Human mesenchymal stem cell-conditioned medium improves cardiac function following myocardial infarction

Systemic delivery of mesenchymal stem cells condition media in repeated doses acts as magic bullets in restoring IFN-γ/IL-4 balance in asthmatic rats

AIMS

With respect to recent advantage in stem cell application, given the concern reported previously after stem cell transplantation, mesenchymal stem cell-derived conditioned media (MSC-CM) could be a potential approach to guarantee more safety and efficient outcomes than the current stem cell-based regenerative therapies.

MAIN METHODS

Male rats were assigned into four experimental groups (n = 6); healthy rats (C group), OVA sensitized rats (S group), OVA sensitized rats received a single dose of 50 μl CM intravenously (S group + SD-CM) and OVA sensitized rats received repeated doses of 50 μl CM intravenously (S group + RD-CM). Two weeks post-allergen challenge, the therapeutic effects of systemic administrated CM in single and repeated dosages were investigated by monitoring the transcription of T-bet, GATA-3, IL-4 and IFN-γ genes along with pathological changes in asthmatic lung tissue. IL-4 and IFN-γ levels and IFN-γ/IL-4 ratio were further evaluated in sera.

KEY FINDINGS

Our data revealed that the systemic introduction of CM in repeated dosages could significantly reduce pathological injures in OVA-sensitized rats by the modulation of expression of T-bet and GATA-3 in lung tissues and interleukins levels (p < 0.001 to p < 0.05). In contrary, CM in single dosage did not yield any beneficial effect.

SIGNIFICANCE

Overall, we indicated that systemic administration of CM in repeated dosages, but not in single dose, could be strategic approach in amelioration of asthmatic changes, presumably by the regulating the differentiation of naive CD4 T cells into Th1/Th2 effector cells via modulation of T-bet and GATA-3 expression in OVA-sensitized male rats.

miRNA-based therapeutic potential of stem cell-derived extracellular vesicles: a safe cell-free treatment to ameliorate radiation-induced brain injury

PURPOSE

This review compiles what is known about extracellular vesicles (EVs), their bioactive cargo, and how they might be used to treat radiation-induced brain injury. Radiotherapy (RT) is effective in cancer treatment, but can cause substantial damage to normal central nervous system tissue. Stem cell therapy has been shown to be effective in treating cognitive dysfunction arising from RT, but there remain safety concerns when grafting foreign stem cells into the brain (i.e. immunogenicity, teratoma). These limitations prompted the search for cell-free alternatives, and pointed to EVs that have been shown to have similar ameliorating effects in other tissues and injury models.

CONCLUSIONS

EVs are nano-scale and lipid-bound vesicles that readily pass the blood-brain barrier. Arguably the most important bioactive cargo within EVs are RNAs, in particular microRNAs (miRNA). A single miRNA can modulate entire gene networks and signalling within the recipient cell. Determining functionally relevant miRNA could lead to therapeutic treatments where synthetically-derived EVs are used as delivery vectors for miRNA. Stem cell-derived EVs can be effective in treating brain injury including radiation-induced cognitive deficits. Of particular interest are systemic modes of administration which obviate the need for invasive procedures.

Guided evaluation and standardisation of mesenchymal stem cell culture conditions to generate conditioned medium favourable to cardiac c-kit cell growth

Mesenchymal stem cells (MSCs) are known to secrete cardioprotective paracrine factors that can potentially activate endogenous cardiac c-kit cells (CCs). This study aims to optimise MSC growth conditions and medium formulation for generating the conditioned medium (CdM) to facilitate CC growth and expansion in vitro. The quality of MSC-CdM after optimisation of seeding density during MSC stabilisation and medium formulation used during MSC stimulation including glucose, ascorbic acid, serum and oxygen levels and the effects of treatment concentration and repeated CdM harvesting were assessed based on CC viability in vitro under growth factor- and serum-deprived condition. Our data showed that functional CdM can be produced from MSCs with a density of 20,000 cells/cm², which were stimulated using high glucose (25 mM), ascorbic acid supplemented, serum-free medium under normoxic condition. The generated CdM, when applied to growth factor- and serum-deprived medium at 1:1 ratio, improved CC viability, migration and proliferation in vitro. Such an effect could further be augmented by generating CdM concentrates without compromising CC gene and protein expressions, while retaining its capability to undergo differentiation to form endothelial, smooth muscle and cardiomyocytes. Nevertheless, CdM could not be repeatedly harvested from the same MSC culture, as the protein content and its effect on CC viability deteriorated after the first harvest. In conclusion, this study provides a proof-of-concept strategy to standardise the production of CdM from MSCs based on rapid, stepwise assessment of CC viability, thus enabling production of CdM favourable to CC growth for in vitro or clinical applications.

Transplantation of Cardiac Mesenchymal Stem Cell-Derived Exosomes Promotes Repair in Ischemic Myocardium

Our previous study demonstrated the beneficial effects of exosomes secreted by cardiac mesenchymal stem cells (C-MSC-Exo) in protecting acute ischemic myocardium from reperfusion injury. Here, we investigated the effect of exosomes from C-MSC on angiogenesis in ischemic myocardium. We intramyocardially injected C-MSC-Exo or PBS into the infarct border zone after induction of acute mouse myocardial infarction (MI). We observed that hearts treated with C-MSC-Exo exhibit improved cardiac function compared to control hearts treated with PBS at one month after MI. Capillary density and Ki67-postive cells were significantly higher following treatment with C-MSC-Exo as compared with PBS. Moreover, C-MSC-Exo treatment increased cardiomyocyte proliferation in infarcted hearts. In conclusion, intramyocardial delivery of C-MSC-Exo after myocardial infarction enhances cardiac angiogenesis, promotes cardiomyocyte proliferation, and preserves heart function. C-MSC-Exo constitute a novel form of cell-free therapy for cardiac repair.

Pro inflammatory stimuli enhance the immunosuppressive functions of adipose mesenchymal stem cells-derived exosomes

The predominant mechanism by which adipose mesenchymal stem cells (AMSCs) participate to tissue repair is through a paracrine activity and their communication with the inflammatory microenvironment is essential part of this process. This hypothesis has been strengthened by the recent discovery that stem cells release not only soluble factors but also extracellular vesicles, which elicit similar biological activity to the stem cells themselves. We demonstrated that the treatment with inflammatory cytokines increases the immunosuppressive and anti-inflammatory potential of AMSCs-derived exosomes, which acquire the ability to shift macrophages from M1 to M2 phenotype by shuttling miRNA regulating macrophages polarization. This suggests that the immunomodulatory properties of AMSCs-derived exosomes may be not constitutive, but are instead induced by the inflammatory microenvironment.

The membrane mesenchymal stem cell derived conditioned medium exerts neuroprotection against focal cerebral ischemia by targeting apoptosis

OBJECTIVE

The mesenchymal stem cells derived from human amniotic membrane have the ability to secrete and release some factors that can promote the repair of damaged tissues. This secretome contains proteins and factors that reduce apoptosis and increase angiogenesis in the ischemia/reperfusion models. The present study was conducted to determine whether this secretome provides protection against transient focal cerebral ischemia.

MATERIALS AND METHODS

A rat model of focal cerebral ischemia was established through middle cerebral artery occlusion (MCAO) for 60 min and 24 h reperfusion. The amniotic mesenchymal stem cells-conditioned medium (AMSC-CM) at the dose of 0.5 μl was injected intracerebroventriculary (ICV) 30 min after reperfusion. Infarct volume, brain edema, neurobehavioral functions, and blood brain barrier (BBB) integrity were assessed 24 h after reperfusion. Neuronal loss and expression of caspase-3, Bax and Bcl-2 in motor cortex were evaluated by nissl staining and immunohistochemistry assay respectively.

RESULTS

ICV administration of AMSC-CM markedly reduced infarct volume, brain edema and the evans blue penetration rate compared with MCAO group (P < 0.05). Additionally, post-treatment with AMSC-CM significantly reduced neuronal loss, neurological motor disorders and expression of caspase-3, Bax and Bcl-2 in motor cortex compared with MCAO group (P < 0.05).

CONCLUSION

The results of this study indicate that treatment with AMSC-CM improves the pathological effects in the acute phase of cerebral ischemia. These findings establish a substantial foundation for stroke therapy and future research.

