Therapeutic applications of mesenchymal stromal cells

Therapeutic Application of Extracellular Vesicles Derived from Mesenchymal Stem Cells in Domestic Animals

Recently, the therapeutic potential of extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) has been extensively studied in both human and veterinary medicine. EVs are nano-sized particles containing biological components commonly found in other biological materials. For that reason, EV isolation and characterization are critical to draw precise conclusions during their investigation. Research on EVs within veterinary medicine is still considered in its early phases, yet numerous papers were published in recent years. The conventional adult tissues for deriving MSCs include adipose tissue and bone marrow. Nonetheless, alternative sources such as synovial fluid, endometrium, gingiva, and milk have also been intermittently used. Fetal adnexa are amniotic membrane/fluid, umbilical cord and Wharton's jelly. Cells derived from fetal adnexa exhibit an intermediate state between embryonic and adult cells, demonstrating higher proliferative and differentiative potential and longer telomeres compared to cells from adult tissues. Summarized here are the principal and recent preclinical and clinical studies performed in domestic animals such as horse, cattle, dog and cat. To minimize the use of antibiotics and address the serious issue of antibiotic resistance as a public health concern, they will undoubtedly also be utilized in the future to treat infections in domestic animals. A number of concerns, including large-scale production with standardization of EV separation and characterization techniques, must be resolved for clinical application.

Human mesenchymal stromal cell adhesion and expansion on fluoropolymer surfaces modified with oxygen and nitrogen-rich plasma polymers

Fluorinated ethylene propylene (FEP) vessels are of significant interest for therapeutic cell biomanufacturing applications due to their chemical inertness, hydrophobic surface, and high oxygen permeability. However, these properties also limit the adhesion and survival of anchorage-dependent cells. Here, we develop novel plasma polymer coatings to modify FEP surfaces, enhancing the adhesion and expansion of human mesenchymal stromal cells (hMSCs). Similar to commercially available tissue culture polystyrene vessels, oxygen-rich or nitrogen-rich surface chemistries can be achieved using this approach. While steam sterilization increased the roughness of the coatings and altered the surface chemistry, the overall wettability and oxygen or nitrogen-rich nature of the coatings were maintained. In the absence of proteins during initial cell attachment, cells adhered to surfaces even in the presence of chelators, whereas adhesion was abrogated with chelator in a protein-containing medium, suggesting that integrin-mediated adhesion predominates over physicochemical tethering in normal protein-containing cell seeding conditions. Albumin adsorption was more elevated on nitrogen-rich coatings compared to the oxygen-rich coatings, which was correlated with a higher extent of hMSC expansion after 3 days. Both the oxygen and nitrogen-rich coatings significantly improved hMSC adhesion and expansion compared to untreated FEP. FEP surfaces with nitrogen-rich coatings were practically equivalent to commercially available standard tissue culture-treated polystyrene surfaces in terms of hMSC yields. Plasma polymer coatings show significant promise in expanding the potential usage of FEP-based culture vessels for cell therapy applications.

The tumor microenvironment: shaping cancer progression and treatment response

The tumor microenvironment (TME) plays a crucial role in cancer progression and treatment response. It comprises a complex network of stromal cells, immune cells, extracellular matrix, and blood vessels, all of which interact with cancer cells and influence tumor behaviour. This review article provides an in-depth examination of the TME, focusing on stromal cells, blood vessels, signaling molecules, and ECM, along with commonly available therapeutic compounds that target these components. Moreover, we explore the TME as a novel strategy for discovering new anti-tumor drugs. The dynamic and adaptive nature of the TME offers opportunities for targeting specific cellular interactions and signaling pathways. We discuss emerging approaches, such as combination therapies that simultaneously target cancer cells and modulate the TME. Finally, we address the challenges and future prospects in targeting the TME. Overcoming drug resistance, improving drug delivery, and identifying new therapeutic targets within the TME are among the challenges discussed. We also highlight the potential of personalized medicine and the integration of emerging technologies, such as immunotherapy and nanotechnology, in TME-targeted therapies. This comprehensive review provides insights into the TME and its therapeutic implications. Understanding the TME's complexity and targeting its components offer promising avenues for the development of novel anti-tumor therapies and improved patient outcomes.

Novel Strategy to Enhance Human Mesenchymal Stromal Cell Immunosuppression: Harnessing Interferon-Gamma Presentation in Metal-Organic Frameworks Embedded on Heparin/Collagen Multilayers

The immunomodulatory potential of human mesenchymal stromal cells (hMSCs) can be boosted when exposed to interferon-gamma (IFN-γ). While pretreating hMSCs with IFN-γ is a common practice to enhance their immunomodulatory effects, the challenge lies in maintaining a continuous IFN-γ presence within cellular environments. Therefore, in this research, we investigate the sustainable presence of IFN-γ in the cell culture medium by immobilizing it in water-stable metal-organic frameworks (MOFs) [PCN-333(Fe)]. The immobilized IFN-γ in MOFs was coated on top of multilayers composed of combinations of heparin (HEP) and collagen (COL) that were used as a bioactive surface. Multilayers were created by using a layer-by-layer assembly technique, with the final layer alternating between collagen (COL) and heparin (HEP). We evaluated the viability, differentiation, and immunomodulatory activity of hMSCs cultured on (HEP/COL) coated with immobilized IFN-γ in MOFs after 3 and 6 days of culture. Cell viability, compared to tissue culture plastic, was not affected by immobilized IFN-γ in MOFs when they were coated on (HEP/COL) multilayers. We also verified that the osteogenic and adipogenic differentiation of the hMSCs remained unchanged. The immunomodulatory activity of hMSCs was evaluated by examining the expression of indoleamine 2,3-dioxygenase (IDO) and 11 essential immunomodulatory markers. After 6 days of culture, IDO expression and the expression of 11 immunomodulatory markers were higher in (HEP/COL) coated with immobilized IFN-γ in MOFs. Overall, (HEP/COL) multilayers coated with immobilized IFN-γ in MOFs provide a sustained presentation of cytokines to potentiate the hMSC immunomodulatory activity.

Omics Analyses of Stromal Cells from ACM Patients Reveal Alterations in Chromatin Organization and Mitochondrial Homeostasis

Arrhythmogenic cardiomyopathy (ACM) is a genetic disorder characterized by ventricular arrhythmias, contractile dysfunctions and fibro-adipose replacement of myocardium. Cardiac mesenchymal stromal cells (CMSCs) participate in disease pathogenesis by differentiating towards adipocytes and myofibroblasts. Some altered pathways in ACM are known, but many are yet to be discovered. We aimed to enrich the understanding of ACM pathogenesis by comparing epigenetic and gene expression profiles of ACM-CMSCs with healthy control (HC)-CMSCs. Methylome analysis identified 74 differentially methylated nucleotides, most of them located on the mitochondrial genome. Transcriptome analysis revealed 327 genes that were more expressed and 202 genes that were less expressed in ACM- vs. HC-CMSCs. Among these, genes implicated in mitochondrial respiration and in epithelial-to-mesenchymal transition were more expressed, and cell cycle genes were less expressed in ACM- vs. HC-CMSCs. Through enrichment and gene network analyses, we identified differentially regulated pathways, some of which never associated with ACM, including mitochondrial functioning and chromatin organization, both in line with methylome results. Functional validations confirmed that ACM-CMSCs exhibited higher amounts of active mitochondria and ROS production, a lower proliferation rate and a more pronounced epicardial-to-mesenchymal transition compared to the controls. In conclusion, ACM-CMSC-omics revealed some additional altered molecular pathways, relevant in disease pathogenesis, which may constitute novel targets for specific therapies.

