Mesenchymal stem cells and immunomodulation: current status and future prospects

Delayed MSC therapy enhances resolution of organized pneumonia induced by antibiotic resistant Klebsiella pneumoniae infection

Introduction

Mesenchymal stromal cells (MSC) are a promising therapeutic for pneumonia-induced sepsis. Here we sought to determine the efficacy of delayed administration of naïve and activated bone marrow (BM), adipose (AD), and umbilical cord (UC) derived MSCs in organized antibiotic resistant Klebsiella pneumosepsis.

Methods

Human BM-, AD-, and UC-MSCs were isolated and expanded and used either in the naïve state or following cytokine pre-activation. The effect of MSC tissue source and activation status was assessed first in vitro. Subsequent experiments assessed therapeutic potential as a delayed therapy at 48 h post infection of rodents with Klebsiella pneumoniae, with efficacy assessed at 120 h.

Results

BM-, AD-, and UC-MSCs accelerated epithelial healing, increased phagocytosis, and reduced ROS-induced epithelial injury in vitro, with AD-MSCs less effective, and naïve MSCs more effective than pre-activated MSCs. Delayed MSC administration in pre-clinical organized Klebsiella pneumosepsis had no effect on physiologic indices, but enhanced resolution of structural lung injury. Delayed therapy with pre-activated MSCs reduced mRNA concentrations of fibrotic factors. Naïve MSC treatment reduced key circulating cell proportions and increased bacterial killing capacity in the lungs whereas pre-activated MSCs enhanced the phagocytic index of pulmonary white cells.

Discussion

Delayed MSC therapy enhanced resolution of lung injury induced by antibiotic resistant Klebsiella infection and favorably modulated immune cell profile. Overall, AD-MSCs were less effective than either UC- or BM-MSCs, while naïve MSCs had a more favorable effect profile compared to pre-activated MSCs.

Small Extracellular Vesicles Secreted by iPSC-Derived MSCs Ameliorate Pulmonary Inflammation and Lung Injury Induced by Sepsis through Delivery of miR-125b-5p

Background

Sepsis-induced acute lung injury is a common critical illness in intensive care units with no effective treatment is currently available. Small extracellular vesicles, secreted by mesenchymal stem cells (MSCs), derived from human-induced pluripotent stem cells (iMSC-sEV), possess striking advantages when incorporated MSCs and iPSCs, which are considered extremely promising cell-free therapeutic agents. However, no studies have yet been conducted to systemically examine the effects and underlying mechanisms of iMSC-sEV application on attenuated lung injury under sepsis conditions.

Method

iMSC-sEV were intraperitoneally administered in a rat septic lung injury model induced by cecal ligation and puncture (CLP). The efficacy of iMSC-sEV was assessed by histology, immunohistochemistry, and pro-inflammatory cytokines of bronchoalveolar lavage fluid. We also evaluated the in vitro effects of iMSC-sEV on the activation of the inflammatory response in alveolar macrophages (AMs). Small RNA sequencing was utilized to detect changes in the miRNA expression profile in lipopolysaccharide (LPS)-treated AMs after iMSC-sEV administration. The effects of miR-125b-5p on the function of AMs were studied.

Results

iMSC-sEV were able to attenuate pulmonary inflammation and lung injury following CLP-induced lung injury. iMSC-sEV were internalized by AMs and alleviated the release of inflammatory factors by inactivating the NF-κB signaling pathway. Moreover, miR-125b-5p showed a fold-change in LPS-treated AMs after iMSC-sEV administration and was enriched in iMSC-sEV. Mechanistically, iMSC-sEV transmitted miR-125b-5p into LPS-treated AMs to target TRAF6.

Conclusion

Our findings demonstrated that iMSC-sEV treatment protects against septic lung injury and exerts anti-inflammatory effects on AMs at least partially through miR-125b-5p, suggesting that iMSC-sEV may provide a novel cell-free strategy for the treatment of septic lung injury.

Reconstitution and post-thaw storage of cryopreserved human mesenchymal stromal cells: Pitfalls and optimizations for clinically compatible formulants

Introduction

The regenerative and immunomodulatory properties of multipotent mesenchymal stromal cells (MSCs) make them an intriguing asset for therapeutic applications. An off-the-shelf approach, using pre-expanded cryopreserved allogenic MSCs, bypasses many practical difficulties of cellular therapy. Reconstitution of a MSC product away from cytotoxic cryoprotectants towards a preferred administration solution might be favorable for several indications. Variations in MSC handling accompanied by a non-standardized use of reconstitution solutions complicate a general clinical standardization of MSC cellular therapies. In this study, we aimed to identify a simple and clinically compatible approach for thawing, reconstitution, and post-thaw storage of cryopreserved MSCs.

Methods

Human adipose tissue-derived MSCs were expanded in human platelet lysate (hPL) supplemented culture medium and cryopreserved using a dimethyl sulfoxide (DMSO)-based cryoprotectant. Isotonic solutions (saline, Ringer's acetate and phosphate buffered saline (PBS)) with or without 2% human serum albumin (HSA) were used as thawing, reconstitution, and storage solutions. MSCs were reconstituted to 5 × 10⁶ MSCs/mL for evaluating MSC stability. Total MSC numbers and viability were determined using 7-aminoactinomycin D (7-AAD) and flow cytometry.

Results

For thawing cryopreserved MSCs the presence of protein was proven to be essential. Up to 50% of MSCs were lost when protein-free thawing solutions were used. Reconstitution and post-thaw storage of MSCs in culture medium and widely used PBS demonstrated poor MSC stability (>40% cell loss) and viability (<80%) after 1 h of storage at room temperature. Reconstitution in simple isotonic saline appeared to be a good alternative for post-thaw storage, ensuring >90% viability with no observed cell loss for at least 4 h. Reconstitution of MSCs to low concentrations was identified as critical. Diluting MSCs to <10⁵/mL in protein-free vehicles resulted in instant cell loss (>40% cell loss) and lower viability (<80%). Addition of clinical grade HSA could prevent cell loss during thawing and dilution.

Conclusion

This study identified a clinically compatible method for MSC thawing and reconstitution that ensures high MSC yield, viability, and stability. The strength of the method lies within the simplicity of implementation which offers an accessible way to streamline MSC therapies across different laboratories and clinical trials, improving standardization in this field.

Extracellular vesicle-mediated intercellular and interorgan crosstalk of pancreatic islet in health and diabetes

Diabetes mellitus (DM) is a systemic metabolic disease with high mortality and morbidity. Extracellular vesicles (EVs) have emerged as a novel class of signaling molecules, biomarkers and therapeutic agents. EVs-mediated intercellular and interorgan crosstalk of pancreatic islets plays a crucial role in the regulation of insulin secretion of β-cells and insulin action in peripheral insulin target tissues, maintaining glucose homeostasis under physiological conditions, and it's also involved in pathological changes including autoimmune response, insulin resistance and β-cell failure associated with DM. In addition, EVs may serve as biomarkers and therapeutic agents that respectively reflect the status and improve function and viability of pancreatic islets. In this review, we provide an overview of EVs, discuss EVs-mediated intercellular and interorgan crosstalk of pancreatic islet under physiological and diabetic conditions, and summarize the emerging applications of EVs in the diagnosis and treatment of DM. A better understanding of EVs-mediated intercellular and interorgan communication of pancreatic islets will broaden and enrich our knowledge of physiological homeostasis maintenance as well as the development, diagnosis and treatment of DM.

Tauroursodeoxycholic Acid Enhances Osteogenic Differentiation through EGFR/p-Akt/CREB1 Pathway in Mesenchymal Stem Cells

BACKGROUND

Mesenchymal stem cells (MSCs) are pluripotent stromal cells that are among the most appealing candidates for regenerative medicine and may aid in the repair and regeneration of skeletal disorders through multiple mechanisms, including angiogenesis, differentiation, and response to inflammatory conditions. Tauroursodeoxycholic acid (TUDCA) has recently been used in various cell types as one of these drugs. The mechanism of osteogenic differentiation by TUDCA in hMSCs remains unknown.

METHODS

Cell proliferation was performed by the WST-1 method, and alkaline phosphatase activity and alizarin red-sulfate staining were used to confirm the osteogenic differentiation indicator. Expression of genes related to bone differentiation and specific genes related to signaling pathways was confirmed by quantitative real-time polymerase chain reaction.

