Toward Development of iMesenchymal Stem Cells for Immunomodulatory Therapy

Exploring the therapeutic potential of different sources of mesenchymal stem cells: a novel approach to combat burn wound infections

The most prevalent and harmful injuries are burns, which are still a major global health problem. Burn injuries can cause issues because they boost the inflammatory and metabolic response, which can cause organ malfunction and systemic failure. On the other hand, a burn wound infection creates an environment that is conducive to the growth of bacteria and might put the patient at risk for sepsis. In addition, scarring is unavoidable, and this results in patients having functional and cosmetic issues. Wound healing is an amazing phenomenon with a complex mechanism that deals with different types of cells and biomolecules. Cell therapy using stem cells is one of the most challenging treatment methods that accelerates the healing of burn wounds. Since 2000, the use of mesenchymal stem cells (MSCs) in regenerative medicine and wound healing has increased. They can be extracted from various tissues, such as bone marrow, fat, the umbilical cord, and the amniotic membrane. According to studies, stem cell therapy for burn wounds increases angiogenesis, has anti-inflammatory properties, slows the progression of fibrosis, and has an excellent ability to differentiate and regenerate damaged tissue. Figuring out the main preclinical and clinical problems that stop people from using MSCs and then suggesting the right ways to improve therapy could help show the benefits of MSCs and move stem cell-based therapy forward. This review's objective was to assess mesenchymal stem cell therapy's contribution to the promotion of burn wound healing.

Galectin-1-producing mesenchymal stem cells restrain the proliferation of T lymphocytes from patients with systemic lupus erythematosus

INTRODUCTION

Bone marrow mesenchymal stem cell (BMMSC) transplantation is beneficial in treating Systemic lupus erythematosus (SLE); however, the underlying mechanism remains elusive. This study investigates the role of BMMSCs in regulating lymphocyte proliferation and cell cycle progression during SLE and delves into the contribution of BMMSC-produced galectin-1.

METHODS

BMMSCs were co-cultured with T lymphocytes to assess their impact on suppressing CD4+ T cells in SLE patients. Proliferation and cell cycle distribution of CD4+ T cells were analyzed using flow cytometry. The expression of cell cycle-related proteins, including p21, p27, and cyclin-dependent kinase 2 (CDK2), was investigated through western blotting. Extracellular and intracellular galectin-1 levels were determined via ELISA and flow cytometry. The role of galectin-1 in CD4+ T cell proliferation and cell cycle was evaluated through RNAi-mediated galectin-1 expression disruption in BMMSCs.

RESULTS AND DISCUSSION

BMMSCs effectively inhibited CD4+ T cell proliferation and impeded their cell cycle progression in SLE patients, concurrently resulting in a reduction in CDK2 levels and an increase in p21 and p27 expression. Moreover, BMMSCs expressed a high level of galectin-1 in the co-culture system. Galectin-1 was found to be critical in maintaining the suppressive activity of BMMSCs and restoring the cell cycle of CD4+ T cells.

CONCLUSION

This study demonstrates that BMMSCs suppress the proliferation and influence the cell cycle of CD4+ T cells in SLE patients, an effect mediated by the upregulation of galectin-1 in BMMSCs.

Bone formation by human paediatric marrow stromal cells in a functional allogeneic immune system

Allogeneic stem-cell based regenerative medicine is a promising approach for bone defect repair. The use of chondrogenically differentiated human marrow stromal cells (MSCs) has been shown to lead to bone formation by endochondral ossification in immunodeficient pre-clinical models. However, an insight into the interactions between the allogeneic immune system and the human MSC-derived bone grafts has not been fully achieved yet. The choice of a potent source of MSCs isolated from pediatric donors with consistent differentiation and high proliferation abilities, as well as low immunogenicity, could increase the chance of success for bone allografts. In this study, we employed an immunodeficient animal model humanised with allogeneic immune cells to study the immune responses towards chondrogenically differentiated human pediatric MSCs (ch-pMSCs). We show that ch-differentiated pMSCs remained non-immunogenic to allogeneic CD4 and CD8 T cells in an in vitro co-culture model. After subcutaneous implantation in mice, ch-pMSC-derived grafts were able to initiate bone mineralisation in the presence of an allogeneic immune system for 3 weeks without the onset of immune responses. Re-exposing the splenocytes of the humanised animals to pMSCs did not trigger further T cell proliferation, suggesting an absence of secondary immune responses. Moreover, ch-pMSCs generated mature bone after 8 weeks of implantation that persisted for up to 6 more weeks in the presence of an allogeneic immune system. These data collectively show that human allogeneic chondrogenically differentiated pediatric MSCs might be a safe and potent option for bone defect repair in the tissue engineering and regenerative medicine setting.

Stimulated Human Umbilical Cord Mesenchymal Stem Cells Enhance the Osteogenesis and Cranial Bone Regeneration through IL-32 Mediated P38 Signaling Pathway

Objective

Our previous study found that it could significantly increase the expression of IL32 after stimulating the human umbilical cord mesenchymal stem cells (S-HuMSCs). However, its role on the osteogenesis and cranial bone regeneration is still largely unknown. Here, we investigated the possible mechanism of this effect. Material and Methods. A series of experiments, including single-cell sequencing, flow cytometry, quantitative real-time polymerase chain reaction, and western blotting, were carried out to evaluate the characteristic and adipogenic-osteogenic differentiation potential of IL-32 overexpression HuMSCs (IL-32highHuMSCs) through mediating the P38 signaling pathway. Moreover, a rat skull bone defect model was established and treated by directly injecting the IL-32highHuMSCs to conduct its role on the cranial bone regeneration.

Results

In total, it found that compared to HuMSCs, IL32 was significantly increased and promoted the osteogenic differentiation (lower expressions of PPARγ, Adiponectin, and C/EBPα, and increased expressions of RUNX2, ALP, BMP2, OPN, SP7, OCN, and DLX5) in the S-HuMSCs (P < 0.05). Meanwhile, the enhanced osteogenic differentiation of HuMSCs was recovered by IL-32 overexpression (IL-32highHuMSCs) through activating the P38 signaling pathway, like as the S-HuMSCs (P < 0.05). However, the osteogenic differentiation potential of IL-32highHuMSCs was significantly reversed by the P38 signaling pathway inhibitor SB203580 (P < 0.05). Additionally, the HuMSCs, S-HuMSCs, and IL-32highHuMSCs all presented adipogenic-osteogenic differentiation potential, with higher levels of CD73, CD90, and CD105, and lower CD14, CD34, and CD45 (P > 0.05). Furthermore, these findings were confirmed by the rat skull bone defect model, in which the cranial bone regeneration was more pronounced in the IL-32highHuMSCs treated group compared to those in the HuMSCs group, with higher expressions of RUNX2, ALP, BMP2, and DLX5 (P < 0.05).

Conclusion

We have confirmed that S-HuMSCs can enhance the osteogenesis and cranial bone regeneration through promoting IL-32-mediated P38 signaling pathway, which is proved that IL-32 may be a therapeutic target, or a biomarker for the treatment of cranial bone injuries.

Regulation of inflammation during wound healing: the function of mesenchymal stem cells and strategies for therapeutic enhancement

A wound takes a long time to heal and involves several steps. Following tissue injury, inflammation is the primary cause of tissue regeneration and repair processes. As a result, the pathophysiological processes involving skin damage, healing, and remodeling depend critically on the control of inflammation. The fact that it is a feasible target for improving the prognosis of wound healing has lately become clear. Mesenchymal stem cells (MSCs) are an innovative and effective therapeutic option for wound healing due to their immunomodulatory and paracrine properties. By controlling the inflammatory milieu of wounds through immunomodulation, transplanted MSCs have been shown to speed up the healing process. In addition to other immunomodulatory mechanisms, including handling neutrophil activity and modifying macrophage polarization, there may be modifications to the activation of T cells, natural killer (NK) cells, and dendritic cells (DCs). Furthermore, several studies have shown that pretreating MSCs improves their ability to modulate immunity. In this review, we summarize the existing knowledge about how MSCs influence local inflammation in wounds by influencing immunity to facilitate the healing process. We also provide an overview of MSCs optimizing techniques when used to treat wounds.

Mesenchymal stromal cells (MSCs) as a therapeutic agent of inflammatory disease and infectious COVID-19 virus: live or dead mesenchymal?

The COVID-19 infection is a worldwide disease that causes numerous immune-inflammatory disorders, tissue damage, and lung dysfunction. COVID-19 vaccines, including those from Pfizer, AstraZeneca, and Sinopharm, are available globally as effective interventions for combating the disease. The severity of COVID-19 can be most effectively reduced by mesenchymal stromal cells (MSCs) because they possess anti-inflammatory activity and can reverse lung dysfunction. MSCs can be harvested from various sources, such as adipose tissue, bone marrow, peripheral blood, inner organs, and neonatal tissues. The regulation of inflammatory cytokines is crucial in inhibiting inflammatory diseases and promoting the presence of anti-inflammatory cytokines for infectious diseases. MSCs have been employed as therapeutic agents for tissue damage, diabetes, autoimmune diseases, and COVID-19 patients. Our research aimed to determine whether live or dead MSCs are more suitable for the treatment of COVID-19 patients. Our findings concluded that dead MSCs, when directly administered to the patient, offer advantages over viable MSCs due to their extended presence and higher levels of immune regulation, such as T-reg, B-reg, and IL-10, compared to live MSCs. Additionally, dead and apoptotic MSCs are likely to be more readily captured by monocytes and macrophages, prolonging their presence compared to live MSCs.