Early committed polarization of intracellular tension in response to cell shape determines the osteogenic differentiation of mesenchymal stromal cells

Within the heterogeneous tissue architecture, a comprehensive understanding of how cell shapes regulate cytoskeletal mechanics by adjusting focal adhesions (FAs) signals to correlate with the lineage commitment of mesenchymal stromal cells (MSCs) remains obscure. Here, via engineered extracellular matrices, we observed that the development of mature FAs, coupled with a symmetrical pattern of radial fiber bundles, appeared at the right-angle vertices in cells with square shape. While circular cells aligned the transverse fibers parallel to the cell edge, and moved them centripetally in a counter-clockwise direction, symmetrical bundles of radial fibers at the vertices of square cells disrupted the counter-clockwise swirling and bridged the transverse fibers to move centripetally. In square cells, the contractile force, generated by the myosin IIA-enriched transverse fibers, were concentrated and transmitted outwards along the symmetrical bundles of radial fibers, to the extracellular matrix through FAs, and thereby driving FA organization and maturation. The symmetrical radial fiber bundles concentrated the transverse fibers contractility inward to the linkage between the actin cytoskeleton and the nuclear envelope. The tauter cytoskeletal network adjusted the nuclear-actomyosin force balance to cause nuclear deformability and to increase nuclear translocation of the transcription co-activator YAP, which in turn modulated the switch in MSC commitment. Thus, FAs dynamically respond to geometric cues and remodel actin cytoskeletal network to re-distribute intracelluar tension towards the cell nucleus, and thereby controlling YAP mechanotransduction signaling in regulating MSC fate decision. STATEMENT OF SIGNIFICANCE: We decipher how cellular mechanics is self-organized depending on extracellular geometric features to correlate with mesenchymal stromal cell lineage commitment. In response to geometry constrains on cell morphology, symmetrical radial fiber bundles are assembled and clustered depending on the maturation state of focal adhesions and bridge with the transverse fibers, and thereby establishing the dynamic cytoskeletal network. Contractile force, generated by the myosin-IIA-enriched transverse fibers, is transmitted and dynamically drives the retrograde movement of the actin cytoskeletal network, which appropriately adjusts the nuclear-actomyosin force balance and deforms the cell nucleus for YAP mechano-transduction signaling in regulating mesenchymal stromal cell fate decision.

Osteogenic Differentiation Effect of Human Periodontal Ligament Stem-Cell Initial Cell Density on Autologous Cells and Human Bone Marrow Stromal Cells

Stem cells have differentiation and regulation functions. Here, we discussed the impact of cell culture density on stem cell proliferation, osteoblastogenesis, and regulation. To discuss the effect of the initial culture density of human periodontal ligament stem cells (hPDLSCs) on the osteogenic differentiation of autologous cells, we found that the hPDLSC proliferation rate decreased with an increase in the initial plating density (0.5-8 × 10⁴ cells/cm²) for the 48 h culture cycle. After hPDLSCs induced osteogenic differentiation for 14 days with different initial cell culture densities, the expression of osteoprotegerin (OPG) and runt-related transcription factor 2(RUNX2) and the OPG/ Receptor Activator of Nuclear Factor-κ B Ligand (RANKL) ratio were the highest in the hPDLSCs initially plated at a density of 2 × 10⁴ cells/cm², and the average cell calcium concentration was also the highest. To study hPDLSCs regulating the osteoblastic differentiation of other cells, we used 50 μg/mL of secreted exosomes derived from hPDLSCs cultured using different initial cell densities to induce human bone marrow stromal cell (hBMSC) osteogenesis. After 14 days, the results indicated that the gene expression of OPG, Osteocalcin(OCN,)RUNX2, and osterix and the OPG/RANKL ratio were the highest in the 2 × 10⁴ cells/cm² initial cell density group, and the average calcium concentration was also the highest. This provides a new idea for the clinical application of stem cell osteogenesis.

Human umbilical cord blood mesenchymal stem cells as a potential therapy for schistosomal hepatic fibrosis: an experimental study

The objective of our study was to assess the effect of human umbilical cord blood (HUCB) mesenchymal stem cells (MSCs) transplantation on schistosomal hepatic fibrosis in mice. The study animals were divided into three groups. Group I is a control group, where the mice were infected with Schistosoma mansoni cercariae and remained untreated. The mice of the other two groups were infected and treated with either praziquantel (Group II) or HUCB-MSCs (Group III). Liver function tests, as well as histopathological evaluation of liver fibrosis using hematoxylin and eosin and Masson's trichrome stains, were performed. Additionally, an immunohistochemical study was carried out using anti-glial fibrillary acidic protein (GFAP) in hepatic stellate cells. Compared to the control group, the treated (praziquantel and MSCs) groups showed a substantial improvement, with a significant difference regarding the histopathological evaluation of liver fibrosis in the MSCs-treated group. In conclusion, MSCs could be a promising and efficient cell therapy for liver fibrosis.

Stem Cells in Kidney Ischemia: From Inflammation and Fibrosis to Renal Tissue Regeneration

Ischemic nephropathy consists of progressive renal function loss due to renal hypoxia, inflammation, microvascular rarefaction, and fibrosis. We provide a literature review focused on kidney hypoperfusion-dependent inflammation and its influence on renal tissue's ability to self-regenerate. Moreover, an overview of the advances in regenerative therapy with mesenchymal stem cell (MSC) infusion is provided. Based on our search, we can point out the following conclusions: 1. endovascular reperfusion is the gold-standard therapy for RAS, but its success mostly depends on treatment timeliness and a preserved downstream vascular bed; 2. anti-RAAS drugs, SGLT2 inhibitors, and/or anti-endothelin agents are especially recommended for patients with renal ischemia who are not eligible for endovascular reperfusion for slowing renal damage progression; 3. TGF-β, MCP-1, VEGF, and NGAL assays, along with BOLD MRI, should be extended in clinical practice and applied to a pre- and post-revascularization protocols; 4. MSC infusion appears effective in renal regeneration and could represent a revolutionary treatment for patients with fibrotic evolution of renal ischemia.

Delivery of Immobilized IFN-γ With PCN-333 and Its Effect on Human Mesenchymal Stem Cells

Interferon-gamma (IFN-γ) plays a vital role in modulating the immunosuppressive properties of human mesenchymal stem/stromal cells (hMSCs) used in cell therapies. However, IFN-γ suffers from low bioavailability and degrades in media, creating a challenge when using IFN-γ during the manufacturing of hMSCs. Metal-organic frameworks (MOFs), with their porous interiors, biocompatibility, high loading capacity, and ability to be functionalized for targeting, have become an increasingly suitable platform for protein delivery. In this work, we synthesize the MOF PCN-333(Fe) and show that it can be utilized to immobilize and deliver IFN-γ to the local extracellular environment of hMSCs. In doing so, the cells proliferate and differentiate appropriately with no observed side effects. We demonstrate that PCN-333(Fe) MOFs containing IFN-γ are not cytotoxic to hMSCs, can promote the expression of proteins that play a role in immune response, and are capable of inducing indoleamine 2,3-dioxygenase (IDO) production similar to that of soluble IFN-γ at lower concentrations. Overall, using MOFs to deliver IFN-γ may be leveraged in the future in the manufacturing of therapeutically relevant hMSCs.

Therapeutic potential of mesenchymal stromal/stem cells in critical-care patients with systemic inflammatory response syndrome

BACKGROUND

Despite notable advances in the support and treatment of patients admitted to the intensive care unit (ICU), the management of those who develop a systemic inflammatory response syndrome (SIRS) still constitutes an unmet medical need.

MAIN BODY

Both the initial injury (trauma, pancreatitis, infections) and the derived uncontrolled response promote a hyperinflammatory status that leads to systemic hypotension, tissue hypoperfusion and multiple organ failure. Mesenchymal stromal/stem cells (MSCs) are emerging as a potential therapy for severe ICU patients due to their potent immunomodulatory, anti-inflammatory, regenerative and systemic homeostasis-regulating properties. MSCs have demonstrated clinical benefits in several inflammatory-based diseases, but their role in SIRS needs to be further explored.

CONCLUSION

In the current review, after briefly overviewing SIRS physiopathology, we explore the potential mechanisms why MSC therapy could aid in the recovery of this condition and the pre-clinical and early clinical evidence generated to date.

