Mesenchymal stem cells: Emerging mechanisms of immunomodulation and therapy

Synovium Derived Mesenchymal Stromal Cells (Sy-MSCs): A Promising Therapeutic Paradigm in the Management of Knee Osteoarthritis

Synovium-derived mesenchymal stromal cell (Sy-MSC) is a newer member of the mesenchymal stromal cell families. The first successful demonstration of the mesenchymal stromal cell from the human synovial membrane was done in 2001 and since then its potential role for musculoskeletal regeneration has been keenly documented. The regenerative effects of Sy-MSCs are through paracrine signaling, direct cell-cell interactions, and extracellular vehicles. Sy-MSCs possess superior chondrogenicity than other sources of mesenchymal stromal cells. This article aims to outline the advancement of synovium-derived mesenchymal stromal cells along with a specific insight into the application for managing osteoarthritis knee.

Stem cell therapy: A promising treatment for COVID-19

Novel coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic. SARS-CoV-2 is an RNA virus and has a glycosylated spike (S) protein used for genome encoding. COVID-19 can lead to a cytokine storm and patients usually have early respiratory signs and further secondary infections, which can be fatal. COVID-19 has entered an emergency phase, but there are still no specific effective drugs for this disease. Mesenchymal stem cells (MSCs) are multipotent stromal cells, which cause antiapoptosis and can repair damaged epithelial cells. Many clinical trials have proved that MSC therapy could be a potential feasible therapy for COVID-19 patients, especially those with acute respiratory distress syndrome, without serious adverse events or toxicities. However, more studies are needed in the future, in order to confirm the effect of this therapy.

Antimicrobial and Regenerative Effects of Placental Multipotent Mesenchymal Stromal Cell Secretome-Based Chitosan Gel on Infected Burns in Rats

Background: There is a need for better strategies to promote burn wound healing and prevent infection. The aim of our study was to develop an easy-to-use placental multipotent mesenchymal stromal cell (MMSC) secretome-based chitosan hydrogel (MSC-Ch-gel) and estimate its antimicrobial and regenerative activity in Staphylococcus aureus-infected burn wounds in rats. Methods: Proteomic studies of the MMSC secretome revealed proteins involved in regeneration, angiogenesis, and defence responses. The MMSC secretome was collected from cultured cells and mixed with water-soluble chitosan to prepare the placental MSC-Ch-gel, which was stored in liquid phase at 4 °C. The wounds of rats with established II-IIIa-degree burns were then infected with S. aureus and externally covered with the MSC-Ch-gel. Three additional rat groups were treated with medical Vaseline oil, the antiseptic drug Miramistin®, or the drug Bepanthen® Plus. Skin wound samples were collected 4 and 8 days after burning for further microbiological and histological analysis. Blood samples were also collected for biochemical analysis. Results: Application of the MSC-Ch-gel cleared the wound of microorganisms (S. aureus wasn’t detected in the washings from the burned areas), decreased inflammation, enhanced re-epithelialisation, and promoted the formation of well-vascularised granulation tissue. Conclusions: MSC-Ch-gel effectively promotes infected wound healing in rats with third-degree burns. Gel preparation can be easily implemented into clinical practice.

Modulating Osteoimmune Responses by Mesoporous Silica Nanoparticles

The immune response plays an important role in biomaterial-mediated osteogenesis. Nanomaterials may influence immune responses and thereby alter bone regeneration. Mesoporous silica nanoparticles (MSNs) have received much attention for drug delivery and bone regeneration. Recently, immunomodulatory effects of MSNs on osteogenesis have been reported. In this Review, we summarize the osteoimmunomodulation of MSNs, including the effects of MSN characteristics on immune cells and osteogenesis. Impacts of MSNs on immune cells vary according to nanoparticle properties, including surface topography and charge, particle size, and ion release. MSNs with suitable doses can inhibit inflammation and create an immune microenvironment beneficial for bone regeneration by activating immune cells and stimulating cytokine release. Further work is needed to explore and clarify the underlying mechanisms, including crosstalk between various types of immune cells and how to design MSNs to create a suitable immune environment for osteogenesis.

The CD4+CD25+FoxP3+ Regulatory T Cells Regulated by MSCs Suppress Plasma Cells in a Mouse Model of Allergic Rhinitis

Background:

Allergic Rhinitis (AR) is the most common immunological disease that has been associated with inflammatory responses and is characterized by sneezing. Previous studies found that AR's allergen exposure significantly induces plasma cells and reduces regulatory T (Treg) cells, a population that contributes to control AR. Therefore, upregulating Treg expression can regulate plasma cells leading to inhibit sneezing in AR. Mesenchymal stem cells (MSCs) are multipotent stem cells that have the immunoregulatory and antiinflammation ability by secreting various cytokines including IL-10 and TGF-β which potent as a promising therapeutic modality for allergic airway diseases, including AR.

Objective:

To investigate the role of MSCs in generating CD4+, CD25+, and Foxp3+ Regulatory T cells associated with suppressing plasma cell in AR model.

Methods:

In this study, fifteen male Wistar rats (6 to 8 weeks old) were randomly divided into three groups (control group, sham group, and MSCs treatment group). OVA nasal challenge was conducted daily from day 15 to 21, and MSCs (1x10⁶) were administrated intraperitoneally to OVA-sensitized rats on day 21. Sneezing was observed from day 22 to 28. The rats were sacrificed on day 22 and day 28. The expression of CD4+ CD25+ Foxp3+ in Treg and plasma cells was analyzed by flow cytometry assay.

Results:

This study showed that the percentage of plasma cell and sneezing times significantly decreased in MSCs treatment. This finding was aligned with the significant increase of CD4+CD25+Foxp3+ Treg level.

Conclusion:

MSCs administration suppress plasma cells population and sneezing times by up regulating Treg to control AR.

Impact of allogeneic feline uterine-derived mesenchymal stromal cell intravenous treatment on renal function of nephrectomized cats with chronic kidney disease

Chronic kidney disease (CKD) is a common condition and leading cause of mortality in cats. Mesenchymal stromal cells (MSCs) may have a therapeutic effect on CKD. The aim of this pilot study was to determine efficacy of systemically-administered allogeneic uterine tissue-derived MSCs (UMSCs) in cats with CKD. Eighteen renal-compromised, unilaterally nephrectomized cats received two doses of 3 × 10⁷ allogeneic UMSCs given intravenously (IV) with a 2-week dose interval. The primary endpoint was renal function, with treatment success defined by a 20% increase in glomerular filtration rate (GFR; iohexol clearance) and/or a 20% decrease in plasma creatinine in 50% of the cats. Secondary endpoints included diet and water consumption, body weight, urine characteristics, and adverse events. Treatment was well tolerated and associated with a statistically meaningful increase in GFR on Days 13, 28, 57, 99, 121 and 182, compared with baseline (P < 0.0001 for Days 13 to 99 inclusive; P = 0.0029 and P = 0.0225 for Days 121 and 182, respectively). Greater than 50% of the cats demonstrated a 20% increase in GFR on all days except Day 150, at which point GFR measurements were consistently above baseline. Statistically meaningful increases in diet and water consumption were observed. Substantial improvements in GFR were observed throughout the six-month evaluation period (excluding Day 150) in more than 50% of cats, thereby meeting the primary endpoint. Therefore, this IV-administered, allogeneic cellular therapy may support both renal function and clinical status of cats with CKD.

Stem Cells in Autologous Microfragmented Adipose Tissue: Current Perspectives in Osteoarthritis Disease

Osteoarthritis (OA) is a chronic debilitating disorder causing pain and gradual degeneration of weight-bearing joints with detrimental effects on cartilage volume as well as cartilage damage, generating inflammation in the joint structure. The etiology of OA is multifactorial. Currently, therapies are mainly addressing the physical and occupational aspects of osteoarthritis using pharmacologic pain treatment and/or surgery to manage the symptomatology of the disease with no specific regard to disease progression or prevention. Herein, we highlight alternative therapeutics for OA specifically considering innovative and encouraging translational methods with the use of adipose mesenchymal stem cells.

Stem Cell Therapy and Its Significance in Pain Management

Pain management has always been a challenging issue, which is why it has been a major focus of many rigorous studies. Chronic pain which typically lasts for more than three months is prevalent at an astounding rate of 11% to 19% of the adult population. Pain management techniques have gone through major advances in the last decade with no major improvement in the quality of life in affected populations. Recently there has been growing interest in the utilization of stem cells for pain management. Advancement of stem cell therapy has been noted for the past few years and is now being used in human clinical trials. Stem cell therapy has shown promising results in the management of neuropathic, discogenic back, osteoarthritis, and musculoskeletal pain. In this article, we will discuss the role of stem cells in the pain management of the aforementioned conditions, along with the mechanism, adverse effects, and risks of stem cell therapy.