Differential Proteomic Analysis Predicts Appropriate Applications for the Secretome of Adipose-Derived Mesenchymal Stem/Stromal Cells and Dermal Fibroblasts

The adult stem cell secretome is currently under investigation as an alternative to cell-based therapy in regenerative medicine, thanks to the remarkable translational opportunity and the advantages in terms of handling and safety. In this perspective, we recently demonstrated the efficient performance of the adipose-derived mesenchymal stem/stromal cell (ASC) secretome in contrasting neuroinflammation in a murine model of diabetic neuropathy, where the administration of factors released by dermal fibroblasts (DFs) did not exert any effect. Up to now, the complex mixture of the constituents of the conditioned medium from ASCs has not been fully deepened, although its appropriate characterization is required in the perspective of a clinical use. Herein, we propose the differential proteomic approach for the identification of the players accounting for the functional effects of the cell secretome with the aim to unravel its appropriate applications. Out of 967 quantified proteins, 34 and 62 factors were found preponderantly or exclusively secreted by ASCs and DFs, respectively. This approach led to the recognition of distinct functions related to the conditioned medium of ASCs and DFs, with the former being involved in the regulation of neuronal death and apoptosis and the latter in bone metabolism and ossification. The proosteogenic effect of DF secretome was validated in vitro on human primary osteoblasts, providing a proof of concept of its osteoinductive potential. Besides discovering new applications of the cell type-specific secretome, the proposed strategy could allow the recognition of the cocktail of bioactive factors which might be responsible for the effects of conditioned media, thus providing a solid rationale to the implementation of a cell-free approach in several clinical scenarios involving tissue regeneration.

Bone marrow cell response after injury and during early stage of regeneration is independent of the tissue-of-injury in 2 injury models

Selectively recruiting bone marrow (BM)-derived stem and progenitor cells to injury sites is a promising therapeutic approach. The coordinated action of soluble factors is thought to trigger the mobilization of stem cells from the BM and recruit them to lesions to contribute to tissue regeneration. Nevertheless, the temporal response profile of the major cellular players and soluble factors involved in priming the BM and recruiting BM-derived cells to promote regeneration is unknown. We show that injury alters the BM cellular composition, introducing population-specific fluctuations during tissue regeneration. We demonstrate that injury causes an immediate, transient response of mesenchymal stromal cells and endothelial cells followed by a nonoverlapping increase in hematopoietic stem and progenitor cells. Moreover, BM reaction is identical whether the injury is inflicted on skin and muscle or also involves a bone defect, but these 2 injury paradigms trigger distinct systemic cytokine responses. Together, our results indicate that the BM response to injury in the early stages of regeneration is independent of the tissue-of-injury based on the 2 models used, but the injured tissue dictates the systemic cytokine response.-Leitão, L., Alves, C. J., Alencastre, I. S., Sousa, D. M., Neto, E., Conceição, F., Leitão, C., Aguiar, P., Almeida-Porada, G., Lamghari, M. Bone marrow cell response after injury and during early stage of regeneration is independent of the tissue-of-injury in 2 injury models.

Future Perspectives on the Role of Stem Cells and Extracellular Vesicles in Vascular Tissue Regeneration

Vascular tissue engineering is an area of regenerative medicine that attempts to create functional replacement tissue for defective segments of the vascular network. One approach to vascular tissue engineering utilizes seeding of biodegradable tubular scaffolds with stem (and/or progenitor) cells wherein the seeded cells initiate scaffold remodeling and prevent thrombosis through paracrine signaling to endogenous cells. Stem cells have received an abundance of attention in recent literature regarding the mechanism of their paracrine therapeutic effect. However, very little of this mechanistic research has been performed under the aegis of vascular tissue engineering. Therefore, the scope of this review includes the current state of TEVGs generated using the incorporation of stem cells in biodegradable scaffolds and potential cell-free directions for TEVGs based on stem cell secreted products. The current generation of stem cell-seeded vascular scaffolds are based on the premise that cells should be obtained from an autologous source. However, the reduced regenerative capacity of stem cells from certain patient groups limits the therapeutic potential of an autologous approach. This limitation prompts the need to investigate allogeneic stem cells or stem cell secreted products as therapeutic bases for TEVGs. The role of stem cell derived products, particularly extracellular vesicles (EVs), in vascular tissue engineering is exciting due to their potential use as a cell-free therapeutic base. EVs offer many benefits as a therapeutic base for functionalizing vascular scaffolds such as cell specific targeting, physiological delivery of cargo to target cells, reduced immunogenicity, and stability under physiological conditions. However, a number of points must be addressed prior to the effective translation of TEVG technologies that incorporate stem cell derived EVs such as standardizing stem cell culture conditions, EV isolation, scaffold functionalization with EVs, and establishing the therapeutic benefit of this combination treatment.

Anti-inflammatory effects of human embryonic stem cell-derived mesenchymal stem cells secretome preconditioned with diazoxide, trimetazidine and MG-132 on LPS-induced systemic inflammation mouse model

Systemic inflammatory response syndrome is a complex pathophysiologic and immunologic response to an insult. Sepsis is a life-threatening condition happening when the body's response to infection causes injury to its own tissues and organs. Stem cell therapy is a new approach to modulate immune responses. Mesenchymal stem cells (MSCs) establish a regenerative niche by secreting secretome and modulating immune responses. MSC secretome can be leveraged for therapeutic applications if production of secretary molecules were optimized. Pharmacological preconditioning using small molecules can increase survival of MSCs after transplantation. The aim of this study was to investigate the effect of secretome of human embryonic-derived mesenchymal stem cells (hESC-MSCs) preconditioned with MG-132,Trimetazidine (TMZ) and Diazoxide (DZ) on immunomodulatory efficiency of these cells in Lipo polysaccharide (LPS) challenged mice models. Mice were injected intraperitoneally with LPS and groups of animals were intraperitoneally given 1 ml 30× secretome 6 h after LPS injection. Serum levels of biochemical parameters were then measured by an auto analyser and serum inflammatory cytokine levels were analysed using commercially available RayBio Mouse Inflammation Antibody Array. Ultimately, histopathology and survival studies were conducted. The results showed that TMZ and DZ-conditioned medium significantly increasing the survival and improvement of histopathological score. We found that MG-132-conditioned medium failed to show significant outcomes. This study demonstrated that human MSC secretome has the potential to control inflammation.

Conditioned medium from bone marrow-derived mesenchymal stem cells inhibits vascular calcification through blockade of the BMP2-Smad1/5/8 signaling pathway

Background

Arterial calcification is associated with cardiovascular disease as a complication of advanced atherosclerosis and is a significant contributor to cardiovascular morbidity and mortality. Osteoblastic differentiation of vascular smooth muscle cells (VSMCs) plays an important role in arterial calcification and is characterized by cellular necrosis, inflammation, and lipoprotein and phospholipid complexes, especially in atherosclerotic calcification. The conditioned medium from bone marrow-derived mesenchymal stem cells (MSC-CM) is well known as a rich source of autologous cytokines and is universally used for tissue regeneration in current clinical medicine. Here, we demonstrate that MSC-CM inhibits beta-glycerophosphate (β-GP)-induced vascular calcification through blockade of the bone morphogenetic protein-2 (BMP2)–Smad1/5/8 signaling pathway.

Methods

VSMC calcification was induced by β-GP followed by treatment with MSC-CM. Mineral deposition was assessed by Alizarin Red S staining. Intracellular calcium content was determined colorimetrically by the o-cresolphthalein complexone method and alkaline phosphatase (ALP) activity was measured by the para-nitrophenyl phosphate method. Expression of BMP2, BMPR1A, BMPR1B, BMPR2, msh homeobox 2 (Msx2), Runt-related transcription factor 2 (Runx2), and osteocalcin (OC), representative osteoblastic markers, was assessed using real-time polymerase chain reaction analysis while the protein expression of BMP2, Runx2, and phosphorylated Smad1/5/8 was detected by western blot analysis.

Results

Our data demonstrated that MSC-CM inhibits osteoblastic differentiation and mineralization of VSMCs as evidenced by decreased calcium content, ALP activity, and decreased expression of BMP-2, Runx2, Msx2, and OC. MSC-CM suppressed the expression of phosphorylated Smad1/5/8 and the β-GP-induced translocation from the cytoplasm to the nucleus. Further study demonstrated that human recombinant BMP-2 overcame the suppression of VSMC calcification by MSC-CM.

