Functional Neuronal Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells

Inflammatory diseases: Function of LncRNAs in their emergence and the role of mesenchymal stem cell secretome in their treatment

One of the best treatments for inflammatory diseases such as COVID-19, respiratory diseases and brain diseases is treatment with stem cells. Here we investigate the effect of stem cell therapy in the treatment of brain diseases.Preclinical studies have shown promising results, including improved functional recovery and tissue repair in animal models of neurodegenerative diseases, strokes,and traumatic brain injuries. However,ethical implications, safety concerns, and regulatory frameworks necessitate thorough evaluation before transitioning to clinical applications. Additionally, the complex nature of the brain and its intricate cellular environment present unique obstacles that must be overcome to ensure the successful integration and functionality of genetically engineered MSCs. The careful navigation of this path will determine whether the application of genetically engineered MSCs in brain tissue regeneration ultimately lives up to the hype surrounding it.

Immunomodulatory Mechanisms and Therapeutic Potential of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are regarded as highly promising cells for allogeneic cell therapy, owing to their multipotent nature and ability to display potent and varied functions in different diseases. The functions of MSCs, including native immunomodulation, high self-renewal characteristic, and secretory and trophic properties, can be employed to improve the immune-modulatory functions in diseases. MSCs impact most immune cells by directly contacting and/or secreting positive microenvironmental factors to influence them. Previous studies have reported that the immunomodulatory role of MSCs is basically dependent on their secretion ability from MSCs. This review discusses the immunomodulatory capabilities of MSCs and the promising strategies to successfully improve the potential utilization of MSCs in clinical research.

The Effects of Programmed Cell Death of Mesenchymal Stem Cells on the Development of Liver Fibrosis

Mesenchymal stem cells have shown noticeable potential for unlimited self-renewal. They can differentiate into specific somatic cells, integrate into target tissues via cell-cell contact, paracrine effects, exosomes, and other processes and then regulate the target cells and tissues. Studies have demonstrated that transplantation of MSCs could decrease the expression and concentration of collagen in the liver, thereby reducing liver fibrosis. A growing body of evidence indicates that apoptotic MSCs could inhibit harmful immune responses and reduce inflammatory responses more effectively than viable MSCs. Accumulating evidence suggests that mitochondrial transfer from MSCs is a novel strategy for the regeneration of various damaged cells via the rescue of their respiratory activities. This study is aimed at reviewing the functions of MSCs and the related roles of the programmed cell death of MSCs, including autophagy, apoptosis, pyroptosis, and ferroptosis, as well as the regulatory pathogenic mechanisms of MSCs in liver fibrosis. Research has demonstrated that the miR-200B-3p gene is differentially expressed gene between LF and normal liver samples, and that the miR-200B-3p gene expression is positively correlated with the degree of liver fibrosis, suggesting that MSCs could inhibit liver fibrosis through pyroptosis. It was confirmed that circulating monocytes could deliver MSC-derived immunomodulatory molecules to different sites by phagocytosis of apoptotic MSCs, thereby achieving systemic immunosuppression. Accordingly, it was suggested that characterization of the programmed cell death-mediated immunomodulatory signaling pathways in MSCs should be a focus of research.

Human Umbilical Cord-Derived Mesenchymal Stem Cells Alleviate Psoriasis Through TNF-α/NF-κB/MMP13 Pathway

Psoriasis is a chronic, immune-mediated disease that affects 2-3% of the global population. Recently, mesenchymal stem cells (MSCs) have been used to alleviate psoriasis. However, the therapeutic mechanisms of MSCs remain unclear. Matrix metalloproteinase-13 (MMP13), a member of the MMPs family, is the key enzyme in the cleavage of type II collagen and plays a pivotal role in extracellular matrix (ECM) remodeling. Here, it was found that Mmp13 was upregulated in the skin lesions of an imiquimod-induced mouse model, which was downregulated after intravenous infusion of human umbilical cord MSCs (hUC-MSCs). Knockdown of MMP13 inhibited the proliferation of keratinocytes and arrested the cell cycle in G1 stage. In addition, hUC-MSCs were co-cultured with THP-1 or PMA-stimulated THP-1 directly in vitro to simulate the fate of systematically infused hUC-MSCs. The level of TNF-α was decreased in the supernatant of co-cultured hUC-MSCs and THP-1 or PMA-stimulated THP-1. Moreover, it was identified that TNF-α upregulated MMP13 through the NF-κB pathway in keratinocytes. In conclusion, we propose that systematically infused hUC-MSCs exert a therapeutic effect on psoriasis through the TNF-α/NF-κB/MMP13 pathway.

