluid (CSF) or the vasculature and influence its nature. The role of several secreted molecules, such as cytokines, growth factors, neurotransmitters, and hormones, in the biology of adult NSCs, has been systematically addressed. Interestingly, in addition to these well-recognized signals, a novel type of intercellular messengers has been identified recently: the extracellular vesicles (EVs). EVs, and particularly exosomes, are implicated in the transfer of mRNAs, microRNAs (miRNAs), proteins and lipids between cells and thus are able to modify the function of recipient cells. Exosomes appear to play a significant role in different stem cell niches such as the mesenchymal stem cell niche, cancer stem cell niche and pre-metastatic niche; however, their roles in adult neurogenic niches remain virtually unexplored. This review focuses on the current knowledge regarding the functional relationship between cellular and extracellular components of the adult SVZ and SGZ neurogenic niches, and the growing evidence that supports the potential role of exosomes in the physiology and pathology of adult neurogenesis.

Exosomes: From Functions in Host-Pathogen Interactions and Immunity to Diagnostic and Therapeutic Opportunities

Since their first description in the 1980s, exosomes, small endosomal-derived extracellular vesicles, have been involved in innate and adaptive immunity through modulating immune responses and mediating antigen presentation. Increasing evidence has reported the role of exosomes in host-pathogen interactions and particularly in the activation of antimicrobial immune responses. The growing interest concerning exosomes in infectious diseases, their accessibility in various body fluids, and their capacity to convey a rich content (e.g., proteins, lipids, and nucleic acids) to distant recipient cells led the scientific community to consider the use of exosomes as potential new diagnostic and therapeutic tools. In this review, we summarize current understandings of exosome biogenesis and their composition and highlight the function of exosomes as immunomodulators in pathological states such as in infectious disorders. The potential of using exosomes as diagnostic and therapeutic tools is also discussed.

Exosomes from human mesenchymal stem cells conduct aerobic metabolism in term and preterm newborn infants

Exosomes are secreted nanovesicles that are able to transfer RNA and proteins to target cells. The emerging role of mesenchymal stem cell (MSC) exosomes as promoters of aerobic ATP synthesis restoration in damaged cells, prompted us to assess whether they contain an extramitochondrial aerobic respiration capacity. Exosomes were isolated from culture medium of human MSCs from umbilical cord of ≥37-wk-old newborns or between 28- to 30-wk-old newborns (i.e.,term or preterm infants). Characterization of samples was conducted by cytofluorometry. Oxidative phosphorylation capacity was assessed by Western blot analysis, oximetry, and luminometric and fluorometric analyses. MSC exosomes express functional respiratory complexes I, IV, and V, consuming oxygen. ATP synthesis was only detectable in exosomes from term newborns, suggestive of a specific mechanism that is not completed at an early gestational age. Activities are outward facing and comparable to those detected in mitochondria isolated from term MSCs. MSC exosomes display an unsuspected aerobic respiratory ability independent of whole mitochondria. This may be relevant for their ability to rescue cell bioenergetics. The differential oxidative metabolism of pretermvs.term exosomes sheds new light on the preterm newborn's clinical vulnerability. A reduced ability to repair damaged tissue and an increased capability to cope with anoxic environment for preterm infants can be envisaged.-Panfoli, I., Ravera, S., Podestà, M., Cossu, C., Santucci, L., Bartolucci, M., Bruschi, M., Calzia, D., Sabatini, F., Bruschettini, M., Ramenghi, L. A., Romantsik, O., Marimpietri, D., Pistoia, V., Ghiggeri, G., Frassoni, F., Candiano, G. Exosomes from human mesenchymal stem cells conduct aerobic metabolism in term and preterm newborn infants.

Exosomes and Their Therapeutic Potentials of Stem Cells

Exosomes, a group of vesicles originating from the multivesicular bodies (MVBs), are released into the extracellular space when MVBs fuse with the plasma membrane. Numerous studies indicate that exosomes play important roles in cell-to-cell communication, and exosomes from specific cell types and conditions display multiple functions such as exerting positive effects on regeneration in many tissues. It is widely accepted that the therapeutic potential of stem cells may be mediated largely by the paracrine factors, so harnessing the paracrine effects of stem and progenitor cells without affecting these living, replicating, and potentially pluripotent cell populations is an advantage in terms of safety and complexity. Ascending evidence indicated that exosomes might be the main components of paracrine factors; thus, understanding the role of exosomes in each subtype of stem cells is far-reaching. In this review, we discuss the functions of exosomes from different types of stem cells and emphasize the therapeutic potentials of exosomes, providing an alternative way of developing strategies to cure diseases.