Conclusion

MSC-CM may act as a novel therapy for VSMC calcification by mediating the BMP2–Smad1/5/8 signaling pathway

Concise Review: Rational Use of Mesenchymal Stem Cells in the Treatment of Ischemic Heart Disease

The capacity of stem and progenitor cells to stimulate cardiac regeneration has been studied for almost 20 years, with very promising preclinical data and mixed clinical results. Several cell types have been studied, identified by their cell surface markers, differentiation capacity and their secreted growth factors. Bone marrow derived mesenchymal stem cells (MSCs) have been found to have potent regenerative capacity, through multiple mechanisms, including mesoderm lineage differentiation, immunomodulation, and paracrine stimulation. MSCs also secrete exosomes and microvesicles, which themselves contain potent angiogenic cytokines or mRNA molecules with effects on their local milieu. This concise review summarizes the mechanisms of MSC-based cardiac regeneration and highlighting results from molecular and preclinical studies. We also discuss clinical trial results to date, and ongoing studies. Furthermore, we discuss novel approaches for the enhancement of MSC based cardiac regeneration, such as genetic modification. Stem Cells Translational Medicine 2018;7:543-550.

Stem cell-inspired secretome-rich injectable hydrogel to repair injured cardiac tissue

The objective of this study was to develop an injectable and biocompatible hydrogel that can deliver a cocktail of therapeutic biomolecules (secretome) secreted by human adipose-derived stem cells (hASCs) to the peri-infarct myocardium. Gelatin and Laponite® were combined to formulate a shear-thinning, nanocomposite hydrogel (nSi Gel) as an injectable carrier of secretome (nSi Gel+). The growth factor composition and the pro-angiogenic activity of the secretome were tested in vitro by evaluating the proliferation, migration and tube formation of human umbilical endothelial cells. The therapeutic efficacy of the nSi Gel + system was then investigated in vivo in rats by intramyocardial injection into the peri-infarct region. Subsequently, the inflammatory response, angiogenesis, scar formation, and heart function were assessed. Biocompatibility of the developed nSi Gel was confirmed by quantitative PCR and immunohistochemical tests which showed no significant differences in the level of inflammatory genes, microRNAs, and cell marker expression compared to the untreated control group. In addition, the only group that showed a significant increase in capillary density, reduction in scar area and improved cardiac function was treated with the nSi Gel+. Our in vitro and in vivo findings demonstrate the potential of this new secretome-loaded hydrogel as an alternative strategy to treat myocardial infarction.

STATEMENT OF SIGNIFICANCE

Stem cell based-therapies represent a possible solution to repair damaged myocardial tissue by promoting cardioprotection, angiogenesis, and reduced fibrosis. However, recent evidence indicates that most of the positive outcomes are likely due to the release of paracrine factors (cytokines, growth factors, and exosomes) from the cells and not because of the local engraftment of stem cells. This cocktail of essential growth factors and paracrine signals is known as secretome can be isolated in vitro, and the biomolecule composition can be controlled by varying stem-cell culture conditions. Here, we propose a straightforward strategy to deliver secretome produced from hASCs by using a nanocomposite injectable hydrogel made of gelatin and Laponite®. The designed secretome-loaded hydrogel represents a promising alternative to traditional stem cell therapy for the treatment of acute myocardial infarction.

Regenerative Medicine Applications of Mesenchymal Stem Cells

A major research challenge is to develop therapeutics that assist with healing damaged tissues and organs because the human body has limited ability to restore the majority of these tissues and organs to their original state. Tissue engineering (TE) and regenerative medicine (RM) promises to offer efficient therapeutic biological strategies that use mesenchymal stem cells (MSCs). MSCs possess the capability for self-renewal, multilineage differentiation, and immunomodulatory properties that make them attractive for clinical applications. They have been extensively investigated in numerous preclinical and clinical settings in an attempt to overcome their challenges and promote tissue regeneration and repair. This review explores the exciting opportunities afforded by MSCs, their desirable properties as cellular therapeutics in RM, and implicates their potential use in clinical practice. Here, we attempt to identify challenges and issues that determine the clinical efficacy of MSCs as treatment for skeletal and non-skeletal tissues.

Extracellular vesicles and cardiovascular disease therapy

Cardiovascular disease (CVD) constitutes one of the leading causes of mortality worldwide, therefore representing a major public health concern. Despite recent advances in the treatment of patients with acute myocardial infarction (AMI), such as bypass surgery or percutaneous coronary intervention, pathological cardiac remodeling often predisposes survivors to fatal heart failure. In this context, the proven efficacy of stem cell-regenerative therapies constitutes a promising therapeutic perspective with is nevertheless slow down by safety and ethical concerns. Recent studies have underscored the capacity of stem cell-derived extracellular vesicles (EV) to recapitulate the regenerative properties of their parental cells therefore offering a therapeutic alternative to cell therapy in cardiovascular regenerative medicine. In this article, we review the functional relevance of using stem cell-derived EV as therapeutically agents and detail the identified molecular pathways that they used to exert their effects. We also discuss the advantages of using such an acellular regenerative therapy, in regard with parental stem cells, and address the limitations, which would need to be resolved, before their clinical translation.

Microvesicles in Atherosclerosis and Angiogenesis: From Bench to Bedside and Reverse

Atherosclerosis (AT) is a progressive chronic disease involving lipid accumulation, fibrosis, and inflammation in medium and large-sized arteries, and it is the main cause of cardiovascular disease (CVD). AT is caused by dyslipidemia and mediated by both innate and adaptive immune responses. Despite lipid-lowering drugs have shown to decrease the risk of cardiovascular events (CVEs), there is a significant burden of AT-related morbidity and mortality. Identification of subjects at increased risk for CVE as well as discovery of novel therapeutic targets for improved treatment strategies are still unmet clinical needs in CVD. Microvesicles (MVs), small extracellular plasma membrane particles shed by activated and apoptotic cells have been widely linked to the development of CVD. MVs from vascular and resident cells by facilitating exchange of biological information between neighboring cells serve as cellular effectors in the bloodstream and play a key role in all stages of disease progression. This article reviews the current knowledge on the role of MVs in AT and CVD. Attention is focused on novel aspects of MV-mediated regulatory mechanisms from endothelial dysfunction, vascular wall inflammation, oxidative stress, and apoptosis to coagulation and thrombosis in the progression and development of atherothrombosis. MV contribution to vascular remodeling is also discussed, with a particular emphasis on the effect of MVs on the crosstalk between endothelial cells and smooth muscle cells, and their role regulating the active process of AT-driven angiogenesis and neovascularization. This review also highlights the latest findings and main challenges on the potential prognostic, diagnostic, and therapeutic value of cell-derived MVs in CVD. In summary, MVs have emerged as new regulators of biological functions in atherothrombosis and might be instrumental in cardiovascular precision medicine; however, significant efforts are still needed to translate into clinics the latest findings on MV regulation and function.

Paracrine Mechanisms of Mesenchymal Stem Cells in Tissue Repair

Tissue regeneration from transplanted mesenchymal stromal cells (MSC) either through transdifferentiation or cell fusion was originally proposed as the principal mechanism underlying their therapeutic action. However, several studies have now shown that both these mechanisms are very inefficient. The low MSC engraftment rate documented in injured areas also refutes the hypothesis that MSC repair tissue damage by replacing cell loss with newly differentiated cells. Indeed, despite evidence of preferential homing of MSC to the site of myocardial ischemia, exogenously administered MSC show poor survival and do not persist in the infarcted area. Therefore, it has been proposed that the functional benefits observed after MSC transplantation in experimental models of tissue injury might be related to the secretion of soluble factors acting in a paracrine fashion. This hypothesis is supported by pre-clinical studies demonstrating equal or even improved organ function upon infusion of MSC-derived conditioned medium (MSC-CM) compared with MSC transplantation. Identifying key MSC-secreted factors and their functional role seems a reasonable approach for a rational design of nextgeneration MSC-based therapeutics. Here, we summarize the major findings regarding both different MSC-mediated paracrine actions and the identification of paracrine mediators.