Stem Cell Therapy in Treating Epilepsy

Epilepsy is a common disabling chronic neurological disorder characterized by an enduring propensity for the generation of seizures that result from abnormal hypersynchronous firing of neurons in the brain. Over 20–30% of epilepsy patients fail to achieve seizure control or soon become resistant to currently available therapies. Prolonged seizures or uncontrolled chronic seizures would give rise to neuronal damage or death, astrocyte activation, reactive oxygen species production, and mitochondrial dysfunction. Stem cell therapy is potentially a promising novel therapeutic strategy for epilepsy. The regenerative properties of stem cell-based treatment provide an attractive approach for long-term seizure control, particularly in drug-resistant epilepsy. Embryonic stem cells (ESCs), mesenchymal stem cells (MSCs), neural stem cells (NSCs), induced pluripotent stem cells (iPSCs), and adipose-derived regenerative cells (ADRCs) are capable of differentiating into specialized cell types has been applied for epilepsy treatment in preclinical animal research and clinical trials. In this review, we focused on the advances in stem cell therapy for epilepsies. The goals of stem cell transplantation, its mechanisms underlying graft effects, the types of grafts, and their therapeutic effects were discussed. The cell and animal models used for investigating stem cell technology in epilepsy treatment were summarized.

Mesenchymal Stromal Cell Therapy in Spinal Cord Injury: Mechanisms and Prospects

Spinal cord injury (SCI) often leads to severe motor, sensory, and autonomic dysfunction in patients and imposes a huge economic cost to individuals and society. Due to its complicated pathophysiological mechanism, there is not yet an optimal treatment available for SCI. Mesenchymal stromal cells (MSCs) are promising candidate transplant cells for use in SCI treatment. The multipotency of MSCs, as well as their rich trophic and immunomodulatory abilities through paracrine signaling, are expected to play an important role in neural repair. At the same time, the simplicity of MSCs isolation and culture and the bypassing of ethical barriers to stem cell transplantation make them more attractive. However, the MSCs concept has evolved in a specific research context to encompass different populations of cells with a variety of biological characteristics, and failure to understand this can undermine the quality of research in the field. Here, we review the development of the concept of MSCs in order to clarify misconceptions and discuss the controversy in MSCs neural differentiation. We also summarize a potential role of MSCs in SCI treatment, including their migration and trophic and immunomodulatory effects, and their ability to relieve neuropathic pain, and we also highlight directions for future research.

Treatment of Inherited Retinal Dystrophies with Somatic Cell Therapy Medicinal Product: A Review

Inherited retinal dystrophies and retinal degenerations related to more common diseases (i.e., age-related macular dystrophy) are a major issue and one of the main causes of low vision in pediatric and elderly age groups. Advancement and understanding in molecular biology and the possibilities raised by gene-editing techniques opened a new era for clinicians and patients due to feasible possibilities of treating disabling diseases and the reduction in their complications burden. The scope of this review is to focus on the state-of-the-art in somatic cell therapy medicinal products as the basis of new insights and possibilities to use this approach to treat rare eye diseases.

Therapeutic Potential of Mesenchymal Stem Cells (MSCs) and MSC-Derived Extracellular Vesicles for the Treatment of Spinal Cord Injury