Hypoxia and interleukin-1-primed mesenchymal stem/stromal cells as novel therapy for stroke

Promising preclinical stroke research has not yielded meaningful and significant success in clinical trials. This lack of success has prompted the need for refinement of preclinical studies with the intent to optimize the chances of clinical success. Regenerative medicine, especially using mesenchymal stem/stromal cells (MSCs), has gained popularity in the last decade for treating many disorders, including central nervous system (CNS), such as stroke. In addition to less stringent ethical constraints, the ample availability of MSCs also makes them an attractive alternative to totipotent and other pluripotent stem cells. The ability of MSCs to differentiate into neurons and other brain parenchymal and immune cells makes them a promising therapy for stroke. However, these cells also have some drawbacks that, if not addressed, will render MSCs unfit for treating ischaemic stroke. In this review, we highlighted the molecular and cellular changes that occur following an ischaemic stroke (IS) incidence and discussed the physiological properties of MSCs suitable for tackling these changes. We also went further to discuss the major drawbacks of utilizing MSCs in IS and how adequate priming using both hypoxia and interleukin-1 can optimize the beneficial properties of MSCs while eliminating these drawbacks.

Breaking the graft-versus-host-disease barrier: Mesenchymal stromal/stem cells as precision healers

Mesenchymal Stromal/Stem Cells (MSCs) are multipotent, non-hematopoietic progenitor cells with a wide range of immune modulation and regenerative potential which qualify them as a potential component of cell-based therapy for various autoimmune/chronic inflammatory ailments. Their immunomodulatory properties include the secretion of immunosuppressive cytokines, the ability to suppress T-cell activation and differentiation, and the induction of regulatory T-cells. Considering this and our interest, we here discuss the significance of MSC for the management of Graft-versus-Host-Disease (GvHD), one of the autoimmune manifestations in human. In pre-clinical models, MSCs have been shown to reduce the severity of GvHD symptoms, including skin and gut damage, which are the most common and debilitating manifestations of this disease. While initial clinical studies of MSCs in GvHD cases were promising, the results were variable in randomized studies. So, further studies are warranted to fully understand their potential benefits, safety profile, and optimal dosing regimens. Owing to these inevitable issues, here we discuss various mechanisms, and how MSCs can be employed in managing GvHD, as a cellular therapeutic approach for this disease.

Substrate topographies modulate the secretory activity of human bone marrow mesenchymal stem cells

BACKGROUND

Mesenchymal stem cells (MSCs) secrete a diversity of factors with broad therapeutic potential, yet current culture methods limit potency outcomes. In this study, we used topographical cues on polystyrene films to investigate their impact on the secretory profile and potency of bone marrow-derived MSCs (hBM-MSCs). hBM-MSCs from four donors were cultured on topographic substrates depicting defined roughness, curvature, grooves and various levels of wettability.

METHODS

The topographical PS-based array was developed using razor printing, polishing and plasma treatment methods. hBM-MSCs from four donors were purchased from RoosterBio and used in co-culture with peripheral blood mononuclear cells (PBMCs) from Cell Applications Inc. in an immunopotency assay to measure immunosuppressive capacity. Cells were cultured on low serum (2%) for 24-48 h prior to analysis. Image-based analysis was used for cell quantification and morphology assessment. Metabolic activity of BM-hMSCs was measured as the mitochondrial oxygen consumption rate using an extracellular flux analyzer. Conditioned media samples of BM-hMSCs were used to quantify secreted factors, and the data were analyzed using R statistics. Enriched bioprocesses were identify using the Gene Ontology tool enrichGO from the clusterprofiler. One-way and two-way ANOVAs were carried out to identify significant changes between the conditions. Results were deemed statistically significant for combined P < 0.05 for at least three independent experiments.

RESULTS

Cell viability was not significantly affected in the topographical substrates, and cell elongation was enhanced at least twofold in microgrooves and surfaces with a low contact angle. Increased cell elongation correlated with a metabolic shift from oxidative phosphorylation to a glycolytic state which is indicative of a high-energy state. Differential protein expression and gene ontology analyses identified bioprocesses enriched across donors associated with immune modulation and tissue regeneration. The growth of peripheral blood mononuclear cells (PBMCs) was suppressed in hBM-MSCs co-cultures, confirming enhanced immunosuppressive potency. YAP/TAZ levels were found to be reduced on these topographies confirming a mechanosensing effect on cells and suggesting a potential role in the immunomodulatory function of hMSCs.

CONCLUSIONS

This work demonstrates the potential of topographical cues as a culture strategy to improve the secretory capacity and enrich for an immunomodulatory phenotype in hBM-MSCs.

Interferon-Gamma Increases the Immune Modulation of Umbilical Cord-Derived Mesenchymal Stem Cells but Decreases Their Chondrogenic Potential

INTRODUCTION

The pro-inflammatory cytokine interferon-gamma (IFN-γ) is reported to be an agent that boosts the immune modulation of mesenchymal stem cells (MSCs). However, the effects of IFN-γ on the chondrogenic potential of treated MSCs have not been evaluated in depth. This study aimed to evaluate the effects of IFN-γ on the immune modulation and chondrogenic potential of human umbilical cord-derived MSCs (hUC-MSCs).

METHODS

UC-MSCs were isolated and expanded following published protocols. They were characterized as MSCs before their use in further experiments. The UC-MSCs were treated with IFN-γ at 10 ng/mL for 48 h. Changes in phenotype were investigated based on changes in MSC markers, immunomodulatory genes (TGF-β, IL-4, and IDO) for immune modulation, and cartilage-related genes during the induction of differentiation (Col1a2, Col2a1, Sox9, Runx2, and Acan) for chondrogenic potential.

RESULTS

IFN-γ-treated UC-MSCs maintained MSC markers and exhibited decreased expression of transcriptional regulatory factors in chondrogenesis (Sox9 and Runx2) and the extracellular matrix-specific genes Col1a2 and Acan but not Col2a1 compared to non-treated cells (p < 0.05). Furthermore, the immunomodulatory capability of IFN-γ-treated UC-MSCs was clearly revealed through their increased expression of IDO and IL-4 and decreased expression of TGF-β compared to non-treated cells (p < 0.05).

CONCLUSION

This study demonstrated that UC-MSCs treated with IFN-γ at 10 ng/mL had reduced expression of chondrocyte-specific genes; however, they maintained multi-lineage differentiation and exhibited immunomodulatory properties.

Bone regeneration in inflammation with aging and cell-based immunomodulatory therapy

Aging of the global population increases the incidence of osteoporosis and associated fragility fractures, significantly impacting patient quality of life and healthcare costs. The acute inflammatory reaction is essential to initiate healing after injury. However, aging is associated with "inflammaging", referring to the presence of systemic low-level chronic inflammation. Chronic inflammation impairs the initiation of bone regeneration in elderly patients. This review examines current knowledge of the bone regeneration process and potential immunomodulatory therapies to facilitate bone healing in inflammaging.Aged macrophages show increased sensitivity and responsiveness to inflammatory signals. While M1 macrophages are activated during the acute inflammatory response, proper resolution of the inflammatory phase involves repolarizing pro-inflammatory M1 macrophages to an anti-inflammatory M2 phenotype associated with tissue regeneration. In aging, persistent chronic inflammation resulting from the failure of M1 to M2 repolarization leads to increased osteoclast activation and decreased osteoblast formation, thus increasing bone resorption and decreasing bone formation during healing.Inflammaging can impair the ability of stem cells to support bone regeneration and contributes to the decline in bone mass and strength that occurs with aging. Therefore, modulating inflammaging is a promising approach for improving bone health in the aging population. Mesenchymal stem cells (MSCs) possess immunomodulatory properties that may benefit bone regeneration in inflammation. Preconditioning MSCs with pro-inflammatory cytokines affects MSCs' secretory profile and osteogenic ability. MSCs cultured under hypoxic conditions show increased proliferation rates and secretion of growth factors. Resolution of inflammation via local delivery of anti-inflammatory cytokines is also a potential therapy for bone regeneration in inflammaging. Scaffolds containing anti-inflammatory cytokines, unaltered MSCs, and genetically modified MSCs can also have therapeutic potential. MSC exosomes can increase the migration of MSCs to the fracture site and enhance osteogenic differentiation and angiogenesis.In conclusion, inflammaging can impair the proper initiation of bone regeneration in the elderly. Modulating inflammaging is a promising approach for improving compromised bone healing in the aging population.

Functional enhancement strategies to potentiate the therapeutic properties of mesenchymal stromal cells for respiratory diseases

Respiratory diseases remain a major health concern worldwide because they subject patients to considerable financial and psychosocial burdens and result in a high rate of morbidity and mortality. Although significant progress has been made in understanding the underlying pathologic mechanisms of severe respiratory diseases, most therapies are supportive, aiming to mitigate symptoms and slow down their progressive course but cannot improve lung function or reverse tissue remodeling. Mesenchymal stromal cells (MSCs) are at the forefront of the regenerative medicine field due to their unique biomedical potential in promoting immunomodulation, anti-inflammatory, anti-apoptotic and antimicrobial activities, and tissue repair in various experimental models. However, despite several years of preclinical research on MSCs, therapeutic outcomes have fallen far short in early-stage clinical trials for respiratory diseases. This limited efficacy has been associated with several factors, such as reduced MSC homing, survival, and infusion in the late course of lung disease. Accordingly, genetic engineering and preconditioning methods have emerged as functional enhancement strategies to potentiate the therapeutic actions of MSCs and thus achieve better clinical outcomes. This narrative review describes various strategies that have been investigated in the experimental setting to functionally potentiate the therapeutic properties of MSCs for respiratory diseases. These include changes in culture conditions, exposure of MSCs to inflammatory environments, pharmacological agents or other substances, and genetic manipulation for enhanced and sustained expression of genes of interest. Future directions and challenges in efficiently translating MSC research into clinical practice are discussed.