Crosslinked Layered Surfaces of Heparin and Poly(L-Lysine) Enhance Mesenchymal Stromal Cell Behavior in the Presence of Soluble Interferon Gamma

Human mesenchymal stromal cells (hMSCs) are multipotent cells that have been proposed for the treatment of immune-mediated diseases. Culturing hMSCs on tissue culture plastic reduces their therapeutic potential in part due to the lack of extracellular matrix components. The aim of this study is to evaluate multilayers of heparin and poly(L-lysine) (HEP/PLL) as a bioactive surface for hMSCs stimulated with soluble interferon gamma (IFN-γ). Multilayers were formed, via layer-by-layer assembly, with HEP as the final layer and supplemented with IFN-γ in the culture medium. Multilayer construction and chemistry were confirmed using Azure A staining, quartz crystal microbalance, and X-ray photoelectron spectroscopy. hMSCs adhesion, viability, and differentiation, were assessed. Results showed that (HEP/PLL) multilayer coatings were poorly adhesive for hMSCs. However, performing chemical crosslinking using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide significantly enhanced hMSCs adhesion and viability. The immunosuppressive properties of hMSCs cultured on crosslinked (HEP/PLL) multilayers were confirmed by measuring indoleamine 2,3-dioxygenase activity. Lastly, hMSCs cultured on crosslinked (HEP/PLL) multilayers in the presence of soluble IFN- γ successfully differentiated towards the osteogenic and adipogenic lineages as confirmed by Alizarin red, and oil-red O staining, as well as alkaline phosphatase activity. This study suggests that crosslinked (HEP/PLL) films can modulate hMSCs response to soluble factors, which may improve hMSCs-based therapies aimed at treating several immune diseases.

An investigation of a self-assembled cell-extracellular complex and its potentials in improving wound healing

BACKGROUND

To maintain and enhance the wound healing effects of mesenchymal stem cells (MSCs), a scaffold for hosting MSCs is needed, which ought to be completely biocompatible, durable, producible, and of human source.

OBJECTIVE

To build a cell-extracellular matrix (ECM) complex assembled by human umbilical cord mesenchymal stem cells (HuMSCs) and to investigate its clinical potentials in promoting wound healing.

METHOD

HuMSCs were isolated and expanded. When the cells of third passage reached confluency, ascorbic acid was added to stimulate the cells to deposit ECM where the cells grew in. Four weeks later, a cells-loaded ECM sheet was formed. The cell-ECM complex was observed under the scanning electron microscopy (SEM) and subjected to histological studies. The supernatants were collected and the cell-ECM complex was harvested at different time points and processed for enzyme-linked immune sorbent assay (ELISA) and mRNA analysis. The in vivo experiments were performed by means of implanting the cell-ECM complex on the mice back for up to 6 months and the specimens were collected for histological studies.

RESULTS

After 4 weeks of cultivation with ascorbic stimulation, a sheet was formed which is mainly composed with HuMSCs, collagen and hyaluronic acid. The cell-ECM complex can sustain to certain tensile force. The mRNA and protein levels of vascular endothelial growth factor-α (VEGF-α), hepatocyte growth factor (HGF), keratinocyte growth factor (KGF), and transforming growth factor-β1 (TGF-β1) were remarkably increased compared to monolayer-cultured cells. The implanted cell-ECM complex on mice was still noticeable with host cells infiltration and vascularization on 6 months.

CONCLUSION

Our studies suggested that HuMSCs can be multi-cultivated through adding ascorbic stimulation and ECM containing collagen and hyaluronic acid were enriched around the cells which self-assembly formed a cell-ECM complex. Cell-ECM complex can improve growth factors secretion remarkably which means it may promote wound healing by paracrine.

Epigenetic Regulation of Methylation in Determining the Fate of Dental Mesenchymal Stem Cells

Dental mesenchymal stem cells (DMSCs) are crucial in tooth development and periodontal health, and their multipotential differentiation and self-renewal ability play a critical role in tissue engineering and regenerative medicine. Methylation modifications could promote the appropriate biological behavior by postsynthetic modification of DNA or protein and make the organism adapt to developmental and environmental prompts by regulating gene expression without changing the DNA sequence. Methylation modifications involved in DMSC fate include DNA methylation, RNA methylation, and histone modifications, which have been proven to exert a significant effect on the regulation of the fate of DMSCs, such as proliferation, self-renewal, and differentiation potential. Understanding the regulation of methylation modifications on the behavior and the immunoinflammatory responses involved in DMSCs contributes to further study of the mechanism of methylation on tissue regeneration and inflammation. In this review, we briefly summarize the key functions of histone methylation, RNA methylation, and DNA methylation in the differentiation potential and self-renewal of DMSCs as well as the opportunities and challenges for their application in tissue regeneration and disease therapy.

Differential Expression Profiling of microRNAs in Human Placenta-Derived Mesenchymal Stem Cells Cocultured with Grooved Porous Hydroxyapatite Scaffolds

Scaffold materials used for bone defect repair are often limited by osteogenic efficacy. Moreover, microRNAs (miRNAs) are involved in regulating the expression of osteogenic-related genes. In previous studies, we verified the enhancement of osteogenesis using a grooved porous hydroxyapatite scaffold (HAG). In the present study, we analyzed the contribution of HAG to the osteogenic differentiation of human placenta-derived mesenchymal stem cells (hPMSCs) from the perspective of miRNA differential expression. Furthermore, results showed that miRNAs were differentially expressed in the osteogenic differentiation of hPMSCs cocultured with HAG. In detail, 16 miRNAs were significantly upregulated and 29 miRNAs were downregulated with HAG. In addition, bioinformatics analyses showed that the differentially expressed miRNAs were enriched in a variety of biological processes, including signal transduction, cell metabolism, cell junctions, cell development and differentiation, and that they were associated with osteogenic differentiation through axon guidance, mitogen-activated protein kinase, and the transforming growth factor beta signaling pathway. Furthermore, multiple potential target genes of these miRNAs were closely related to osteogenic differentiation. Importantly, overexpression of miR-146a-5p (an upregulated miRNA) promoted the osteogenic differentiation of hPMSCs, and miR-145-5p overexpression (a downregulated miRNA) inhibited the osteogenic differentiation of hPMSCs.

Mesenchymal Stem/Stromal Cells Overexpressing CXCR4R334X Revealed Enhanced Migration: A Lesson Learned from the Pathogenesis of WHIM Syndrome

C-X-C chemokine receptor type 4 (CXCR4), initially recognized as a co-receptor for HIV, contributes to several disorders, including the WHIM (Warts, Hypogammaglobulinemia, Infections, and Myelokathexis) syndrome. CXCR4 binds to its ligand SDF-1 to make an axis involved in the homing property of stem cells. This study aimed to employ WHIM syndrome pathogenesis as an inspirational approach to reinforce cell therapies. Wild type and WHIM-type variants of the CXCR4 gene were chemically synthesized and cloned in the pCDH-513B-1 lentiviral vector. Molecular cloning of the synthetic genes was confirmed by DNA sequencing, and expression of both types of CXCR4 at the protein level was confirmed by western blotting in HEK293T cells. Human adipose-derived mesenchymal stem cells (Ad-MSCs) were isolated, characterized, and subjected to lentiviral transduction with Wild type and WHIM-type variants of CXCR4. The presence of copGFP-positive MSCs confirmed the high efficiency of transduction. The migration ability of both groups of transduced cells was then assessed by transwell migration assay in the presence or absence of a CXCR4-blocking agent. Our qRT-PCR results showed overexpression of CXCR4 at mRNA level in both groups of transduced MSCs, and expression of WHIM-type CXCR4 was significantly higher than Wild type CXCR4 (P<0.05). Our results indicated that the migration of genetically modified MSCs expressing WHIM-type CXCR4 had significantly enhanced towards SDF1 in comparison with Wild type CXCR4 (P<0.05), while it was reduced after treatment with CXCR4 antagonist. These data suggest that overexpression of WHIM-type CXCR4 could lead to enhanced and sustained expression of CXCR4 on human MSCs, which would increase their homing capability; hence it might be an appropriate strategy to improve the efficiency of cell-based therapies.