Therapeutic application of mesenchymal stem cells in osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is a degenerative disease characterized by cartilage degradation and subchondral bone alterations. This disease represents a global public health problem whose prevalence is rapidly growing with the increasing aging of the population. With the discovery of mesenchymal stem cells (MSC) as possible therapeutic agents, their potential for repairing cartilage damage in OA is under investigation.

AREAS COVERED

Characterization of MSCs and their functional properties are mentioned with an insight into their trophic function and secretory profile. We present a special focus on the types of extracellular vesicles (EVs) that are produced by MSCs and their role in the paracrine activity of MSCs. We then discuss the therapeutic approaches that have been evaluated in pre-clinical models of OA and the results coming out from the clinical trials in patients with OA.

EXPERT OPINION

MSC-based therapy seems a promising approach for the treatment of patients with OA. Further research is still needed to demonstrate their efficacy in clinical trials using controlled, prospective studies. However, the emergence of MSC-derived EVs as possible therapeutic agents could be an alternative to cell-based therapy.

The potential of mesenchymal stem cells in the management of radiation enteropathy

Although radiotherapy is effective in managing abdominal and pelvic malignant tumors, radiation enteropathy is still unavoidable. This disease severely affects the quality of life of cancer patients due to some refractory lesions, such as intestinal ischemia, mucositis, ulcer, necrosis or even perforation. Current drugs or prevailing therapies are committed to alleviating the symptoms induced by above lesions. But the efficacies achieved by these interventions are still not satisfactory, because the milieus for tissue regeneration are not distinctly improved. In recent years, regenerative therapy for radiation enteropathy by using mesenchymal stem cells is of public interests. Relevant results of preclinical and clinical studies suggest that this regenerative therapy will become an attractive tool in managing radiation enteropathy, because mesenchymal stem cells exhibit their pro-regenerative potentials for healing the injuries in both epithelium and endothelium, minimizing inflammation and protecting irradiated intestine against fibrogenesis through activating intrinsic repair actions. In spite of these encouraging results, whether mesenchymal stem cells promote tumor growth is still an issue of debate. On this basis, we will discuss the advances in anticancer therapy by using mesenchymal stem cells in this review after analyzing the pathogenesis of radiation enteropathy, introducing the advances in managing radiation enteropathy using regenerative therapy and exploring the putative actions by which mesenchymal stem cells repair intestinal injuries. At last, insights gained from the potential risks of mesenchymal stem cell-based therapy for radiation enteropathy patients may provide clinicians with an improved awareness in carrying out their studies.

Therapeutic Potential of Multipotent Mesenchymal Stromal Cells and Their Extracellular Vesicles

The therapeutic potential of mesenchymal stromal cells (MSCs) is evident by the number of new and ongoing trials targeting an impressive variety of conditions. In bone and cartilage repair, MSCs are expected to replace the damaged tissue, while in other therapies they modulate a therapeutic response by the secretion of bioactive molecules. MSCs possess a phenotypic plasticity and harbor an arsenal of bioactive molecules that can be released upon sensing signals in the local milieu either directly or packaged in extracellular vesicles (EVs). The reported paracrine effects comprise many of the important functions of MSCs, including supporting hematopoietic stem cells in the bone marrow, promoting angiogenesis, and modulating the immune system. The major drawback in MSC therapy is the incomplete understanding of cell fate following systemic administration as well as the mechanisms by which these cells correct disease. In this review we discuss what is known about MSC engraftment, hemocompatibility, and immunomodulation, as well as the potential of bringing the MSC-EV field toward a clinical translation.