Human adipose-derived mesenchymal stem cell-conditioned media suppresses inflammatory bone loss in a lipopolysaccharide-induced murine model

Conditioned media (CM) from mesenchymal stem cells (MSCs) contains various cytokines, growth factors and microRNAs, which may serve important roles in modulating the inflammatory process. However, the effect of MSC-CM on inflammatory bone loss remains unknown. The present study investigated the effects of conditioned media from human adipose-derived mesenchymal stem cells (AMSC-CM) on the prevention of lipopolysaccharide (LPS)-mediated bone loss in mice. To investigate the underlying mechanisms of this effect, the effects of AMSC-CM on serum levels of inflammation-associated cytokines [tumor necrosis factor (TNF)-α, interleukin (IL)-1, IL-6 and IL-10] in LPS-treated mice, in addition to their mRNA expression in LPS-treated macrophages, was investigated. Micro-computed tomography and histological analysis revealed that AMSC-CM administration effectively inhibited LPS-induced bone destruction in vivo. ELISA analysis indicated that AMSC-CM significantly reduced the serum levels of proinflammatory cytokines (TNF-α, IL-1 and IL-6) in LPS-treated mice. Furthermore, AMSC-CM treatment significantly decreased the mRNA expression levels of TNF-α, IL-1 and IL-6 in macrophages treated with LPS. These findings indicate that AMSC-CM inhibits LPS-induced bone loss by decreasing the production of proinflammatory cytokines, suggesting that the use of AMSC-CM may be a potential therapeutic strategy for the treatment of inflammatory bone loss.

Myocardial Regeneration via Progenitor Cell-Derived Exosomes

In the past 20 years, a variety of cell products has been evaluated in terms of their capacity to treat patients with acute myocardial infarction and chronic heart failure. Despite initial enthusiasm, therapeutic efficacy has overall been disappointing, and clinical application is costly and complex. Recently, a subset of small extracellular vesicles (EVs), commonly referred to as "exosomes," was shown to confer cardioprotective and regenerative signals at a magnitude similar to that of their donor cells. The conceptual advantage is that they may be produced in industrial quantities and stored at the point-of-care for off-the-shelf application, ideally without eliciting a relevant recipient immune response or other adverse effects associated with viable cells. The body of evidence on beneficial exosome-mediated effects in animal models of heart diseases is rapidly growing. However, there is significant heterogeneity in terms of exosome source cells, isolation process, therapeutic dosage, and delivery mode. This review summarizes the current state of research on exosomes as experimental therapy of heart diseases and seeks to identify roadblocks that need to be overcome prior to clinical application.

A new bioluminescent reporter system to study the biodistribution of systematically injected tumor-derived bioluminescent extracellular vesicles in mice

In vivo biodistribution and fate of extracellular vesicles (EVs) are still largely unknown and require reliable in vivo tracking techniques. In this study, in vivo bioluminescence imaging (BLI) using Renilla luciferase (Rluc) was developed and applied to monitoring of EVs derived from thyroid cancer (CAL-62 cells) and breast cancer (MDA-MB-231) in nude mice after intravenous administration and was compared with a dye-based labeling method for EV derived from CAL-62 cells. The EVs were successfully labeled with Rluc and visualized by BLI in mice. In vivo distribution of the EVs, as measured by BLI, was consistent with the results of ex vivo organ analysis. EV-CAL-62/Rluc showed strong signals at lung followed by liver, spleen & kidney (P < 0.05). EV-MDA-MB-231/Rluc showed strong signals at liver followed by lung, spleen & kidney (P < 0.05). EV-CAL-62/Rluc and EV-MDA-MB-231/Rluc stayed in animal till day 9 and 3, respectively; showed a differential distribution. Spontaneous EV-CAL-62/Rluc shown distributed mostly to lung followed by liver, spleen & kidney. The new BLI system used to show spontaneous distribution of EV-CAL-62/Rluc in subcutaneous CAL-62/Rluc bearing mice. Dye (DiR)-labeled EV-CAL-62/Rluc showed a different distribution in vivo & ex vivo compared to EV-CAL-62/Rluc. Fluorescent signals were predominately detected in the liver (P < 0.05) and spleen (P < 0.05) regions. The bioluminescent EVs developed in this study may be used for monitoring of EVs in vivo. This novel reporter-imaging approach to visualization of EVs in real time is expected to pave the way for monitoring of EVs in EV-based treatments.

Secretome of Aggregated Embryonic Stem Cell-Derived Mesenchymal Stem Cell Modulates the Release of Inflammatory Factors in Lipopolysaccharide-Induced Peripheral Blood Mononuclear Cells

Background:

Bone marrow mesenchymal stem cells (BM-MSCs) have emerged as a potential therapy for various inflammatory diseases. Because of some limitations, several recent studies have suggested the use of embryonic stem cell-derived MSCs (ESC-MSCs) as an alternative for BM-MSCs. Some of the therapeutic effects of the ESC-MSCs are related to the secretion of a broad array of cytokines and growth factors, known as secretome. Harnessing this secretome for therapeutic applications requires the optimization of production of secretary molecules. It has been shown that aggregation of MSCs into 3D spheroids, as a preconditioning strategy, can enhance immunomodulatory potential of such cells. In this study, we investigated the effect of secretome derived from human ESC-MSCs (hESC-MSCs) spheroids on secretion of IL-1β, IL-10, and tumor necrosis factor α (TNF-α) from lipopolysaccharide (LPS)-induced peripheral blood mononuclear cells (PBMCs).

Methods:

In the present study, after immunophenotyping and considering mesodermal differentiation of hESC-MSCs, the cells were non-adherently grown to prepare 3D aggregates, and then conditioned medium or secretome was extracted from the cultures. Afterwards, the anti-inflammatory effects of the secretome were assessed in an in vitro model of inflammation.

Results:

Results from this study showed that aggregate-prepared secretome from hESC-MSCs was able to significantly decrease the secretion of TNF-α (301.7 ± 5.906, p < 0.0001) and IL-1β (485.2 ± 48.38, p < 0.001) from LPS-induced PBMCs as the indicators of inflammation, in comparison with adherent culture-prepared secretome (TNF-α: 166.6 ± 8.04, IL-1β: 125.2 ± 2.73).

Conclusion:

Our study indicated that cell aggregation can be an appropriate strategy to increase immunomodulatory characteristics of hESC-MSCs.

Hepatoma-Derived Growth Factor Secreted from Mesenchymal Stem Cells Reduces Myocardial Ischemia-Reperfusion Injury

Objectives

The present study aimed to explore the major factors that account for the beneficial effects of mesenchymal stem cells (MSCs).

Methods

Using isobaric tags for relative and absolute quantitation method, hepatoma-derived growth factor (HDGF) was identified as an important factor secreted by MSCs, but not by cardiac fibroblasts (CFs). The protective effects of conditioned medium (CdM) from MSCs or CFs were tested by using either H9C2 cells that were exposed by hypoxia-reoxygenation (H/R) insult or an in vivo mouse model of myocardial ischemia-reperfusion.

Results

Compared to CF-CdM, MSC-CdM conferred protection against reperfusion injury. CdM obtained from MSCs that were treated with HDGF-targeted shRNA failed to offer any protection in vitro. In addition, administration of recombinant HDGF alone recapitulated the beneficial effects of MSC-CdM, which was associated with increased protein kinase C epsilon (PKCε) phosphorylation, enhanced mitochondria aldehyde dehydrogenase family 2 activity, and decreased 4-hydroxy-2-nonenal accumulation. A significant decrease in infarct size and ameliorated cardiac dysfunction was achieved by administration of HDGF in wild-type mice, which was absent in PKCε dominant negative mice, indicating the essential roles of PKCε in HDGF-mediated protection.

Conclusions

HDGF secreted from MSCs plays a key role in the protection against reperfusion injury through PKCε activation.

Placenta-derived PLX-PAD mesenchymal-like stromal cells are efficacious in rescuing blood flow in hind limb ischemia mouse model by a dose- and site-dependent mechanism of action

BACKGROUND

In peripheral artery disease (PAD), blockage of the blood supply to the limbs, most frequently the legs, leads to impaired blood flow and tissue ischemia. Pluristem's PLX-PAD cells are placenta-derived mesenchymal stromal-like cells currently in clinical trials for the treatment of peripheral artery diseases.

METHODS

In this work, the hind limb ischemia (HLI) mouse model was utilized to study the efficacy and mechanism of action of PLX-PAD cells. ELISA assays were performed to characterize and quantitate PLX-PAD secretions in vitro.

RESULTS

PLX-PAD cells administered intramuscularly rescued blood flow to the lower limb after HLI induction in a dose-dependent manner. While rescue of blood flow was site-dependent, numerous administration regimes enabled rescue of blood flow, indicating a systemic effect mediated by PLX-PAD secretions. Live PLX-PAD cells were more efficacious than cell lysate in rescuing blood flow, indicating the importance of prolonged cytokine secretion for maximal blood flow recovery. In vitro studies showed a multifactorial secretion profile including numerous pro-angiogenic proteins; these are likely involved in the PLX-PAD mechanism of action.