Spinal cord injury (SCI) is a life-threatening condition that leads to permanent disability with partial or complete loss of motor, sensory, and autonomic functions. SCI is usually caused by initial mechanical insult, followed by a cascade of several neuroinflammation and structural changes. For ameliorating the neuroinflammatory cascades, MSC has been regarded as a therapeutic agent. The animal SCI research has demonstrated that MSC can be a valuable therapeutic agent with several growth factors and cytokines that may induce anti-inflammatory and regenerative effects. However, the therapeutic efficacy of MSCs in animal SCI models is inconsistent, and the optimal method of MSCs remains debatable. Moreover, there are several limitations to developing these therapeutic agents for humans. Therefore, identifying novel agents for regenerative medicine is necessary. Extracellular vesicles are a novel source for regenerative medicine; they possess nucleic acids, functional proteins, and bioactive lipids and perform various functions, including damaged tissue repair, immune response regulation, and reduction of inflammation. MSC-derived exosomes have advantages over MSCs, including small dimensions, low immunogenicity, and no need for additional procedures for culture expansion or delivery. Certain studies have demonstrated that MSC-derived extracellular vesicles (EVs), including exosomes, exhibit outstanding chondroprotective and anti-inflammatory effects. Therefore, we reviewed the principles and patho-mechanisms and summarized the research outcomes of MSCs and MSC-derived EVs for SCI, reported to date.

Potential Role of Growth Factors Controlled Release in Achieving Enhanced Neuronal Trans-differentiation from Mesenchymal Stem Cells for Neural Tissue Repair and Regeneration

With an increase in the incidence of neurodegenerative diseases, a need to replace incapable conventional methods has arisen. To overcome this burden, stem cells therapy has emerged as an efficient treatment option. Endeavours to accomplish this have paved the path to neural regeneration through efficient neuronal transdifferentiation. Despite their potential, the use of stem cells still entails several limitations, such as low differentiation efficiency and difficulties in guiding differentiation. The process of neural differentiation through the stem cells is achieved through the use of chemical inducers or growth factors and their direct introduction reduces their bioavailability in the system. To address these limitations, neural regeneration ventures require growth factors to be effectively implemented on stem cells in order to produce functional neuronal precursor cells. An efficient technique to achieve it is through the delivery of growth factors via microcarriers for their sustained release. It ensures the presence of commensurable concentration even at later stages of neuronal transdifferentiation. Nanofibers and nanoparticles, along with liposomes and such, have been used to implement this. The interaction between such carriers and the growth factors is mainly electrostatic. Such interaction enables them to form a stable assembly through immobilisation of the growth factor either onto their surfaces or within the core of their structures. The rate of sustained release depends upon the release kinetics associated with the polymeric structure employed and its interaction with the encapsulated growth factor. The sustained release ensures that the stem cells immerse under the effect of the growth factors for a prolonged period, ultimately aiding in the formation of cells showing ample characteristics of neuron precursors. This review analyses the various carriers that have been employed for the release of growth factors in an orderly fashion and their constituents, along with the advantages and the limitations they pose in delivering the growth factors for facilitating the process of neuronal transdifferentiation.

Mesenchymal Stem/Stromal Cells Derived from Human and Animal Perinatal Tissues-Origins, Characteristics, Signaling Pathways, and Clinical Trials

Mesenchymal stem/stromal cells (MSCs) are currently one of the most extensively researched fields due to their promising opportunity for use in regenerative medicine. There are many sources of MSCs, of which cells of perinatal origin appear to be an invaluable pool. Compared to embryonic stem cells, they are devoid of ethical conflicts because they are derived from tissues surrounding the fetus and can be safely recovered from medical waste after delivery. Additionally, perinatal MSCs exhibit better self-renewal and differentiation properties than those derived from adult tissues. It is important to consider the anatomy of perinatal tissues and the general description of MSCs, including their isolation, differentiation, and characterization of different types of perinatal MSCs from both animals and humans (placenta, umbilical cord, amniotic fluid). Ultimately, signaling pathways are essential to consider regarding the clinical applications of MSCs. It is important to consider the origin of these cells, referring to the anatomical structure of the organs of origin, when describing the general and specific characteristics of the different types of MSCs as well as the pathways involved in differentiation.