RESULTS

We found that cell proliferation was higher as the concentration increased, and showed that the induction of osteogenic differentiation was significantly enhanced. We also show that osteogenic differentiation genes were upregulated, with the expression of the epidermal growth factor receptor (EGFR) and cAMP responsive element binding protein 1 (CREB1) being specifically high. To confirm the participation of the EGFR signaling pathway, the osteogenic differentiation index and expression of osteogenic differentiation genes were determined after using an EGFR inhibitor. As a result, EGFR expression was remarkably low, and that of CREB1, cyclin D1, and cyclin E1 was also significantly low.

CONCLUSIONS

Therefore, we suggest that TUDCA-induced osteogenic differentiation of human MSCs is enhanced through the EGFR/p-Akt/CREB1 pathway.

Mesenchymal-Stromal-Cell-Conditioned Media and Their Implication for Osteochondral Regeneration

Despite significant advances in biomedical research, osteochondral defects resulting from injury, an autoimmune condition, cancer, or other pathological conditions still represent a significant medical problem. Even though there are several conservative and surgical treatment approaches, in many cases, they do not bring the expected results and further permanent damage to the cartilage and bones occurs. Recently, cell-based therapies and tissue engineering have gradually become promising alternatives. They combine the use of different types of cells and biomaterials to induce regeneration processes or replace damaged osteochondral tissue. One of the main challenges of this approach before clinical translation is the large-scale in vitro expansion of cells without changing their biological properties, while the use of conditioned media which contains various bioactive molecules appears to be very important. The presented manuscript provides a review of the experiments focused on osteochondral regeneration by using conditioned media. In particular, the effect on angiogenesis, tissue healing, paracrine signaling, and enhancing the properties of advanced materials are pointed out.

Combination of natural scaffolds and conditional medium to induce the differentiation of adipose-derived mesenchymal stem cells into keratocyte-like cells and its safety evaluation in the animal cornea

Keratocytes are the main cellular components of the corneal stroma. This cell is quiescent and cannot be cultured easily. The aim of this study was to investigate differentiate human adipose mesenchymal stem cells (hADSCs) into corneal keratocyte cells by combining natural scaffolds and conditioned medium (CM) and evaluating their safety in the rabbit's cornea. Keratocytes were cultured in an optimal culture medium and this medium was collected and kept as a CM. hADSCs were cultured on the decellularized human small incision lenticule extraction (SMILE) lenticule (SL), amniotic membrane (AM), and collagen-coated plates, and were exposed to keratocyte-CM (KCM) for 7, 14, and 21 days. Differentiation was evaluated using Real-time PCR and immunocytochemistry (ICC). hADSCs were cultured on the SL scaffolds and implanted in the corneal stroma of 8 New Zealand male rabbits. Rabbits were followed for 3 months and the safety was evaluated by clinical and histological variables. Real-time PCR results showed a significant increase in the expression of keratocyte-specific markers on the 21 day of differentiation compared to the control group. ICC also confirmed the induction of differentiation. Implantation of SLs containing differentiated cells in the cornea of animals showed no serious complications including neovascularization, corneal opacity, inflammation, or signs of tissue rejection. Furthermore, the evaluation of the presence of keratocyte-like cells after three months in the rabbit stroma was confirmed by Real-time PCR and immunohistochemistry (IHC) analysis. Our results showed that combination of combination of corneal extracellular matrix and KCM can induced keratocytes differentiation of hADSC and can be introduced as a alternative method to supply the required keratocytes in corneal tissue engineering.

Wound-Healing Effects of Mesenchymal Stromal Cell Secretome in the Cornea and the Role of Exosomes

Mesenchymal stromal/stem cells (MSCs) and their secreted factors have been shown to have immunomodulatory and regenerative effects. In this study, we investigated human bone-marrow-derived MSC secretome (MSC-S) for the treatment of corneal epithelial wounds. Specifically, we evaluated the role of MSC extracellular vesicles (EV)/exosomes in mediating the wound-healing effects of the MSC-S. In vitro studies using human corneal epithelial cells showed that MSC-CM increased cell proliferation in HCEC and HCLE cells, while EV-depleted MSC-CM showed lower cell proliferation in both cell lines compared to the MSC-CM group. In vitro and in vivo experiments revealed that 1X MSC-S consistently promoted wound healing more effectively than 0.5X MSC-S, and MSC-CM promoted wound healing in a dose-dependent manner, while exosome deprivation delayed wound healing. We further evaluated the incubation period of MSC-CM on corneal wound healing and showed that MSC-S collected for 72 h is more effective than MSC-S collected for 48 h. Finally, we evaluated the stability of MSC-S under different storage conditions and found that after one cycle of freeze-thawing, MSC-S is stable at 4 °C for up to 4 weeks. Collectively, we identified the following: (i) MSC-EV/Exo as the active ingredient in MSC-S that mediates the wound-healing effects in the corneal epithelium, providing a measure to optimize its dosing for a potential clinical product; (ii) Treatment with EV/Exo-containing MSC-S resulted in an improved corneal barrier and decreased corneal haze/edema relative to EV/Exo-depleted MSC-S; (iii) The stability of MSC-CM for up to 4 weeks showed that the regular storage condition did not significantly impact its stability and therapeutic functions.

Cellular nanovesicles for therapeutic immunomodulation: A perspective on engineering strategies and new advances

Cellular nanovesicles which are referred to as cell-derived, nanosized lipid bilayer structures, have emerged as a promising platform for regulating immune responses. Owing to their outstanding advantages such as high biocompatibility, prominent structural stability, and high loading capacity, cellular nanovesicles are suitable for delivering various immunomodulatory molecules, such as small molecules, nucleic acids, peptides, and proteins. Immunomodulation induced by cellular nanovesicles has been exploited to modulate immune cell behaviors, which is considered as a novel cell-free immunotherapeutic strategy for the prevention and treatment of diverse diseases. Here we review emerging concepts and new advances in leveraging cellular nanovesicles to activate or suppress immune responses, with the aim to explicate their applications for immunomodulation. We overview the general considerations and principles for the design of engineered cellular nanovesicles with tailored immunomodulatory activities. We also discuss new advances in engineering cellular nanovesicles as immunotherapies for treating major diseases.

Mesenchymal stem cell-derived exosomes for treatment of sepsis

Introduction

The pathogenesis of sepsis is an imbalance between pro-inflammatory and anti-inflammatory responses. At the onset of sepsis, the lungs are severely affected, and the injury progresses to acute respiratory distress syndrome (ARDS), with a mortality rate of up to 40%. Currently, there is no effective treatment for sepsis. Cellular therapies using mesenchymal stem cells (MSCs) have been initiated in clinical trials for both ARDS and sepsis based on a wealth of pre-clinical data. However, there remains concern that MSCs may pose a tumor risk when administered to patients. Recent pre-clinical studies have demonstrated the beneficial effects of MSC-derived extracellular vesicles (EVs) for the treatment of acute lung injury (ALI) and sepsis.

Methods

After recovery of initial surgical preparation, pneumonia/sepsis was induced in 14 adult female sheep by the instillation of Pseudomonas aeruginosa (~1.0×1011 CFU) into the lungs by bronchoscope under anesthesia and analgesia. After the injury, sheep were mechanically ventilated and continuously monitored for 24 h in a conscious state in an ICU setting. After the injury, sheep were randomly allocated into two groups: Control, septic sheep treated with vehicle, n=7; and Treatment, septic sheep treated with MSC-EVs, n=7. MSC-EVs infusions (4ml) were given intravenously one hour after the injury.

Results

The infusion of MSCs-EVs was well tolerated without adverse events. PaO2/FiO2 ratio in the treatment group tended to be higher than the control from 6 to 21 h after the lung injury, with no significant differences between the groups. No significant differences were found between the two groups in other pulmonary functions. Although vasopressor requirement in the treatment group tended to be lower than in the control, the net fluid balance was similarly increased in both groups as the severity of sepsis progressed. The variables reflecting microvascular hyperpermeability were comparable in both groups.

Conclusion

We have previously demonstrated the beneficial effects of bone marrow-derived MSCs (10×106 cells/kg) in the same model of sepsis. However, despite some improvement in pulmonary gas exchange, the present study demonstrated that EVs isolated from the same amount of bone marrow-derived MSCs failed to attenuate the severity of multiorgan dysfunctions.