Tumour necrosis factor alpha, interleukin 1 beta and interferon gamma have detrimental effects on equine tenocytes that cannot be rescued by IL-1RA or mesenchymal stromal cell-derived factors

Tendon injuries occur commonly in both human and equine athletes, and poor tendon regeneration leads to functionally deficient scar tissue and an increased frequency of re-injury. Despite evidence suggesting inadequate resolution of inflammation leads to fibrotic healing, our understanding of the inflammatory pathways implicated in tendinopathy remains poorly understood, meaning successful targeted treatments are lacking. Here, we demonstrate IL-1β, TNFα and IFN-γ work synergistically to induce greater detrimental consequences for equine tenocytes than when used individually. This includes altering tendon associated and matrix metalloproteinase gene expression and impairing the cells' ability to contract a 3-D collagen gel, a culture technique which more closely resembles the in vivo environment. Moreover, these adverse effects cannot be rescued by direct suppression of IL-1β using IL-1RA or factors produced by BM-MSCs. Furthermore, we provide evidence that NF-κB, but not JNK, P38 MAPK or STAT 1, is translocated to the nucleus and able to bind to DNA in tenocytes following TNFα and IL-1β stimulation, suggesting this signalling cascade may be responsible for the adverse downstream consequences of these inflammatory cytokines. We suggest a superior approach for treatment of tendinopathy may therefore be to target specific signalling pathways such as NF-κB.

Inflammatory priming with IL-1β promotes the immunomodulatory behavior of adipose derived stem cells

Inflammatory processes contribute to osteoarthritis (OA) severity and progression. Mesenchymal stem cells, particularly those derived from adipose tissue (ASCs), are able to sense and control the inflammatory environment. This immunomodulatory potential can be boosted by different priming strategies based on inflammatory stimulation. The aim of the present study is to investigate the transcriptional modulation of a huge panel of genes and functionally verify the predicted immunomodulatory ability of ASCs after interleukin one beta (IL-1β) priming. ASCs were isolated from adipose tissue obtained from three donors and expanded. After stimulation with 1 ng/ml of IL-1β for 48 h, cells were collected for gene array and functional tests. Pooled cells from three donors were used for RNA extraction and gene array analysis. Gene Ontology (GO) enrichment analysis and Gene Set Enrichment Analysis (GSEA) were performed to assess the involvement of the modulated genes after priming in specific biological processes and pathways. Functional co-culture tests of ASCs with T cells and macrophages were performed to assess the ability of primed ASCs to modulate immune cell phenotype. Among the overall genes analyzed in the gene array, about the 18% were up- or down-regulated in ASCs after IL-1β priming. GO enrichment analysis of up- or down-regulated genes in ASCs after IL-1β priming allowed identifying specific pathways involved in the modulation of inflammation and extracellular matrix remodeling. The main processes enriched according to the GSEA are related to the inflammatory response and cell proliferative processes. Functional tests on immune cells showed that primed and non-primed ASCs induced a decrease in the CD3+ T lymphocytes survival rate and an anti-inflammatory macrophage polarization. In conclusion, IL-1β priming represents a tailored strategy to enhance the ability of ASCs to direct macrophages towards an anti-inflammatory phenotype and, consequently, improve the efficacy of ASCs in counteracting the OA inflammatory component.

Recent advances to enhance the immunomodulatory potential of mesenchymal stem cells

Considering the unique therapeutic potential of mesenchymal stem cells (MSCs), including their immunosuppressive and immunomodulatory properties as well as their ability to improve tissue regeneration, these cells have attracted the attention of scientists and clinicians for the treatment of different inflammatory and immune system mediated disorders. However, various clinical trials using MSCs for the therapeutic purpose are conflicting and differ from the results of promising preclinical studies. This inconsistency is caused by several factors such as poor migration and homing capacities, low survival rate, low level of proliferation and differentiation, and donor-dependent variation of the cells. Enhancement and retention of persistent therapeutic effects of the cells remain a challenge to overcome in MSC-based therapy. In this review, we summarized various approaches to enhance the clinical outcomes of MSC-based therapy as well as revised current and future perspectives for the creation of cellular products with improved potential for diverse clinical applications.

Mesenchymal Stromal Cell-Derived Extracellular Vesicles as Biological Carriers for Drug Delivery in Cancer Therapy

Cancer is the second leading cause of death worldwide, with 10.0 million cancer deaths in 2020. Despite advances in targeted therapies, some pharmacological drawbacks associated with anticancer chemo and immunotherapeutic agents include high toxicities, low bioavailability, and drug resistance. In recent years, extracellular vesicles emerged as a new promising platform for drug delivery, with the advantage of their inherent biocompatibility and specific targeting compared to artificial nanocarriers, such as liposomes. Particularly, mesenchymal stem/stromal cells were proposed as a source of extracellular vesicles for cancer therapy because of their intrinsic properties: high in vitro self-renewal and proliferation, regenerative and immunomodulatory capacities, and secretion of extracellular vesicles that mediate most of their paracrine functions. Moreover, extracellular vesicles are static and safer in comparison with mesenchymal stem/stromal cells, which can undergo genetic/epigenetic or phenotypic changes after their administration to patients. In this review, we summarize currently reported information regarding mesenchymal stem/stromal cell-derived extracellular vesicles, their proper isolation and purification techniques - from either naive or engineered mesenchymal stem/stromal cells - for their application in cancer therapy, as well as available downstream modification methods to improve their therapeutic properties. Additionally, we discuss the challenges associated with extracellular vesicles for cancer therapy, and we review some preclinical and clinical data available in the literature.

Insight in Hypoxia-Mimetic Agents as Potential Tools for Mesenchymal Stem Cell Priming in Regenerative Medicine

Hypoxia-mimetic agents are new potential tools in MSC priming instead of hypoxia incubators or chambers. Several pharmaceutical/chemical hypoxia-mimetic agents can be used to induce hypoxia in the tissues: deferoxamine (DFO), dimethyloxaloylglycine (DMOG), 2,4-dinitrophenol (DNP), cobalt chloride (CoCl2), and isoflurane (ISO). Hypoxia-mimetic agents can increase cell proliferation, preserve or enhance differentiation potential, increase migration potential, and induce neovascularization in a concentration- and stem cell source-dependent manner. Moreover, hypoxia-mimetic agents may increase HIF-1α, changing the metabolism and enhancing glycolysis like hypoxia. So, there is clear evidence that treatment with hypoxia-mimetic agents is beneficial in regenerative medicine, preserving stem cell capacities. These agents are not studied so wildly as hypoxia but, considering the low cost and ease of use, are believed to find application as pretreatment of many diseases such as ischemic heart disease and myocardial fibrosis and promote cardiac and cartilage regeneration. The knowledge of MSC priming is critical in evaluating safety procedures and use in clinics. In this review, similarities and differences between hypoxia and hypoxia-mimetic agents in terms of their therapeutic efficiency are considered in detail. The advantages, challenges, and future perspectives in MSC priming with hypoxia mimetic agents are also discussed.

Pre-Conditioning with IFN-γ and Hypoxia Enhances the Angiogenic Potential of iPSC-Derived MSC Secretome

Induced pluripotent stem cell (iPSC) derived mesenchymal stem cells (iMSCs) represent a promising source of progenitor cells for approaches in the field of bone regeneration. Bone formation is a multi-step process in which osteogenesis and angiogenesis are both involved. Many reports show that the secretome of mesenchymal stromal stem cells (MSCs) influences the microenvironment upon injury, promoting cytoprotection, angiogenesis, and tissue repair of the damaged area. However, the effects of iPSC-derived MSCs secretome on angiogenesis have seldom been investigated. In the present study, the angiogenic properties of IFN-γ pre-conditioned iMSC secretomes were analyzed. We detected a higher expression of the pro-angiogenic genes and proteins of iMSCs and their secretome under IFN-γ and hypoxic stimulation (IFN-H). Tube formation and wound healing assays revealed a higher angiogenic potential of HUVECs in the presence of IFN-γ conditioned iMSC secretome. Sprouting assays demonstrated that within Coll/HA scaffolds, HUVECs spheroids formed significantly more and longer sprouts in the presence of IFN-γ conditioned iMSC secretome. Through gene expression analyses, pro-angiogenic genes (FLT-1, KDR, MET, TIMP-1, HIF-1α, IL-8, and VCAM-1) in HUVECs showed a significant up-regulation and down-regulation of two anti-angiogenic genes (TIMP-4 and IGFBP-1) compared to the data obtained in the other groups. Our results demonstrate that the iMSC secretome, pre-conditioned under inflammatory and hypoxic conditions, induced the highest angiogenic properties of HUVECs. We conclude that pre-activated iMSCs enhance their efficacy and represent a suitable cell source for collagen/hydroxyapatite with angiogenic properties.

Strategies to improve regenerative potential of mesenchymal stem cells

In the last few decades, stem cell-based therapies have gained attention worldwide for various diseases and disorders. Adult stem cells, particularly mesenchymal stem cells (MSCs), are preferred due to their significant regenerative potential in cellular therapies and are currently involved in hundreds of clinical trials. Although MSCs have high self-renewal as well as differentiation potential, such abilities are compromised with “advanced age” and “disease status” of the donor. Similarly, cell-based therapies require high cell number for clinical applications that often require in vitro expansion of cells. It is pertinent to note that aged individuals are the main segment of population for stem cell-based therapies, however; autologous use of stem cells for such patients (aged and diseased) does not seem to give optimal results due to their compromised potential. In vitro expansion to obtain large numbers of cells also negatively affects the regenerative potential of MSCs. It is therefore essential to improve the regenerative potential of stem cells compromised due to “in vitro expansion”, “donor age” and “donor disease status” for their successful autologous use. The current review has been organized to address the age and disease depleted function of resident adult stem cells, and the strategies to improve their potential. To combat the problem of decline in the regenerative potential of cells, this review focuses on the strategies that manipulate the cell environment such as hypoxia, heat shock, caloric restriction and preconditioning with different factors.