Inhibitory Effect of Bovine Adipose-Derived Mesenchymal Stem Cells on Lipopolysaccharide Induced Inflammation of Endometrial Epithelial Cells in Dairy Cows

Endometritis is a disease that affects reproductive health in dairy cows and causes serious economic damage to the dairy industry world-wide. Although in recent years, the application of mesenchymal stem cell (MSC) therapy for the treatment of inflammatory diseases has attracted much attention, there are few reports of the use of MSCs in dairy cows. In the present study, our objective was to explore the inhibitory effects of bovine adipose-derived mesenchymal stem cells (bAD-MSCs) on lipopolysaccharide (LPS) induced inflammation in bovine endometrial epithelial cells (bEECs) along with the potential underlying molecular mechanisms. We characterized isolated bAD-MSCs using cell surface marker staining and adipogenic/osteogenic differentiation, and analyzed them using immunofluorescence, flow cytometry (surface marker staining), and adipogenic and osteogenic differentiation. Furthermore, to understand the anti-inflammatory effects of bAD-MSCs on LPS induced bEEC inflammation, we used a bAD-MSC/bEEC co-culture system. The results showed that bAD-MSC treatments could significantly decrease LPS induced bEEC apoptosis and pro-inflammatory cytokine expression levels, such as interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α). Furthermore, our results showed that bAD-MSC treatments could also significantly downregulate LPS induced p38, IkB-a, and JAK1 phosphorylation and Bax protein expression levels, which are closely related to inflammatory progress and cellular apoptosis in bEECs. Our findings demonstrate that bAD-MSCs play an inhibitory role in LPS induced bEEC inflammation and provide new insights for the clinical therapy of endometritis in dairy cows.

Hydrothermally treated titanium surfaces for enhanced osteogenic differentiation of adipose derived stem cells

Implant surface plays a crucial role in improving osseointegration and long-term implant life. When the implant comes in contact with the bone tissue, the bone marrow mesenchymal cells interact with the implant surface and the surface properties such as morphology, wettability, mechanical properties and chemistry influences cell migration, proliferation and differentiation. Different surface modification strategies such as ceramic coatings, surface dealloying, and surface topography modifications for improving osteointegration have been investigated. However, studies have not yet established which of the surface property is more influential. In this study, titanium surfaces were treated hydrothermally with sodium hydroxide and sulfuric acid separately. This treatment led to the development of two unique surface topography at nanoscale. These modified surfaces were characterized for surface morphology, wettability, chemistry, and crystallinity. Cytotoxicity, cell adhesion, proliferation, morphology, and differentiation of adipose derived stem cells on modified surfaces was investigated. The results indicate that wettability does influence initial cell adhesion. However, the surface morphology can play major role in cell spreading, proliferation and differentiation. The results indicate that titanium surfaces treated hydrothermally with sodium hydroxide led to a nanoporous architecture that promoted appropriate cell interaction with the surface promoting osteoblastic lineage.

Direct differentiation of tonsillar biopsy-derived stem cells to the neuronal lineage

BACKGROUND

Neurological disorders are considered one of the greatest burdens to global public health and a leading cause of death. Stem cell therapies hold great promise for the cure of neurological disorders, as stem cells can serve as cell replacement, while also secreting factors to enhance endogenous tissue regeneration. Adult human multipotent stem cells (MSCs) reside on blood vessels, and therefore can be found in many tissues throughout the body, including palatine tonsils. Several studies have reported the capacity of MSCs to differentiate into, among other cell types, the neuronal lineage. However, unlike the case with embryonic stem cells, it is unclear whether MSCs can develop into mature neurons.

METHODS

Human tonsillar MSCs (T-MSCs) were isolated from a small, 0.6-g sample, of tonsillar biopsies with high viability and yield as we recently reported. Then, these cells were differentiated by a rapid, multi-stage procedure, into committed, post-mitotic, neuron-like cells using defined conditions.

RESULTS

Here we describe for the first time the derivation and differentiation of tonsillar biopsy-derived MSCs (T-MSCs), by a rapid, multi-step protocol, into post-mitotic, neuron-like cells using defined conditions without genetic manipulation. We characterized our T-MSC-derived neuronal cells and demonstrate their robust differentiation in vitro.

CONCLUSIONS

Our procedure leads to a rapid neuronal lineage commitment and loss of stemness markers, as early as three days following neurogenic differentiation. Our studies identify biopsy-derived T-MSCs as a potential source for generating neuron-like cells which may have potential use for in vitro modeling of neurodegenerative diseases or cell replacement therapies.