TNF-α/IL-1β-licensed hADSCs alleviate cholestatic liver injury and fibrosis in mice via COX-2/PGE2 pathway

BACKGROUND

Adipose tissue-derived stem cell (ADSC) transplantation has been shown to be effective for the management of severe liver disorders. Preactivation of ADSCs enhanced their therapeutic efficacy. However, these effects have not yet been examined in relation to cholestatic liver injury.

METHODS

In the present study, a cholestatic liver injury model was established by bile duct ligation (BDL) in male C57BL/6 mice. Human ADSCs (hADSCs) with or without tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) pretreatment were administrated into the mice via tail vein injections. The efficacy of hADSCs on BDL-induced liver injury was assessed by histological staining, real-time quantitative PCR (RT-qPCR), Western blot, and enzyme-linked immune sorbent assay (ELISA). In vitro, the effects of hADSC conditioned medium on the activation of hepatic stellate cells (HSCs) were investigated. Small interfering RNA (siRNA) was used to knock down cyclooxygenase-2 (COX-2) in hADSCs.

RESULTS

TNF-α/IL-1β preconditioning could downregulate immunogenic gene expression and enhance the engraftment efficiency of hADSCs. Compared to control hADSCs (C-hADSCs), TNF-α/IL-1β-pretreated hADSCs (P-hADSCs) significantly alleviated BDL-induced liver injury, as demonstrated by reduced hepatic cell death, attenuated infiltration of Ly6G + neutrophils, and decreased expression of pro-inflammatory cytokines TNF-α, IL-1β, C-X-C motif chemokine ligand 1 (CXCL1), and C-X-C motif chemokine ligand 2 (CXCL2). Moreover, P-hADSCs significantly delayed the development of BDL-induced liver fibrosis. In vitro, conditioned medium from P-hADSCs significantly inhibited HSC activation compared to that from C-hADSCs. Mechanistically, TNF-α/IL-1β upregulated COX-2 expression and increased prostaglandin E2 (PGE2) secretion. The blockage of COX-2 by siRNA transfection reversed the benefits of P-hADSCs for PGE2 production, HSC activation, and liver fibrosis progression.

CONCLUSION

In conclusion, our results suggest that TNF-α/IL-1β pretreatment enhances the efficacy of hADSCs in mice with cholestatic liver injury, partially through the COX-2/PGE2 pathway.

Bioengineered Mesenchymal-Stromal-Cell-Derived Extracellular Vesicles as an Improved Drug Delivery System: Methods and Applications

Extracellular vesicles (EVs) are cell-derived nano-sized lipid membranous structures that modulate cell-cell communication by transporting a variety of biologically active cellular components. The potential of EVs in delivering functional cargos to targeted cells, their capacity to cross biological barriers, as well as their high modification flexibility, make them promising drug delivery vehicles for cell-free therapies. Mesenchymal stromal cells (MSCs) are known for their great paracrine trophic activity, which is largely sustained by the secretion of EVs. MSC-derived EVs (MSC-EVs) retain important features of the parental cells and can be bioengineered to improve their therapeutic payload and target specificity, demonstrating increased therapeutic potential in numerous pre-clinical animal models, including in the treatment of cancer and several degenerative diseases. Here, we review the fundamentals of EV biology and the bioengineering strategies currently available to maximize the therapeutic value of EVs, focusing on their cargo and surface manipulation. Then, a comprehensive overview of the methods and applications of bioengineered MSC-EVs is presented, while discussing the technical hurdles yet to be addressed before their clinical translation as therapeutic agents.

Mesenchymal Stromal Cells Suppress T-Cell-Mediated Delayed-Type Hypersensitivity via ALCAM-CD6 Interaction

Mounting evidence suggests mesenchymal stromal cells (MSCs) suppress CD4+ T-cell activation, but whether MSCs directly regulate activation and expansion of allogeneic T cells has not been fully deciphered. Here, we identified that both human and murine MSCs constitutively express ALCAM, a cognate ligand for CD6 receptors on T cells, and investigated its immunomodulatory function using in vivo and in vitro experiments. Our controlled coculture assays demonstrated that ALCAM-CD6 pathway is critical for MSCs to exert its suppressive function on early CD4+CD25- T-cell activation. Moreover, neutralizing ALCAM or CD6 results in the abrogation of MSC-mediated suppression of T-cell expansion. Using a murine model of delayed-type hypersensitivity response to alloantigen, we show that ALCAM-silenced MSCs lose the capacity to suppress the generation of alloreactive IFNγ-secreting T cells. Consequently, MSCs, following ALCAM knockdown, failed to prevent allosensitization and alloreactive T-cell-mediated tissue damage.

Biology and therapeutic potential of mesenchymal stem cell extracellular vesicles in axial spondyloarthritis

Axial spondyloarthritis (AxSpA) is a chronic, inflammatory, autoimmune disease that predominantly affects the joints of the spine, causes chronic pain, and, in advanced stages, may result in spinal fusion. Recent developments in understanding the immunomodulatory and tissue-differentiating properties of mesenchymal stem cell (MSC) therapy have raised the possibility of applying such treatment to AxSpA. The therapeutic effectiveness of MSCs has been shown in numerous studies spanning a range of diseases. Several studies have been conducted examining acellular therapy based on MSC secretome. Extracellular vesicles (EVs) generated by MSCs have been proven to reproduce the impact of MSCs on target cells. These EVs are associated with immunological regulation, tissue remodeling, and cellular homeostasis. EVs' biological effects rely on their cargo, with microRNAs (miRNAs) integrated into EVs playing a particularly important role in gene expression regulation. In this article, we will discuss the impact of MSCs and EVs generated by MSCs on target cells and how these may be used as unique treatment strategies for AxSpA.

Encapsulation of Human Umbilical Cord Mesenchymal Stem Cells in LunaGel Photocrosslinkable Extracellular Matrix and Subcutaneous Transplantation in Mice

Stem cells have significant potential in regenerative medicines. However, a major issue with implanting stem cells in the regeneration of new tissue is the methods to implant them and cell viability and functions before and after implantation. Here we developed a simple yet effective method that used photo-crosslinkable gelatin-based hydrogel (LunaGel^TM) as a scaffold for the encapsulation, expansion, and eventually, transplantation of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) into mice subcutaneously. We demonstrated the proliferation and maintenance of the original expression of mesenchymal stem cell markers as well as the ability to differentiate into mesoderm-derived cells. The hydrogel was highly stable with no signs of degradation after 20 days in PBS. The hUC-MSCs remained viable after transplantation into mice's subcutaneous pockets and migrated to integrate with the surrounding tissues. We showed a collagen-rich layer surrounding the transplanted cell-laden scaffold indicating the effects of growth factors secreted by the hUC-MSCs. A connective tissue layer was found between the implanted cell-laden scaffold and the collagen layer, and immunohistochemical staining results suggested that this tissue was derived from the MSCs which migrated from within the scaffold. The results, thus, also suggested a protective effect the scaffold has on the encapsulated cells from the antibodies and cytotoxic cells of the host immune system.

Dental pulp and apical papilla cells senescence: causes, consequences, and prevention

Dental pulp under physiological conditions has a defense function, repair capacity, and important mechanisms in pathological processes. In addition, the dental papilla is involved in important defense processes and an essential function in the pulp revascularization process. It is known that dental pulp and apical papilla undergo a natural aging process, in addition to stressful situations such as bruxism, inflammation, and infections. Both aging and stressful situations can lead to cellular senescence. Some evidence indicates that the changes resulting from this cellular state can directly affect the efficiency of cells in these tissues and affect conservative and regenerative clinical treatments. Thus, it is necessary to understand the causes and consequences of cellular senescence in addition to the development of methods for senescence prevention. This review aims to provide an overview of possible causes and consequences of senescence in dental pulp and stem cells from apical papilla and discusses possible methods to prevent this cellular state.

The effects of mesenchymal stem cells on the chemotherapy of colorectal cancer

Colorectal cancer (CRC) has been the third commonest cancer in the world. The prognosis of patients with CRC is related to the molecular subtypes and gene mutations, which is prone to recurrence, metastasis, and drug resistance. Mesenchymal stem cells (MSCs) are a group of progenitor ones with the capabilities of self-renewal， multi-directional differentiation, and tissue re-population, which could be isolated from various kinds of tissues and be differentiated into diverse cell types. In recent years, MSCs are applied for mechanisms study of tissue repairing, graft-versus-host disease (GVHD) and autoimmune-related disease, and tumor development, with the advantages of anti-inflammation, multi-lineage differentiation, and homing capability. Integrating the chemotherapy and MSCs therapy might provide a novel treatment approach for CRC patients. In this review, we summarize the current progress in the integrated treatment of integrating the MSCs and chemotherapy for CRC.