IFN-γ Licensing Does Not Enhance the Reduced Immunomodulatory Potential and Migratory Ability of Differentiation-Induced Porcine Bone Marrow-Derived Mesenchymal Stem Cells in an In Vitro Xenogeneic Application

IFN-γ licensing to mesenchymal stem cells (MSCs) is applied to enhance the therapeutic potential of MSCs. However, although the features of MSCs are affected by several stimuli, little information is available on changes to the therapeutic potential of IFN-γ-licensed differentiated MSCs during xenogeneic applications. Therefore, the present study is aimed at clarifying the effects of adipogenic/osteogenic differentiation and IFN-γ licensing on the in vitro immunomodulatory and migratory properties of porcine bone marrow-derived MSCs in xenogeneic applications using human peripheral blood mononuclear cells (PBMCs). IFN-γ licensing in differentiated MSCs lowered lineage-specific gene expression but did not affect MSC-specific cell surface molecules. Although indoleamine 2,3 deoxygenase (IDO) activity and expression were increased after IFN-γ licensing in undifferentiated MSCs, they were reduced after differentiation. IFN-γ licensing to differentiated MSCs elevated the reduced IDO expression in differentiated MSCs; however, the increase was not sufficient to reach to the level achieved by undifferentiated MSCs. During a mixed lymphocyte reaction with quantification of TNF-α concentration, proliferation and activation of xenogeneic PBMCs were suppressed by undifferentiated MSCs but inhibited to a lesser extent by differentiated MSCs. IFN-γ licensing increasingly suppressed proliferation of PBMCs in undifferentiated MSCs but it was incapable of elevating the reduced immunosuppressive ability of differentiated MSCs. Migratory ability through a scratch assay and gene expression study was reduced in differentiated MSCs than their undifferentiated counterparts; IFN-γ licensing was unable to enhance the reduced migratory ability in differentiated MSCs. Similar results were found in a Transwell system with differentiated MSCs in the upper chamber toward xenogeneic PBMCs in the lower chamber, despite IFN-γ licensing increased the migratory ability of undifferentiated MSCs. Overall, IFN-γ licensing did not enhance the reduced immunomodulatory and migratory properties of differentiated MSCs in a xenogeneic application. This study provides a better understanding of the ways in which MSC therapy can be applied.

Role of extracellular vesicles from adipose tissue- and bone marrow-mesenchymal stromal cells in endothelial proliferation and chondrogenesis

The secretome of mesenchymal stromal cells (MSCs) derived from different tissue sources is considered an innovative therapeutic tool for regenerative medicine. Although adipose tissue‐and bone marrow‐derived MSCs (ADSCs and BMSCs, respectively) share many biological features, the different tissue origins can be mirrored by variations in their secretory profile, and in particular in the secreted extracellular vesicles (EVs). In this study, we carried out a detailed and comparative characterization of middle‐ and small‐sized EVs (mEVs and sEVs, respectively) released by either ADSCs or BMSCs. Their involvement in an endochondral ossification setting was investigated using ex vivo metatarsal culture models that allowed to explore both blood vessel sprouting and bone growth plate dynamics. Although EVs separated from both cell sources presented similar characteristics in terms of size, concentration, and marker expression, they exhibited different characteristics in terms of protein content and functional effects. ADSC‐EVs overexpressed pro‐angiogenic factors in comparison to the BMSC‐counterpart, and, consequently, they were able to induce a significant increase in endothelial cord outgrowth. On the other hand, BMSC‐EVs contained a higher amount of pro‐differentiation and chemotactic proteins, and they were able to prompt growth plate organization. The present study highlights the importance of selecting the appropriate cell source of EVs for targeted therapeutic applications.

Current therapeutic strategies for respiratory diseases using mesenchymal stem cells

Mesenchymal stromal/stem cells (MSCs) have a great potential to proliferate, undergo multi-directional differentiation, and exert immunoregulatory effects. There is already much enthusiasm for their therapeutic potentials for respiratory inflammatory diseases. Although the mechanism of MSCs-based therapy has been well explored, only a few articles have summarized the key advances in this field. We hereby provide a review over the latest progresses made on the MSCs-based therapies for four types of inflammatory respiratory diseases, including idiopathic pulmonary fibrosis, acute respiratory distress syndrome, chronic obstructive pulmonary disease, and asthma, and the uncovery of their underlying mechanisms from the perspective of biological characteristics and functions. Furthermore, we have also discussed the advantages and disadvantages of the MSCs-based therapies and prospects for their optimization.

Characterization and response to inflammatory stimulation of human endometrial-derived mesenchymal stem/stromal cells

BACKGROUND AIMS

The human endometrium has emerged as an attractive source of endometrial-derived mesenchymal stem/stromal cells (eMSCs) that can be easily isolated by non-invasive procedures. The prominent capacity of the endometrium for efficient and scarless regeneration each menstrual cycle indicates the increased eMSC immunomodulatory and pro-angiogenic properties. Herein the authors investigated the molecular responses of eMSCs to an inflammatory environment and whether those intrinsic responses affected their functional attributes.

METHODS

Human eMSCs immunophenotypic, transcriptional and secretory profiles were evaluated at passage three (P3) and passage eight (P8) to determine culture effects. Functionally, P3 and P8 non-induced and TNF-α/IFN-γ-induced eMSCs were interrogated for their capacity to suppress stimulated peripheral blood mononuclear cell (PBMC) proliferation, whereas non-induced eMSCs were assessed for their support to vascular network formation in co-cultures with human umbilical vein endothelial cells in vitro.

RESULTS

Non-induced P3 and P8 eMSCs exhibited similar spindle-shaped morphology and clonogenic capacity. Nevertheless, P8 eMSCs showed reduced growth rate capacity and telomere length. The eMSCs displayed the typical MSC-related immunophenotypic profile, with P3 and P8 eMSCs expressing high levels (>98%) of CD140β, intermediate levels (35-60%) of CD146 and SUSD2 and low levels (∼8%) of NG2 pericytic markers. Non-induced P3 and P8 showed similar transcriptional and secretory profiles, though the expression of immunomodulatory HLA-G and IL-8 genes was significantly downregulated in P8 compared with P3 eMSCs. Upon TNF-α/IFN-γ induction, eMSCs showed an immunophenotypic profile similar to that of non-induced eMSCs, except for significant upregulation of HLA-DR protein expression in both induced P3 and P8 eMSCs. However, induced P3 and P8 eMSCs showed significant upregulation of CD10, HLA-G, IDO, IL-6, IL-8, LIF and TSG gene expression compared with non-induced cultures. TNF-α/IFN-γ induction strongly increased the secretion of inflammatory-/angiogenesis-related molecules, whereas growth factor secretion was similar to the non-induced eMSCs. Functionally, P3 and P8 eMSCs showed a strong inhibitory effect on stimulated PBMC proliferation and the capacity to support neovascularization in vitro.

CONCLUSIONS

The authors' study suggests that serial expansion does not affect eMSC immunophenotypic, transcriptional and secretory profiles. This is directly reflected by the functional immunomodulatory and pro-angiogenic properties of eMSCs, which remain unaltered until P8 in vitro. However, exposure of eMSCs to inflammatory environments enhances their immunomodulatory transcriptional and inflammatory-/angiogenesis-related secretory profiles. Therefore, the resulting evidence of eMSCs serial expansion and exposure to inflammation could serve as a foundation for improved eMSCs manufacturing and potential clinical translation efforts.

Wharton's Jelly-Derived Mesenchymal Stem Cells Reduce Fibrosis in a Mouse Model of Duchenne Muscular Dystrophy by Upregulating microRNA 499

The aim of this study was to evaluate the therapeutic effects and mechanisms of Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) in an animal model of Duchenne muscular dystrophy (DMD). Mdx mice (3-5 months old) were administered five different doses of WJ-MSCs through their tail veins. A week after injection, grip strength measurements, creatine kinase (CK) assays, immunohistochemistry, and western blots were performed for comparison between healthy mice, mdx control mice, and WJ-MSC-injected mdx mice. WJ-MSCs exerted dose-dependent multisystem therapeutic effects in mdx mice, by decreasing CK, recovering normal behavior, regenerating muscle, and reducing apoptosis and fibrosis in skeletal muscle. We also confirmed that miR-499-5p is significantly downregulated in mdx mice, and that intravenous injection of WJ-MSCs enhanced its expression, leading to anti-fibrotic effects via targeting TGFβR 1 and 3. Thus, WJ-MSCs may represent novel allogeneic "off-the-shelf" cellular products for the treatment of DMD and possibly other muscle disorders.