Mesenchymal Stem Cells in Treatment of Spinal Cord Injury and Amyotrophic Lateral Sclerosis

Preclinical and clinical studies with various stem cells, their secretomes, and extracellular vesicles (EVs) indicate their use as a promising strategy for the treatment of various diseases and tissue defects, including neurodegenerative diseases such as spinal cord injury (SCI) and amyotrophic lateral sclerosis (ALS). Autologous and allogenic mesenchymal stem cells (MSCs) are so far the best candidates for use in regenerative medicine. Here we review the effects of the implantation of MSCs (progenitors of mesodermal origin) in animal models of SCI and ALS and in clinical studies. MSCs possess multilineage differentiation potential and are easily expandable in vitro. These cells, obtained from bone marrow (BM), adipose tissue, Wharton jelly, or even other tissues, have immunomodulatory and paracrine potential, releasing a number of cytokines and factors which inhibit the proliferation of T cells, B cells, and natural killer cells and modify dendritic cell activity. They are hypoimmunogenic, migrate toward lesion sites, induce better regeneration, preserve perineuronal nets, and stimulate neural plasticity. There is a wide use of MSC systemic application or MSCs seeded on scaffolds and tissue bridges made from various synthetic and natural biomaterials, including human decellularized extracellular matrix (ECM) or nanofibers. The positive effects of MSC implantation have been recorded in animals with SCI lesions and ALS. Moreover, promising effects of autologous as well as allogenic MSCs for the treatment of SCI and ALS were demonstrated in recent clinical studies.

Compounded topographical and physicochemical cueing by micro-engineered chitosan substrates on rat dorsal root ganglion neurons and human mesenchymal stem cells

Given the intertwined physicochemical effects exerted in vivo by both natural and synthetic (e.g., biomaterial) interfaces on adhering cells, the evaluation of structure-function relationships governing cellular response to micro-engineered surfaces for applications in neuronal tissue engineering requires the use of in vitro testing platforms which consist of a clinically translatable material with tunable physiochemical properties. In this work, we micro-engineered chitosan substrates with arrays of parallel channels with variable width (20 and 60 μm). A citric acid (CA)-based crosslinking approach was used to provide an additional level of synergistic cueing on adhering cells by regulating the chitosan substrate's stiffness. Morphological and physicochemical characterization was conducted to unveil the structure-function relationships which govern the activity of rat dorsal root ganglion neurons (DRGs) and human mesenchymal stem cells (hMSCs), ultimately singling out the key role of microtopography, roughness and substrate's stiffness. While substrate's stiffness predominantly affected hMSC spreading, the modulation of the channels' design affected the neuronal architecture's complexity and guided the morphological transition of hMSCs. Finally, the combined analysis of tubulin expression and cell morphology allowed us to cast new light on the predominant role of the microtopography over substrate's stiffness in the process of hMSCs neurogenic differentiation.

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.

Cyclic Strain and Electrical Co-stimulation Improve Neural Differentiation of Marrow-Derived Mesenchymal Stem Cells

The current study investigated the combinatorial effect of cyclic strain and electrical stimulation on neural differentiation potential of rat bone marrow-derived mesenchymal stem cells (BMSCs) under epidermal growth factor (EGF) and fibroblast growth factor 2 (FGF2) inductions in vitro. We developed a prototype device which can provide cyclic strain and electrical signal synchronously. Using this system, we demonstrated that cyclic strain and electrical co-stimulation promote the differentiation of BMCSs into neural cells with more branches and longer neurites than strain or electrical stimulation alone. Strain and electrical co-stimulation can also induce a higher expression of neural markers in terms of transcription and protein level. Neurotrophic factors and the intracellular cyclic AMP (cAMP) are also upregulated with co-stimulation. Importantly, the co-stimulation further enhances the calcium influx of neural differentiated BMSCs when responding to acetylcholine and potassium chloride (KCl). Finally, the phosphorylation of extracellular-signal-regulated kinase (ERK) 1 and 2 and protein kinase B (AKT) was elevated under co-stimulation treatment. The present work suggests a synergistic effect of the combination of cyclic strain and electrical stimulation on BMSC neuronal differentiation and provides an alternative approach to physically manipulate stem cell differentiation into mature and functional neural cells in vitro.