Tocilizumab-coated solid lipid nanoparticles loaded with cannabidiol as a novel drug delivery strategy for treating COVID-19: A review

Commonly used clinical strategies against coronavirus disease 19 (COVID-19), including the potential role of monoclonal antibodies for site-specific targeted drug delivery, are discussed here. Solid lipid nanoparticles (SLN) tailored with tocilizumab (TCZ) and loading cannabidiol (CBD) are proposed for the treatment of COVID-19 by oral route. TCZ, as a humanized IgG1 monoclonal antibody and an interleukin-6 (IL-6) receptor agonist, can attenuate cytokine storm in patients infected with SARS-CoV-2. CBD (an anti-inflammatory cannabinoid and TCZ agonist) alleviates anxiety, schizophrenia, and depression. CBD, obtained from Cannabis sativa L., is known to modulate gene expression and inflammation and also shows anti-cancer and anti-inflammatory properties. It has also been recognized to modulate angiotensin-converting enzyme II (ACE2) expression in SARS-CoV-2 target tissues. It has already been proven that immunosuppressive drugs targeting the IL-6 receptor may ameliorate lethal inflammatory responses in COVID-19 patients. TCZ, as an immunosuppressive drug, is mainly used to treat rheumatoid arthritis, although several attempts have been made to use it in the active hyperinflammatory phase of COVID-19, with promising outcomes. TCZ is currently administered intravenously. It this review, we discuss the potential advances on the use of SLN for oral administration of TCZ-tailored CBD-loaded SLN, as an innovative platform for managing SARS-CoV-2 and related infections.

Evaluation of the relationship between mesenchymal stem cells and immune system in vitro conditions

BACKGROUND

Mesenchymal stem cells (MSCs), are a novel therapeutic option as the most common cell source, play an important role in the immunomodulation. In this study, it was aimed to determine the effect of MSCs on cytokines secreted by the immune system cells.

METHODS

Intracellular cytokine levels (Interleukin-4 (IL-4), Interferon-γ (IFN-γ), and Interleukin-17 (IL-17)) detected by flow cytometry before and after co-culture between peripheral blood mononuclear cells (PBMCs) and MCSs. At the same time, supernatant cytokine levels were measured using the ELISA.

RESULTS

In our study, MSCs were isolated from cord blood (CB) and Wharton's Jelly (WJ), and their surface markers (CD44 (100%), CD73 (99.6%), CD90 (100%), CD105 (88%)) shown by flow cytometry method. Both CB-MSCs and WJ-MSCs were used in co-culture MSC/PBMC ratios of 1/5 and 1/10, incubation times of 24 h and 72 h. In the present study, when we compared co-cultures of CB-MSC or WJ-MSC with PBMCs, intracellular levels of cytokines IFN-γ, IL-17 (pro-inflamatory) and IL-4 (anti-inflamatory) were increased, and supernatant levels were decreased significantly (p < 0.05). The level of transforming growth factor beta (TGF-β) (anti-inflamatory) was significantly decreased for both CB-MSC and WJ-MSC in supernatant (p < 0.05).

CONCLUSIONS

It was investigated pro-inflammatory and anti-inflammatory effects of CB-MSCs and WJ-MSCs on PBMCs with the obtained results. According to the results, MSCs demonstrated different immunologic effects after the incubation time and ratios. For further studies, it should be known between interaction of MSCs and immune system.

Autologous Synovial Mesenchymal Stem Cell Transplantation Suppresses Inflammation Caused by Synovial Harvesting and Promotes Healing in a Micro Minipig Repaired Meniscus Model

PURPOSE

Allogeneic synovial mesenchymal stem cells (MSCs) effectively promote meniscus healing in micro minipigs. We investigated the effect of autologous synovial MSC transplantation on meniscus healing in a micro minipig model of meniscus repair showing synovitis after synovial harvesting.

MATERIALS AND METHODS

Synovium was harvested from the left knee of the micro minipigs after arthrotomy and used to prepare synovial MSCs. The left medial meniscus in the avascular region was injured, repaired, and transplanted with synovial MSCs. First, synovitis was compared after 6 weeks in knees with and without synovial harvesting. Second, the repaired meniscus was compared for the autologous MSC group and the control group (in which synovium was harvested but MSCs were not transplanted) 4 weeks after transplantation.

RESULTS

Synovitis was more severe in knees subjected to synovium harvesting than in knees not subjected to harvesting. Menisci treated with autologous MSCs showed no red granulation at the tear of the meniscus, but menisci not treated with MSCS showed red granulation. Macroscopic scores, inflammatory cell infiltration scores, and matrix scores assessed by toluidine blue staining were all significantly better in the autologous MSC group than in the control group without MSCs (n = 6).

CONCLUSION

Autologous synovial MSC transplantation suppressed the inflammation caused by synovial harvesting in micro minipigs and promoted healing of the repaired meniscus.

Role of curcumin and its nanoformulations in the treatment of neurological diseases through the effects on stem cells

Curcumin from turmeric is a natural phenolic compound with a promising potential to regulate fundamental processes involved in neurological diseases, including inflammation, oxidative stress, protein aggregation, and apoptosis at the molecular level. In this regard, employing nanoformulation can improve curcumin efficiency by reducing its limitations, such as low bioavailability. Besides curcumin, growing data suggest that stem cells are a noteworthy candidate for neurodegenerative disorders therapy due to their anti-inflammatory, anti-oxidative, and neuronal-differentiation properties, which result in neuroprotection. Curcumin and stem cells have similar neurogenic features and can be co-administered in a cell-drug delivery system to achieve better combination therapeutic outcomes for neurological diseases. Based on the evidence, curcumin can induce the neuroprotective activity of stem cells by modulating their related signalling pathways. The present review is about the role of curcumin and its nanoformulations in the improvement of neurological diseases alone and through the effect on different categories of stem cells by discussing the underlying mechanisms to provide a roadmap for future investigations.

Human dental pulp stem cell monolayer and spheroid therapy after spinal motor root avulsion in adult rats

Spinal cord injuries result in severe neurological deficits and neuronal loss, with poor functional recovery. Mesenchymal stem cells have shown promising results; therefore the present objective of this work was to compare motor recovery after treatment with human dental pulp stem cells (hDPSC) cultivated in monolayer (2D) or as spheroids (3D), following avulsion and reimplantation of spinal motor roots in adult rats. Thus, 72 adult female Lewis rats were divided into 4 groups: avulsion (AV); avulsion followed by reimplantation (AR); avulsion associated with reimplant and 2D cell therapy (AR + 2D), and avulsion associated with reimplant and 3D cell therapy (AR + 3D). The application of the cells in 2D and 3D was performed by microsurgery, with subsequent functional assessment using a walking track test (Catwalk system), immunohistochemistry, neuronal survival, and qRT-PCR in 1-, 4-, and 12-weeks post-injury. The animals in the AR + 2D and AR + 3D groups showed the highest neuronal survival rates, and immunofluorescence revealed downregulation of GFAP, and Iba-1, with preservation of synaptophysin, indicating a reduction in glial reactivity, combined with the maintenance of pre-synaptic inputs. There was an increase in anti-inflammatory (IL-4, TGFβ) and a reduction of pro-inflammatory factors (IL-6, TNFα) in animals treated with reimplantation and hDPSC. As for the functional recovery, in all analyzed parameters, the AR + 2D group performed better and was superior to the avulsion alone. Overall, our results indicate that the 2D and 3D cell therapy approaches provide successful immunomodulation and motor recovery, consistent with advanced therapies after spinal cord injury.

Mesenchymal stem cell-released oncolytic virus: an innovative strategy for cancer treatment

Oncolytic viruses (OVs) infect, multiply, and finally remove tumor cells selectively, causing no damage to normal cells in the process. Because of their specific features, such as, the ability to induce immunogenic cell death and to contain curative transgenes in their genomes, OVs have attracted attention as candidates to be utilized in cooperation with immunotherapies for cancer treatment. This treatment takes advantage of most tumor cells' inherent tendency to be infected by certain OVs and both innate and adaptive immune responses are elicited by OV infection and oncolysis. OVs can also modulate tumor microenvironment and boost anti-tumor immune responses. Mesenchymal stem cells (MSC) are gathering interest as promising anti-cancer treatments with the ability to address a wide range of cancers. MSCs exhibit tumor-trophic migration characteristics, allowing them to be used as delivery vehicles for successful, targeted treatment of isolated tumors and metastatic malignancies. Preclinical and clinical research were reviewed in this study to discuss using MSC-released OVs as a novel method for the treatment of cancer. Video Abstract.