Oral Cavity as a Source of Mesenchymal Stem Cells Useful for Regenerative Medicine in Dentistry

The use of mesenchymal stem cells (MSCs) for regenerative purposes has become common in a large variety of diseases. In the dental and maxillofacial field, there are emerging clinical needs that could benefit from MSC-based therapeutic approaches. Even though MSCs can be isolated from different tissues, such as bone marrow, adipose tissue, etc., and are known for their multilineage differentiation, their different anatomical origin can affect the capability to differentiate into a specific tissue. For instance, MSCs isolated from the oral cavity might be more effective than adipose-derived stem cells (ASCs) for the treatment of dental defects. Indeed, in the oral cavity, there are different sources of MSCs that have been individually proposed as promising candidates for tissue engineering protocols. The therapeutic strategy based on MSCs can be direct, by using cells as components of the tissue to be regenerated, or indirect, aimed at delivering local growth factors, cytokines, and chemokines produced by the MSCs. Here, the authors outline the major sources of mesenchymal stem cells attainable from the oral cavity and discuss their possible usage in some of the most compelling therapeutic frontiers, such as periodontal disease and dental pulp regeneration.

Human Umbilical Cord Mesenchymal Stromal Cell Treatment of Severe COVID-19 Patients: A 3-Month Follow-Up Study Following Hospital Discharge

Previously, we demonstrated the therapeutic effects of human umbilical cord mesenchymal stromal cells (hUC-MSCs) in severe coronavirus disease 2019 (COVID-19) patients. In this 3-month follow-up study, we examined discharged patients who had received hUC-MSC therapy to assess the safety of this therapy and the health-related quality of life (HRQL) of these patients. The follow-up cohort consisted of 28 discharged severe COVID-19 patients who received either the standard treatment (the control group) or the standard treatment plus hUC-MSC therapy. We examined liver function, kidney function, pulmonary function, coagulation, tumor markers, and vision. We also conducted electrocardiography (ECG) analysis, let the patients answer the St. George's Respiratory Questionnaire (SGRQ), and performed computed tomography (CT) imaging for assessing the lung changes. No obvious adverse effects were observed in the hUC-MSC group after 3 months. Measurements of blood routine index, C-reactive protein and procalcitonin, liver and kidney function, coagulation, ECG, tumor markers, and vision were almost within the normal ranges in both the treatment and control groups. Forced expiratory volumes in 1 s (FEV1) (% of predicted) were 71.88% ± 8.46% and 59.45% ± 27.45% in the hUC-MSC and control groups (P < 0.01), respectively, and FEV1/forced vital capacity (FEV1/FVC) ratios were 79.95% ± 8.00% and 58.97% ± 19.16% in the hUC-MSC and control groups, respectively (P < 0.05). SGRQ scores were lower in the hUC-MSC group than in the control group (15.25 ± 3.69 vs. 31.9 ± 8.78, P < 0.05). The rate of wheezing in the hUC-MSC group was also significantly lower than that in the control group (37.5% vs. 75%, P < 0.05). There were no significant differences in CT scores between the two groups (0.60 ± 0.88 vs. 1.00 ± 1.31, P = 0.917). Overall, the intravenous transplantation of hUC-MSCs accelerated partial pulmonary function recovery and improved HRQL, indicating relative safety and preliminary efficacy of this treatment for patients with severe COVID-19.

The role of CD71+ erythroid cells in the regulation of the immune response

Complex regulation of the immune response is necessary to support effective defense of an organism against hostile invaders and to maintain tolerance to harmless microorganisms and autoantigens. Recent studies revealed previously unappreciated roles of CD71⁺ erythroid cells (CECs) in regulation of the immune response. CECs physiologically reside in the bone marrow where erythropoiesis takes place. Under stress conditions, CECs are enriched in some organs outside of the bone marrow as a result of extramedullary erythropoiesis. However, the role of CECs goes well beyond the production of erythrocytes. In neonates, increased numbers of CECs contribute to their vulnerability to infectious diseases. On the other side, neonatal CECs suppress activation of immune cells in response to abrupt colonization with commensal microorganisms after delivery. CECs are also enriched in the peripheral blood of pregnant women as well as in the placenta and are responsible for the regulation of feto-maternal tolerance. In patients with cancer, anemia leads to increased frequency of CECs in the peripheral blood contributing to diminished antiviral and antibacterial immunity, as well as to accelerated cancer progression. Moreover, recent studies revealed the role of CECs in HIV and SARS-CoV-2 infections. CECs use a full arsenal of mechanisms to regulate immune response. These cells suppress proinflammatory responses of myeloid cells and T-cell proliferation by the depletion of ʟ-arginine by arginase. Moreover, CECs produce reactive oxygen species to decrease T-cell proliferation. CECs also secrete cytokines, including transforming growth factor β (TGF-β), which promotes T-cell differentiation into regulatory T-cells. Here, we comprehensively describe the role of CECs in orchestrating immune response and indicate some therapeutic approaches that might be used to regulate their effector functions in the treatment of human conditions.

Application of marine collagen for stem-cell-based therapy and tissue regeneration (Review)

Tissue engineering and regenerative medicine is becoming an important component in modern biological scientific research. Tissue engineering, a branch of regenerative medicine, is a field that is actively developing to meet the challenges presented in biomedical applications. This particularly applies to the research area of stem cells and biomaterials, due to both being pivotal determinants for the successful restoration or regeneration of damaged tissues and organs. Recently, the development of innovative marine collagen-based biomaterials has attracted attention due to the reported environmentally friendly properties, the lack of zoonotic disease transmission, biocompatibility, bioactivity, the lack of ethics-related concerns and cost-effectiveness for manufacturing. The present review aimed to summarize the potential application and function of marine collagen in stem cell research in a medical and clinical setting. In addition, the present review cited recent studies regarding the latest research advances into using marine collagen for cartilage, bone, periodontal and corneal regeneration. It also characterized the distinct advantages of using marine collagen for stem cell-based tissue repair and regeneration. In addition, the present review comprehensively discussed the most up to date information on stem cell biology, particularly the possibility of treating stem cells with marine collagen to maximize their multi-directional differentiation capability, which highlights the potential use of marine collagen in regenerative medicine. Furthermore, recent research progress on the potential immunomodulatory capacity of mesenchymal stem cells following treatment with marine collagen to improve the understanding of cell-matrix interactions was investigated. Finally, perspectives on the possible future research directions for the application of marine collagen in the area of regenerative medicine are provided.

Characteristics and Developments in Mesenchymal Stem Cell Therapy for COVID-19: An Update

The outbreak of coronavirus disease 2019 (COVID-19) has so far resulted in over a hundred million people being infected. COVID-19 poses a threat to human health around the world. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been confirmed as the pathogenic virus of COVID-19. SARS-CoV-2 belongs to the β-coronavirus family of viruses and is mainly transmitted through the respiratory tract. It has been proven that SARS-CoV-2 mainly targets angiotensin-converting enzyme II (ACE2) receptors on the surface of various cells in humans. The main clinical symptoms of COVID-19 include fever, cough, and severe acute respiratory distress syndrome (ARDS). Current evidence suggests that the damage caused by the virus may be closely related to the induction of cytokine storms in COVID-19. No specific drugs or measures have yet to be shown to cure COVID-19 completely. Cell-based approaches, primarily mesenchymal stem cells (MSCs), have been identified to have anti-inflammatory and immune functions in COVID-19. Clinical studies about using MSCs and its derivatives-exosomes for COVID-19 treatment-are under investigation. Here, we review the current progress of the biological characteristics, clinical manifestations, and cell-based treatment development for COVID-19. Providing up-to-date information on COVID-19 and potential MSC therapies will help highlight routes to prevent and treat the disease.

Extracellular Vesicles from Mesenchymal Stem Cells as Potential Treatments for Osteoarthritis

Osteoarthritis (OA) is a chronic degenerative disorder of the joint and its prevalence and severity is increasing owing to ageing of the population. Osteoarthritis is characterized by the degradation of articular cartilage and remodeling of the underlying bone. There is little understanding of the cellular and molecular processes involved in pathophysiology of OA. Currently the treatment for OA is limited to painkillers and anti-inflammatory drugs, which only treat the symptoms. Some patients may also undergo surgical procedures to replace the damaged joints. Extracellular vesicles (EV) play an important role in intercellular communications and their concentration is elevated in the joints of OA patients, although their mechanism is unclear. Extracellular vesicles are naturally released by cells and they carry their origin cell information to be delivered to target cells. On the other hand, mesenchymal stem cells (MSCs) are highly proliferative and have a great potential in cartilage regeneration. In this review, we provide an overview of the current OA treatments and their limitations. We also discuss the role of EV in OA pathophysiology. Finally, we highlight the therapeutic potential of MSC-derived EV in OA and their challenges.