The Inflammatory Lung Microenvironment; a Key Mediator in MSC Licensing

Recent clinical trials of mesenchymal stromal cell (MSC) therapy for various inflammatory conditions have highlighted the significant benefit to patients who respond to MSC administration. Thus, there is strong interest in investigating MSC therapy in acute inflammatory lung conditions, such as acute respiratory distress syndrome (ARDS). Unfortunately, not all patients respond, and evidence now suggests that the differential disease microenvironment present across patients and sub-phenotypes of disease or across disease severities influences MSC licensing, function and therapeutic efficacy. Here, we discuss the importance of licensing MSCs and the need to better understand how the disease microenvironment influences MSC activation and therapeutic actions, in addition to the need for a patient-stratification approach.

Human Tendon Stem/Progenitor Cell Features and Functionality Are Highly Influenced by in vitro Culture Conditions

Our understanding of tendon biology continues to evolve, thus leading to opportunities for developing novel, evidence-based effective therapies for the treatment of tendon disorders. Implementing the knowledge of tendon stem/progenitor cells (TSPCs) and assessing their potential in enhancing tendon repair could fill an important gap in this regard. We described different molecular and phenotypic profiles of TSPCs modulated by culture density, as well as their multipotency and secretory activities. Moreover, in the same experimental setting, we evaluated for different responses to inflammatory stimuli mediated by TNFα and IFNγ. We also preliminarily investigated their immunomodulatory activity and their role in regulating degradation of substance P. Our findings indicated that TSPCs cultured at low density (LD) exhibited cobblestone morphology and a reduced propensity to differentiate. A distinctive immunophenotypic profile was also observed with high secretory and promising immunomodulatory responses when primed with TNFα and IFNγ. In contrast, TSPCs cultured at high density (HD) showed a more elongated fibroblast-like morphology, a greater adipogenic differentiation potential, and a higher expression of tendon-related genes with respect to LD. Finally, HD TSPCs showed immunomodulatory potential when primed with TNFα and IFNγ, which was slightly lower than that shown by LD. A shift from low to high culture density during TSPC expansion demonstrated intermediate features confirming the cellular adaptability of TSPCs. Taken together, these experiments allowed us to identify relevant differences in TSPCs based on culture conditions. This ability of TSPCs to acquire distinguished morphology, phenotype, gene expression profile, and functional response advances our current understanding of tendons at a cellular level and suggests responsivity to cues in their in situ microenvironment.

Immunomodulatory Effects of Canine Adipose Tissue Mesenchymal Stem Cell-Derived Extracellular Vesicles on Stimulated CD4+ T Cells Isolated from Peripheral Blood Mononuclear Cells

Adipose tissue-derived mesenchymal stem cells (ADSCs) have anti-inflammatory and immunomodulatory characteristics. Many studies have suggested that the immunomodulation of ADSCs is largely mediated by secreted paracrine factors. Various factors are secreted from ADSCs, among which extracellular vesicles are considered to play a major role in the communication between ADSCs and target cells. Several studies have reported the function of canine ADSC-derived extracellular vesicles (cADSC-EVs), but few studies have reported the immunomodulatory effects of cADSC-EVs on immune cells. The purpose of this study was to investigate the effects of cADSC-EVs on in vitro-stimulated CD4⁺ T cells isolated from peripheral blood mononuclear cells (PBMCs). cADSC-EVs were isolated from cADSCs under naive conditions or primed conditions by tumor necrosis factor-α (TNFα) and interferon-γ (IFNγ). The expression levels of several microRNAs in cADSC-EVs were altered by priming with TNFα and IFNγ. Culturing PBMCs stimulated with concanavalin A in the presence of naive or primed cADSC-EVs inhibited the differentiation of PBMCs and CD4⁺ T cells and promoted apoptosis of PBMCs. CD4⁺, CD8⁺, and CD4⁺CD8⁺ T cells were decreased, while CD3⁺CD4^-CD8^- T cells were increased. T helper (Th) 1, Th2, Th17, and regulatory T (Treg) cells were analyzed by flow cytometry. cADSC-EVs inhibited the proliferation of Th1 and Th17 cells and enhanced Th2 and Treg cell proliferation. However, CD4⁺ T cells that had incorporated labeled cADSC-EVs comprised only a few percent of all cells. Therefore, these responses of stimulated CD4⁺ T cells may be due to not only direct effects of cADSC-EVs but also to indirect effects through interactions between cADSC-EVs and other immune cells. In conclusion, cADSC-EVs exert immunosuppressive effects on stimulated CD4⁺ T cells in vitro. These findings may be useful for further studies of immune diseases.

From Mesenchymal Stromal/Stem Cells to Insulin-Producing Cells: Immunological Considerations

Mesenchymal stem cell (MSC)-based therapy for type 1 diabetes mellitus (T1DM) has been the subject matter of many studies over the past few decades. The wide availability, negligible teratogenic risks and differentiation potential of MSCs promise a therapeutic alternative to traditional exogenous insulin injections or pancreatic transplantation. However, conflicting arguments have been reported regarding the immunological profile of MSCs. While some studies support their immune-privileged, immunomodulatory status and successful use in the treatment of several immune-mediated diseases, others maintain that allogeneic MSCs trigger immune responses, especially following differentiation or in vivo transplantation. In this review, the intricate mechanisms by which MSCs exert their immunomodulatory functions and the influencing variables are critically addressed. Furthermore, proposed avenues to enhance these effects, including cytokine pretreatment, coadministration of mTOR inhibitors, the use of Tregs and gene manipulation, are presented. As an alternative, the selection of high-benefit, low-risk donors based on HLA matching, PD-L₁ expression and the absence of donor-specific antibodies (DSAs) are also discussed. Finally, the necessity for the transplantation of human MSC (hMSC)-derived insulin-producing cells (IPCs) into humanized mice is highlighted since this strategy may provide further insights into future clinical applications.

3D-printed nerve guidance conduits multi-functionalized with canine multipotent mesenchymal stromal cells promote neuroregeneration after sciatic nerve injury in rats

Background

Nerve injuries are debilitating, leading to long-term motor deficits. Remyelination and axonal growth are supported and enhanced by growth factor and cytokines. Combination of nerve guidance conduits (NGCs) with adipose-tissue-derived multipotent mesenchymal stromal cells (AdMSCs) has been performing promising strategy for nerve regeneration.

Methods

3D-printed polycaprolactone (PCL)-NGCs were fabricated. Wistar rats subjected to critical sciatic nerve damage (12-mm gap) were divided into sham, autograft, PCL (empty NGC), and PCL + MSCs (NGC multi-functionalized with 10⁶ canine AdMSCs embedded in heterologous fibrin biopolymer) groups. In vitro, the cells were characterized and directly stimulated with interferon-gamma to evaluate their neuroregeneration potential. In vivo, the sciatic and tibial functional indices were evaluated for 12 weeks. Gait analysis and nerve conduction velocity were analyzed after 8 and 12 weeks. Morphometric analysis was performed after 8 and 12 weeks following lesion development. Real-time PCR was performed to evaluate the neurotrophic factors BDNF, GDNF, and HGF, and the cytokine and IL-10. Immunohistochemical analysis for the p75^NTR neurotrophic receptor, S100, and neurofilament was performed with the sciatic nerve.

Results

The inflammatory environment in vitro have increased the expression of neurotrophins BDNF, GDNF, HGF, and IL-10 in canine AdMSCs. Nerve guidance conduits multi-functionalized with canine AdMSCs embedded in HFB improved functional motor and electrophysiological recovery compared with PCL group after 12 weeks. However, the results were not significantly different than those obtained using autografts. These findings were associated with a shift in the regeneration process towards the formation of myelinated fibers. Increased immunostaining of BDNF, GDNF, and growth factor receptor p75^NTR was associated with the upregulation of BDNF, GDNF, and HGF in the spinal cord of the PCL + MSCs group. A trend demonstrating higher reactivity of Schwann cells and axonal branching in the sciatic nerve was observed, and canine AdMSCs were engrafted at 30 days following repair.

Conclusions

3D-printed NGCs multi-functionalized with canine AdMSCs embedded in heterologous fibrin biopolymer as cell scaffold exerted neuroregenerative effects. Our multimodal approach supports the trophic microenvironment, resulting in a pro-regenerative state after critical sciatic nerve injury in rats.

Clinical application of mesenchymal stem cells therapy in musculoskeletal injuries in dogs-a review of the scientific literature

Mesenchymal stem cells (MSCs) are multipotent, which is defined by their ability to self-renew while maintaining the capacity to differentiate into a certain number of cells, presumably from their own germinal layer. MSCs therapy is based on their anti-inflammatory, immunomodulatory (immunosuppressive), and regenerative potential. This review aims to provide a clinical overview of the MSCs potential as a therapeutic option for orthopedic diseases in dogs. A total of 25 clinical studies published in the scientific literature in the last 15 years on various diseases will be presented: semitendinosus myopathy, supraspinatus tendinopathy, cruciate ligament rupture, bone fractures and defects, and also osteoarthritis (OA). All articles involved in this study include only diseases that have naturally occurred in canine patients. MSCs therapy in the veterinary orthopedic field has great potential, especially for OA. All studies presented promising results. However, MSCs bone healing capacity did not reveal such favorable outcomes in the long term. Besides, most of these clinical studies did not include immunohistochemistry, immunofluorescence, and histopathology to confirm that MSCs have differentiated and incorporated into the injured tissues. This review summarizes the current knowledge of canine MSCs biology, immunology, and clinical application in canine orthopedic diseases. Despite the positive results in its use, there is still a lack of defined protocols, heterogeneous samples, and concomitant medications used with MSCs therapy compromising therapeutic effects. Further studies are needed in the hope of overcoming its limitation in upcoming trials.