Emerging role of mesenchymal stem/stromal cells (MSCs) and MSCs-derived exosomes in bone- and joint-associated musculoskeletal disorders: a new frontier

Exosomes are membranous vesicles with a 30 to 150 nm diameter secreted by mesenchymal stem/stromal cells (MSCs) and other cells, such as immune cells and cancer cells. Exosomes convey proteins, bioactive lipids, and genetic components to recipient cells, such as microRNAs (miRNAs). Consequently, they have been implicated in regulating intercellular communication mediators under physiological and pathological circumstances. Exosomes therapy as a cell-free approach bypasses many concerns regarding the therapeutic application of stem/stromal cells, including undesirable proliferation, heterogeneity, and immunogenic effects. Indeed, exosomes have become a promising strategy to treat human diseases, particularly bone- and joint-associated musculoskeletal disorders, because of their characteristics, such as potentiated stability in circulation, biocompatibility, low immunogenicity, and toxicity. In this light, a diversity of studies have indicated that inhibiting inflammation, inducing angiogenesis, provoking osteoblast and chondrocyte proliferation and migration, and negative regulation of matrix-degrading enzymes result in bone and cartilage recovery upon administration of MSCs-derived exosomes. Notwithstanding, insufficient quantity of isolated exosomes, lack of reliable potency test, and exosomes heterogeneity hurdle their application in clinics. Herein, we will deliver an outline respecting the advantages of MSCs-derived exosomes-based therapy in common bone- and joint-associated musculoskeletal disorders. Moreover, we will have a glimpse the underlying mechanism behind the MSCs-elicited therapeutic merits in these conditions.

Ginkgolide A improves the pleiotropic function and reinforces the neuroprotective effects by mesenchymal stem cell-derived exosomes in 6-OHDA-induced cell model of Parkinson's disease

Parkinson's disease (PD) is a common disorder attributed to the loss of midbrain dopamine (mDA) neurons and reduced dopamine secretion. Currently, the treatment regimes for PD comprise deep brain stimulations, however, it attenuates the PD progression marginally and does not improve neuronal cell death. We investigated the function of Ginkgolide A (GA) to reinforce Wharton's Jelly-derived mesenchymal stem cells (WJMSCs) for treating the in vitro model of PD. GA enhanced the self-renewal, proliferation, and cell homing function of WJMSCs as assessed by MTT and transwell co-culture assay with a neuroblastoma cell line. GA pre-treated WJMSCs can restore 6-hydroxydopamine (6-OHDA)-induced cell death in a co-culture assay. Furthermore, exosomes isolated from GA pre-treated WJMSCs significantly rescued 6-OHDA-induced cell death as determined by MTT assay, flow cytometry, and TUNEL assay. Western blotting showed that apoptosis-related proteins were decreased following GA-WJMSCs exosomal treatment which further improved mitochondrial dysfunction. We further demonstrated that exosomes isolated from GA-WJMSCs could restore autophagy using immunofluorescence staining and immunoblotting assay. Finally, we used the alpha-synuclein recombinant protein and found that exosomes derived from GA-WJMSCs led to the reduced aggregation of alpha-synuclein compared to that in control. Our results suggested that GA could be a potential candidate for strengthening stem cell and exosome therapy for PD.

NK cells are never alone: crosstalk and communication in tumour microenvironments

Immune escape is a hallmark of cancer. The dynamic and heterogeneous tumour microenvironment (TME) causes insufficient infiltration and poor efficacy of natural killer (NK) cell-based immunotherapy, which becomes a key factor triggering tumour progression. Understanding the crosstalk between NK cells and the TME provides new insights for optimising NK cell-based immunotherapy. Here, we present new advances in direct or indirect crosstalk between NK cells and 9 specialised TMEs, including immune, metabolic, innervated niche, mechanical, and microbial microenvironments, summarise TME-mediated mechanisms of NK cell function inhibition, and highlight potential targeted therapies for NK-TME crosstalk. Importantly, we discuss novel strategies to overcome the inhibitory TME and provide an attractive outlook for the future.

Tissue buccal fat pad-stromal vascular fraction as a safe source in maxillofacial bone regeneration: A clinical pilot study

AIM

The purpose of this study was to examine the biological properties of the buccal fat pad (BFP)-derived tissue stromal vascular fraction (tSVF) in vitro and compare them with BFP-derived cellular SVF (cSVF). Furthermore, a clinical pilot study assessed the safety of using BFP-derived tSVF for maxillofacial bone regeneration.

MATERIALS AND METHODS

This study was performed in two sections: 1) experimental section: BFP tissue was harvested from three healthy donors, and then cSVF and tSVF were isolated by enzymatic and mechanical methods to assess their biological properties and 2) clinical section: Ten patients with maxillofacial bone defects were enrolled according to eligibility criteria and offered two options for surgery, including autologous BFP-tSVF (n = 5) and autologous bone grafting (n = 5), to evaluate safety after a year of follow-up.

RESULTS

The BFP-tSVF exhibited high cell viability and various cell surface markers, including CD45, CD31, and CD34. There was no population-doubling time and multilineage differentiation capacity compared with BFP-cSVF. BFP-tSVF is safe because of the lack of intervention-related adverse events reported in donor and surgery sites during a one-year period. In addition, cell therapy was feasible because it can be performed during surgery and requires little preparation time. Patients in the ABG group experienced pain and tenderness in the iliac crest, leading to dissatisfaction and complications.

CONCLUSION

The experimental results confirmed that the cells isolated from BFP-tSVF have stemness properties similar to BFP-cSVF. Clinical evaluation also indicated that this cellular product could be used safely to regenerate maxillofacial bone defects.

Mesenchymal stem cells in the treatment of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a disease caused by mutations in different genes resulting in mild, severe, or lethal forms. With no cure, researchers have investigated the use of cell therapy to correct the underlying molecular defects of OI. Mesenchymal stem cells (MSCs) are of particular interest because of their differentiation capacity, immunomodulatory effects, and their ability to migrate to sites of damage. MSCs can be isolated from different sources, expanded in culture, and have been shown to be safe in numerous clinical applications. This review summarizes the preclinical and clinical studies of MSCs in the treatment of OI. Altogether, the culmination of these studies show that MSCs from different sources: 1) are safe to use in the clinic, 2) migrate to fracture sites and growth sites in bone, 3) engraft in low levels, 4) improve clinical outcome but have a transient effect, 5) have a therapeutic effect most likely due to paracrine mechanisms, and 6) have a reduced therapeutic potential when isolated from patients with OI.

Nerves within bone and their application in tissue engineering of bone regeneration

Nerves within bone play an irreplaceable role in promoting bone regeneration. Crosstalk between the nerve system and bone has arisen to the attention of researchers in the field of basic medicine, clinical medicine, and biomaterials science. Successful bone regeneration relies on the appropriate participation of neural system components including nerve fibers, signaling molecules, and neural-related cells. Furthermore, more about the mechanisms through which nerves took part in bone regeneration and how these mechanisms could be integrated into tissue engineering scaffolds were under exploration. In the present review, we aimed to systematically elaborate on the structural and functional interrelationship between the nerve system and bone. In particular, peripheral nerves interact with the bone through innervated axons, multiple neurotrophins, and bone resident cells. Also, we aimed to summarize research that took advantage of the neuro-osteogenic network to design tissue engineering scaffolds for bone repair.