MRI detection of the malignant transformation of stem cells through reporter gene expression driven by a tumor-specific promoter

Background

Existing evidence has shown that mesenchymal stem cells (MSCs) can undergo malignant transformation, which is a serious limitation of MSC-based therapies. Therefore, it is necessary to monitor malignant transformation of MSCs via a noninvasive imaging method. Although reporter gene-based magnetic resonance imaging (MRI) has been successfully applied to longitudinally monitor MSCs, this technique cannot distinguish the cells before and after malignant transformation. Herein, we investigated the feasibility of using a tumor-specific promoter to drive reporter gene expression for MRI detection of the malignant transformation of MSCs.

Methods

The reporter gene ferritin heavy chain (FTH1) was modified by adding a promoter from the tumor-specific gene progression elevated gene-3 (PEG3) and transduced into MSCs to obtain MSCs-PEG3-FTH1. Cells were induced to undergo malignant transformation via indirect coculture with C6 glioma cells, and these transformed cells were named MTMSCs-PEG3-FTH1. Western blot analysis of FTH1 expression, Prussian blue staining and transmission electron microscopy (TEM) to detect intracellular iron, and MRI to detect signal changes were performed before and after malignant transformation. Then, the cells before and after malignant transformation were inoculated subcutaneously into nude mice, and MRI was performed to observe the signal changes in the xenografts.

Results

After induction of malignant transformation, MTMSCs demonstrated tumor-like features in morphology, proliferation, migration, and invasion. FTH1 expression was significantly increased in MTMSCs-PEG3-FTH1 compared with MSCs-PEG3-FTH1. Prussian blue staining and TEM showed a large amount of iron particles in MTMSCs-PEG3-FTH1 but a minimal amount in MSCs-PEG3-FTH1. MRI demonstrated that the T2 value was significantly decreased in MTMSCs-PEG3-FTH1 compared with MSCs-PEG3-FTH1. In vivo, mass formation was observed in the MTMSCs-PEG3-FTH1 group but not the MSCs-PEG3-FTH1 group. T2-weighted MRI showed a significant signal decrease, which was correlated with iron accumulation in the tissue mass.

Conclusions

We developed a novel MRI model based on FTH1 reporter gene expression driven by the tumor-specific PEG3 promoter. This approach could be applied to sensitively detect the occurrence of MSC malignant transformation.

Mesenchymal stromal cell secretome in liver failure: Perspectives on COVID-19 infection treatment

Due to their immunomodulatory potential and release of trophic factors that promote healing, mesenchymal stromal cells (MSCs) are considered important players in tissue homeostasis and regeneration. MSCs have been widely used in clinical trials to treat multiple conditions associated with inflammation and tissue damage. Recent evidence suggests that most of the MSC therapeutic effects are derived from their secretome, including the extracellular vesicles, representing a promising approach in regenerative medicine application to treat organ failure as a result of inflammation/fibrosis. The recent outbreak of respiratory syndrome coronavirus, caused by the newly identified agent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has forced scientists worldwide to use all available instruments to fight the infection, including the inflammatory cascade caused by this pandemic disease. The use of MSCs is a valid approach to combat organ inflammation in different compartments. In addition to the lungs, which are considered the main inflammatory target for this virus, other organs are compromised by the infection. In particular, the liver is involved in the inflammatory response to SARS-CoV-2 infection, which causes organ failure, leading to death in coronavirus disease 2019 (COVID-19) patients. We herein summarize the current implications derived from the use of MSCs and their soluble derivatives in COVID-19 treatment, and emphasize the potential of MSC-based therapy in this clinical setting.

Role of iron and iron-related proteins in mesenchymal stem cells: Cellular and clinical aspects

Mesenchymal stem cells (MSCs) are located in various tissues where these cells show niche-dependent multilineage differentiation and secrete immunomodulatory molecules to support numerous physiological processes. Due to their regenerative and reparative properties, MSCs are extremely valuable for cell-based therapy in tackling several pathological conditions including COVID-19. Iron is essential for MSC processes but iron-loading, which is common in several chronic conditions, hinders normal MSC functionality. This not only aggravates disease pathology but can also affect allogeneic and autologous MSC therapy. Thus, understanding MSCs from an iron perspective is of clinical significance. Accordingly, this review highlights the roles of iron and iron-related proteins in MSC physiology. It describes the contribution of iron and endogenous iron-related effectors like hepcidin, ferroportin, transferrin receptor, lactoferrin, lipocalin-2, bone morphogenetic proteins and hypoxia inducible factors in MSC biology. It summarises the excess-iron-induced alterations in MSC components, processes and discusses signalling pathways involving ROS, PI3K/AKT, MAPK, p53, AMPK/MFF/DRP1 and Wnt. Additionally, it evaluates the endogenous and exogenous saviours of MSCs against iron-toxicity. Lastly, it elaborates on the involvement of MSCs in the pathology of clinical conditions of iron-excess, namely, hereditary hemochromatosis, diabetes, β-thalassaemia and myelodysplastic syndromes. This unique review integrates the distinct fields of iron regulation and MSC physiology. Through an iron-perspective, it describes both mechanistic and clinical aspects of MSCs and proposes an iron-linked MSC-contribution to physiology, pathology and therapeutics. It advances the understanding of MSC biology and may aid in identifying signalling pathways, molecular targets and compounds for formulating adjunctive iron-based therapies for excess-iron conditions, and thereby inform regenerative medicine.

Autophagy-Mediated Activation of Mucosal-Associated Invariant T Cells Driven by Mesenchymal Stem Cell-Derived IL-15

Mucosal-associated invariant T (MAIT) cells are innate-like unconventional T cells that are abundant in humans and have attracted increasing attention in recent years. Mesenchymal stem cells (MSCs) are crucial regulators of immune cells. However, whether MAIT cells are regulated by MSCs is unclear. Here, we explored the effect of MSCs on MAIT cells and revealed the underlying mechanism. We found that MSCs did not influence the proliferation of MAIT cells but strikingly induced an activated phenotype with an increased expression of CD69, TNF-α, IFN-γ, and granzyme B. Moreover, MSCs activated MAIT cells in a TCR-MR1-independent mechanism through MSC-secreted IL-15. We revealed that MSC-derived IL-15 activated MAIT cells by enhancing autophagy activity, which was abolished by the autophagy inhibitor 3-methyladenine. Based on our findings, MAIT cells are activated by MSCs through IL-15-induced autophagy, which may help elucidate the mechanisms underlying some immune responses and diseases and provide guidance for future research.

The Effect of Sirtuin 2 (Sirt2) Overexpressing Bone Marrow Mesenchymal Stem Cells on the Growth of Human Epidermal Growth Factor Receptor 2 (Her-2) Breast Cancer Cells and Its Mechanism

Our study investigates the effect of high expression of Sirt2 in MSCs (MSCs-Sirt2) on Her-2 breast cancer cell proliferation. A mouse subcutaneous xenograft tumor model was established and MSCssirt2 analysis was performed on nude mice. TUNEL staining, flow cytometry, western-blot, real-time PCR and immunohistochemistry were used to detect cancer cell apoptosis. The number of NK cells infiltrated by flow cytometry detected the tumor tissue of tumor-bearing mice, and its killing activity on tumor-bearing mice was detected by isotope labeling and release method. The levels of TNF-α, IFN-γ, IL-8, IL-6 and IL-10 were detected by ELISA. Caspase-3 level was decreased in the MSCs group (P <0.01) while increased in the MSCs-sirt2 group (P <0.001). However, PCNA expression showed an opposite profile in the Her-2 group and MSCs-sirt2 group compared to Caspase-3 level (P <0.01). The tumor volume and weight in the MSCs-sirt2 group was significantly reduced (P < 0.01), while increased in the MSCs group significantly (P < 0.05). The number of Ki-67-positive tumor cells in MSCs-sirt2 group was significantly reduced (P <0.01) and increased in MSCs group (P < 0.001) with oppositive number of TUNEL-positive tumor cells in the MSCs-sirt2 group and MSCs group (P <0.01). IFN-γ level showed an upward trend (P <0.001). The NK cell toxicity of MSCs-Sirt2 group was significantly higher (P <0.001). MSCs-Sirt2 has an inhibitory effect on Her-2 breast cancer cell growth by enhancing the local inflammatory response of NK cells.

Stem Cells Therapy as a Possible Therapeutic Option in Treating COVID-19 Patients

An unfortunate emergence of a new virus SARS-CoV-2, causing a disease known as COVID-19, has spread all around the globe and has caused a pandemic. It primarily affects the respiratory tract and lungs in some cases causing severe organ damage and pneumonia due to overwhelming immune responses. Clinical reports show that the most commons symptoms are fever, dry cough, and shortness of breath, along with several other symptoms. It is thought that an immense cytokine dysregulation in COVID-19 patients is caused following the virus infection. Notably, if patients present with pre-existing specific comorbidities like diabetes or high blood pressure, rates of COVID-19 induced complications and deaths are escalated. Mesenchymal stem cell (MSC) therapy has been shown to alleviate pneumonia and acute respiratory syndrome (ARDS) symptoms, through their immunomodulatory activities in COVID-19 patients. Although more research studies and clinical trial results are needed to elucidate the exact mechanism by which MSCs provide relief to COVID-19 infected patients. Results from clinical trials are encouraging as patients treated with MSCs, regain lung functions and have restored levels of cytokines and trophic factors underscoring the fact that stem cell therapy can be, at least, a complementary therapy to alleviate sufferings in COVID-19 patients. This review discusses the possible therapeutic uses of MSCs for treating COVID-19. Graphical Abstract.