DISCUSSION

Live PLX-PAD cells were efficacious in rescuing blood flow after the induction of HLI in the mouse model in a dose- and site-dependent manner. The fact that various administration routes of PLX-PAD rescued blood flow indicates that the mechanism of action likely involves one of systemic secretions which promote angiogenesis. Taken together, the data support the further clinical testing of PLX-PAD cells for PAD indications.

Dual-targeting Theranostic System with Mimicking Apoptosis to Promote Myocardial Infarction Repair via Modulation of Macrophages

Currently unsatisfactory treatment of myocardial infarction (MI) is due to the unbridled inflammation and the delayed diagnosis at the early stage. To address these problems, firstly, phosphatidylserine (PS) was used to modulate the phenotypes of macrophages (MΦ) and resolve the early inflammation via binding to PS receptors (PSR) on macrophage surface. Secondly, highly-sensitive magnetic iron oxide nanocubes (MIONs) were adopted to realize the early visualization via magnetic resonance imaging (MRI). However, the major drawback for MIONs as contrast agents was their hydrophobic properties and insufficient delivery. Hence, zwitterionic biodegradable copolymer poly(lactide)-polycarboxybetaine (PLA-PCB, PP), companied with PS, was used to provide a good colloidal stability and long blood circulation for the nanocubes. Given the above, a theranostic nanosystem (PP/PS@MIONs) was constructed for early treatment of MI. With external magnetic field-induced targeting and PS targeting, the nanosystem enhanced the accumulation in infarcted area, and accelerated the resolution of early inflammatory responses. Moreover, the nanocubes in system were promoted to escape from endosomes/lysosomes via protonation of PCB, which contributes to accurate MRI. This nanosystem showed good inflammation-resolving effects and imaging ability in MI model rats. Therefore, this theranostic nanosystem can realize accurate visualization and significantly improve the treatment efficacy of MI at early stage.

Insights into the Diagnostic Potential of Extracellular Vesicles and Their miRNA Signature from Liquid Biopsy as Early Biomarkers of Diabetic Micro/Macrovascular Complications

Extracellular vesicles (EVs) represent a heterogeneous population of small vesicles, consisting of a phospholipidic bilayer surrounding a soluble interior cargo. Almost all cell types release EVs, thus they are naturally present in all body fluids. Among the several potential applications, EVs could be used as drug delivery vehicles in disease treatment, in immune therapy because of their immunomodulatory properties and in regenerative medicine. In addition to general markers, EVs are characterized by the presence of specific biomarkers (proteins and miRNAs) that allow the identification of their cell or tissue origin. For these features, they represent a potential powerful diagnostic tool to monitor state and progression of specific diseases. A large body of studies supports the idea that endothelial derived (EMPs) together with platelet-derived microparticles (PMPs) are deeply involved in the pathogenesis of diseases characterized by micro- and macrovascular damages, including diabetes. Existing literature suggests that the detection of circulating EMPs and PMPs and their specific miRNA profile may represent a very useful non-invasive signature to achieve information on the onset of peculiar disease manifestations. In this review, we discuss the possible utility of EVs in the early diagnosis of diabetes-associated microvascular complications, specifically related to kidney.

Mesenchymal Stem Cell Secretome: Toward Cell-Free Therapeutic Strategies in Regenerative Medicine

Earlier research primarily attributed the effects of mesenchymal stem cell (MSC) therapies to their capacity for local engrafting and differentiating into multiple tissue types. However, recent studies have revealed that implanted cells do not survive for long, and that the benefits of MSC therapy could be due to the vast array of bioactive factors they produce, which play an important role in the regulation of key biologic processes. Secretome derivatives, such as conditioned media or exosomes, may present considerable advantages over cells for manufacturing, storage, handling, product shelf life and their potential as a ready-to-go biologic product. Nevertheless, regulatory requirements for manufacturing and quality control will be necessary to establish the safety and efficacy profile of these products. Among MSCs, human uterine cervical stem cells (hUCESCs) may be a good candidate for obtaining secretome-derived products. hUCESCs are obtained by Pap cervical smear, which is a less invasive and painful method than those used for obtaining other MSCs (for example, from bone marrow or adipose tissue). Moreover, due to easy isolation and a high proliferative rate, it is possible to obtain large amounts of hUCESCs or secretome-derived products for research and clinical use.

Emerging role of extracellular vesicles in communication of preimplantation embryos in vitro

In vitro, efficient communication between mammalian embryos in groups or between embryos and cocultured somatic cells implies that there is a sender, a message and a receiver that is able to decode the message. Embryos secrete a variety of autocrine and paracrine factors and, of these, extracellular vesicles have recently been implicated as putative messengers in embryo-embryo communication, as well as in communication of the embryo with the maternal tract. Extracellular vesicles (EVs) are membrane-bound vesicles that are found in biofluids and in culture media conditioned by the presence of embryos or cells. EVs carry and transfer regulatory molecules, such as microRNAs, mRNAs, lipids and proteins. We conducted a systematic search of the literature to review and present the currently available evidence regarding the possible roles of EVs in in vitro embryo communication and embryo development. It is important to note that there is limited information available on the molecular mechanisms and many of the biologically plausible functions of EVs in embryo communication have not yet been substantiated by conclusive experimental evidence. However, indirect evidence, such as the use of media conditioned by embryos or by somatic cells with improved embryo development as a result, may indicate that EVs can be an important asset for the development of tailor-made media, allowing better embryo development in vitro, even for single embryo culture.

Extracellular vesicles from mesenchymal stem cells activates VEGF receptors and accelerates recovery of hindlimb ischemia

Extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) are potential therapies for various diseases, but their angiogenic mechanisms of therapeutic efficacy remain unclear. Here, we describe how MSC-EVs, activates VEGF receptors and downstream angiogenesis pathways. Mouse MSC-EVs were isolated from cell culture medium and characterized using transmission electron microscopy, nanoparticle analysis, and western blotting. In vitro migration, proliferation, and tube formation assays using endothelial cells were used to assess the angiogenic potential of MSC-EVs, and revealed higher levels of cellular migration, proliferation, and tube formation after treatment. qRT-PCR and western blotting (WB) revealed higher protein and mRNA expression of the angiogenic genes VEGFR1 and VEGFR2 in mouse SVEC-4 endothelial cells after MSC-EVs treatment. Additionally, other vital pro-angiogenic pathways (SRC, AKT, and ERK) were activated by in vitro MSC-EV treatment. WB and qRT-PCR revealed enriched presence of VEGF protein and miR-210-3p in MSC-EV. The hindlimb ischemia mouse model was established and MSC-EVs with or without Matrigel (EV-MSC+Gel) were injected into the ischemic area and blood reperfusion was monitored using molecular imaging techniques. The in vivo administration of MSC-EVs increased both blood reperfusion and the formation of new blood vessels in the ischemic limb, with the addition of matrigel enhancing this effect further by releasing EVs slowly. MSC-EVs enhance angiogenesis in ischemic limbs, most likely via the overexpression of VEGFR1 and VEGFR2 in endothelial cells. These findings reveal a novel mechanism of activating receptors by MSC-EVs influence the angiogenesis.

Therapy with mesenchymal stromal cells or conditioned medium reverse cardiac alterations in a high-fat diet-induced obesity model

BACKGROUND

Obesity is associated with numerous cardiac complications, including arrhythmias, cardiac fibrosis, remodeling and heart failure. Here we evaluated the therapeutic potential of mesenchymal stromal cells (MSCs) and their conditioned medium (CM) to treat cardiac complications in a mouse model of high-fat diet (HFD)-induced obesity.

METHODS

After obesity induction and HFD withdrawal, obese mice were treated with MSCs, CM or vehicle. Cardiac function was assessed using electrocardiography, echocardiography and treadmill test. Body weight and biochemical parameters were evaluated. Cardiac tissue was used for real time (RT)-polymerase chain reaction (PCR) and histopathologic analysis.