Human Allogeneic Bone Marrow-Derived Mesenchymal Stem Cell Therapy for Cerebellar Ataxia: A Case Report

To date, there is no curable treatment option for non-hereditary degenerative cerebellar ataxia. Here we report the case of a patient with sporadic adult-onset ataxia (SAOA) who underwent allogeneic bone marrow-derived mesenchymal stem cell (MSC) therapy via the intrathecal route. A 60-year-old male patient visited our clinic complaining of progressive gait disturbance that commenced two years ago. Upon neurologic examination, the patient exhibited limb dysmetria and gait ataxia. Brain magnetic resonance imaging (MRI) revealed cerebellar atrophy whereas the autonomic function test was normal. The patient was diagnosed with SAOA. The medications that were initially prescribed had no significant effects on the course of this disease and the symptoms deteriorated progressively. At the age of 64, the patient was treated with allogeneic bone marrow-derived MSC therapy. The subsequent K-SARA (Korean version of the Scale for the Assessment and Rating of Ataxia) scores demonstrated a distinct improvement up until 10 months post-administration. No adverse events were reported. The improved post-treatment K-SARA scores may suggest that the MSC therapy can have a neuroprotective effect and that stem cell therapy may serve as a potential therapeutic option for degenerative cerebellar ataxia.

Mesenchymal Stem Cell-Based Therapy for Retinal Degenerative Diseases: Experimental Models and Clinical Trials

Retinal degenerative diseases, such as age-related macular degeneration, retinitis pigmentosa, diabetic retinopathy or glaucoma, represent the main causes of a decreased quality of vision or even blindness worldwide. However, despite considerable efforts, the treatment possibilities for these disorders remain very limited. A perspective is offered by cell therapy using mesenchymal stem cells (MSCs). These cells can be obtained from the bone marrow or adipose tissue of a particular patient, expanded in vitro and used as the autologous cells. MSCs possess potent immunoregulatory properties and can inhibit a harmful inflammatory reaction in the diseased retina. By the production of numerous growth and neurotrophic factors, they support the survival and growth of retinal cells. In addition, MSCs can protect retinal cells by antiapoptotic properties and could contribute to the regeneration of the diseased retina by their ability to differentiate into various cell types, including the cells of the retina. All of these properties indicate the potential of MSCs for the therapy of diseased retinas. This view is supported by the recent results of numerous experimental studies in different preclinical models. Here we provide an overview of the therapeutic properties of MSCs, and their use in experimental models of retinal diseases and in clinical trials.

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.

Human amniotic mesenchymal stem cells to promote/suppress cancer: two sides of the same coin

Cancer is a leading cause of death in both developed and developing countries, and because of population growth and aging, it is a growing medical burden worldwide. With robust development in medicine, the use of stem cells has opened new treatment modalities in cancer therapy. In adult stem cells, mesenchymal stem cells (MSCs) are showing rising promise in cancer treatment due to their unique properties. Among different sources of MSCs, human amniotic fluid/membrane is an attractive and suitable reservoir. There are conflicting opinions about the role of human amniotic membrane/fluid mesenchymal stem cells (hAMSCS/hAFMSCs) in cancer, as some studies demonstrating the anticancer effects of these cells and others suggesting their progressive effects on cancer. This review focuses on recent findings about the role of hAMSCs/hAFMSCs in cancer treatment and summarizes the suppressing as well as promoting effects of these cells on cancer progression and underling mechanisms.

Mesenchymal stem cells as a double-edged sword in tumor growth: focusing on MSC-derived cytokines

Mesenchymal stem cells (MSCs) show homing capacity towards tumor sites. Numerous reports indicate that they are involved in multiple tumor-promoting processes through several mechanisms, including immunosuppression; stimulation of angiogenesis; transition to cancer-associated fibroblasts; inhibition of cancer cell apoptosis; induction of epithelial-mesenchymal transition (EMT); and increase metastasis and chemoresistance. However, other studies have shown that MSCs suppress tumor growth by suppressing angiogenesis, incrementing inflammatory infiltration, apoptosis and cell cycle arrest, and inhibiting the AKT and Wnt signaling pathways. In this review, we discuss the supportive and suppressive impacts of MSCs on tumor progression and metastasis. We also discuss MSC-based therapeutic strategies for cancer based on their potential for homing to tumor sites.