Mechanisms behind therapeutic potentials of mesenchymal stem cell mitochondria transfer/delivery

Mesenchymal stromal/stem cells (MSCs) perform their therapeutic effects through various mechanisms, including their ability to differentiate, producing different growth factors, immunomodulatory factors, and extracellular vesicles (EVs). In addition to the mentioned mechanisms, a new aspect of the therapeutic potential of MSCs has recently been noticed, which occurs through mitochondrial transfer. Various methods of MSCs mitochondria transfer have been used in studies to benefit from their therapeutic potential. Among these methods, mitochondrial transfer after MSCs transplantation in cell-to-cell contact, EVs-mediated transfer of mitochondria, and the use of MSCs isolated mitochondria (MSCs-mt) are well studied. Pathological conditions can affect the cells in the damaged microenvironment and lead to cells mitochondrial damage. Since the defect in the mitochondrial function of the cell leads to a decrease in ATP production and the subsequent cell death, restoring the mitochondrial content, functions, and hemostasis can affect the functions of the damaged cell. Various studies show that the transfer of MSCs mitochondria to other cells can affect vital processes such as proliferation, differentiation, cell metabolism, inflammatory responses, cell senescence, cell stress, and cell migration. These changes in cell attributes and behavior are very important for therapeutic purposes. For this reason, their investigation can play a significant role in the direction of the researchers'.

Engineered adult stem cells: a promising tool for anti-cancer therapy

Cancers are one of the most dreaded diseases in human history and have been targeted by numerous trials including surgery, chemotherapy, radiation therapy, and anti-cancer drugs. Adult stem cells (ASCs), which can regenerate tissues and repair damage, have emerged as leading therapeutic candidates due to their homing ability toward tumor foci. Stem cells can precisely target malicious tumors, thereby minimizing the toxicity of normal cells and unfavorable side effects. ASCs, such as mesenchymal stem cells (MSCs), neural stem cells (NSCs), and hematopoietic stem cells (HSCs), are powerful tools for delivering therapeutic agents to various primary and metastatic cancers. Engineered ASCs act as a bridge between the tumor sites and tumoricidal reagents, producing therapeutic substances such as exosomes, viruses, and anti-cancer proteins encoded by several suicide genes. This review focuses on various anti-cancer therapies implemented via ASCs and summarizes the recent treatment progress and shortcomings. [BMB Reports 2023; 56(2): 71-77].

Engineered adult stem cells: a promising tool for anti-cancer therapy

Cancers are one of the most dreaded diseases in human history and have been targeted by numerous trials including surgery, chemotherapy, radiation therapy, and anti-cancer drugs. Adult stem cells (ASCs), which can regenerate tissues and repair damage, have emerged as leading therapeutic candidates due to their homing ability toward tumor foci. Stem cells can precisely target malicious tumors, thereby minimizing the toxicity of normal cells and unfavorable side effects. ASCs, such as mesenchymal stem cells (MSCs), neural stem cells (NSCs), and hematopoietic stem cells (HSCs), are powerful tools for delivering therapeutic agents to various primary and metastatic cancers. Engineered ASCs act as a bridge between the tumor sites and tumoricidal reagents, producing therapeutic substances such as exosomes, viruses, and anti-cancer proteins encoded by several suicide genes. This review focuses on various anti-cancer therapies implemented via ASCs and summarizes the recent treatment progress and shortcomings. [BMB Reports 2023; 56(2): 71-77].

Assessment of therapeutic role of mesenchymal stromal cells in mouse models of graft-versus-host disease using cryo-imaging

Insights regarding the biodistribution and homing of mesenchymal stromal cells (MSCs), as well as their interaction with alloreactive T-cells are critical for understanding how MSCs can regulate graft-versus-host disease (GVHD) following allogeneic (allo) bone marrow transplantation (BMT). We developed novel assays based on 3D, microscopic, cryo-imaging of whole-mouse-sized volumes to assess the therapeutic potential of human MSCs using an established mouse GVHD model. Following infusion, we quantitatively tracked fluorescently labeled, donor-derived, T-cells and third party MSCs in BMT recipients using multispectral cryo-imaging. Specific MSC homing sites were identified in the marginal zones in the spleen and the lymph nodes, where we believe MSC immunomodulation takes place. The number of MSCs found in spleen of the allo BMT recipients was about 200% more than that observed in the syngeneic group. To more carefully define the effects MSCs had on T cell activation and expansion, we developed novel T-cell proliferation assays including secondary lymphoid organ (SLO) enlargement and Carboxyfluoescein succinimidyl ester (CFSE) dilution. As anticipated, significant SLO volume enlargement and CFSE dilution was observed in allo but not syn BMT recipients due to rapid proliferation and expansion of labeled T-cells. MSC treatment markedly attenuated CFSE dilution and volume enlargement of SLO. These assays confirm evidence of potent, in vivo, immunomodulatory properties of MSC following allo BMT. Our innovative platform includes novel methods for tracking cells of interest as well as assessing therapeutic function of MSCs during GVHD induction. Our results support the use of MSCs treatment or prevention of GVHD and illuminate the wider adoption of MSCs as a standard medicinal cell therapy.

Toward transplantation tolerance with adipose tissue-derived therapeutics

Solid organ and composite tissue allotransplanation have been widely applied to treat end-stage organ failure and massive tissue defects, respectively. Currently there are a lot of research endeavors focusing on induction of transplantation tolerance, to relieve the burden derived from long-term immunosuppressant uptake. The mesenchymal stromal cells (MSCs) have been demonstrated with potent immunomodulatory capacities and applied as promising cellular therapeutics to promote allograft survival and induce tolerance. As a rich source of adult MSCs, adipose tissue provides additional advantages of easy accessibility and good safety profile. In recent years, the stromal vascular fraction (SVF) isolated from adipose tissues following enzymatic or mechanical processing without in vitro culture and expansion has demonstrated immunomodulatory and proangiogenic properties. Furthermore, the secretome of AD-MSCs has been utilized in transplantation field as a potential "cell-free" therapeutics. This article reviews recent studies that employ these adipose-derived therapeutics, including AD-MSCs, SVF, and secretome, in various aspects of organ and tissue allotransplantation. Most reports validate their efficacies in prolonging allograft survival. Specifically, the SVF and secretome have performed well for graft preservation and pretreatment, potentially through their proangiogenic and antioxidative capacities. In contrast, AD-MSCs were suitable for peri-transplantation immunosuppression. The proper combination of AD-MSCs, lymphodepletion and conventional immunosuppressants could consistently induce donor-specific tolerance to vascularized composite allotransplants (VCA). For each type of transplantation, optimizing the choice of therapeutics, timing, dose, and frequency of administration may be required. Future progress in the application of adipose-derived therapeutics to induce transplantation tolerance will be further benefited by continued research into their mechanisms of action and the development of standardized protocols for isolation methodologies, cell culture, and efficacy evaluation.

Therapeutic targeting and HSC proliferation by small molecules and biologicals

Hematopoietic stem cells (HSCs) have considerably therapeutic value on autologous and allogeneic transplantation for many malignant/non-malignant hematological diseases, especially with improvement of gene therapy. However, acquirement of limited cell dose from HSC sources is the main handicap for successful transplantation. Therefore, many strategies based on the utilization of various cytokines, interaction of stromal cells, modulation of several extrinsic and intrinsic factors have been developed to promote ex vivo functional HSC expansion with high reconstitution ability until today. Besides all these strategies, small molecules become prominent with their ease of use and various advantages when they are translated to the clinic. In the last two decades, several small molecule compounds have been investigated in pre-clinical studies and, some of them were evaluated in different stages of clinical trials for their safety and efficiencies. In this chapter, we will present an overview of HSC biology, function, regulation and also, pharmacological HSC modulation with small molecules from pre-clinical and clinical perspectives.

The role of miRNAs from mesenchymal stem/stromal cells-derived extracellular vesicles in neurological disorders

Mesenchymal stem/stromal cells (MSCs) are multipotent cells with immunomodulatory effects that have been attempted as a possible treatment for neurologic disorders. Since currently available drugs for neurologic disorders are limited, special attention has been paid to MSCs. With the ability to differentiate into neural cells, it has been shown that MSCs exert their effects in a paracrine manner by producing extracellular vesicles (EVs). Extracellular vesicles are small vesicles with a size of 30-1000 nm that are released by cells, such as MSCs, T cells, B cells, etc. EVs contain various molecules, including proteins, lipids, mRNAs, and microRNAs (miRNAs). In recent years, the administration of EVs in models of neurological disorders has been shown to improve neurological dysfunctions. miRNAs from MSC-EVs as one of the important mediators which regulate various genes and reduce neuropathological change have been identified in different neurological disorders. Here, we review the effects of EVs miRNAs from MSCs on different neurological disorders and their potential applications.