RESULTS/DISCUSSION

Characterization of CM by protein array showed the presence of different cytokines and growth factors, including chemokines, osteopontin, cystatin C, Serpin E1 and Gas 6. HFD-fed mice presented cardiac arrhythmias, altered cardiac gene expression and fibrosis reflected in physical exercise incapacity associated with obesity and diabetes. Administration of MSCs or CM improved arrhythmias and exercise capacity. This functional improvement correlated with normalization of GATA4 gene expression in the hearts of MSC- or CM-treated mice. The gene expression of connexin 43, troponin I, adiponectin, transforming growth factor (TGF) β, peroxisome proliferator activated receptor gamma (PPARγ), insulin-like growth factor 1 (IGF-1), matrix metalloproteinase-9 (MMP9) and tissue inhibitor of metalloproteinases 1 (TIMP1) were significantly reduced in MSCs, but not in CM-treated mice. Moreover, MSC or CM administration reduced the intensity of cardiac fibrosis.

CONCLUSION

Our results suggest that MSCs and CM have a recovery effect on cardiac disturbances due to obesity and corroborate to the paracrine action of MSCs in heart disease models.

Concise Review: Developing Best-Practice Models for the Therapeutic Use of Extracellular Vesicles

Growing interest in extracellular vesicles (EVs, including exosomes and microvesicles) as therapeutic entities, particularly in stem cell-related approaches, has underlined the need for standardization and coordination of development efforts. Members of the International Society for Extracellular Vesicles and the Society for Clinical Research and Translation of Extracellular Vesicles Singapore convened a Workshop on this topic to discuss the opportunities and challenges associated with development of EV-based therapeutics at the preclinical and clinical levels. This review outlines topic-specific action items that, if addressed, will enhance the development of best-practice models for EV therapies. Stem Cells Translational Medicine 2017;6:1730-1739.

Immunomodulatory effects of soluble factors secreted by feline adipose tissue-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) have immunomodulatory functions and differentiation capacity, and their clinical use is increasing in veterinary species. Although MSCs have been applied in the treatment in various inflammatory diseases, mechanistic research on feline MSCs is lacking. Accordingly, in this study, we aimed to investigate the immunomodulatory mechanisms of MSCs isolated from feline adipose tissue (fATMSCs). fATMSCs from healthy cats were cultured in an appropriate manner and cocultured with transwell-separated allogeneic feline peripheral blood mononuclear cells (fPBMCs) and RAW264.7 murine macrophages. After 48h of coculture, RNA was extracted from RAW264.7 cells and fPBMCs. Cytokine expression in these cells was measured using quantitative real-time polymerase chain reaction (qRT-PCR) and compared according to the presence of fATMSCs. The mRNA levels of pro-inflammatory cytokines, e.g., tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase, and interleukin (IL)-1β, were significantly decreased in cocultures of mitogen-stimulated RAW264.7 cells with fATMSCs compared with that in the RAW264.7 cells control group. Additionally, changes in the expression of mRNAs extracted from fPBMCs were as follows: pro-inflammatory TNF-α, interferon-γ, and IL-6 were decreased, and anti-inflammatory IL-10 was increased during coculture of mitogen-stimulated allogeneic fPBMCs with fATMSCs. We also extracted RNA and collected supernatants from fATMSCs during transwell culture for measurement of the expression and secretion of soluble factors by qRT-PCR and enzyme-linked immunosorbent assays, respectively. The mRNA expression of immunomodulatory factors from fATMSCs, including cyclooxygenase-2 (COX-2), transforming growth factor (TGF)-β, indoleamine-2,3-dioxygenase (IDO) and hepatocyte growth factor, increased in the presence of RAW264.7 cells. Similarly, TGF-β, COX-2, and IDO mRNA expression and prostaglandin E₂ (PGE₂) secretion from fATMSCs increased in the presence of allogeneic fPBMCs. Finally, we measured the viability of fPBMCs under various conditions. Cell viability decreased in fPBMCs suspended in fATMSC-derived conditioned medium, and this reduction was alleviated in the group supplemented with NS-398 a PGE₂ inhibitor. Our data suggested that soluble factors, including PGE₂, secreted by fATMSCs played an important role in the immunomodulatory effects of these cells. These findings may be helpful in the application of fATMSCs to feline patients with immune-related diseases.

Fibrous scaffolds potentiate the paracrine function of mesenchymal stem cells: A new dimension in cell-material interaction

While the studies on the material interaction with mesenchymal stem cells (MSCs) have been mainly focused on the ability of materials to provide environment to regulate cell viability, proliferation or differentiation, the therapeutic effects of MSC-material constructs may result from the secretion of immunomodulatory and angiogenic cytokines from MSCs. Here, electrospun scaffolds composed of fibers in random, aligned and mesh-like patterns were fabricated, and the paracrine behavior of adipose-derived MSCs (Ad-MSCs) on the scaffolds were investigated in comparison to the cell culture via conventional microplates. It was found that the Ad-MSCs on the electrospun fibers produced significantly higher levels of anti-inflammatory and pro-angiogenic cytokines compared to those cultured on microplates. The enhanced modulatory effects of the secreted products of Ad-MSCs on fibrous electrospun scaffolds were also proven in the cultures of endothelial cells and the LPS-stimulated macrophages, with three types of scaffolds showing distinct influences on the paracrine function of Ad-MSCs. In a skin excisional wound-healing model in rat, the conditioned medium collected from the MSC-scaffold system accelerated the wound closure, promoted the macrophage recruitment and enhanced the polarization of macrophages toward the pro-healing phenotype in the wound bed. Our study demonstrates that the fibrous topography of scaffolds is a key material property that modulates the paracrine function of cells. The discovery elucidates a new aspect of material functions, laying the foundation for developing scaffold materials to promote tissue regeneration/repair through guiding the paracrine signaling network.

Biomaterials that promote cell-cell interactions enhance the paracrine function of MSCs

Mesenchymal stromal cells (MSCs) secrete paracrine factors that play crucial roles during tissue regeneration. Whether this paracrine function is influenced by the properties of biomaterials in general, and those used for cell delivery in particular, largely remains unexplored. Here, we investigated if three-dimensional culture in distinct microenvironments - nanoporous hydrogels (mean pore size ∼5 nm) and macroporous scaffolds (mean pore size ∼120 μm) - affects the secretion pattern of MSCs, and consequently leads to differential paracrine effects on target progenitor cells such as myoblasts. We report that compared to MSCs encapsulated in hydrogels, scaffold seeded MSCs show an enhanced secretion profile and exert beneficial paracrine effects on various myoblast functions including migration and proliferation. Additionally, we show that the heightened paracrine effects of scaffold seeded cells can in part be attributed to N-cadherin mediated cell-cell interactions during culture. In hydrogels, this physical interaction between cells is prevented by the encapsulating matrix. Functionally blocking N-cadherin negatively affected the secretion profile and paracrine effects of MSCs on myoblasts, with stronger effects observed for scaffold seeded compared to hydrogel encapsulated cells. Together, these findings demonstrate that the therapeutic potency of MSCs can be enhanced by biomaterials that promote cell-cell interactions.

Extracellular Vesicles: Satellites of Information Transfer in Cancer and Stem Cell Biology

The generation and shedding of extracellular vesicles (EVs), including exosomes and microvesicles (MVs), by cells has emerged as a form of intercellular communication with important roles in several physiological processes and diseases such as cancer. These membrane-enclosed packets can transfer specific proteins, RNA transcripts, microRNAs, and even DNA to target cells, thereby altering their function. Despite the exponential growth of the EV field, a great deal remains unclear about the mechanisms that regulate exosome and MV biogenesis, as well as about how to isolate different classes of EVs and how to best take advantage of them for clinical applications.

Restoring heart function and electrical integrity: closing the circuit

Cardiovascular diseases are the main cause of death in the world and are often associated with the occurrence of arrhythmias due to disruption of myocardial electrical integrity. Pathologies involving dysfunction of the specialized cardiac excitatory/conductive tissue are also common and constitute an added source of morbidity and mortality since current standard therapies withstand a great number of limitations. As electrical integrity is essential for a well-functioning heart, innovative strategies have been bioengineered to improve heart conduction and/or promote myocardial repair, based on: (1) gene and/or cell delivery; or (2) conductive biomaterials as tools for cardiac tissue engineering. Herein we aim to review the state-of-art in the area, while briefly describing the biological principles underlying the heart electrical/conduction system and how this system can be disrupted in heart disease. Suggestions regarding targets for future studies are also presented.