Therapeutic Properties of Mesenchymal Stromal/Stem Cells: The Need of Cell Priming for Cell-Free Therapies in Regenerative Medicine

Mesenchymal stromal/stem cells (MSCs) are multipotent adult stem cells that support homeostasis during tissue regeneration. In the last decade, cell therapies based on the use of MSCs have emerged as a promising strategy in the field of regenerative medicine. Although these cells possess robust therapeutic properties that can be applied in the treatment of different diseases, variables in preclinical and clinical trials lead to inconsistent outcomes. MSC therapeutic effects result from the secretion of bioactive molecules affected by either local microenvironment or MSC culture conditions. Hence, MSC paracrine action is currently being explored in several clinical settings either using a conditioned medium (CM) or MSC-derived exosomes (EXOs), where these products modulate tissue responses in different types of injuries. In this scenario, MSC paracrine mechanisms provide a promising framework for enhancing MSC therapeutic benefits, where the composition of secretome can be modulated by priming of the MSCs. In this review, we examine the literature on the priming of MSCs as a tool to enhance their therapeutic properties applicable to the main processes involved in tissue regeneration, including the reduction of fibrosis, the immunomodulation, the stimulation of angiogenesis, and the stimulation of resident progenitor cells, thereby providing new insights for the therapeutic use of MSCs-derived products.

Extracellular vesicle mimics made from iPS cell-derived mesenchymal stem cells improve the treatment of metastatic prostate cancer

BACKGROUND

Extracellular vesicles (EVs) and their mimics from mesenchymal stem cells (MSCs) are promising drug carriers to improve cancer treatment, but their application is hindered by donor variations and expansion limitations of conventional tissue-derived MSCs. To circumvent these issues, we made EV-mimicking nanovesicles from standardized MSCs derived from human induced pluripotent stem cells (iPSCs) with a theoretically limitless expandability, and examined the targeting capacity of these nanovesicles to prostate cancer.

METHODS

Nanovesicles are made from intact iPSC-MSCs through serial extrusion. The selective uptake of fluorescently labeled nanovesicles by prostate cancer cells vs. non-tumor cells was examined with flow cytometry. For in vivo tracing, nanovesicles were labeled with fluorescent dye DiR or renilla luciferase. In mice carrying subcutaneous or bone metastatic PC3 prostate cancer, the biodistribution of systemically infused nanovesicles was examined with in vivo and ex vivo imaging of DiR and luminescent signals. A chemotherapeutic drug, docetaxel, was loaded into nanovesicles during extrusion. The cytotoxicities of nanovesicle-encapsulated docetaxel on docetaxel-sensitive and -resistant prostate cancer cells and non-tumor cells were examined in comparison with free docetaxel. Therapeutic effects of nanovesicle-encapsulated docetaxel were examined in mice carrying subcutaneous or bone metastatic prostate cancer by monitoring tumor growth in comparison with free docetaxel.

RESULTS

iPSC-MSC nanovesicles are more selectively taken up by prostate cancer cells vs. non-tumor cells in vitro compared with EVs, membrane-only EV-mimetic nanoghosts and liposomes, which is not affected by storage for up to 6 weeks. In mouse models of subcutaneous and bone metastatic PC3 prostate cancer, systemically infused nanovesicles accumulate in tumor regions with significantly higher selectivity than liposomes. The loading of docetaxel into nanovesicles was efficient and did not affect the selective uptake of nanovesicles by prostate cancer cells. The cytotoxicities of nanovesicle-encapsulated docetaxel are significantly stronger on docetaxel-resistant prostate cancer cells and weaker on non-tumor cells than free docetaxel. In mouse models of subcutaneous and bone metastatic prostate cancer, nanovesicle-encapsulated docetaxel significantly decreased the tumor growth and toxicity to white blood cells compared with free docetaxel.

CONCLUSIONS

Our data indicate that EV-mimicking iPSC-MSC nanovesicles are promising to improve the treatment of metastatic prostate cancer.

Microfluidics generation of chitosan microgels containing glycerylphytate crosslinker for in situ human mesenchymal stem cells encapsulation

Human mesenchymal stem cells (hMSCs) are an attractive source for cell therapies because of their multiple beneficial properties, i.e. via immunomodulation and secretory factors. Microfluidics is particularly attractive for cell encapsulation since it provides a rapid and reproducible methodology for microgel generation of controlled size and simultaneous cell encapsulation. Here, we report the fabrication of hMSC-laden microcarriers based on in situ ionotropic gelation of water-soluble chitosan in a microfluidic device using a combination of an antioxidant glycerylphytate (G1Phy) compound and tripolyphosphate (TPP) as ionic crosslinkers (G1Phy:TPP-microgels). These microgels showed homogeneous size distributions providing an average diameter of 104 ± 12 μm, somewhat lower than that of control (127 ± 16 μm, TPP-microgels). The presence of G1Phy in microgels maintained cell viability over time and upregulated paracrine factor secretion under adverse conditions compared to control TPP-microgels. Encapsulated hMSCs in G1Phy:TPP-microgels were delivered to the subcutaneous space of immunocompromised mice via injection, and the delivery process was as simple as the injection of unencapsulated cells. Immediately post-injection, equivalent signal intensities were observed between luciferase-expressing microgel-encapsulated and unencapsulated hMSCs, demonstrating no adverse effects of the microcarrier on initial cell survival. Cell persistence, inferred by bioluminescence signal, decreased exponentially over time showing relatively higher half-life values for G1Phy:TPP-microgels compared to TPP-microgels and unencapsulated cells. In overall, results position the microfluidics generated G1Phy:TPP-microgels as a promising microcarrier for supporting hMSC survival and reparative activities.

Bioengineering Approaches to Accelerate Clinical Translation of Stem Cell Therapies Treating Osteochondral Diseases

The osteochondral tissue is an interface between articular cartilage and bone. The diverse composition, mechanical properties, and cell phenotype in these two tissues pose a big challenge for the reconstruction of the defected interface. Due to the availability and inherent regenerative therapeutic properties, stem cells provide tremendous promise to repair osteochondral defect. This review is aimed at highlighting recent progress in utilizing bioengineering approaches to improve stem cell therapies for osteochondral diseases, which include microgel encapsulation, adhesive bioinks, and bioprinting to control the administration and distribution. We will also explore utilizing synthetic biology tools to control the differentiation fate and deliver therapeutic biomolecules to modulate the immune response. Finally, future directions and opportunities in the development of more potent and predictable stem cell therapies for osteochondral repair are discussed.

TNFR2 Is a Crucial Hub Controlling Mesenchymal Stem Cell Biological and Functional Properties

Mesenchymal stem cells (MSCs) have drawn lots of attention as gold standard stem cells in fundamental and clinical researches during the last 20 years. Due to their tissue and vascular repair capacities, MSCs have been used to treat a variety of degenerative disorders. Moreover, MSCs are able to modulate immune cells’ functions, particularly T cells while inducing regulatory T cells (iTregs). MSCs are very sensitive to inflammatory signals. Their biological functions could remarkably vary after exposure to different pro-inflammatory cytokines, notably TNFα. In this article, we have explored the importance of TNFR2 expression in a series of MSCs’ biological and functional properties. Thus, MSCs from wild-type (WT) and TNFR2 knockout (TNFR2 KO) mice were isolated and underwent several ex vivo experiments to investigate the biological significance of TNFR2 molecule in MSC main functions. Hampering in TNFR2 signaling resulted in reduced MSC colony-forming units and proliferation rate and diminished the expression of all MSC characteristic markers such as stem cell antigen-1 (Sca1), CD90, CD105, CD44, and CD73. TNFR2 KO-MSCs produced more pro-inflammatory cytokines like TNFα, IFNγ, and IL-6 and less anti-inflammatory mediators such as IL-10, TGFβ, and NO and induced Tregs with less suppressive effect. Furthermore, the TNFR2 blockade remarkably decreased MSC regenerative functions such as wound healing, complex tube formation, and endothelial pro-angiogenic support. Therefore, our results reveal the TNFα–TNFR2 axis as a crucial regulator of MSC immunological and regenerative functions.

Potential of Extracellular Vesicle-Associated TSG-6 from Adipose Mesenchymal Stromal Cells in Traumatic Brain Injury

Multipotent mesenchymal stromal cells (MSC) represent a promising strategy for a variety of medical applications. Although only a limited number of MSC engraft and survive after in vivo cellular infusion, MSC have shown beneficial effects on immunomodulation and tissue repair. This indicates that the contribution of MSC exists in paracrine signaling, rather than a cell-contact effect of MSC. In this review, we focus on current knowledge about tumor necrosis factor (TNF)-stimulated gene-6 (TSG-6) and mechanisms based on extracellular vesicles (EV) that govern long-lasting immunosuppressive and regenerative activity of MSC. In this context, in particular, we discuss the very robust set of findings by Jha and colleagues, and the opportunity to potentially extend their research focus on EV isolated in concentrated conditioned media (CCM) from adipose tissue derived MSC (ASC). Particularly, the authors showed that ASC-CCM mitigated visual deficits after mild traumatic brain injury in mice. TSG-6 knockdown ASC were, then, used to generate TSG-6-depleted CCM that were not able to replicate the alleviation of abnormalities in injured animals. In light of the presented results, we envision that the infusion of much distilled ASC-CCM could enhance the alleviation of visual abnormalities. In terms of EV research, the advantages of using size-exclusion chromatography are also highlighted because of the enrichment of purer and well-defined EV preparations. Taken together, this could further delineate and boost the benefit of using MSC-based regenerative therapies in the context of forthcoming clinical research testing in diseases that disrupt immune system homeostasis.

Functional enhancement strategies for immunomodulation of mesenchymal stem cells and their therapeutic application

Mesenchymal stem cells (MSCs) have recently been considered a promising alternative treatment for diverse immune disorders due to their unique biomedical potentials including the immunomodulatory property and ability to promote tissue regeneration. However, despite many years of pre-clinical studies in the research field, results from clinical trials using these cells have been diverse and conflicting. This discrepancy is caused by several factors such as poor engraftment, low survival rate, and donor-dependent variation of the cells. Enhancement of consistency and efficacy of MSCs remains a challenge to overcome the current obstacles to MSC-based therapy and subsequently achieve an improved therapeutic outcome. In this review, we investigated function enhancement strategies by categorizing as preconditioning, genetic manipulation, usage of supportive materials, and co-administration with currently used drugs. Preconditioning prior to MSC application makes up a large proportion of improvement strategies and preconditioning reagents include bioactive substances (cytokines, growth factors, and innate immune receptor agonists), hypoxia, and modification in culture method. With the piled results from previous studies using each method, disease- or patient-specific therapy has become more important than ever. On the other hand, genetic manipulation targeting therapeutic-associated factors or co-administration of biocompatible materials has also arisen as other therapeutic strategies. Thus, we summarized several specialized tactics by analyzing up-to-date results in the field and proposed some promising enhancement methods to improve the clinical outcomes for MSC therapy.