Senotherapeutics for mesenchymal stem cell senescence and rejuvenation

Mesenchymal stem cells (MSCs) are susceptible to replicative senescence and senescence-associated functional decline, which hampers their use in regenerative medicine. Senotherapeutics are drugs that target cellular senescence through senolytic and senomorphic functions to induce apoptosis and suppress chronic inflammation caused by the senescence-associated secreted phenotype (SASP), respectively. Therefore, senotherapeutics could delay aging-associated degeneration. They could also be used to eliminate senescent MSCs during in vitro expansion or bioprocessing for transplantation. In this review, we discuss the role of senotherapeutics in MSC senescence, rejuvenation, and transplantation, with examples of some tested compounds in vitro. The prospects, challenges, and the way forward in clinical applications of senotherapeutics in cell-based therapeutics are also discussed.

Immunomodulatory effect of IL-2 induced bone marrow mononuclear cell therapy on control of allergic asthma

Asthma is a chronic airway disease. Allergic reactions and T helper (h)2 immune response play a key role in asthma occurrence. Cell therapy can control inflammation and remodeling responses in allergic asthma, and cytokines can change this effect. Therefore, in this study, the effect of treated cell therapy with IL-2 to control allergic asthma was studied. Bone marrow cells were extracted and co-cultured with IL-2 and the cells were used via intra-tracheal administration in allergic asthma mice. Levels of IL-4, IL-5, IL-13, Leukotriene B4 and C4, and remodeling factors were measured. At least, a histopathology test of lung tissue was done. Type2 cytokines, leukotrienes, remodeling factors, mucus secretion, goblet cell hyperplasia, peri-bronchial and peri-vascular inflammation were significantly (p˂0.05) decreased by treating with bone marrow-derived mononuclear cells (BMDMCs) and IL-2-BMDMCs. Treatment with IL-2-BMDMCs could significantly decrease IL-13, transforming growth factor (TGF)-β, HP levels, and mucus secretion (p˂0.05) compared to BMDMCs treatment. In this study, BMDMCs and IL-2-BMDMCs therapy could decrease inflammation, allergic, and remodeling factors in allergic asthma. Cell therapy with BMDMCs had a strong and notable effect on the control of allergic asthma pathophysiology when co-cultured and used with IL-2.

Epstein-Barr virus-induced gene 3 commits human mesenchymal stem cells to differentiate into chondrocytes via endoplasmic reticulum stress sensor

Mesenchymal stem cells (MSC) can differentiate into chondrocytes. Epstein-Barr virus-induced gene 3 (EBI3) is differentially expressed during chondrogenic differentiation and can be produced by MSC. EBI3 is also a subunit of interleukin (IL)-27 and IL-35, and it accumulates in the endoplasmic reticulum (ER) when its partners, such as IL-27 p28 and IL-35 p35, are insufficient. ER stress induced by protein accumulation is responsible for chondrogenic differentiation. However, the role of EBI3 and its relevance to the ER stress in chondrogenic differentiation of MSC have never been addressed. Here, we demonstrate that EBI3 protein is expressed in the early stage of chondrogenic differentiation of MSC. Additionally, knockdown, overexpression, or induction of EBI3 through IL-1β inhibits chondrogenesis. We show that EBI3 localizes and accumulates in the ER of MSC after overexpression or induction by IL-1β and TNF-α, whereas ER stress inhibitor 4-phenylbutyric acid decreases its accumulation in MSC. Moreover, EBI3 modulates ER stress sensor inositol-requiring enzyme 1 α (IRE1α) after induced by IL-1β, and MSC-like cells coexpress EBI3 and IRE1α in rheumatoid arthritis (RA) synovial tissue. Altogether, these data demonstrate that intracellular EBI3 commits to chondrogenic differentiation by regulating ER stress sensor IRE1α.

A Novel Perspective on Tissue Engineering Potentials of Periodontal Ligament Stem Cells

It is challenging to completely and predictably regenerate the missing periodontal tissues caused by the trauma or disease. To regenerate the periodontium, there is a need to consider several aspects that co-occur with periodontal development. This study provides an overview of the most up-to-date investigations on the characteristics and immunomodulatory features of Periodontal Ligament Stem Cells (PDLSCs) and the recent interventions performed using these cells, focusing on cell survival, proliferation, and differentiation. Keeping in mind the relationship between age and potency of PDLSCs, this work also demonstrates the necessity of establishing dental-derived stem cell banks for tissue regeneration applications. The data were collected from Pubmed and Google Scholar databases with the keywords of periodontal ligament stem cells, tissue engineering, characteristics, and stem cell therapy. The results showed the presence of wide-ranging research reports supporting the usability of PDLSCs for periodontal reconstruction. However, a better understanding of self-restoration for adequate regulation of adult stem cell growth is needed for various applied purposes.

Development of Allogeneic Stem Cell-Based Platform for Delivery and Potentiation of Oncolytic Virotherapy

We describe the repurposing and optimization of the TK-positive (thymidine kinase) vaccinia virus strain ACAM1000/ACAM2000™ as an oncolytic virus. This virus strain has been widely used as a smallpox vaccine and was also used safely in our recent clinical trial in patients with advanced solid tumors and Acute Myeloid Leukemia (AML). The vaccinia virus was amplified in CV1 cells and named CAL1. CAL1 induced remarkable oncolysis in various human and mouse cancer cells and preferentially amplified in cancer cells, supporting the use of this strain as an oncolytic virus. However, the therapeutic potential of CAL1, as demonstrated with other oncolytic viruses, is severely restricted by the patients' immune system. Thus, to develop a clinically relevant oncolytic virotherapy agent, we generated a new off-the-shelf therapeutic called Supernova1 (SNV1) by loading CAL1 virus into allogeneic adipose-derived mesenchymal stem cells (AD-MSC). Culturing the CAL1-infected stem cells allows the expression of virally encoded proteins and viral amplification prior to cryopreservation. We found that the CAL1 virus loaded into AD-MSC was resistant to humoral inactivation. Importantly, the virus-loaded stem cells (SNV1) released larger number of infectious viral particles and virally encoded proteins, leading to augmented therapeutic efficacy in vitro and in animal tumor models.

Mesenchymal stem cells for regenerative medicine in central nervous system

Mesenchymal stem cells (MSCs) are multipotent stem cells, whose paracrine and immunomodulatory potential has made them a promising candidate for central nervous system (CNS) regeneration. Numerous studies have demonstrated that MSCs can promote immunomodulation, anti-apoptosis, and axon re-extension, which restore functional neural circuits. The therapeutic effects of MSCs have consequently been evaluated for application in various CNS diseases including spinal cord injury, cerebral ischemia, and neurodegenerative disease. In this review, we will focus on the research works published in the field of mechanisms and therapeutic effects of MSCs in CNS regeneration.

IL-1b in the Secretomes of MSCs Seeded on Human Decellularized Allogeneic Bone Promotes Angiogenesis

Angiogenesis plays an important role in the development of bone and bone regeneration to provide the required molecules. Mesenchymal stem cells (MSCs) are pluripotent, self-renewing, and spindle-shaped cells, which can differentiate into multiple lineages such as chondrocytes, osteocytes, and adipocytes. MSCs derived from bone marrow (BMMSCs), adipose tissue (ADMSCs), and Wharton's jelly (UCMSCs) are popular in the field of tissue regeneration. MSCs have been proposed that can promote bone regeneration by enhancing vascularization. In this study, the angiogenic potential of secretomes of undifferentiated and osteo-differentiated BMMSCs, ADMSCs, and UCMSCs seeded on human decellularized allogeneic bone were compared. Human umbilical vein endothelial cells (HUVECs) were treated with MSC secretomes. Cell growth, cell migration, and angiogenesis of HUVECs were analyzed by MTT, wound healing, and tube formation assays. Angiogenic gene expression levels of MSCs were evaluated using real-time quantitative PCR. Antibody neutralization was performed to validate the candidate target. Our study demonstrates that the angiogenic gene expression profile is tissue-dependent and the angiogenic ability of secretomes is independent of the state of differentiation. We also explore that IL-1b is important for MSC angiogenic potential. Taken together, this study proves that IL-1b in the secretomes plays a vital role in angiogenesis.

Olfactory Ecto-mesenchymal Stem Cell-derived Exosomes Ameliorate Murine Sjögren's Syndrome via Suppressing Tfh Cell Response

Objectives

To investigate the effect of olfactory ecto-mesenchymal stem cell-derived exosomes (OE-MSC-Exos) on T follicular helper (Tfh) cell response and their implication in treating experimental Sjögrens syndrome (ESS).