A new perfusion mode of culture for WJ-MSCs expansion in a stirred and online monitored bioreactor

As a clinical dose requires a minimum of 10⁶ cells per kilogram of patients, it is, therefore, crucial to develop a scalable method of production of Wharton Jelly mesenchymal stem cells (WJ-MSCs) with maintained inner characteristics. Scalable expansion of WJ-MSCs on microcarriers usually found in cell culture, involves specific cell detachment using trypsin and could have harmful effects on cells. In this study, the performance of batch, fed-batch, and perfused-continuous mode of culture were compared. The batch and fed-batch modes resulted in expansion factors of 5 and 43, respectively. The perfused-continuous mode strategy consisted of the implementation of a settling tube inside the bioreactor. The diameter of the tube was calculated to maintain microcarriers colonized by cells in the bioreactor whereas empty microcarriers (responsible for potentially damaging collisions) were removed, using a continuous flow rate based on MSCs physiological requirements. Thanks to this strategy, a maximal number of 800 million cells was obtained in a 1.5 L bioreactor in 10 days. Lastly, online dielectric spectroscopy was implemented in the bioreactor and indicated that cell growth could be monitored during the culture.

Extracellular vesicles for the treatment of central nervous system diseases

The interest in extracellular vesicles (EVs) increased during the last decade. It is now established that these vesicles play a role in the pathogenesis of central nervous system diseases (CNS), which explains why they are studied as biomarkers in these pathologies. On the other hand, EVs can also present therapeutic properties, often similar to their parent cells, as observed with mesenchymal stem cell-derived EVs. They can then be used as therapeutics, alone or combined with a bioactive molecule, for the treatment of CNS diseases, as they can cross the blood-brain barrier more easily than synthetic nanomedicines and are less immunogenic. A few clinical trials are currently on-going but there are still challenges to overcome for further clinical translation such as the scale-up of the production, the lack of standardization for isolation and characterization methods and the low encapsulation efficiency.

Oxysterols and mesenchymal stem cell biology

Mesenchymal stem cells have the ability to differentiate into several cell types when exposed to determined substances, including oxysterols. Oxysterols are cholesterol products derived from its auto-oxidation by reactive species or from enzymatic action. They are present in the body in low quantities under physiological conditions and exhibit several physiological and pharmacological actions according to both the types of oxysterol and tissue. Some of them are cytotoxic while others have been shown to promote cell differentiation through the action on several different receptors, such as nuclear LXR receptors and Smoothened receptor ligands. Here, we review the main pathways by which oxysterols have been associated with cell differentiation and death of mesenchymal stem cells.

Resident vs nonresident multipotent mesenchymal stromal cell interactions with B lymphocytes result in disparate outcomes

Multipotent human mesenchymal stromal cells (MSCs) from multiple organs including the bone marrow (BM) and placenta harbor clinically relevant immunomodulation best demonstrated toward T lymphocytes. Surprisingly, there is limited knowledge on interactions with B lymphocytes, which originate from the BM where there is a resident MSC. With increasing data demonstrating MSC tissue‐specific propensities impacting therapeutic outcome, we therefore investigated the interactions of BM‐MSCs—its resident and “niche” MSC—and placental MSCs (P‐MSCs), another source of MSCs with well‐characterized immunomodulatory properties, on the global functional outcomes of pan‐peripheral B cell populations. We found that P‐MSCs but not BM‐MSCs significantly inhibit proliferation and further differentiation of stimulated human peripheral B populations in vitro. Moreover, although BM‐MSCs preserve multiple IL‐10‐producing regulatory B cell (Breg) subsets, P‐MSCs significantly increase all subsets. To corroborate these in vitro findings in vivo, we used a mouse model of B‐cell activation and found that adoptive transfer of P‐MSCs but not BM‐MSCs significantly decreased activated B220⁺ B cells. Moreover, adoptive transfer of P‐MSCs but not BM‐MSCs significantly decreased the overall B220⁺ B‐cell proliferation and further differentiation, similar to the in vitro findings. P‐MSCs also increased two populations of IL‐10‐producing murine Bregs more strongly than BM‐MSCs. Transcriptome analyses demonstrated multifactorial differences between BM‐ and P‐MSCs in the profile of relevant factors involved in B lymphocyte proliferation and differentiation. Our results highlight the divergent outcomes of tissue‐specific MSCs interactions with peripheral B cells, and demonstrate the importance of understanding tissue‐specific differences to achieve more efficacious outcome with MSC therapy.

Extracellular vesicles derived from mesenchymal stem cells: A platform that can be engineered

Mesenchymal stem cells play an important role in tissue damage and repair. This role is mainly due to a paracrine mechanism, and extracellular vesicles (EVs) are an important part of the paracrine function. EVs play a vital role in many aspects of cell homeostasis, physiology, and pathology, and EVs can be used as clinical biomarkers, vaccines, or drug delivery vehicles. A large number of studies have shown that EVs derived from mesenchymal stem cells (MSC-EVs) play an important role in the treatment of various diseases. However, the problems of low production, low retention rate, and poor targeting of MSC-EVs are obstacles to current clinical applications. The engineering transformation of MSC-EVs can make up for those shortcomings, thereby improving treatment efficiency. This review summarizes the latest research progress of MSC-EV direct and indirect engineering transformation from the aspects of improving MSC-EV retention rate, yield, targeting, and MSC-EV visualization research, and proposes some feasible MSC-EV engineering methods of transformation.

Culture density of menstrual blood-derived stromal/stem cells determines the quality of T cell responses: An experimental study

BACKGROUND

Menstrual blood-derived stromal/stem cells (MenSCs) are a new population of refreshing and highly proliferative stem cells. Immunomodulatory effects of MenSCs profoundly depend on their relative density.

OBJECTIVE

To find whether MenSCs cultured at varying numbers would differentially affect the allogenic peripheral blood mononuclear cells (PBMCs) key features.

MATERIALS AND METHODS

PBMCs were co-cultured with various MenSCs numbers. PBMCs proliferation was investigated via3 H-thymidine incorporation. Flow cytometry was used to assess human leukocyte antigen (HLA)-DR, HLA-ABC, HLA-G, and co-stimulatory markers on MenSCs and the percentage of regulatory T cells (Tregs) among PBMCs. The concentration of cytokines was determined in supernatant of co-cultures.

RESULTS

The support of PBMCs proliferation at low MenSCs densities correlated with higher levels of pro-inflammatory interferon gamma (IFN-γ) in MenSCs/PBMCs co-culture and increased expression of HLA-DR by MenSCs. On the other hand, the suppressive property of MenSCs at higher densities was independent of Treg frequency, but correlated with a high concentration of Interleukin (IL)-6 and IL-10 in the co-cultures.

CONCLUSION

Totally, at different seeding densities, MenSCs could differentially interact with PBMCs leading to significant changes in the level of anti- and/or pro-inflammatory factors. These preliminary in vitro results are suggested to be taken into consideration in experimental models of MenSC-based immunomodulation. Nonetheless, for efficient utilization of MenSCs anti-inflammatory features in pre-clinical disease models, we still need to broaden our knowledge on MenSC-immune system cross-talk; this could play a part in designing more optimized MenSCs injection modalities in the case of future pre-clinical and subsequently clinical settings.

Characteristics and clinical potential of a cellularly modified gelatin sponge

BACKGROUND

Human umbilical cord mesenchymal stem cells (HuMSCs) injected directly have been proven effective for improving chronic wounds. However, HuMSCs largely die within 14 days. The aim of study is to establish a cellularly modified gelatin sponge and investigate its characteristics and clinical potential.