Psoriatic mesenchymal stem cells stimulate the angiogenesis of human umbilical vein endothelial cells in vitro

OBJECTIVE

To investigate the regulation of psoriatic dermal mesenchymal stem cells (p-DMSCs) in the expression of vascular growth factor (VEGF), and migration and angiogenesis of human umbilical vein endothelial cells (HUVECs) in vitro.

METHODS

A co-culture model of HUVECs and dermal mesenchymal stem cells (DMSCs)was used in this study. After 7-day co-culture, changes in expression levels of VEGF mRNA and protein in HUVECs were assessed using RT-PCR and Western Blotting, respectively. Migration and tubular formation of HUVECs were also assessed following co-culture of DMSCs and HUVECs.

RESULTS

In comparison to either HUVECs alone or co-culture of n-DMSCs and HUVECs, co-culture of HUVECs and p-DMSCs significantly increased expression levels of both VEGF mRNA (p < 0.01 vs. HUVECs alone) and protein in HUVECs (p < 0.001 vs. both HUVECs alone and HUVECs co-cultured with n-DMSCs). Moreover, p-DMSCs stimulated HUVEC migration and vascular formation (p < 0.05 vs. both HUVECs alone and co-culture of n-DMSCs and HUVECs).

CONCLUSION

Psoriatic DMSCs can upregulate VEGF expression, and stimulate migration and angiogenesis of HUVECs, suggesting a pathogenic role of p-DMSCs in psoriasis.

Stem Cell Therapies in Alzheimer's Disease: Applications for Disease Modeling

Alzheimer's disease (AD) is a neurodegenerative disease with complex pathologic and biologic characteristics. Extracellular β-amyloid deposits, such as senile plaques, and intracellular aggregation of hyperphosphorylated tau, such as neurofibrillary tangles, remain the main neuropathological criteria for the diagnosis of AD. There is currently no effective treatment of the disease, and many clinical trials have failed to prove any benefits of new therapeutics. More recently, there has been increasing interest in harnessing the potential of stem cell technologies for drug discovery, disease modeling, and cell therapies, which have been used to study an array of human conditions, including AD. The recently developed and optimized induced pluripotent stem cell (iPSC) technology is a critical platform for screening anti-AD drugs and understanding mutations that modify AD. Neural stem cell (NSC) transplantation has been investigated as a new therapeutic approach to treat neurodegenerative diseases. Mesenchymal stem cells (MSCs) also exhibit considerable potential to treat neurodegenerative diseases by secreting growth factors and exosomes, attenuating neuroinflammation. This review highlights recent progress in stem cell research and the translational applications and challenges of iPSCs, NSCs, and MSCs as treatment strategies for AD. Even though these treatments are still in relative infancy, these developing stem cell technologies hold considerable promise to combat AD and other neurodegenerative disorders. SIGNIFICANCE STATEMENT: Alzheimer's disease (AD) is a neurodegenerative disease that results in learning and memory defects. Although some drugs have been approved for AD treatment, fewer than 20% of patients with AD benefit from these drugs. Therapies based on stem cells, including induced pluripotent stem cells, neural stem cells, and mesenchymal stem cells, provide promising therapeutic strategies for AD.

Human Dental Pulp Stem Cells Modulate Cytokine Production in vitro by Peripheral Blood Mononuclear Cells From Coronavirus Disease 2019 Patients

A subset of patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) developed a condition of hyper-inflammation, which can cause multi-organ damage and the more severe forms of coronavirus disease 2019 (COVID-19). Mesenchymal stem cells (MSCs) can promote tissue regeneration and modulate immune responses and, thus, have the rational requirements to be used to counteract SARS-CoV-2-induced pneumonia and hyper-inflammation. The aim of the present study was to gain insight into possible mechanisms of action of MSCs obtained from human dental pulp [dental pulp stem cells (DPSCs)] in COVID-19 patients. We investigated the concentrations of 18 cytokines in supernatants of peripheral blood mononuclear cells (PBMCs) obtained from COVID-19 patients cultured in vitro alone and in contact with DPSCs. The modulation of cytokines in PBMCs was confirmed by real-time PCR. IL-6 was the sole cytokine detected in supernatants of DPSCs. In resting conditions, co-culture increased IL-1β, IL-2, IL-5, IL-6, IL-10, IL-18, TNFα, and granulocyte macrophage colony-stimulating factor (GM-CSF) levels. When PBMCs were activated with anti-CD3/CD28 antibody-coated beads, co-culture increased IL-6 and GM-CSF, whereas it decreased IFNγ, TNFα, IL-2, IL-5, IL-9, IL-10, IL-12 (p70), IL-17A, IL-18, IL-21, IL-23, and IL-27 levels. Concentrations of IL-1β, IL-4, IL-13, and IL-22 were not affected. The comparison of cytokine concentrations in supernatants of PBMCs from COVID-19 patients vs. healthy subjects revealed lower concentrations of IL-10 and higher concentrations of IL-18 in supernatants of CD3/CD28-activated PBMCs from COVID-19 patients. Results are explorative but indicate that DPSCs can modulate the production of cytokines deregulated in COVID-19 patients, supporting their potential use in COVID-19.

The use of mesenchymal stem cells in the process of treatment and tissue regeneration after recovery in patients with Covid-19

In addition to causing health concerns, the new coronavirus has been considered in the world with its unknown mechanism of physiopathogenesis and long-term effects after patient recovery. Pulmonary, renal, hepatic and cardiac complications have been reported so far. Beside the researchers' focus on finding vaccines and using conventional therapies, cell-based therapy might be an effective therapeutic strategy. The use of mesenchymal stem cells (MSCs) is one of the options due to their immunomodulatory properties and their proven effects in the treatment of many diseases. As MSCs are not infected with covid-19, there is evidence that it modulates the immune system and prevents the virus from clotting. Despite the beginning of numerous clinical trials in the use of mesenchymal stem cells, it is necessary to set a practical guideline that specifies items such as cell origin, number of cells, frequency of injection, injection site, etc.

Extracellular Vesicles Do Not Mediate the Anti-Inflammatory Actions of Mouse-Derived Adipose Tissue Mesenchymal Stem Cells Secretome

Adipose tissue represents an abundant source of mesenchymal stem cells (MSC) for therapeutic purposes. Previous studies have demonstrated the anti-inflammatory potential of adipose tissue-derived MSC (ASC). Extracellular vesicles (EV) present in the conditioned medium (CM) have been shown to mediate the cytoprotective effects of human ASC secretome. Nevertheless, the role of EV in the anti-inflammatory effects of mouse-derived ASC is not known. The current study has investigated the influence of mouse-derived ASC CM and its fractions on the response of mouse-derived peritoneal macrophages against lipopolysaccharide (LPS). CM and its soluble fraction reduced the release of pro-inflammatory cytokines, adenosine triphosphate and nitric oxide in stimulated cells. They also enhanced the migration of neutrophils or monocytes, in the absence or presence of LPS, respectively, which is likely related to the presence of chemokines, and reduced the phagocytic response. The anti-inflammatory effect of CM may be dependent on the regulation of toll-like receptor 4 expression and nuclear factor-κB activation. Our results demonstrate the anti-inflammatory effects of mouse-derived ASC secretome in mouse-derived peritoneal macrophages stimulated with LPS and show that they are not mediated by EV.

K2 Transfection System Boosts the Adenoviral Transduction of Murine Mesenchymal Stromal Cells

Adenoviral vectors are important vehicles for delivering therapeutic genes into mammalian cells. However, the yield of the adenoviral transduction of murine mesenchymal stromal cells (MSC) is low. Here, we aimed to improve the adenoviral transduction efficiency of bone marrow-derived MSC. Our data showed that among all the potential transduction boosters that we tested, the K2 Transfection System (K2TS) greatly increased the transduction efficiency. After optimization of both K2TS components, the yield of the adenoviral transduction increased from 18% to 96% for non-obese diabetic (NOD)-derived MSC, from 30% to 86% for C57BL/6-derived MSC, and from 0.6% to 63% for BALB/c-derived MSC, when 250 transduction units/cell were used. We found that MSC derived from these mouse strains expressed different levels of the coxsackievirus and adenovirus receptors (MSC from C57BL/6≥NOD>>>BALB/c). K2TS did not increase the level of the receptor expression, but desensitized the cells to foreign DNA and facilitated the virus entry into the cell. The expression of Stem cells antigen-1 (Sca-1) and 5'-nucleotidase (CD73) MSC markers, the adipogenic and osteogenic differentiation potential, and the immunosuppressive capacity were preserved after the adenoviral transduction of MSC in the presence of the K2TS. In conclusion, K2TS significantly enhanced the adenoviral transduction of MSC, without interfering with their main characteristics and properties.