Phorbol ester activates human mesenchymal stem cells to inhibit B cells and ameliorate lupus symptoms in MRL.Fas lpr mice

Rationale: Systemic lupus erythematosus (SLE) is a multi-organ autoimmune disease characterized by autoantibody production by hyper-activated B cells. Although mesenchymal stem cells (MSCs) ameliorate lupus symptoms by inhibiting T cells, whether they inhibit B cells has been controversial. Here we address this issue and reveal how to prime MSCs to inhibit B cells and improve the efficacy of MSCs in SLE.

Methods: We examined the effect of MSCs on purified B cells in vitro and the therapeutic efficacy of MSCs in lupus-prone MRL.Fas^lpr mice. We screened chemicals for their ability to activate MSCs to inhibit B cells.

Results: Mouse bone marrow-derived MSCs inhibited mouse B cells in a CXCL12-dependent manner, whereas human bone marrow-derived MSCs (hMSCs) did not inhibit human B (hB) cells. We used a chemical approach to overcome this hurdle and found that phorbol myristate acetate (PMA), phorbol 12,13-dibutyrate, and ingenol-3-angelate rendered hMSCs capable of inhibiting IgM production by hB cells. As to the mechanism, PMA-primed hMSCs attracted hB cells in a CXCL10-dependent manner and induced hB cell apoptosis in a PD-L1-dependent manner. Finally, we showed that PMA-primed hMSCs were better than naïve hMSCs at ameliorating SLE progression in MRL.Fas^lpr mice.

Conclusion: Taken together, our data demonstrate that phorbol esters might be good tool compounds to activate MSCs to inhibit B cells and suggest that our chemical approach might allow for improvements in the therapeutic efficacy of hMSCs in SLE.

Mesenchymal Stem Cells: A new front emerge in COVID19 treatment

Currently, treating coronavirus disease 2019 (COVID-19) patients, particularly those afflicted with severe pneumonia, is challenging, as no effective pharmacotherapy for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exists. Severe pneumonia is recognized as a clinical syndrome characterized by hyper-induction of pro-inflammatory cytokine production, which can induce organ damage, followed by edema, dysfunction of air exchange, acute respiratory distress syndrome, acute cardiac injury, secondary infection and increased mortality. Owing to the immunoregulatory and differentiation potential of mesenchymal stem cells (MSCs), we aimed to outline current insights into the clinical application of MSCs in COVID-19 patients. Based on results from preliminary clinical investigations, it can be predicted that MSC therapy for patients infected with SARS-CoV-2 is safe and effective, although multiple clinical trials with a protracted follow-up will be necessary to determine the long-term effects of the treatment on COVID-19 patients.

Modifying MSC Phenotype to Facilitate Bone Healing: Biological Approaches

Healing of fractures and bone defects normally follows an orderly series of events including formation of a hematoma and an initial stage of inflammation, development of soft callus, formation of hard callus, and finally the stage of bone remodeling. In cases of severe musculoskeletal injury due to trauma, infection, irradiation and other adverse stimuli, deficient healing may lead to delayed or non-union; this results in a residual bone defect with instability, pain and loss of function. Modern methods of mechanical stabilization and autologous bone grafting are often successful in achieving fracture union and healing of bone defects; however, in some cases, this treatment is unsuccessful because of inadequate biological factors. Specifically, the systemic and local microenvironment may not be conducive to bone healing because of a loss of the progenitor cell population for bone and vascular lineage cells. Autologous bone grafting can provide the necessary scaffold, progenitor and differentiated lineage cells, and biological cues for bone reconstruction, however, autologous bone graft may be limited in quantity or quality. These unfavorable circumstances are magnified in systemic conditions with chronic inflammation, including obesity, diabetes, chronic renal disease, aging and others. Recently, strategies have been devised to both mitigate the necessity for, and complications from, open procedures for harvesting of autologous bone by using minimally invasive aspiration techniques and concentration of iliac crest bone cells, followed by local injection into the defect site. More elaborate strategies (not yet approved by the U.S. Food and Drug Administration-FDA) include isolation and expansion of subpopulations of the harvested cells, preconditioning of these cells or inserting specific genes to modulate or facilitate bone healing. We review the literature pertinent to the subject of modifying autologous harvested cells including MSCs to facilitate bone healing. Although many of these techniques and technologies are still in the preclinical stage and not yet approved for use in humans by the FDA, novel approaches to accelerate bone healing by modifying cells has great potential to mitigate the physical, economic and social burden of non-healing fractures and bone defects.

Pre-conditioning of Equine Bone Marrow-Derived Mesenchymal Stromal Cells Increases Their Immunomodulatory Capacity

Mesenchymal stem/stromal cells (MSCs) are increasingly explored for the treatment of degenerative and inflammatory diseases in human and veterinary medicine. One of the key characteristics of MSCs is that they modulate inflammation mainly through the secretion of soluble mediators. However, despite widespread clinical use, knowledge regarding the effector mechanisms of equine MSCs, and consequently their effectiveness in the treatment of diseases, is still unknown. The objectives of this study were to determine the mechanisms underlying inhibition of lymphocyte proliferation by equine bone marrow-derived MSCs, and to evaluate the effect of pre-conditioning of equine MSCs with different pro-inflammatory cytokines on inhibition of lymphocyte proliferation. We determined that inhibition of lymphocyte proliferation by equine MSCs depends on activity of prostaglandin-endoperoxide synthase 2 and indoleamine 2,3-dioxygenase. Additionally, pre-conditioning of MSCs with TNF-α, IFN-γ or their combination significantly increased the expression of prostaglandin-endoperoxide synthase 2, indoleamine 2,3-dioxygenase, iNOS and IL-6. This upregulation correlated with an increased inhibitory effect of MSCs on lymphocyte proliferation. In conclusion, pre-conditioning of bone marrow-derived MSC increases their inhibitory effect on lymphocyte proliferation in horses.

Inflammatory priming enhances mesenchymal stromal cell secretome potential as a clinical product for regenerative medicine approaches through secreted factors and EV-miRNAs: the example of joint disease

BACKGROUND

Mesenchymal stromal cell (MSC)-enriched products showed positive clinical outcomes in regenerative medicine, where tissue restoration and inflammation control are needed. GMP-expanded MSCs displayed an even higher potential due to exclusive secretion of therapeutic factors, both free and conveyed within extracellular vesicles (EVs), collectively termed secretome. Moreover, priming with biochemical cues may influence the portfolio and biological activities of MSC-derived factors. For these reasons, the use of naive or primed secretome gained attention as a cell-free therapeutic option. Albeit, at present, a homogenous and comprehensive secretome fingerprint is still missing. Therefore, the aim of this work was to deeply characterize adipose-derived MSC (ASC)-secreted factors and EV-miRNAs, and their modulation after IFNγ preconditioning. The crucial influence of the target pathology or cell type was also scored in osteoarthritis to evaluate disease-driven potency.

METHODS

ASCs were isolated from four donors and cultured with and without IFNγ. Two-hundred secreted factors were assayed by ELISA. ASC-EVs were isolated by ultracentrifugation and validated by flow cytometry, transmission electron microscopy, and nanoparticle tracking analysis. miRNome was deciphered by high-throughput screening. Bioinformatics was used to predict the modulatory effect of secreted molecules on pathologic cartilage and synovial macrophages based on public datasets. Models of inflammation for both macrophages and chondrocytes were used to test by flow cytometry the secretome anti-inflammatory potency.

RESULTS

Data showed that more than 60 cytokines/chemokines could be identified at varying levels of intensity in all samples. The vast majority of factors are involved in extracellular matrix remodeling, and chemotaxis or motility of inflammatory cells. IFNγ is able to further increase the capacity of the secretome to stimulate cell migration signals. Moreover, more than 240 miRNAs were found in ASC-EVs. Sixty miRNAs accounted for > 95% of the genetic message that resulted to be chondro-protective and M2 macrophage polarizing. Inflammation tipped the balance towards a more pronounced tissue regenerative and anti-inflammatory phenotype. In silico data were confirmed on inflamed macrophages and chondrocytes, with secretome being able to increase M2 phenotype marker CD163 and reduce the chondrocyte inflammation marker VCAM1, respectively. IFNγ priming further enhanced secretome anti-inflammatory potency.

CONCLUSIONS

Given the portfolio of soluble factors and EV-miRNAs, ASC secretome showed a marked capacity to stimulate cell motility and modulate inflammatory and degenerative processes. Preconditioning is able to increase this ability, suggesting inflammatory priming as an effective strategy to obtain a more potent clinical product which use should always be driven by the molecular mark of the target pathology.

Cytokine pre-activation of cryopreserved xenogeneic-free human mesenchymal stromal cells enhances resolution and repair following ventilator-induced lung injury potentially via a KGF-dependent mechanism

BACKGROUND

Human mesenchymal stem/stromal cells (hMSCs) represent a promising therapeutic strategy for ventilator-induced lung injury (VILI) and acute respiratory distress syndrome. Translational challenges include restoring hMSC efficacy following cryopreservation, developing effective xenogeneic-free (XF) hMSCs and establishing true therapeutic potential at a clinically relevant time point of administration. We wished to determine whether cytokine pre-activation of cryopreserved, bone marrow-derived XF-hMSCs would enhance their capacity to facilitate injury resolution following VILI and elucidate mechanisms of action.