METHODS

HuMSCs were isolated, expanded and seeded in a poly-L-lysine (PLL)-coated gelatin sponge. Fabricated gelatin sponges were estimated through observation of morphological surface and ultrastructure, following confirmed by histology method. Supernatants were collected at different times for enzyme-linked immunosorbent assays (ELISAs) to measure growth factors. The cell embedded gelatin sponges were implanted subcutaneously on the backs of mice and the samples were harvested and studied histologically.

RESULTS

HuMSCs gradually modified the gelatin sponge by depositing collagen and hyaluronic acid, and degrading the structure of gelatin, resulting in a dense, and elastic structure. Compared with cells cultured in monolayer, the levels of growth factors increased remarkably when HuMSCs were cultivated in the gelatin sponge. Upon subcutaneous implantation in the backs of mice, the cellularized gelatin sponges persisted for up to 2 months and eventually integrated into the host tissue, while blank gelatin sponges degraded completely by the end of the second month.

CONCLUSION

Gelatin sponge is a clinically accessible scaffold for HuMSCs implantation to maintain short-term survival of the cells and high-level production of growth factors, which demonstrates good clinical potential for enhancing wound healing.

Unraveling the therapeutic effects of mesenchymal stem cells in asthma

Asthma is a chronic inflammatory disease associated with airway hyper-responsiveness, chronic inflammatory response, and excessive structural remodeling. The current therapeutic strategies in asthmatic patients are based on controlling the activity of type 2 T helper lymphocytes in the pulmonary tissue. However, most of the available therapies are symptomatic and expensive and with diverse side outcomes in which the interruption of these modalities contributes to the relapse of asthmatic symptoms. Up to date, different reports highlighted the advantages and beneficial outcomes regarding the transplantation of different stem cell sources, and relevant products from for the diseases' alleviation and restoration of injured sites. However, efforts to better understand by which these cells elicit therapeutic effects are already underway. The precise understanding of these mechanisms will help us to translate stem cells into the clinical setting. In this review article, we described current knowledge and future perspectives related to the therapeutic application of stem cell-based therapy in animal models of asthma, with emphasis on the underlying therapeutic mechanisms.

Human Placental MSC-Secreted IL-1β Enhances Neutrophil Bactericidal Functions during Hypervirulent Klebsiella Infection

Hypervirulent Klebsiella pneumoniae (hvKP) causes severe infections even in healthy individuals by escaping surveillance and killing from polymorphonuclear neutrophils (PMNs), the first-line leukocytes in bacterial infections; moreover, the emergence of multidrug-resistant strains further limits treatment options. We therefore assess whether multilineage mesenchymal stem cells (MSCs), best known for immunomodulation toward T cells, could be therapeutic for highly virulent bacterial infections via modulation of PMNs. We find that both bone marrow MSCs and placental MSCs (PMSCs) preserve in vitro PMN survival, but only PMSCs significantly enhance multiple PMN bactericidal functions, including phagocytosis, through secretion of interleukin-1β (IL-1β). PMSC treatment of hvKP-infected mice suppresses T and natural killer (NK) cell responses as expected but can preferentially recruit PMNs and enhance antibacterial functions to allow for disease survival; IL-1β knockdown in PMSCs significantly decreases hvKP clearance, worsening survival and resulting in 100% lethality. Our data strongly implicate the possible use of PMSCs for infections of PMN-resistant hvKP strains.

Protective Effect of Wharton's Jelly-derived Mesenchymal Stem Cells on Renal Fibrosis in Rats with Unilateral Ureteral Obstruction

Background

Renal failure is a global medical problem. The use of mesenchymal stem cells (MSCs) for preservation and regeneration of renal tissue in acute and chronic kidney diseases has recently been the focus of investigation.

Objective

To evaluate the protective effect of MSC injections in a rat model of kidney obstruction.

Design setting and participants

We assigned 15 male Wistar rats to three separate groups: the normal group underwent left nephrectomy; the control group underwent laparotomy and left ureter ligation followed by saline injection into the aorta; and the study group received MSCs injected into the aorta inferior to the left renal artery after ligation of the left ureter. Kidneys were harvested 4 wk later and renal parenchyma samples were used for trichrome staining and for expression analyses.

Outcome measurements and statistical analysis

The degree of kidney fibrosis was assessed on pathology. Real-time polymerase chain reaction was used to determine expression levels of VEGF, TNF-α, and E-cadherin, and ΔCT and ΔΔCT values were calculated. Data were analyzed using SPSS v19 with paired t tests and nonparametric independent-sample Kruskal-Wallis tests.

Results and limitations

Fibrosis in the study group decreased from grade 3 or 4 to grade 1. In the control group, TNF-α expression increased and E-cadherin expression decreased. After MSC injection into obstructed kidneys, TNF-α and E-cadherin expression levels decreased and increased respectively, reaching similar levels to those in the normal group. No correlation between tissue regeneration and VEGF levels was observed. More research is needed to focus on other angiogenic factors.

Conclusions

MSC injection could prevent fibrosis in obstructed rat kidney via alterations in TNF-α and E-cadherin expression.

Patient summary

We investigated the effect of stem cell injection in rats with kidney obstruction. The treatment led to changes in the levels of two biomarkers and reduced the amount of kidney fibrosis caused by kidney obstruction.

HLA-G Expression in Human Mesenchymal Stem Cells (MSCs) Is Related to Unique Methylation Pattern in the Proximal Promoter as well as Gene Body DNA

Multipotent human mesenchymal stem cells (MSCs) harbor clinically relevant immunomodulation, and HLA-G, a non-classical MHC class I molecule with highly restricted tissue expression, is one important molecule involved in these processes. Understanding of the natural regulatory mechanisms involved in expression of this elusive molecule has been difficult, with near exclusive reliance on cancer cell lines. We therefore studied the transcriptional control of HLA-G in primary isolated human bone marrow- (BM), human embryonic stem cell-derived (hE-), as well as placenta-derived MSCs (P-MSCs), and found that all 3 types of MSCs express 3 of the 7 HLA-G isoforms at the gene level; however, fibroblasts did not express HLA-G. Protein validation using BM- and P-MSCs demonstrated expression of 2 isoforms including a larger HLA-G-like protein. Interferon-γ (IFN-γ) stimulation upregulated both gene and protein expression in MSCs but not the constitutively expressing JEG-3 cell line. Most interestingly in human MSCs and placental tissue, hypomethylation of CpG islands not only occurs on the HLA-G proximal promoter but also on the gene body as well, a pattern not seen in either of the 2 commonly used choriocarcinoma cell lines which may contribute to the unique HLA-G expression patterns and IFN-γ-responsiveness in MSCs. Our study implicates the importance of using normal cells and tissues for physiologic understanding of tissue-specific transcriptional regulation, and highlight the utility of human MSCs in unraveling the transcriptional regulation of HLA-G for better therapeutic application.

The application of stem cell therapy and brown adipose tissue transplantation in metabolic disorders

The discovery of brown fat in adult humans has led to increased research of the thermogenic function of this tissue in various metabolic diseases. In addition, high levels of brown fat have been correlated with lower body mass index values. Therefore, increasing brown fat mass and/or activity through methods such as the browning of white fat is considered a promising strategy to prevent and treat obesity-associated diseases. Cell-based approaches using mesenchymal stromal cells and brown adipose tissue (BAT) have been utilized to directly increase BAT mass/activity through cell and tissue implantation into animals. In addition, recent studies evaluating the transplantation of human embryonic stem cells and induced pluripotent stem (iPS) cells have shown promising results in terms of positive metabolic function. In this comprehensive review, we provide a summary of the research over the past 10 years with regard to stem cell therapy and brown fat tissue transplantation for the effective treatment of metabolic syndrome. Recent advancements in stem cell methods have allowed for the production of brown adipocytes from human iPS cells, which represent an unlimited source of cellular material with which to study adipocyte development. In addition, this process is expected to be used to further explore drug- and cell-based therapies to treat obesity-related metabolic complications.