Stem Cells and Regenerative Medicine: Myth or Reality of the 21th Century

Since the 1960s and the therapeutic use of hematopoietic stem cells of bone marrow origin, there has been an increasing interest in the study of undifferentiated progenitors that have the ability to proliferate and differentiate into various tissues. Stem cells (SC) with different potency can be isolated and characterised. Despite the promise of embryonic stem cells, in many cases, adult or even fetal stem cells provide a more interesting approach for clinical applications. It is undeniable that mesenchymal stem cells (MSC) from bone marrow, adipose tissue, or Wharton's Jelly are of potential interest for clinical applications in regenerative medicine because they are easily available without ethical problems for their uses. During the last 10 years, these multipotent cells have generated considerable interest and have particularly been shown to escape to allogeneic immune response and be capable of immunomodulatory activity. These properties may be of a great interest for regenerative medicine. Different clinical applications are under study (cardiac insufficiency, atherosclerosis, stroke, bone and cartilage deterioration, diabetes, urology, liver, ophthalmology, and organ's reconstruction). This review focuses mainly on tissue and organ regeneration using SC and in particular MSC.

Using exosomes, naturally-equipped nanocarriers, for drug delivery

Exosomes offer distinct advantages that uniquely position them as highly effective drug carriers. Comprised of cellular membranes with multiple adhesive proteins on their surface, exosomes are known to specialize in cell-cell communications and provide an exclusive approach for the delivery of various therapeutic agents to target cells. In addition, exosomes can be amended through their parental cells to express a targeting moiety on their surface, or supplemented with desired biological activity. Development and validation of exosome-based drug delivery systems are the focus of this review. Different techniques of exosome isolation, characterization, drug loading, and applications in experimental disease models and clinic are discussed. Exosome-based drug formulations may be applied to a wide variety of disorders such as cancer, various infectious, cardiovascular, and neurodegenerative disorders. Overall, exosomes combine benefits of both synthetic nanocarriers and cell-mediated drug delivery systems while avoiding their limitations.

Adipose-Derived Mesenchymal Stem Cells Transplantation Alleviates Renal Injury in Streptozotocin-Induced Diabetic Nephropathy

Previous studies have illustrated that bone marrow-derived mesenchymal stem cell (BMMSC) transplantation has therapeutic effects on diabetes and can prevent mice from renal damage and diabetic nephropathy (DN). Moreover, adipose-derived MSCs possess similar characteristics to BMMSCs. We investigated the effect of ADMSC transplantation on streptozotocin (STZ)-induced renal injury. Diabetes was induced in rats by STZ injection. After ADMSC treatment, renal histological changes and cell apoptosis were evaluated as were the expression of apoptosis-related proteins, Wnt/β-catenin pathway members, and klotho levels. We found that ADMSCs improved renal histological changes. Next, NRK-52E cells were exposed to normal glucose (NG; 5.5 mM glucose plus 24.5 mM mannitol)/high glucose (HG) or ADMSCs, and then measured for changes in the aforementioned proteins. Similarly, changes in these proteins were also determined following transient transfection of klotho siRNA. We found that both ADMSC transplantation and co-incubation reduced the rate of cellular apoptosis, decreased Bax and Wnt/β-catenin levels, and elevated Bcl-2 and klotho levels. Interestingly, klotho knockdown reversed the effects of ADMSCs on the expression of apoptosis-related proteins and Wnt/β-catenin pathway members. Taken together, ADMSCs transplantation might attenuate renal injury in DN via activating klotho and inhibiting the Wnt/β-catenin pathway. This study may provide evidence for the treatment of DN using ADMSCs.

Therapeutic Potential of Differentiated Mesenchymal Stem Cells for Treatment of Osteoarthritis

Osteoarthritis (OA) is a chronic, progressive, and irreversible degenerative joint disease. Conventional OA treatments often result in complications such as pain and limited activity. However, transplantation of mesenchymal stem cells (MSCs) has several beneficial effects such as paracrine effects, anti-inflammatory activity, and immunomodulatory capacity. In addition, MSCs can be differentiated into several cell types, including chondrocytes, osteocytes, endothelia, and adipocytes. Thus, transplantation of MSCs is a suggested therapeutic tool for treatment of OA. However, transplanted naïve MSCs can cause problems such as heterogeneous populations including differentiated MSCs and undifferentiated cells. To overcome this problem, new strategies for inducing differentiation of MSCs are needed. One possibility is the application of microRNA (miRNA) and small molecules, which regulate multiple molecular pathways and cellular processes such as differentiation. Here, we provide insight into possible strategies for cartilage regeneration by transplantation of differentiated MSCs to treat OA patients.