Preventive Vaccination with Mesenchymal Stem Cells Protects Mice from Lethal Infection Caused by Herpes Simplex Virus 1

Herpes simplex viruses 1 and 2 (HSV-1 and HSV-2) infect almost all organs and tissues, cause genital herpes-the most common sexually transmitted disease-disorders of the central nervous system (CNS), and lead to severe complications in children. Despite the available drugs, the incidence of HSV-1/2 continues to rise. None of the prophylactic vaccine candidates have shown a protective effect in trials nor approval for use in clinical practice. We have investigated the protective properties of mesenchymal stem cells (MSC) isolated from the bone marrow of mice. A comparative analysis of the protective response to the introduction of primary and modified MSCs (mMSC) was carried out using the plasmid containing gene of the HSV and an inactivated virus in a model of lethal HSV-1 infection in mice. mMSCs were obtained by transfection of the Us6 gene encoding glycoprotein D (gD) of the HSV, the plasmid contained the same gene. After twofold immunization with primary MSCs, the formation of antibodies interacting with the viral antigen (according to enzyme immunoassay data) and neutralizing the infectious activity of HSV-1 in the reaction of biological neutralization was observed in the peripheral blood of mice. In addition, the introduction of primary MSCs induced the production of interferon gamma (INF-γ) which is detected in the peripheral blood of mice. After infection with HSV-1, the immunized mice showed significantly increased titers of virus-specific antibodies, an increased level of IFNγ, and were completely protected from lethal HSV-1 infection. The protective effect of the other three immunogens was lower and did not exceed 50-65%. Considering the wide availability of MSCs, the proven safety of intravenous administration, and the results obtained in this work on the ability to induce innate, adaptive and protective immunity to HSV-1, MSCs can be considered a promising basis for the development of new cellular vaccines for the prevention of herpesvirus and other viral infections.

Mesenchymal Stem cells in the context of canine atopic dermatitis: A Review

ABSTRACT Canine atopic dermatitis (CAD) is a chronic inflammatory skin disease and has a high frequency among dermatological diseases. The interaction of genetic factors, skin and environmental conditions affect the expression of the disease, developing a complex pathology. Current multimodal treatment has numerous adverse effects and variations in its efficacy and safety, demonstrating the need to develop safe and effective therapeutic resources for patients with CAD. Mesenchymal stem cells (MSCs) are multipotent cells, with special characteristics, such as self-renewal, immunomodulatory properties, and de-differentiation, making them useful for several clinical problems. The discovery of the immunosuppressive effect of MSCs on T cells has opened the potential for new perspectives with its use as a therapeutic agent for immune diseases, such as CAD. The scarce number of research using the MSC as a treatment for CAD result in the lack of knowledge about the benefits and possible protocols to be followed for the use of this cell therapy. In this review, we highlighted the clinical studies and potential biological mechanisms of MSC-based cell therapy effects attenuating canine atopic dermatitis compared to conventional treatment, which might lead to a safe improvement of the animal’s clinical condition in a short period without causing adverse effects.

Aging of Bone Marrow Mesenchymal Stromal Cells: Hematopoiesis Disturbances and Potential Role in the Development of Hematologic Cancers

Simple Summary

As for many other cancers, the risk of developing hematologic malignancies increases considerably as people age. In recent years, a growing number of studies have highlighted the influence of the aging microenvironment on hematopoiesis and tumor progression. Mesenchymal stromal cells are a major player in intercellular communication inside the bone marrow microenvironment involved in hematopoiesis support. With aging, their functions may be altered, leading to hematopoiesis disturbances which can lead to hematologic cancers. A good understanding of the mechanisms involved in mesenchymal stem cell aging and the consequences on hematopoiesis and tumor progression is therefore necessary for a better comprehension of hematologic malignancies and for the development of therapeutic approaches.

Abstract

Aging of bone marrow is a complex process that is involved in the development of many diseases, including hematologic cancers. The results obtained in this field of research, year after year, underline the important role of cross-talk between hematopoietic stem cells and their close environment. In bone marrow, mesenchymal stromal cells (MSCs) are a major player in cell-to-cell communication, presenting a wide range of functionalities, sometimes opposite, depending on the environmental conditions. Although these cells are actively studied for their therapeutic properties, their role in tumor progression remains unclear. One of the reasons for this is that the aging of MSCs has a direct impact on their behavior and on hematopoiesis. In addition, tumor progression is accompanied by dynamic remodeling of the bone marrow niche that may interfere with MSC functions. The present review presents the main features of MSC senescence in bone marrow and their implications in hematologic cancer progression.

Efficacy and safety of intra-articular injection of mesenchymal stem cells in the treatment of knee osteoarthritis: A systematic review and meta-analysis

OBJECTIVE

To evaluate the effects and safety of intra-articular injection of mesenchymal stem cells on patients with knee osteoarthritis by a systematic review and meta-analysis.

METHODS

PubMed, EMBASE, and Cochrane Library were retrieved. An assessment of the risk of bias was done through the Cochrane Collaborative Bias Risk Tool, publication bias was assessed by plotting funnel plots and Egger tests. Pain and functional improvements in patients with knee osteoarthritis were determined by changes in VAS scores and WOMAC scores at baseline and follow-up endpoints. For the evaluation of MRI, the WORMS score and changes in cartilage volume were used. In addition, the number of adverse events in the intervention group and the control group were counted to explore the safety.

RESULTS

A total of 10 randomized controlled trials involving 335 patients were included. In the pooled analysis, compared with the control groups, the VAS scores of MSC groups decreased significantly (MD,-19.24; 95% CI: -26.31 to -12.18, P < .00001. All of the WOMAC scores also improved significantly: the total scores (SMD, - 0.66; 95% CI: - 1.09 to -0.23, P = .003), pain scores (SMD, - 0.46; 95% CI: - 0.75 to -0.17, P = .002), stiffness scores (SMD, -0.32; 95% CI: -0.64 to 0.00 P = 0.05), and functional scores (SMD, -0.36; 95% CI: -0.69 to -0.04, P = .03). Two studies with non-double-blind designs were the main source of heterogeneity. In terms of cartilage repair, there was no significant difference in the WORMS score, but there was a significant increase in cartilage volume in the MSC group (SMD, 0.69; 95% CI: 0.25 to 1.13, P = .002). The proportion of patients with adverse events in the MSCs treatment group was significantly higher than that in the control group (OR, 3.20; 95% CI: 1.50 to 6.83, P = .003).

CONCLUSIONS

Intra-articular injection of mesenchymal stem cells is effective and safety to relieve pain and improve motor function of patients with knee osteoarthritis in a short term which is different to conclusions of previous study.

Characterization of Mesenchymal Stem Cell Differentiation within Miniaturized 3D Scaffolds through Advanced Microscopy Techniques

Three-dimensional culture systems and suitable substrates topographies demonstrated to drive stem cell fate in vitro by mechanical conditioning. For example, the Nichoid 3D scaffold remodels stem cells and shapes nuclei, thus promoting stem cell expansion and stemness maintenance. However, the mechanisms involved in force transmission and in biochemical signaling at the basis of fate determination are not yet clear. Among the available investigation systems, confocal fluorescence microscopy using fluorescent dyes enables the observation of cell function and shape at the subcellular scale in vital and fixed conditions. Contrarily, nonlinear optical microscopy techniques, which exploit multi-photon processes, allow to study cell behavior in vital and unlabeled conditions. We apply confocal fluorescence microscopy, coherent anti-Stokes Raman scattering (CARS), and second harmonic generation (SHG) microscopy to characterize the phenotypic expression of mesenchymal stem cells (MSCs) towards adipogenic and chondrogenic differentiation inside Nichoid scaffolds, in terms of nuclear morphology and specific phenotypic products, by comparing these techniques. We demonstrate that the Nichoid maintains a rounded nuclei during expansion and differentiation, promoting MSCs adipogenic differentiation while inhibiting chondrogenesis. We show that CARS and SHG techniques are suitable for specific estimation of the lipid and collagenous content, thus overcoming the limitations of using unspecific fluorescent probes.