Therapeutic potential of mature adipocyte-derived dedifferentiated fat cells for inflammatory bowel disease

PURPOSE

Our previous studies demonstrated that mature adipocyte-derived dedifferentiated fat (DFAT) cells possess similar multipotency as mesenchymal stem cells. Here, we examined the immunoregulatory potential of DFAT cells in vitro and the therapeutic effect of DFAT cell transplantation in a mouse inflammatory bowel disease (IBD) model.

METHODS

The effect of DFAT cell co-culture on T cell proliferation and expression of immunosuppression-related genes in DFAT cells were evaluated. To create IBD, CD4⁺CD45RB^high T cells were intraperitoneally injected into SCID mice. One week later, DFAT cells (1 × 10⁵, DFAT group) or saline (Control group) were intraperitoneally injected. Subsequently bodyweight was measured every week and IBD clinical and histological scores were evaluated at 5 weeks after T cell administration.

RESULTS

The T cell proliferation was inhibited by co-cultured DFAT cells in a cell density-dependent manner. Gene expression of TRAIL, IDO1, and NOS2 in DFAT cells was upregulated by TNFα stimulation. DFAT group improved IBD-associated weight loss, IBD clinical and histological scores compared to Control group.

CONCLUSION

DFAT cells possess immunoregulatory potential and the cell transplantation promoted recovery from colon damage and improved clinical symptoms in the IBD model. DFAT cells could play an important role in the treatment of IBD.

Mesenchymal Stem Cell-Derived Extracellular Vesicles: Challenges in Clinical Applications

Stem cell therapy has garnered much attention and application in the past decades for the treatment of diseases and injuries. Mesenchymal stem cells (MSCs) are studied most extensively for their therapeutic roles, which appear to be derived from their paracrine activity. Recent studies suggest a critical therapeutic role for extracellular vesicles (EV) secreted by MSCs. EV are nano-sized membrane-bound vesicles that shuttle important biomolecules between cells to maintain physiological homeostasis. Studies show that EV from MSCs (MSC-EV) have regenerative and anti-inflammatory properties. The use of MSC-EV, as an alternative to MSCs, confers several advantages, such as higher safety profile, lower immunogenicity, and the ability to cross biological barriers, and avoids complications that arise from stem cell-induced ectopic tumor formation, entrapment in lung microvasculature, and immune rejection. These advantages and the growing body of evidence suggesting that MSC-EV display therapeutic roles contribute to the strong rationale for developing EV as an alternative therapeutic option. Despite the success in preclinical studies, use of MSC-EV in clinical settings will require careful consideration; specifically, several critical issues such as (i) production methods, (ii) quantification and characterization, (iii) pharmacokinetics, targeting and transfer to the target sites, and (iv) safety profile assessments need to be resolved. Keeping these issues in mind, the aim of this mini-review is to shed light on the challenges faced in MSC-EV research in translating successful preclinical studies to clinical platforms.

Exosomes Could Offer New Options to Combat the Long-Term Complications Inflicted by Gestational Diabetes Mellitus

Gestational diabetes Mellitus (GDM) is a complex clinical condition that promotes pelvic floor myopathy, thus predisposing sufferers to urinary incontinence (UI). GDM usually regresses after birth. Nonetheless, a GDM history is associated with higher risk of subsequently developing type 2 diabetes, cardiovascular diseases (CVD) and UI. Some aspects of the pathophysiology of GDM remain unclear and the associated pathologies (outcomes) are poorly addressed, simultaneously raising public health costs and diminishing women's quality of life. Exosomes are small extracellular vesicles produced and actively secreted by cells as part of their intercellular communication system. Exosomes are heterogenous in their cargo and depending on the cell sources and environment, they can mediate both pathogenetic and therapeutic functions. With the advancement in knowledge of exosomes, new perspectives have emerged to support the mechanistic understanding, prediction/diagnosis and ultimately, treatment of the post-GMD outcomes. Here, we will review recent advances in knowledge of the role of exosomes in GDM and related areas and discuss the possibilities for translating exosomes as therapeutic agents in the GDM clinical setting.

Bone marrow mesenchymal stem cells alleviate the daunorubicin-induced subacute myocardial injury in rats through inhibiting infiltration of T lymphocytes and antigen-presenting cells

INTRODUCTION

Bone marrow mesenchymal stem cells (BMSCs) have been extensively investigated from a perspective on cardiac regeneration therapy. The current study aimed to investigate the protective effect conferred by BMSCs in subacute myocardial injury, and to identify an appropriate BMSC reinfusion time.

METHODS

BMSCs were isolated from human bone marrow blood. Daunorubicin (DNR)-induced subacute myocardial models were subsequently established. The rats with DNR-induced subacute myocardial injury were injected with dexrazoxane (DZR) and/or BMSCs at varying time points, after which cardiac function was evaluated by assessing left ventricular ejection fraction (LVEF) and fraction shortening (FS). The myocardial structural changes were analyzed, after which the levels of CD3 and human leukocyte antigen DR (HLA-DR) were examined to further validate the mechanism by which BMSCs could influence subacute myocardial injury.

RESULTS

BMSCs combined with DZR treatment enhanced the cardiac function of rats with DNR-induced myocardial injury, as reflected by increased LVEF and FS. DNR-induced myocardial injuries were mitigated via the application of BMSCs combined with treatment of DZR, accompanied by diminished infiltration or vacuolization. Moreover, BMSCs were observed to alleviate infiltration of T lymphocyte and antigen-presenting cells, as evidenced by reduced expression of CD3 and HLA-DR.

CONCLUSION

Taken together, this study demonstrates that BMSCs could protect against DNR-induced myocardial injury, especially in the first three days of DNR administration. BMSCs combined with DZR exert a better therapeutic effect, but there are individual differences.

Exosomes Released by Bone Marrow Mesenchymal Stem Cells Attenuate Lung Injury Induced by Intestinal Ischemia Reperfusion via the TLR4/NF-κB Pathway

Purpose: Acute lung injury (ALI) is a primary component of multiple organ dysfunction syndromes triggered by intestinal ischemia-reperfusion (IIR) which results in high mortality. Existing treatment options remain unsatisfactory. Mesenchymal stem cells (MSCs) have shown considerable promise as a biological therapy for ALI in preclinical studies. However, there are many limitations to stem cell treatment. This study aimed to investigate whether MSC-derived exosomes, a non-cellular alternative, are able to act in a protective capacity similar to that of MSCs for ALI triggered by IIR in a rat model and to explore the underlying mechanisms. Methods: The IIR model involved occlusion of the superior mesenteric artery of a rat for 75 min then reperfusion for 20 h. Rats then received an intravenous injection of either bone marrow-derived MSCs or MSC-derived exosomes. Pathologic alteration of lung tissue, levels of pro-inflammatory cytokines, apoptotic proteins and TLR4/NF-κB signaling were measured to evaluate the therapeutic effect of treatment with either MSCs or exosomes. Results: Manifestations of acute lung injury after IIR were observed as edema and hemorrhage of alveoli and mesenchyme, and inflammatory cell infiltration. MSCs and MSC-derived exosomes both attenuated IIR-induced lung damage by decreased apoptosis and inflammation accompanied by down-regulation of TLR4 and NF-κB expression. Conclusions: MSC-derived exosomes provide protection similar to that of MSCs against IIR-induced ALI via inhibition of TLR4/NF-κB signaling, suggesting that a potential strategy against IIR-mediated acute lung injury could be therapy with exosomes as a non-cellular alternative to MSC transplantation.