METHODS

Initially, in vitro studies examined the potential for the secretome from cytokine pre-activated XF-hMSCs to attenuate pulmonary epithelial injury induced by cyclic mechanical stretch. Later, anaesthetised rats underwent VILI and, 6 h following injury, were randomized to receive 1 × 107 XF-hMSC/kg that were (i) naive fresh, (ii) naive cryopreserved, (iii) cytokine pre-activated fresh or (iv) cytokine pre-activated cryopreserved, while control animals received (v) vehicle. The extent of injury resolution was measured at 24 h after injury. Finally, the role of keratinocyte growth factor (KGF) in mediating the effect of pre-activated XF-hMSCs was determined in a pulmonary epithelial wound repair model.

RESULTS

Pre-activation enhanced the capacity of the XF-hMSC secretome to decrease stretch-induced pulmonary epithelial inflammation and injury. Both pre-activated fresh and cryopreserved XF-hMSCs enhanced resolution of injury following VILI, restoring oxygenation, improving lung compliance, reducing lung leak and improving resolution of lung structural injury. Finally, the secretome of pre-activated XF-hMSCs enhanced epithelial wound repair, in part via a KGF-dependent mechanism.

CONCLUSIONS

Cytokine pre-activation enhanced the capacity of cryopreserved, XF-hMSCs to promote injury resolution following VILI, potentially via a KGF-dependent mechanism.

Modulation of the Inflammatory Response and Bone Healing

The optimal treatment for complex fractures and large bone defects is an important unsolved issue in orthopedics and related specialties. Approximately 5-10% of fractures fail to heal and develop non-unions. Bone healing can be characterized by three partially overlapping phases: the inflammatory phase, the repair phase, and the remodeling phase. Eventual healing is highly dependent on the initial inflammatory phase, which is affected by both the local and systemic responses to the injurious stimulus. Furthermore, immune cells and mesenchymal stromal cells (MSCs) participate in critical inter-cellular communication or crosstalk to modulate bone healing. Deficiencies in this inter-cellular exchange, inhibition of the natural processes of acute inflammation, and its resolution, or chronic inflammation due to a persistent adverse stimulus can lead to impaired fracture healing. Thus, an initial and optimal transient stage of acute inflammation is one of the key factors for successful, robust bone healing. Recent studies demonstrated the therapeutic potential of immunomodulation for bone healing by the preconditioning of MSCs to empower their immunosuppressive properties. Preconditioned MSCs (also known as "primed/ licensed/ activated" MSCs) are cultured first with pro-inflammatory cytokines (e.g., TNFα and IL17A) or exposed to hypoxic conditions to mimic the inflammatory environment prior to their intended application. Another approach of immunomodulation for bone healing is the resolution of inflammation with anti-inflammatory cytokines such as IL4, IL10, and IL13. In this review, we summarize the principles of inflammation and bone healing and provide an update on cellular interactions and immunomodulation for optimal bone healing.

Pathogenetic substantiation of the combined transplantation use of multipotent mesenchymal stromal cells and hepatic stellate cells to restore the liver morphofunctional state after acute toxic hepatitis in the old body

The purpose of this study was to study the cotransplantation influence of multipotent mesenchymal stromal (MMSC) and hepatic stellate (HSC) cells on liver regeneration of old laboratory animals in conditions of its toxic damage. Acute toxic hepatitis was caused by single intraperitoneal CC14 injection at a dose of 50 μg/kg. The introduction of MMSC and HSC was carried out at doses of 4 million cl/kg and 9 million cl/kg respectively 1 hour after toxic hepatitis modelling. The morphofunctional liver state of old laboratory mice was evaluated on the 1st, 3rd, 7th day after combined injection of MMSC and HSC in laboratory animals with toxic hepatitis. As a result of the study, it was obtained that MMSC and HSC cotransplantation leads to cellular and intracellular liver regeneration activation in old mice with acute toxic hepatitis. Also, the introduction of these cell types leads to decreased liver mutagenesis, inhibition of programmed cellular hepatocytes death. Thus, the conducted studies indicate the ability of combined MMSC and HSC transplantation to restore the morphofunctional liver state of the old organism under the conditions of its toxic damage.

Mesenchymal stem cells therapy in companion animals: useful for immune-mediated diseases?

Mesenchymal stem cells are multipotent cells, with capacity for self-renewal and differentiation into tissues of mesodermal origin. These cells are possible therapeutic agents for autoimmune disorders, since they present remarkable immunomodulatory ability.The increase of immune-mediated diseases in veterinary medicine has led to a growing interest in the research of these disorders and their medical treatment. Conventional immunomodulatory drug therapy such as glucocorticoids or other novel therapies such as cyclosporine or monoclonal antibodies are associated with numerous side effects that limit its long-term use, leading to the need for developing new therapeutic strategies that can be more effective and safe.The aim of this review is to provide a critical overview about the therapeutic potential of these cells in the treatment of some autoimmune disorders (canine atopic dermatitis, feline chronic gingivostomatitis, inflammatory bowel disease and feline asthma) compared with their conventional treatment.Mesenchymal stem cell-based therapy in autoimmune diseases has been showing that this approach can ameliorate clinical signs or even cause remission in most animals, with the exception of canine atopic dermatitis in which little to no improvement was observed.Although mesenchymal stem cells present a promising future in the treatment of most of these disorders, the variability in the outcomes of some clinical trials has led to the current controversy among authors regarding their efficacy. Mesenchymal stem cell-based therapy is currently requiring a deeper and detailed analysis that allows its standardization and better adaptation to the intended therapeutic results, in order to overcome current limitations in future trials.

CD90low MSCs modulate intratumoral immunity to confer antitumor activity in a mouse model of ovarian cancer

Both anti-tumoral and pro-tumoral effects of mesenchymal stem cells (MSCs) in preclinical treatment of ovarian cancer have been controversially demonstrated. In this study, we profiled the phenotypes of mouse compact bone-derived MSCs (CB-MSCs) and bone marrow-derived MSCs (BM-MSCs) and found that CB-MSCs expressed lower CD90 compared to BM-MSCs. We examined gene expression of immune regulating cytokines of CB-MSCs in 2D and 3D culture and under stimulation with TLR4 agonist LPS or immune activator VIC-008. Our data showed that when CB-MSCs were cultured in simulated in vivo 3D condition, CD90 expression was further decreased. Moreover, gene expressions of immune activating cytokines IL-12, IL-21, IFNγ and a pro-inflammatory cytokine CXCL10 in CB-MSCs were increased in 3D culture whereas gene expression of anti-inflammatory cytokines IL-10 and CCL5 were downregulated. Stimulation of CB-MSCs by LPS or VIC-008 presented similar profile of the cytokine gene expressions to that in 3D culture which might benefit the anti-tumor efficacy of CD90low MSCs. The anti-tumor effects of CD90low CB-MSCs alone or in combination with VIC-008 were evaluated in a syngeneic orthotopic mouse model of ovarian cancer. Treatment that combines CB-MSCs and VIC-008 significantly decreased tumor growth and prolonged mouse survival. This was associated with the increase of activated anti-tumoral CD4+ and CD8+ T cells and the decrease of Treg cells in the tumor microenvironment. Taken together, our study demonstrates the synergistic anti-tumoral efficacy by application of CB-MSCs combined with immune activator VIC-008 and provides new insight into CD90low MSCs as a new anti-tumor arsenal.

Conditioned Serum Enhances the Chondrogenic and Immunomodulatory Behavior of Mesenchymal Stem Cells

Osteoarthritis is one of the most common chronic health conditions associated with pain and disability. Advanced therapies based on mesenchymal stem cells have become valuable options for the treatment of these pathologies. Conditioned serum (CS, “Orthokine”) has been used intra-articularly for osteoarthritic patients. In this work, we hypothesized that the rich content on anti-inflammatory proteins and growth factors of CS may exert a beneficial effect on the biological activity of human adipose-derived mesenchymal stem cells (hAdMSCs). In vitro studies were designed using hAdMSCs cocultured with CS at different concentrations (2.5, 5, and 10%). Chondrogenic differentiation assays and immunomodulatory experiments using in vitro-stimulated lymphocytes were performed. Our results demonstrated that CS significantly enhanced the differentiation of hAdMSCs toward chondrocytes. Moreover, hAdMSCs pre-sensitized with CS reduced the lymphocyte proliferation as well as their differentiation toward activated lymphocytes. These results suggest that in vivo coadministration of CS and hAdMSCs may have a beneficial effect on the therapeutic potential of hAdMSCs. Moreover, these results indicate that intra-articular administration of CS might influence the biological behavior of resident stem cells increasing their chondrogenic differentiation and inherent immunomodulatory activity. To our knowledge, this is the first in vitro study reporting this combination.

Priming approaches to improve the efficacy of mesenchymal stromal cell-based therapies

Multipotent mesenchymal stromal cells (MSC) have been widely explored for cell-based therapy of immune-mediated, inflammatory, and degenerative diseases, due to their immunosuppressive, immunomodulatory, and regenerative potentials. Preclinical studies and clinical trials have demonstrated promising therapeutic results although these have been somewhat limited. Aspects such as low in vivo MSC survival in inhospitable disease microenvironments, requirements for ex vivo cell overexpansion prior to infusions, intrinsic differences between MSC and different sources and donors, variability of culturing protocols, and potency assays to evaluate MSC products have been described as limitations in the field. In recent years, priming approaches to empower MSC have been investigated, thereby generating cellular products with improved potential for different clinical applications. Herein, we review the current priming approaches that aim to increase MSC therapeutic efficacy. Priming with cytokines and growth factors, hypoxia, pharmacological drugs, biomaterials, and different culture conditions, as well as other diverse molecules, are revised from current and future perspectives.