Canine colostrum exosomes: characterization and influence on the canine mesenchymal stem cell secretory profile and fibroblast anti-oxidative capacity

Background

Canine colostrum milk (CCM) is a specific secretion of the mammary gland that is fundamental for the survival of the newborn. CCM has many described components (immunoglobulins, proteins or fat), but its small vesicles, named exosomes, are largely unknown.

Results

A characterization of CCM exosomes was performed. Exosomes were abundant in CCM and appeared with the characteristic cup-shaped morphology and well-defined round vesicles. The size distribution of exosomes was between 37 and 140 nm, and western blot analysis showed positive expression of specific exosomal markers. Proteomic analysis revealed a total of 826 proteins in exosome cargo. We also found that exosomes modified the proliferation and secretory profiles in canine mesenchymal stem cells derived from bone marrow (cBM-MSCs) and adipose tissue (cAd-MSCs). Additionally, CCM exosomes demonstrated a potent antioxidant effect on canine fibroblasts in culture.

Conclusions

Our findings highlight, for the first time, the abundant presence of exosomes in CCM and their ability to interact with mesenchymal stem cells (MSCs). The addition of exosomes to two types of MSCs in culture resulted in specific secretory profiles with functions related to angiogenesis, migration and chemotaxis of immune cells. In particular, the cAd-MSCs secretory profile showed higher potential in adipose tissue development and neurogenesis, while cBM-MSC production was associated with immunity, cell mobilization and haematopoiesis. Finally, exosomes also presented antioxidant capacity on fibroblasts against reactive oxygen species activity within the cell, demonstrating their fundamental role in the development and maturation of dogs in the early stages of their life.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s12917-020-02623-w.

Coronavirus disease 2019 (COVID-19): Immunological approaches and emerging pharmacologic treatments

The SARS-CoV-2 virus is an etiological agent of pandemic COVID-19, which spreads rapidly worldwide. No proven effective therapies currently exist for this virus, and efforts to develop antiviral strategies for the treatment of COVID-19 are underway. The rapidly increasing understanding of SARS-CoV-2 virology provides a notable number of possible immunological procedures and drug targets. However, gaps remain in our understanding of the pathogenesis of COVID-19. In this review, we describe the latest information in the context of immunological approaches and emerging current antiviral strategies for COVID-19 treatment.

Improving the immunosuppressive potential of articular chondroprogenitors in a three-dimensional culture setting

Cartilage repair in osteoarthritic patients remains a challenge. Identifying resident or donor stem/progenitor cell populations is crucial for augmenting the low intrinsic repair potential of hyaline cartilage. Furthermore, mediating the interaction between these cells and the local immunogenic environment is thought to be critical for long term repair and regeneration. In this study we propose articular cartilage progenitor/stem cells (CPSC) as a valid alternative to bone marrow-derived mesenchymal stem cells (BMMSC) for cartilage repair strategies after trauma. Similar to BMMSC, CPSC isolated from osteoarthritic patients express stem cell markers and have chondrogenic, osteogenic, and adipogenic differentiation ability. In an in vitro 2D setting, CPSC show higher expression of SPP1 and LEP, markers of osteogenic and adipogenic differentiation, respectively. CPSC also display a higher commitment toward chondrogenesis as demonstrated by a higher expression of ACAN. BMMSC and CPSC were cultured in vitro using a previously established collagen-chondroitin sulfate 3D scaffold. The scaffold mimics the cartilage niche, allowing both cell populations to maintain their stem cell features and improve their immunosuppressive potential, demonstrated by the inhibition of activated PBMC proliferation in a co-culture setting. As a result, this study suggests articular cartilage derived-CPSC can be used as a novel tool for cellular and acellular regenerative medicine approaches for osteoarthritis (OA). In addition, the benefit of utilizing a biomimetic acellular scaffold as an advanced 3D culture system to more accurately mimic the physiological environment is demonstrated.

The use of mesenchymal stromal cells in the treatment of coronavirus disease 2019

More than seven months into the coronavirus disease -19 (COVID-19) pandemic, infection from the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has led to over 21.2 million cases and resulted in over 760,000 deaths worldwide so far. As a result, COVID-19 has changed all our lives as we battle to curtail the spread of the infection in the absence of specific therapies against coronaviruses and in anticipation of a proven safe and efficacious vaccine. Common with previous outbreaks of coronavirus infections, SARS and Middle East respiratory syndrome, COVID-19 can lead to acute respiratory distress syndrome (ARDS) that arises due to an imbalanced immune response. While several repurposed antiviral and host-response drugs are under examination as potential treatments, other novel therapeutics are also being explored to alleviate the effects on critically ill patients. The use of mesenchymal stromal cells (MSCs) for COVID-19 has become an attractive avenue down which almost 70 different clinical trial teams have ventured. Successfully trialled for the treatment of other conditions such as multiple sclerosis, osteoarthritis and graft versus host disease, MSCs possess both regenerative and immunomodulatory properties, the latter of which can be harnessed to reduce the severity and longevity of ARDS in patients under intensive care due to SARS-CoV-2 infection.

Mesenchymal Stem Cell-Derived Extracellular Vesicles: Opportunities and Challenges for Clinical Translation

Extracellular vesicles (EVs), including exosomes and microvesicles, derived from mesenchymal stem/stromal cells (MSCs) exert similar effects as their parental cells, and are of interest for various therapeutic applications. EVs can act through uptake by the target cells followed by release of their cargo inside the cytoplasm, or through interaction of membrane-bound ligands with receptors expressed on target cells to stimulate downstream intracellular pathways. EV-based therapeutics may be directly used as substitutes of intact cells or after modification for targeted drug delivery. However, for the development of EV-based therapeutics, several production, isolation, and characterization requirements have to be met and the quality of the final product has to be tested before its clinical implementation. In this review, we discuss the challenges associated with the development of EV-based therapeutics and the regulatory specifications for their successful clinical translation.

Co-cultured bone marrow mesenchymal stem cells repair thioacetamide-induced hepatocyte damage

Adult stem cells, such as bone marrow mesenchymal stem cells (BMSCs), are postdevelopmental cells found in many bone tissues. They are capable of multipotent differentiation and have low immune-rejection characteristics. Hepatocytes may become inflamed and produce a large number of free radicals when affected by drugs, poisoning, or a viral infection. The excessive accumulation of free radicals in the extracellular matrix (ECM) eventually leads to liver fibrosis. This study aims to investigate the restorative effects of mouse bone marrow mesenchymal stem cells (mBMSCs) on thioacetamide (TAA)-induced damage in hepatocytes. An in vitro transwell co-culture system of HepG2 cells were co-cultured with mBMSCs. The effects of damage done to TAA-treated HepG2 cells were reflected in the overall cell survival, the expression of antioxidants (SOD1, GPX1, and CAT), the ECM (COL1A1 and MMP9), antiapoptosis characteristics (BCL2), and inflammation (TNF) genes. The majority of the damage done to HepG2 by TAA was significantly reduced when cells were co-cultured with mBMSCs. The signal transducer and activator of transcription 3 (STAT3) and its phosphorylated STAT3 (p-STAT3), as related to cell growth and survival, were detected in this study. The results show that STAT3 was significantly decreased in the TAA-treated HepG2 cells, but the STAT3 and p-STAT3 of HepG2 cells were significantly activated when the TAA-treated HepG2 co-cultured with mBMSCs. Strong expression of interleukin (Il6) messenger RNA in co-cultured mBMSCs/HepG2 indicated mBMSCs secret the cytokines IL-6, which promotes cell survival through downstream STAT3 activation and aid in the recovery of HepG2 cells damaged by TAA.

Heparin/collagen surface coatings modulate the growth, secretome, and morphology of human mesenchymal stromal cell response to interferon-gamma

The therapeutic potential of human mesenchymal stromal cells (h-MSC) is dependent on the viability and secretory capacity of cells both modulated by the culture environment. Our previous studies introduced heparin and collagen I (HEP/COL) alternating stacked layers as a potential substrate to enhance the secretion of immunosuppressive factors of h-MSCs. Herein, we examined the impact of HEP/COL multilayers on the growth, morphology, and secretome of bone marrow and adipose-derived h-MSCs. The physicochemical properties and stability of the HEP/COL coatings were confirmed at 0 and 30 days. Cell growth was examined using cell culture media supplemented with 2 and 10% serum for 5 days. Results showed that HEP/COL multilayers supported h-MSC growth in 2% serum at levels equivalent to 10% serum. COL and HEP as single component coatings had limited impact on cell growth. Senescent studies performed over three sequential passages showed that HEP/COL multilayers did not impair the replicative capacity of h-MSCs. Examination of 27 cytokines showed significant enhancements in eight factors, including intracellular indoleamine 2, 3-dioxygenase, on HEP/COL multilayers when stimulated with interferon-gamma (IFN-γ). Image-based analysis of cell micrographs showed that serum influences h-MSC morphology; however, HEP-ended multilayers generated distinct morphological changes in response to IFN-γ, suggesting an optical detectable assessment of h-MSCs immunosuppressive potency. This study supports HEP/COL multilayers as a culture substrate for undifferentiated h-MSCs cultured in reduced serum conditions.