Regenerative Capacity of Adipose Derived Stem Cells (ADSCs), Comparison with Mesenchymal Stem Cells (MSCs)

Adipose tissue is now on the top one of stem cell sources regarding its accessibility, abundance, and less painful collection procedure when compared to other sources. The adipose derived stem cells (ADSCs) that it contains can be maintained and expanded in culture for long periods of time without losing their differentiation capacity, leading to large cell quantities being increasingly used in cell therapy purposes. Many reports showed that ADSCs-based cell therapy products demonstrated optimal efficacy and efficiency in some clinical indications for both autologous and allogeneic purposes, hence becoming considered as potential tools for replacing, repairing, and regenerating dead or damaged cells. In this review, we analyzed the therapeutic advancement of ADSCs in comparison to bone marrow (BM) and umbilical cord (UC)-mesenchymal stem cells (MSCs) and designed the specific requirements to their best clinical practices and safety. Our analysis was focused on the ADSCs, rather than the whole stromal vascular fraction (SVF) cell populations, to facilitate characterization that is related to their source of origins. Clinical outcomes improvement suggested that these cells hold great promise in stem cell-based therapies in neurodegenerative, cardiovascular, and auto-immunes diseases.

Regenerative Capacity of Adipose Derived Stem Cells (ADSCs), Comparison with Mesenchymal Stem Cells (MSCs)

Adipose tissue is now on the top one of stem cell sources regarding its accessibility, abundance, and less painful collection procedure when compared to other sources. The adipose derived stem cells (ADSCs) that it contains can be maintained and expanded in culture for long periods of time without losing their differentiation capacity, leading to large cell quantities being increasingly used in cell therapy purposes. Many reports showed that ADSCs-based cell therapy products demonstrated optimal efficacy and efficiency in some clinical indications for both autologous and allogeneic purposes, hence becoming considered as potential tools for replacing, repairing, and regenerating dead or damaged cells. In this review, we analyzed the therapeutic advancement of ADSCs in comparison to bone marrow (BM) and umbilical cord (UC)-mesenchymal stem cells (MSCs) and designed the specific requirements to their best clinical practices and safety. Our analysis was focused on the ADSCs, rather than the whole stromal vascular fraction (SVF) cell populations, to facilitate characterization that is related to their source of origins. Clinical outcomes improvement suggested that these cells hold great promise in stem cell-based therapies in neurodegenerative, cardiovascular, and auto-immunes diseases.

Adipose-Derived Mesenchymal Stromal Cells Improve the Healing of Colonic Anastomoses Following High Dose of Irradiation Through Anti-Inflammatory and Angiogenic Processes

Cancer patients treated with radiotherapy (RT) could develop severe late side effects that affect their quality of life. Long-term bowel complications after RT are mainly characterized by a transmural fibrosis that could lead to intestinal obstruction. Today, surgical resection is the only effective treatment. However, preoperative RT increases the risk of anastomotic leakage. In this study, we attempted to use mesenchymal stromal cells from adipose tissue (Ad-MSCs) to improve colonic anastomosis after high-dose irradiation. MSCs were isolated from the subcutaneous fat of rats, amplified in vitro, and characterized by flow cytometry. An animal model of late radiation side effects was induced by local irradiation of the colon. Colonic anastomosis was performed 4 wk after irradiation. It was analyzed another 4 wk later (i.e., 8 wk after irradiation). The Ad-MSC-treated group received injections several times before and after the surgical procedure. The therapeutic benefit of the Ad-MSC treatment was determined by colonoscopy and histology. The inflammatory process was investigated using Fluorine-182-Fluoro-2-Deoxy-d-Glucose Positron Emission Tomography and Computed Tomography (¹⁸F-FDG-PET/CT) imaging and macrophage infiltrate analyses. Vascular density was assessed using immunohistochemistry. Results show that Ad-MSC treatment reduces ulcer size, increases mucosal vascular density, and limits hemorrhage. We also determined that 1 Ad-MSC injection limits the inflammatory process, as evaluated through ¹⁸F-FDG-PET-CT (at 4 wk), with a greater proportion of type 2 macrophages after iterative cell injections (8 wk). In conclusion, Ad-MSC injections promote anastomotic healing in an irradiated colon through enhanced vessel formation and reduced inflammation. This study also determined parameters that could be improved in further investigations.

Effect of mesenchymal stem cells-derived exosomes on tumor microenvironment: Tumor progression versus tumor suppression

Mesenchymal stem cells (MSCs) are multipotent cells with the potential to differentiate into different cell types. Owing to their immunosuppressive and anti-inflammatory properties, they are widely used in regenerative medicine, but they have a dual effect on cancer progression and exert both growth-stimulatory or -inhibitory effects on different cancer types. It has been proposed that these controversial effects of MSC in tumor microenvironment (TME) are mediated by their polarization to proinflammatory or anti-inflammatory phenotype. In addition, they can polarize the immune system cells that in turn influence tumor progression. One of the mechanisms involved in the TME communications is extracellular vesicles (EVs). MSCs, as one of cell populations in TME, produce a large amount of EVs that can influence tumor development. Similar to MSC, MSC-EVs can exert both anti- or protumorigenic effects. In the current study, we will investigate the current knowledge related to MSC role in cancer progression with a focus on the MSC-EV content in limiting tumor growth, angiogenesis, and metastasis. We suppose MSC-EVs can be used as safe vehicles for delivering antitumor agents to TME.

Effect of Ghrelin on Caspase 3 and Bcl2 Gene Expression in H2O2 Treated Rat's Bone Marrow Stromal Cells

Purpose: The antiapoptotic effect of ghrelin in various cell lines including bone marrow stromal cells (BMSCs) has been proved. However, the real mechanism of this effect is not clear. Caspase3 and Bcl2 are well-known pro- and antiapoptotic regulatory genes in eukaryotes. The aim of the study was to find out the effect of ghrelin on Caspase 3 and Bcl2 change in BMSCs.

Methods: Rat BMSCs were cultivated in DMEM. Passage 3 BMSCs were treated with ghrelin 100 μM for 48 h. Real-time PCR for Caspase 3 and Bcl2 was carried out from B (untreated BMSCs), BH (BMSCs treated with 125 µM H2O2), BGH (BMSCs treated with 100 µM ghrelin then 125 µM H2O2) and BG (BMSCs treated with 100 µM ghrelin) groups. For immunofluorescence, cells were incubated with anti Caspase 3 and Bcl2monoclonal antibodies. Primary antibodies were visualized using the FITC method. All data are presented as means ± SEM. Values of P<0.05 were considered statistically significant.

Results: Ghrelin decreased mRNA expressions of Caspase-3 significantly as compared to the BH group (P<0.05). Also, Bcl-2 gene expression showed an increment in BG group as compare with BH and BGH groups (P<0.05). A high present of Bcl-2 positive cells were observed in the BGH group while Caspase-3 positive cells were significantly decreased in the BGH group compared with the BH group (P<0.05).

Conclusion: Ghrelin probably enhances BMSCs viability through regulation of pro- and antiapoptotic genes Caspase 3 and Bcl2. However the signaling pathway of this effect should be elucidated in the future.

Endothelial precursor cells stimulate pericyte-like coverage of bone marrow-derived mesenchymal stem cells through platelet-derived growth factor-BB induction, which is enhanced by substance P

OBJECTIVE

The aim of this study was to evaluate the angiogenicity of a combination of BM-EPCs and BM-MSCs in vitro in the presence of SP and its working mechanism.

METHODS

BM-MSCs and BM-EPCs were cocultured with or without SP. ELISA and RT-PCR were performed to detect angiogenic factors such as VEGF and PDGF-BB. N-cadherin was detected by Western blot analysis. The tubular network-forming ability was evaluated by a Matrigel tube-forming assay.

RESULTS

BM-EPCs coculture with BM-MSCs strongly stimulated the recruitment of BM-MSCs onto the BM-EPC-generated endothelial tubular network. Upon SP treatment, endothelial branching point, tubule length, and tubular recruitment of BM-MSCs were further increased and stabilized. The coculture of BM-EPCs and BM-MSCs synergistically stimulated expression of VEGF, VEGF receptor, N-cadherin, and PDGF-BB, all of which were further enhanced by SP treatment. Blockade of PDGF-BB by its functional blocking antibodies markedly reduced the BM-MSC incorporation into the endothelial tubules. SP-pretreated BM-MSCs were preferentially incorporated into the preformed BM-EPC tubular network.