Serum from Asthmatic Mice Potentiates the Therapeutic Effects of Mesenchymal Stromal Cells in Experimental Allergic Asthma

Asthma is a chronic inflammatory disease characterized by airway inflammation and remodeling, which can lead to progressive decline of lung function. Although mesenchymal stromal cells (MSCs) have shown beneficial immunomodulatory properties in preclinical models of allergic asthma, effects on airway remodeling have been limited. Mounting evidence suggests that prior exposure of MSCs to specific inflammatory stimuli or environments can enhance their immunomodulatory properties. Therefore, we investigated whether stimulating MSCs with bronchoalveolar lavage fluid (BALF) or serum from asthmatic mice could potentiate their therapeutic properties in experimental asthma. In a house dust mite (HDM) extract asthma model in mice, unstimulated, asthmatic BALF‐stimulated, or asthmatic serum‐stimulated MSCs were administered intratracheally 24 hours after the final HDM challenge. Lung mechanics and histology; BALF protein, cellularity, and biomarker levels; and lymph‐node and bone marrow cellularity were assessed. Compared with unstimulated or BALF‐stimulated MSCs, serum‐stimulated MSCs further reduced BALF levels of interleukin (IL)‐4, IL‐13, and eotaxin, total and differential cellularity in BALF, bone marrow and lymph nodes, and collagen fiber content, while increasing BALF IL‐10 levels and improving lung function. Serum stimulation led to higher MSC apoptosis, expression of various mediators (transforming growth factor‐β, interferon‐γ, IL‐10, tumor necrosis factor‐α‐stimulated gene 6 protein, indoleamine 2,3‐dioxygenase‐1, and IL‐1 receptor antagonist), and polarization of macrophages to M2 phenotype. In conclusion, asthmatic serum may be a novel strategy to potentiate therapeutic effects of MSCs in experimental asthma, leading to further reductions in both inflammation and remodeling than can be achieved with unstimulated MSCs. stem cells translational medicine2019;8:301&312

Mesenchymal Stromal/Stem Cells in Regenerative Medicine and Tissue Engineering

As a result of over five decades of investigation, mesenchymal stromal/stem cells (MSCs) have emerged as a versatile and frequently utilized cell source in the fields of regenerative medicine and tissue engineering. In this review, we summarize the history of MSC research from the initial discovery of their multipotency to the more recent recognition of their perivascular identity in vivo and their extraordinary capacity for immunomodulation and angiogenic signaling. As well, we discuss long-standing questions regarding their developmental origins and their capacity for differentiation toward a range of cell lineages. We also highlight important considerations and potential risks involved with their isolation, ex vivo expansion, and clinical use. Overall, this review aims to serve as an overview of the breadth of research that has demonstrated the utility of MSCs in a wide range of clinical contexts and continues to unravel the mechanisms by which these cells exert their therapeutic effects.

Mesenchymal stromal cells from human umbilical cord prevent the development of lung fibrosis in immunocompetent mice

Lung fibrosis is a severe condition resulting from several interstial lung diseases (ILD) with different etiologies. Current therapy of ILD, especially those associated with connective tissue diseases, is rather limited and new anti-fibrotic strategies are needed. In this study, we investigated the anti-fibrotic activity in vivo of human mesenchymal stromal cells obtained from whole umbilical cord (hUC-MSC). Adult immunocompetent C57BL/6 mice (n. = 8 for each experimental condition) were injected intravenously with hUC-MSC (n. = 2.5 × 10⁵) twice, 24 hours and 7 days after endotracheal injection of bleomycin. Upon sacrifice at days 8, 14, 21, collagen content, inflammatory cytokine profile, and hUC-MSC presence in explanted lung tissue were analyzed. Systemic administration of a double dose of hUC-MSC significantly reduced bleomycin-induced lung injury (inflammation and fibrosis) in mice through a selective inhibition of the IL6-IL10-TGFβ axis involving lung M2 macrophages. Only few hUC-MSC were detected from explanted lungs, suggesting a “hit and run” mechanism of action of this cellular therapy. Our data indicate that hUC-MSC possess strong in vivo anti-fibrotic activity in a mouse model resembling an immunocompetent human subject affected by inflammatory ILD, providing proof of concept for ad-hoc clinical trials.

Eicosapentaenoic Acid Enhances the Effects of Mesenchymal Stromal Cell Therapy in Experimental Allergic Asthma

Asthma is characterized by chronic lung inflammation and airway hyperresponsiveness. Despite recent advances in the understanding of its pathophysiology, asthma remains a major public health problem and, at present, there are no effective interventions capable of reversing airway remodeling. Mesenchymal stromal cell (MSC)-based therapy mitigates lung inflammation in experimental allergic asthma; however, its ability to reduce airway remodeling is limited. We aimed to investigate whether pre-treatment with eicosapentaenoic acid (EPA) potentiates the therapeutic properties of MSCs in experimental allergic asthma. Seventy-two C57BL/6 mice were used. House dust mite (HDM) extract was intranasally administered to induce severe allergic asthma in mice. Unstimulated or EPA-stimulated MSCs were administered intratracheally 24 h after final HDM challenge. Lung mechanics, histology, protein levels of biomarkers, and cellularity in bronchoalveolar lavage fluid (BALF), thymus, lymph nodes, and bone marrow were analyzed. Furthermore, the effects of EPA on lipid body formation and secretion of resolvin-D₁ (RvD₁), prostaglandin E₂ (PGE₂), interleukin (IL)-10, and transforming growth factor (TGF)-β1 by MSCs were evaluated in vitro. EPA-stimulated MSCs, compared to unstimulated MSCs, yielded greater therapeutic effects by further reducing bronchoconstriction, alveolar collapse, total cell counts (in BALF, bone marrow, and lymph nodes), and collagen fiber content in airways, while increasing IL-10 levels in BALF and M2 macrophage counts in lungs. In conclusion, EPA potentiated MSC-based therapy in experimental allergic asthma, leading to increased secretion of pro-resolution and anti-inflammatory mediators (RvD₁, PGE₂, IL-10, and TGF-β), modulation of macrophages toward an anti-inflammatory phenotype, and reduction in the remodeling process. Taken together, these modifications may explain the greater improvement in lung mechanics obtained. This may be a promising novel strategy to potentiate MSCs effects.

Challenges in vascular tissue engineering for diabetic patients

Hyperglycemia and dyslipidemia coexist in diabetes and result in inflammation, degeneration, and impaired tissue remodeling, processes which are not conducive to the desired integration of tissue engineered products into the surrounding tissues. There are several challenges for vascular tissue engineering such as non-thrombogenicity, adequate burst pressure and compliance, suturability, appropriate remodeling responses, and vasoactivity, but, under diabetic conditions, an additional challenge needs to be considered: the aggressive oxidative environment generated by the high glucose and lipid concentrations that lead to the formation of advanced glycation end products (AGEs) in the vascular wall. Extracellular matrix-based scaffolds have adequate physical properties and are biocompatible, however, these scaffolds are altered in diabetes by the formation AGEs and impaired collagen degradation, consequently increasing vascular wall stiffness. In addition, vascular cells detect and respond to altered stimuli from the matrix by pathological remodeling of the vascular wall. Due to the immunomodulatory effects of mesenchymal stem cells (MSCs), they are frequently used in tissue engineering in order to protect the scaffolds from inflammation. MSCs together with antioxidant treatments of the scaffolds are expected to protect the vascular grafts from diabetes-induced alterations. In conclusion, as one of the most daunting environments that could damage the ECM and its interaction with cells is progressively built in diabetes, we recommend that cells and scaffolds used in vascular tissue engineering for diabetic patients are tested in diabetic animal models, in order to obtain valuable results regarding their resistance to diabetic adversities.

STATEMENT OF SIGNIFICANCE

Almost 25 million Americans have diabetes, characterized by high levels of blood sugar that binds to tissues and disturbs the function of cardiovascular structures. Therefore, patients with diabetes have a high risk of cardiovascular diseases. Surgery is required to replace diseased arteries with implants, but these fail after 5-10 years because they are made of non-living materials, not resistant to diabetes. New tissue engineering materials are developed, based on the patients' own stem cells, isolated from fat, and added to extracellular matrix-based scaffolds. Our main concern is that diabetes could damage the tissue-like implants. Thus we review studies related to the effect of diabetes on tissue components and recommend antioxidant treatments to increase the resistance of implants to diabetes.

Interleukin-25 enhances the capacity of mesenchymal stem cells to induce intestinal epithelial cell regeneration

BACKGROUND

This study aimed to investigate the influence of IL-25 on the capacity of mesenchymal stem cells (MSCs) to induce intestinal epithelial cell regeneration.

METHODS

The CD4⁺IL-25R⁺ cells and LGR5⁺IL-25R⁺ cells in colonic mucosa of Crohn's disease (CD) patients, ulcerative colitis (UC) patients and healthy controls were detected by immunofluorescence staining, and the CD4⁺IL-25R⁺ cells in peripheral blood were detected by flow cytometry. Rat MSCs were separated and stimulated with IL-25. Then, MSCs were further incubated in IL-25-free DMEM for 24 h, and this DMEM was collected as conditioned medium (CM). IEC-6 cells were divided into 3 groups: experimental group (CM and TNF-α), control group (DMEM and TNF-α) and negative control group (DMEM).

RESULTS

The CD4⁺IL-25R⁺ cells and LGR5⁺IL-25R⁺ cells significantly increased in the colonic mucosa of active CD patients and UC patients compared with IBD patients in remission and healthy controls. The CD4⁺IL-25R⁺ cells reduced in peripheral blood of IBD patients, which was inversely correlated with inflammatory markers (ESR and CRP). CM facilitated the migration and proliferation of IEC-6 cells in the presence of TNF-α. The protein expression of AKT, p38 and ERK increased in IEC-6 cells after treatment with CM and TNF-α.

CONCLUSION

IL-25R is involved in Th-related mucosal inflammation and proliferation of intestinal stem cells in IBD. IL-25 enhances the capacity of MSC to induce intestinal epithelial cell regeneration, and MSC therapy with IL-25 may be a new direction for IBD treatment.