Methods

C57BL/6 mice were immunized with salivary glands (SG) proteins to induce ESS mouse model. OE-MSC-Exos were added to the Tfh cell polarization condition, and the proportion of Tfh cells was detected by FCM. The PD-L1 of OE-MSCs was silenced with small interfering RNA to extract siPD-L1-OE-MSC-Exos.

Results

We found that transfer of OE-MSC-Exos markedly attenuated disease progression and reduced Tfh cell response in mice with ESS. In culture, OE-MSC-Exos potently inhibited the differentiation of Tfh cells from naïve T cells. Moreover, OE-MSC-Exos expressed high level of the ligand for the programmed cell death protein 1 (PD-L1), knocking down PD-L1 expression in OE-MSC-Exos significantly decreased their capacity to suppress Tfh cell differentiation in vitro. Consistently, transfer of OE-MSC-Exos with PD-L1 knockdown exhibited profoundly diminished therapeutic effect in ESS mice, accompanied with sustained Tfh cell response and high levels of autoantibody production.

Conclusion

Our results suggest that OE-MSC-Exos may exert their therapeutic effect in ameliorating ESS progression via suppressing Tfh cell response in a PD-L1-dependent manner.

Overexpression of NDST1 Attenuates Fibrotic Response in Murine Adipose-Derived Stem Cells

Adipose-derived stem cells (ADSCs) hold tremendous potential for treating diseases and repairing damaged tissues. Heparan sulfate (HS) plays various roles in cellular signaling mechanisms. The importance of HS in stem cell function has been reported and well documented. However, there has been little progress in using HS for therapeutic purposes. We focused on one of the sulfotransferases, NDST1, which influences overall HS chain extent and sulfation pattern, with the expectation to enhance stem cell function by increasing the N-sulfation level. We herein performed transfections of a green fluorescent protein-vector control and NDST1-vector into mouse ADSCs to evaluate stem cell functions. Overexpression of NDST1 suppressed the osteogenic differentiation of ADSCs. There was no pronounced effect observed on the stemness, inflammatory gene expression, nor any noticeable effect in adipogenic and chondrogenic differentiation. Under the tumor necrosis factor-alpha stimulation, NDST1 overexpression induced several chemokine productions that attract neutrophils and macrophages. Finally, we identified an antifibrotic response in ADSCs overexpressing NDST1. This study provides a foundation for the evaluation of HS-related effects in ADSCs undergoing ex vivo gene manipulation.

Therapeutic Potential of Extracellular Vesicles in Aging and Age-Related Diseases

Aging is associated with an alteration of intercellular communication. These changes in the extracellular environment contribute to the aging phenotype and have been linked to different aging-related diseases. Extracellular vesicles (EVs) are factors that mediate the transmission of signaling molecules between cells. In the aging field, these EVs have been shown to regulate important aging processes, such as oxidative stress or senescence, both in vivo and in vitro. EVs from healthy cells, particularly those coming from stem cells (SCs), have been described as potential effectors of the regenerative potential of SCs. Many studies with different animal models have shown promising results in the field of regenerative medicine. EVs are now viewed as a potential cell-free therapy for tissue damage and several diseases. Here we propose EVs as regulators of the aging process, with an important role in tissue regeneration and a raising therapy for age-related diseases.

BMSCs Promote Differentiation of Enteric Neural Precursor Cells to Maintain Neuronal Homeostasis in Mice With Enteric Nerve Injury

BACKGROUND & AIMS

Our previous study showed that transplantation of bone marrow-derived mesenchymal stem cells (BMSCs) promoted functional enteric nerve regeneration in denervated mice but not through direct transdifferentiation. Homeostasis of the adult enteric nervous system (ENS) is maintained by enteric neural precursor cells (ENPCs). Whether ENPCs are a source of regenerated nerves in denervated mice remains unknown.

METHODS

Genetically engineered mice were used as recipients, and ENPCs were traced during enteric nerve regeneration. The mice were treated with benzalkonium chloride to establish a denervation model and then transplanted with BMSCs 3 days later. After 28 days, the gastric motility and ENS regeneration were analyzed. The interaction between BMSCs and ENPCs in vitro was further assessed.

RESULTS

Twenty-eight days after transplantation, gastric motility recovery (gastric emptying capacity, P < .01; gastric contractility, P < .01) and ENS regeneration (neurons, P < .01; glial cells, P < .001) were promoted in BMSCs transplantation groups compared with non-transplanted groups in denervated mice. More importantly, we found that ENPCs could differentiate into enteric neurons and glial cells in denervated mice after BMSCs transplantation, and the proportion of Nestin⁺/Ngfr⁺ cells differentiated into neurons was significantly higher than that of Nestin⁺ cells. A small number of BMSCs located in the myenteric plexus differentiated into glial cells. In vitro, glial cell-derived neurotrophic factor (GDNF) from BMSCs promotes the migration, proliferation, and differentiation of ENPCs.

CONCLUSIONS

In the case of enteric nerve injury, ENPCs can differentiate into enteric neurons and glial cells to promote ENS repair and gastric motility recovery after BMSCs transplantation. BMSCs expressing GDNF enhance the migration, proliferation, and differentiation of ENPCs.

Close-to-native bone repair via tissue-engineered endochondral ossification approaches

In order to solve the clinical challenges related to bone grafting, several tissue engineering (TE) strategies have been proposed to repair critical-sized defects. Generally, the classical TE approaches are designed to promote bone repair via intramembranous ossification. Although promising, strategies that direct the osteogenic differentiation of mesenchymal stem/stromal cells are usually characterized by a lack of functional vascular supply, often resulting in necrotic cores. A less explored alternative is engineering bone constructs through a cartilage-mediated approach, resembling the embryological process of endochondral ossification. The remodeling of an intermediary hypertrophic cartilaginous template triggers vascular invasion and bone tissue deposition. Thus, employing this knowledge can be a promising direction for the next generation of bone TE constructs. This review highlights the most recent biomimetic strategies for applying endochondral ossification in bone TE while discussing the plethora of cell types, culture conditions, and biomaterials essential to promote a successful bone regeneration process.

Intrapericardial Exosome Therapy Dampens Cardiac Injury via Activating Foxo3

BACKGROUND

Mesenchymal stem cell (MSC)-derived exosomes are well recognized immunomodulating agents for cardiac repair, while the detailed mechanisms remain elusive. The Pericardial drainage pathway provides the heart with immunosurveillance and establishes a simplified model for studying the mechanisms underlying the immunomodulating effects of therapeutic exosomes.

METHODS

Myocardial infarction (MI) models with and without pericardiectomy (corresponding to Tomy MI and NonTomy MI) were established to study the functions of pericardial drainage pathway in immune activation of cardiac-draining mediastinal lymph node (MLN). Using the NonTomy MI model, MSC exosomes or vehicle PBS was intrapericardially injected for MI treatment. Via cell sorting and RNA-seq (RNA-sequencing) analysis, the differentially expressed genes were acquired for integrated pathway analysis to identify responsible mechanisms. Further, through functional knockdown/inhibition studies, application of cytokines and neutralizing antibodies, western blot, flow cytometry, and cytokine array, the molecular mechanisms were studied. In addition, the therapeutic efficacy of intrapericardially injected exosomes for MI treatment was evaluated through functional and histological analyses.

RESULTS

We show that the pericardial draining pathway promoted immune activation in the MLN following MI. Intrapericardially injected exosomes accumulated in the MLN and induced regulatory T cell differentiation to promote cardiac repair. Mechanistically, uptake of exosomes by major histocompatibility complex (MHC)-II+ antigen-presenting cells (APCs) induced Foxo3 activation via the protein phosphatase (PP)-2A/p-Akt/forkhead box O3 (Foxo3) pathway. Foxo3 dominated APC cytokines (IL-10, IL-33, and IL-34) expression and built up a regulatory T cell (Treg)-inducing niche in the MLN. The differentiation of Tregs as well as their cardiac deployment were elevated, which contributed to cardiac inflammation resolution and cardiac repair.

CONCLUSIONS

This study reveals a novel mechanism underlying the immunomodulation effects of MSC exosomes and provides a promising candidate (PP2A/p-Akt/Foxo3 signaling pathway) with a favorable delivery route (intrapericardial injection) for cardiac repair.