CONCLUSIONS

BM-EPCs along with SP promote the pericyte-like coverage of BM-MSCs on endothelial tubules possibly through the induction of PDGF-BB.

Isolation and Characterization of Cardiac Mesenchymal Stromal Cells from Endomyocardial Bioptic Samples of Arrhythmogenic Cardiomyopathy Patients

A normal adult heart is composed of several different cell types, among which cardiac mesenchymal stromal cells represent an abundant population. The isolation of these cells offers the possibility of studying their involvement in cardiac diseases, and, in addition, provides a useful primary cell model to investigate biological mechanisms. Here, the method for the isolation of C-MSC from arrhythmogenic cardiomyopathy patients' bioptic samples is described. The endomyocardial biopsy sampling is guided in the right ventricular areas adjacent to the scar visualized by electro-anatomical mapping. The digestion of the biopsies in collagenase and their plating on a plastic dish in culture medium to allow C-MSC growth is described. The isolated cells can be expanded in culture for several passages. To confirm their mesenchymal phenotype, the description of immuno-phenotypical characterization is provided. C-MSC are able to differentiate into several cell types like adipocytes, chondrocytes, and osteoblasts: in the context of ACM, characterized by adipocyte deposits in patients' hearts, the protocols for the adipogenic differentiation of C-MSC and the characterization of lipid droplet accumulation are described.

Adipose-derived cellular therapies in solid organ and vascularized-composite allotransplantation

PURPOSE OF REVIEW

Controlling acute allograft rejection following vascularized composite allotransplantation requires strict adherence to courses of systemic immunosuppression. Discovering new methods to modulate the alloreactive immune response is essential for widespread application of vascularized composite allotransplantation. Here, we discuss how adipose-derived cellular therapies represent novel treatment options for immune modulation and tolerance induction in vascularized composite allotransplantation.

RECENT FINDINGS

Adipose-derived mesenchymal stromal cells are cultured from autologous or allogeneic adipose tissue and possess immunomodulatory qualities capable of prolonging allograft survival in animal models of vascularized composite allotransplantation. Similar immunosuppressive and immunomodulatory effects have been observed with noncultured adipose stromal-vascular-fraction-derived therapies, albeit publication of in-vivo stromal vascular fraction cell modulation in transplantation models is lacking. However, both stromal vascular fraction and adipose derived mesenchymal stem cell therapies have the potential to effectively modulate acute allograft rejection via recruitment and induction of regulatory immune cells.

SUMMARY

To date, most reports focus on adipose derived mesenchymal stem cells for immune modulation in transplantation despite their phenotypic plasticity and reliance upon culture expansion. Along with the capacity for immune modulation, the supplemental wound healing and vasculogenic properties of stromal vascular fraction, which are not shared by adipose derived mesenchymal stem cells, hint at the profound therapeutic impact stromal vascular fraction-derived treatments could have on controlling acute allograft rejection and tolerance induction in vascularized composite allotransplantation. Ongoing projects in the next few years will help design the best applications of these well tolerated and effective treatments that should reduce the risk/benefit ratio and allow more patients access to vascularized composite allotransplantation therapy.

Mesenchymal stem cells correct impaired diabetic wound healing by decreasing ECM proteolysis

Impaired diabetic wound healing is associated with a dermal extracellular matrix protein profile favoring proteolysis; within the healing diabetic wound, this is represented by an increase in activated matrix metalloproteinase (MMPs). Treatment of diabetic wounds with mesenchymal stem cells (MSCs) has been shown to improve wound healing; however, there has not yet been an assessment of their ability to correct dysregulation of MMPs in diabetic wounds. Furthermore, there has been no prior assessment of the role of microRNA29b (miR-29b), an inhibitory regulatory molecule that targets MMP-9 mRNA. Using in vitro models of fibroblast coculture with MSCs and in vivo murine wound healing models, we tested the hypothesis that MSCs correct dysregulation of MMPs in a microRNA-29b-dependent mechanism. In this study, we first demonstrated that collagen I and III protein content is significantly reduced in diabetic wounds, and treatment with MSCs significantly improves collagen I content in both nondiabetic and diabetic wounds. We then found that MMP-9 gene expression and protein content were significantly upregulated in diabetic wounds, indicating elevated proteolysis. Treatment with MSCs resulted in a decrease in MMP-9 gene expression and protein content level in diabetic wounds 3 and 7 days after wounding. Zymographic analysis indicated that MSC treatment also decreased the amount of activated MMP-9 present in diabetic wounds. Furthermore, miR-29b expression was inversely associated with MMP-9 gene expression; miR-29b expression was decreased in diabetic wounds and diabetic fibroblast. Following treatment of diabetic wounds with MSCs, as well as in diabetic fibroblasts cocultured with MSCs, miR-29b was significantly increased. These findings suggest a potential mechanism through which MSCs enhance diabetic wound healing by improving collagen I content in diabetic wounds through decreasing MMP-9 expression and increasing miR-29b expression.

* Substituted Borosilicate Glasses with Improved Osteogenic Capacity for Bone Tissue Engineering

Borosilicate bioactive glasses (BBGs) have shown the capacity to promote higher formation of new bone when compared with silicate bioactive glasses. Herein, we assessed the capacity of BBGs to induce osteogenic differentiation of bone marrow mesenchymal stem cells (BM-MSCs) as a function of their substituted divalent cations (Mg²⁺, Ca²⁺, Sr²⁺). To this purpose, we synthesized BBG particles by melt quenching. The cell viability, proliferation, and morphology (i.e., PrestoBlue^®, PicoGreen^®, and DAPI and Phalloidin stainings, respectively), as well as protein expression (i.e., alkaline phosphatase, ALP; osteopontin, OP; and osteocalcin, OC), of BM-MSCs in contact with BBGs were evaluated for 21 days. We observed an enhanced expression of bone-specific proteins (ALP, OP, and OC) and high mineralization of BM-MSCs under BBG-Mg and BBG-Sr-conditioned osteogenic media for concentrations of 20 and 50 mg/mL with low cytotoxic effects. Moreover, BBG-Sr, at a concentration of 50 mg/mL, was able to increase the mineralization and expression of the same bone-specific proteins even under basal medium conditions. These results indicated that the proposed BBGs improved osteogenic differentiation of BM-MSCs, therefore showing their potential as relevant biomaterials for bone tissue regeneration, not only by bonding to bone tissue but also by stimulating new bone formation.

Synergistic suppression of autoimmune arthritis through concurrent treatment with tolerogenic DC and MSC

Rheumatoid arthritis (RA) is an autoimmune disease characterized by progressive immune-mediated joint deterioration. Current treatments are not antigen specific and are associated with various adverse. We have previously demonstrated that tolerogenic dendritic cells (Tol-DC) are potent antigen-specific immune regulators, which hold great promise in immunotherapy of autoimmune diseases. In this study, we aimed to develop new immunotherapy by combining Tol-DC and mesenchymal stem cells (MSC). We demonstrated that RelB gene silencing resulted in generation of Tol-DC that suppressed T cell responses and selectively promoted Treg generation. The combination of MSC synergized the tolerogenic capacity of Tol-DC in inhibition of T cell responses. In murine collagen-induced arthritis (CIA) model, we demonstrated that progression of arthritis was inhibited with administration of RelB gene-silenced Tol-DC or MSC. This therapeutic effect was remarkably enhanced with concurrent treatment of combination Tol-DC and MSC as demonstrated by improved clinical symptoms, decreased clinical scores and attenuated joint damage. These therapeutic effects were associated with suppression of CII-specific T cell responses, polarization of Th and inhibition of proinflammatory cytokines, and reduced cartilage degeneration. This study for the first time demonstrates a new approach to treat autoimmune inflammatory joint disease with concurrent treatment of RelB gene-silenced Tol-DC and MSC.