Contributory Anti-Inflammatory Effects of Mesenchymal Stem Cells, Not Conditioned Media, On Ovalbumin-Induced Asthmatic Changes in Male Rats

Our aim in selecting an appropriate cell fraction and conditioned media (CM) was to achieve the suitable candidate for ameliorating long-term chronic asthmatic changes of respiratory tract. Thirty-six rats were classified into healthy and sensitized groups, which were further divided into three subgroups; rats received systemically 50 μl volume of PBS, CM, or 2 × 10⁶ rat bone marrow-derived mesenchymal stem cells (rBMMSCs). Tracheal responsiveness (TR), immunologic responses, and recruitment of rBMMSCs into the lungs were evaluated. A high degree of TR and total WBC and percentages of eosinophils and neutrophils was significantly recorded in all sensitized groups rather than of controls (p < 0.001 to p < 0.05). Concurrently, a significant improvement of TR and eosinophil and neutrophil return toward normal levels was evident in sensitized rats receiving cells as compared to parallel asthmatic animals. Flow cytometric monitoring of lymphocyte subpopulation revealed a decrease in the number of CD3⁺CD4⁺ and concurrent increase in CD3⁺CD8⁺ in all sensitized rats as compared to control (p < 0.001 to p < 0.05). Noticeably, no significant modulatory effects of either cell or CM administration were achieved on the CD3⁺CD4⁺ and CD3⁺CD8⁺ populations in non-asthmatic rats. Corroborating our results, the number of CD3⁺CD4⁺ tended to increase (p < 0.05) which coincided with a decreased manner of CD3⁺CD8⁺ populations as compared to other asthmatic groups (p < 0.01 to p < 0.05). Moreover, stem cells could efficiently transmigrate to the lung parenchyma, albeit the dynamic of asthmatic changes stimulated the rate of recruited cells. Our study shed light on superior effects of mesenchymal stem cells, but not CM, in attenuating chronic asthmatic changes in the model of rat.

Higher functionality of extracellular vesicles isolated using size-exclusion chromatography compared to ultracentrifugation

Extracellular vesicles (EVs) are nano-sized, lipid bilayer-enclosed particles involved in intercellular communication. EVs are increasingly being considered as drug delivery vehicles or as cell-free approach to regenerative medicine. However, one of the major challenges for their clinical application is finding a scalable EV isolation method that yields functional EVs. Although the golden standard for EV isolation is ultracentrifugation (UC), a recent study suggested that isolation using size-exclusion chromatography (SEC) yielded EVs with more intact biophysical properties. Whether this also leads to differences in functionality remained to be investigated. Therefore, we investigated possible differences in functionality of cardiomyocyte progenitor cell-derived EVs isolated using UC and SEC. Western blot analysis showed higher pERK/ERK ratios in endothelial cells after stimulation with SEC-EVs compared to UC-EVs, indicating that SEC-EVs bear higher functionality. Therefore, we propose to use SEC-EVs for further investigation of EVs' therapeutic potential. Further optimization of isolation protocols may accelerate clinical adoption of therapeutic EVs.

Exploring pericyte and cardiac stem cell secretome unveils new tactics for drug discovery

Ischaemic diseases remain a major cause of morbidity and mortality despite continuous advancements in medical and interventional treatments. Moreover, available drugs reduce symptoms associated with tissue ischaemia, without providing a definitive repair. Cardiovascular regenerative medicine is an expanding field of research that aims to improve the treatment of ischaemic disorders through restorative methods, such as gene therapy, stem cell therapy, and tissue engineering. Stem cell transplantation has salutary effects through direct and indirect actions, the latter being attributable to growth factors and cytokines released by stem cells and influencing the endogenous mechanisms of repair. Autologous stem cell therapies offer less scope for intellectual property coverage and have limited scalability. On the other hand, off-the-shelf cell products and derivatives from the stem cell secretome have a greater potential for large-scale distribution, thus enticing commercial investors and reciprocally producing more significant medical and social benefits. This review focuses on the paracrine properties of cardiac stem cells and pericytes, two stem cell populations that are increasingly attracting the attention of regenerative medicine operators. It is likely that new cardiovascular drugs are introduced in the next future by applying different approaches based on the refinement of the stem cell secretome.

Emerging applications of exosomes in cancer therapeutics and diagnostics

Exosomes are nanoscale extracellular vesicles that are shed from different cells in the body. Exosomes encapsulate several biomolecules including lipids, proteins, and nucleic acids, and can therefore play a key role in cellular communication. These vesicles can be isolated from different body fluids and their small sizes make them attractive in various biomedical applications. Here, we review state-of-the art approaches in exosome isolation and purification, and describe their potential use in cancer vaccines, drug delivery, and diagnostics.

Comparison of the proliferation, migration and angiogenic properties of human amniotic epithelial and mesenchymal stem cells and their effects on endothelial cells

In vivo studies have shown that amnion-produced growth factors participate in many diseases that involve angiogenesis, re-epithelialization and immunomodulation. Although human amniotic epithelial cells (hAECs) and human amniotic mesenchymal stem cells (hAMSCs) can be obtained from amniotic membranes, there is little information regarding their biological differences. The aim of the present study was to isolate and characterize cells from human amnions, to investigate the biological potential and behavior of these cells on the function of endothelial cells in vivo and in vitro and to examine variations in the expression profile of growth factors in different human amnion-derived cell types. Amnion fragments were enzymatically digested into two cell fractions, which were analyzed by mesenchymal and epithelial cell markers. Human aortic endothelial cells (hAoECs) were cultured with conditioned medium (CdM) collected from hAECs or hAMSCs. We used scratch and Transwell assays to evaluate migration ability; Cell Counting Kit-8 (CCK-8) and cell cycle analysis to evaluate proliferation ability; and a Matrigel tube formation assay to evaluate angiogenesis ability. To detect expression of angiogenesis-related genes, qPCR and enzyme-linked immunosorbent assay (ELISA) analyses were conducted. As stem cells, hAECs and hAMSCs all expressed the stem cell markers SSEA-4, OCT-4 and SOX-2. CdM obtained from hAECs promoted cell migration; CdM obtained from hAMSCs promoted cell proliferation; CdM obtained from hAECs and hAMSCs both promoted angiogenesis in hAoECs. Amnion-derived cells secreted significant amounts of angiogenic factors including HGF, IGF-1, VEGF, EGF, HB-EGF and bFGF, although differences in the cellular expression profile of these soluble factors were observed. Our results highlight that human amniotic epithelial and mesenchymal stem cells, which showed differences in their soluble factor secretion and angiogenic functions, could be ideal cell sources for regenerative medicine.

Exosomes: The Messengers of Health and Disease

Exosomes are small vesicles comprised of a lipid bilayer containing various proteins, RNAs and bioactive lipids. They act as intercellular messengers that give the ability to communicate between both cells of the same type and other cell types. They are released by healthy cells, both constitutively and upon cell activation and play an important role in immune system function. Exosomes are essential for healthy physiological conditions, however under pathological circumstances, they act to potentiate cellular stress and damage. This review explores the characteristics, biogenesis, role(s) in the pathogenesis of diseases and role(s) in progression of cancer of these nano-sized messages-in-a-vesicle: exosomes.

Extracellular vesicles in coronary artery disease

Membrane vesicles released in the extracellular space are composed of a lipid bilayer enclosing soluble cytosolic material and nuclear components. Extracellular vesicles include apoptotic bodies, exosomes, and microvesicles (also known previously as microparticles). Originating from different subcellular compartments, the role of extracellular vesicles as regulators of transfer of biological information, acting locally and remotely, is now acknowledged. Circulating vesicles released from platelets, erythrocytes, leukocytes, and endothelial cells contain potential valuable biological information for biomarker discovery in primary and secondary prevention of coronary artery disease. Extracellular vesicles also accumulate in human atherosclerotic plaques, where they affect major biological pathways, including inflammation, proliferation, thrombosis, calcification, and vasoactive responses. Extracellular vesicles also recapitulate the beneficial effect of stem cells to treat cardiac consequences of acute myocardial infarction, and now emerge as an attractive alternative to cell therapy, opening new avenues to vectorize biological information to target tissues. Although interest in microvesicles in the cardiovascular field emerged about 2 decades ago, that for extracellular vesicles, in particular exosomes, started to unfold a decade ago, opening new research and therapeutic avenues. This Review summarizes current knowledge on the role of extracellular vesicles in coronary artery disease, and their emerging potential as biomarkers and therapeutic agents.