Plasminogen regulates mesenchymal stem cell-mediated tissue repair after ischemia through Cyr61 activation

Stem cell transplantation has emerged as a promising strategy in regenerative medicine. However, the poor survival and persistence of the transplanted cells, including mesenchymal stem cells (MSCs), in the hostile ischemic microenvironments represents a major therapeutic barrier. Here we report that plasminogen (Plg) stimulated MSC functions and promoted MSC survival during tissue repair after ischemia. Genetic Plg ablation abolished MSC survival, migration, and proliferation in mouse ischemic limbs, and abrogated MSC-mediated blood reperfusion, neovascularization, and tissue repair after ischemia, suggesting a critical role for Plg in MSC-mediated tissue repair. Furthermore, multiplex cytokine array analysis identified that Plg cleaved and activated cysteine-rich protein 61 (Cyr61), an ECM-associated growth factor, to stimulate MSC survival and migration. Overexpression with truncated Cyr61 in MSCs rescued blood reperfusion after hind limb ischemia in Plg-deficient mice. Finally, Plg-mediated Cyr61 cleavage promoted endothelial cell migration and neovascularization in vitro and in vivo. Our study reveals that Plg promotes MSC survival, persistence, and paracrine effects and improves postischemic neovascularization and tissue repair through Cyr61 cleavage and activation. Thus, targeting Plg/Cyr61 may offer exciting therapeutic opportunities for strengthening MSC therapy in ischemic diseases.

Plasminogen promotes mesenchymal stem cell function and improves post-ischemic neovascularization and tissue repair through cysteine-rich protein 61 activation.

Fibrinogen-Depleted Equine Platelet Lysate Affects the Characteristics and Functionality of Mesenchymal Stem Cells

Fetal bovine serum (FBS) is widely used to culture mesenchymal stem cells (MSCs) in the laboratory; however, FBS has been linked to adverse immune-mediated reactions prompting the search for alternative cell culture medium. Platelet lysate (PL) as an FBS substitute has been shown to promote MSCs growth without compromising their functionality. Fibrinogen contained in PL has been shown to negatively impact the immune modulating properties of MSCs; therefore, we sought to deplete fibrinogen from PL and compare proliferation, viability, and immunomodulatory capacities of MSCs in FBS or PL without fibrinogen. We depleted fibrinogen from equine platelet lysate (ePL) and measured platelet-derived growth factor-beta (PDGF-β), transforming growth factor-beta (TGF-β) and tumor necrosis factor-alpha (TNF-α) through ELISA. First, we determined the ability of 10% ePL or fibrinogen-depleted lysate (fdePL) compared with 10% FBS to suppress monocyte activation by measuring TNF-α from culture supernatants. We then evaluated proliferation, viability, and immunomodulatory characteristics of bone marrow-derived MSCs (BM-MSCs) cultured in FBS or ePL with or without fibrinogen. Growth factor concentrations decreased in ePL after fibrinogen depletion. Lipopolysaccharide (LPS)-stimulated monocytes exposed to ePL and fdePL produced less TNF-α than LPS-stimulated monocytes in 10% FBS. BM-MSCs cultured in fdePL exhibited lower proliferation rates, but similar viability compared with BM-MSCs in ePL. BM-MSCs in fdePL did not effectively suppress TNF-α expression from LPS-stimulated monocytes compared with BM-MSCs in FBS. Depleting fibrinogen results in a lysate that suppresses TNF-α expression from LPS-stimulated monocytes, but that does not support proliferation and immune-modulatory capacity of BM-MSCs as effectively as nondepleted lysate.

Mesenchymal stem cells and mesenchymal stem cell-derived extracellular vesicles: Potential roles in rheumatic diseases

BACKGROUND

Mesenchymal stem cells (MSCs) have been widely investigated in rheumatic disease due to their immunomodulatory and regenerative properties. Recently, mounting studies have implicated the therapeutic potency of MSCs mostly due to the bioactive factors they produce. Extracellular vesicles (EVs) derived from MSCs have been identified as a promising cell-free therapy due to low immunogenicity. Rheumatic disease, primarily including rheumatoid arthritis and osteoarthritis, is a group of diseases in which immune dysregulation and chronic progressive inflammation lead to irreversible joint damage. Targeting MSCs and MSC-derived EVs may be a more effective and promising therapeutic strategy for rheumatic diseases.

AIM

To evaluate the potential therapeutic effectiveness of MSCs and EVs generated from MSCs in rheumatic diseases.

METHODS

PubMed was searched for the relevant literature using corresponding search terms alone or in combination. Papers published in English language from January 1999 to February 2020 were considered. Preliminary screening of papers concerning analysis of "immunomodulatory function" or "regenerative function" by scrutinizing the titles and abstracts of the literature, excluded the papers not related to the subject of the article. Some other related studies were obtained by manually retrieving the reference lists of papers that comply with the selection criteria, and these studies were screened to meet the final selection and exclusion criteria.

RESULTS

Eighty-six papers were ultimately selected for analysis. After analysis of the literature, it was found that both MSCs and EVs generated from MSCs have great potential in multiple rheumatic diseases, such as rheumatoid arthritis and osteoarthritis, in repair and regeneration of tissues, inhibition of inflammatory response, and regulation of body immunity via promoting chondrogenesis, regulating innate and adaptive immune cells, and regulating the secretion of inflammatory factors. But EVs from MSCs exhibit much more advantages over MSCs, which may represent another promising cell-free restorative strategy. Targeting MSCs and MSC-derived EVs may be a more efficient treatment for patients with rheumatic diseases.

CONCLUSION

The enormous potential of MSCs and EVs from MSCs in immunomodulation and tissue regeneration offers a new idea for the treatment of rheumatism. However, more in-depth exploration is needed before their clinical application.

The Exposure to Osteoarthritic Synovial Fluid Enhances the Immunomodulatory Profile of Adipose Mesenchymal Stem Cell Secretome

Objective

Several clinical studies have proposed the infusion of adipose mesenchymal stem cells (AMSCs) as an alternative therapy for joint diseases with inflammatory components, such as osteoarthritis. Indeed, AMSCs are able to stimulate tissue repair through a paracrine activity and the interaction with the inflammatory microenvironment seems to have a critical role.

Design

To reproduce the inflammatory microenvironment, AMSCs were exposed to osteoarthritic synovial fluid (SF) for 48 h and the effect of their secretome on differentiation of monocytes (M0) into macrophages M1-like and mature dendritic cells (mDCs) was evaluated. Furthermore, the effect of the secretome of AMSCs exposed to SF was evaluated on the T cell population in terms of T cell proliferation and expansion of T regulatory cells (T reg).

Results

Our data show that the exposure of AMSCs to SF activates cells and promotes the release of immunosuppressive factors, which induce macrophage polarization of M0 into the M2-like phenotype and inhibit differentiation of monocytes into mature dendritic cells (mDCs). Only the secretome of exposed AMSCs was able to inhibit T cell proliferation and promote T reg expansion.

Conclusions

Our results suggest that the microenvironment plays a fundamental role for the development of anti-inflammatory and immunomodulatory properties of AMSCs.

Adipose Tissue-Derived Stem Cells Retain Their Adipocyte Differentiation Potential in Three-Dimensional Hydrogels and Bioreactors †

Osteoarthritis (OA) is a common joint disorder with a significant economic and healthcare impact. The knee joint is composed of cartilage and the adjoining bone, a synovial capsule, the infrapatellar fat pad (IPFP), and other connective tissues such as tendons and ligaments. Adipose tissue has recently been highlighted as a major contributor to OA through strong inflammation mediating effects. In this study, methacrylated gelatin (GelMA) constructs seeded with adipose tissue-derived mesenchymal stem cells (ASCs) and cultured in a 3D printed bioreactor were investigated for use in microphysiological systems to model adipose tissue in the knee joint. Four patient-derived ASC populations were seeded at a density of 20 million cells/mL in GelMA. Live/Dead and boron-dipyrromethene/4′,6-diamidino-2-phenylindole (BODIPY/DAPI) staining of cells within the constructs demonstrated robust cell viability after 28 days in a growth (control) medium, and robust cell viability and lipid accumulation in adipogenic differentiation medium. qPCR gene expression analysis and protein analysis demonstrated an upregulated expression of key adipogenesis-associated genes. Overall, these data indicate that ASCs retain their adipogenic potential when seeded within GelMA hydrogels and cultured within perfusion bioreactors, and thus can be used in a 3D organ-on-a-chip system to study the role of the IPFP in the pathobiology of the knee OA.