Current Perspectives on In Vivo Noninvasive Tracking of Extracellular Vesicles with Molecular Imaging

Clinical and preclinical in vivo tracking of extracellular vesicles (EVs) are a crucial tool for the development and optimization of EV-based diagnosis and treatment. EVs have gained interest due to their unique properties that make them excellent candidates for biological applications. Noninvasive in vivo EV tracking has allowed marked progress towards elucidating the mechanisms and functions of EVs in real time in preclinical and clinical studies. In this review, we summarize several molecular imaging methods that deal with EVs derived from different cells, which have allowed investigations of EV biodistribution, as well as their tracking, delivery, and tumor targeting, to determine their physiological functions and to exploit imaging-derived information for EV-based theranostics.

Re-Engineering Extracellular Vesicles as Smart Nanoscale Therapeutics

In the past decade, extracellular vesicles (EVs) have emerged as a key cell-free strategy for the treatment of a range of pathologies, including cancer, myocardial infarction, and inflammatory diseases. Indeed, the field is rapidly transitioning from promising in vitro reports toward in vivo animal models and early clinical studies. These investigations exploit the high physicochemical stability and biocompatibility of EVs as well as their innate capacity to communicate with cells via signal transduction and membrane fusion. This review focuses on methods in which EVs can be chemically or biologically modified to broaden, alter, or enhance their therapeutic capability. We examine two broad strategies, which have been used to introduce a wide range of nanoparticles, reporter systems, targeting peptides, pharmaceutics, and functional RNA molecules. First, we explore how EVs can be modified by manipulating their parent cells, either through genetic or metabolic engineering or by introducing exogenous material that is subsequently incorporated into secreted EVs. Second, we consider how EVs can be directly functionalized using strategies such as hydrophobic insertion, covalent surface chemistry, and membrane permeabilization. We discuss the historical context of each specific technology, present prominent examples, and evaluate the complexities, potential pitfalls, and opportunities presented by different re-engineering strategies.

Umbilical cord-derived mesenchymal stromal cell-conditioned medium exerts in vitro antiaging effects in human fibroblasts

BACKGROUND AIMS

Chronic wounds are a common complication of diabetes. Fibroblast-myofibroblast differentiation is important for wound repair, which is commonly impaired in non-healing wounds, and the underlying mechanisms need to be further elucidated.

METHODS

We used high glucose (HG) to simulated the diabetes microenvironment and explored its effects on the biological features of fibroblasts in vitro.

RESULTS

The results showed that prolonged HG induced senescence in fibroblasts through activation of p21 and p16 in a reactive oxygen species (ROS)-dependent manner, further delayed the viability and migration in fibroblasts and also depressed fibroblast differentiation through the TGF-β/Smad signaling pathway. However, mesenchymal stromal cell-conditioned medium (MSC-CM) counteracts the effects of HG. Treatment of fibroblasts with MSC-CM decreased HG-induced ROS overproduction, ameliorated HG-induced senescence in fibroblasts and reversed the defects in myofibroblast formation. Our results may provide clues for the pathogenesis of chronic wounds and a theoretical basis to develop MSC-CM as an alternative therapeutic method to treatment of chronic wounds.

Profiling the Secretome of Human Stem Cells from Dental Apical Papilla

Recent studies have shown that secretion of bioactive factors from mesenchymal stem cells (MSCs) plays a primary role in MSC-mediated therapy; especially for bone marrow-derived MSCs (BMSCs). MSCs from dental apical papilla (SCAPs) are involved in root development and may play a critical role in the formation of dentin and pulp. Bioactive factors secreted from SCAPs actively contribute to their environment; however, the SCAPs secretome remains unclear. To address this and gain a deeper understanding of the relevance of SCAPs secretions in a clinical setting, we used isobaric chemical tags and high-performance liquid chromatography with tandem mass spectrometry to profile the secretome of human SCAPs and then compared it to that of BMSCs. A total of 2,046 proteins were detected from the conditioned medium of SCAPs, with a false discovery rate of less than 1.0%. Included were chemokines along with angiogenic, immunomodulatory, antiapoptotic, and neuroprotective factors and extracellular matrix (ECM) proteins. The secreted levels of 151 proteins were found to differ by at least twofold when BMSCs and SCAPs were compared. Relative to BMSCs, SCAPs exhibited increased secretion of proteins that are involved in metabolic processes and transcription and lower levels of those associated with biological adhesion, developmental processes, and immune function. In addition, SCAPs secreted significantly larger amounts of chemokines and neurotrophins than BMSCs, whereas BMSCs secreted more ECM proteins and proangiogenic factors. These results may provide important clues regarding the molecular mechanisms associated with tissue regeneration and how they differ between cell sources.

Bone marrow mesenchymal stem cells and their conditioned media could potentially ameliorate ovalbumin-induced asthmatic changes

BACKGROUND

The major feature of asthma is governed by chronic airway inflammation. This investigation was proposed to achieve the suitable candidate for ameliorating long-term chronic asthmatic changes of respiratory tract.

METHODS

36 rats were classified into healthy (C) and ovalbumin (OVA)-sensitized animals (S). To sensitize, the rats were exposed to OVA over a course of 32±1days. One day after sensitization, equal six different groups were subjected to experimental procedure (n=6); Rats only received intratracheally 50ml PBS (CPT and SPT groups), 50μl conditioned medium (CM) (CST and SST groups) and 50μl PBS containing 2×10⁶ rat bone marrow-derived mesenchymal stem cells (rBMMSCs) (CCT and SCT groups). Two weeks after treatment, tracheal responsiveness, immunologic responses and recruitment of rBMMSCs into the lung as well as pathological changes were evaluated.

RESULTS

A high degree of tracheal responsiveness, total white blood cell and percentages of eosinophil and neutrophil was significantly recorded in all sensitized groups rather than of controls (p<0.001 to p<0.05). Of interest, all above-mentioned parameters decreased significantly in SST and notably SCT groups as compared to S group (p<0.001 to p<0.05). The results revealed decrease number of blood CD3⁺CD4⁺ and concurrent increase in CD3⁺CD8⁺ in all sensitized rats as compared to control (p<0.001 to p<0.05). Noticeably, no significant modulatory effects of either cell or CM administration were achieved on the CD3⁺CD4⁺ and CD3⁺CD8⁺ populations in non-asthmatic rats. Moreover, the number of CD3⁺CD4⁺ in SST and SCT groups tended to increase, which coincided with a decreased manner of CD3⁺CD8⁺ populations as compared with S group (p<0.001 to p<0.05). However, the CD3⁺CD4⁺ cells in SCT rats were significantly higher than the group SST (p<0.01) whereas CD3⁺CD8⁺ cells diminished simultaneously (p<0.001). Real-time PCR analysis further showed that both CM and particularly MSCs changed the expression of interleukin (IL)-4 and IL-10 in the asthmatic groups to the near level of control rats (p<0.001 to p<0.05). Histopathological analysis revealed a profound reduction of lungs injuries in asthmatic rats when received CM and peculiarly mesenchymal stem cells (p<0.01 to p<0.05).

CONCLUSION

Our study shed light on the superior effects of rBMMSCs, rather than CM, in attenuating of chronic asthmatic changes in the rat model.

Combined MSC and GLP-1 Therapy Modulates Collagen Remodeling and Apoptosis following Myocardial Infarction

Background. Mesenchymal stem cells (MSCs) and glucagon-like peptide-1 (GLP-1) are being tested as treatment strategies for myocardial infarction (MI); however, their mechanisms in the heart are not fully understood. Methods. We examined the effects of MSCs, either native, or engineered to secrete a GLP-1 fusion protein (MSCs ± GLP-1), on human cardiomyocyte apoptosis in vitro. The effect on cardiac remodeling when encapsulated in alginate beads (CellBeads-MSC and CellBeads-MSC + GLP-1) was also evaluated in a pig MI model, whereby pigs were treated with Empty Beads, CellBeads-MSC, or CellBeads-MSC + GLP-1 and sacrificed at one or four weeks following MI. Results. MSC + GLP-1 conditioned media demonstrated antiapoptotic effects on ischaemic human cardiomyocytes in vitro. In vivo, qRT-PCR revealed large changes in the expression of several genes involved in extracellular matrix remodeling, which were altered following MSC ± GLP treatment. After four weeks, infarcted areas were imaged using atomic force microscopy, demonstrating significant alterations between groups in the structure of collagen fibrils and resulting scar. Conclusions. These data demonstrate that MSCs ± GLP-1 exhibit modulatory effects on healing post-MI, affecting both apoptosis and collagen scar formation. These data support the premise that both MSCs and GLP-1 could be beneficial in MI treatment.