The Anti-Inflammatory Properties of Mesenchymal Stem Cells in Epilepsy: Possible Treatments and Future Perspectives

Mesenchymal stem cells (MSCs) are multipotent adult cells with self-renewing capacities. MSCs display specific properties, such as the ability to repair damaged tissues, resulting in optimal candidates for cell therapy against degenerative diseases. In addition to the reparative functions of MSCs, growing evidence shows that these cells have potent immunomodulatory and anti-inflammatory properties. Therefore, MSCs are potential tools for treating inflammation-related neurological diseases, including epilepsy. In this regard, over the last decades, epilepsy has no longer been considered a purely neuronal pathology, since inflammatory events underlying the genesis of epilepsy have been demonstrated. This review assessed current knowledge on the use of MSCs in the treatment of epilepsy. Mostly, attention will be focused on the anti-inflammatory and immunological skills of MSCs. Understanding the mechanisms by which MSCs might modulate the severity of the disease will contribute to the development of new potential alternatives for both prophylaxis and treatment against epilepsy.

Therapeutic Advancement in Neuronal Transdifferentiation of Mesenchymal Stromal Cells for Neurological Disorders

Neurodegenerative disorders have become the leading cause of chronic pain and death. Treatments available are not sufficient to help the patients as they only alleviate the symptoms and not the cause. In this regard, stem cells therapy has emerged as an upcoming option for the replacement of dead and damaged neurons. Stem cells, in general, are characterized as cells exhibiting potency properties, i.e., on being subjected to specific conditions they transform into cells of another lineage. Of all the types, mesenchymal stem cells (MSCs) are known for their pluripotent nature without the obstacle of ethical concern surrounding the procurement of other cell types. Although fibroblasts are quite similar to MSCs morphologically, certain markers like CD73, CD 90 are specific to MSCs, making both the cell types distinguishable from each other. This is implemented while procuring MSCs from a plethora of sources like umbilical cord blood, adipose tissue, bone marrow, etc. Among these, bone marrow MSCs are the most widely used type for neural regeneration. Neural regeneration is achieved via transdifferentiation. Several studies have either transplanted the stem cells into rodent models or have carried out transdifferentiation in vitro. The process involves a combination of growth factors, pre-treatment factors, and neuronal differentiation inducing mediums. The results obtained are characterized by neuron-like morphology, expression of markers, along with electrophysical activity in some. Recent attempts involve exploring biomaterials that may mimic the native ECM and therefore can be directly introduced at the site of interest. The review gives a brief description of MSCs, their sources and markers, and the different attempts that have been made towards achieving the goal of differentiating MSCs into neurons.

Highly elastic, electroconductive, immunomodulatory graphene crosslinked collagen cryogel for spinal cord regeneration

Novel amino-functionalized graphene crosslinked collagen based nerve conduit having appropriate electric (3.8 ± 0.2 mSiemens/cm) and mechanical cues (having young modulus value of 100-347 kPa) for stem cell transplantation and neural tissue regeneration was fabricated using cryogelation. The developed conduit has shown sufficiently high porosity with interconnectivity between the pores. Raman spectroscopy analysis revealed the increase in orderliness and crosslinking of collagen molecules in the developed cryogel due to the incorporation of amino-functionalized graphene. BM-MSCs grown on graphene collagen cryogels have shown enhanced expression of CD90 and CD73 gene upon electric stimulation (100 mV/mm) contributing towards maintaining their stemness. Furthermore, an increased secretion of ATP from BM-MSCs grown on graphene collagen cryogel was also observed upon electric stimulation that may help in regeneration of neurons and immuno-modulation. Neuronal differentiation of BM-MSCs on graphene collagen cryogel in the presence of electric stimulus showed an enhanced expression of MAP-2 kinase and β-tubulin III. Immunohistochemistry studies have also demonstrated the improved neuronal differentiation of BM-MSCs. BM-MSCs grown on electro-conductive collagen cryogels under inflammatory microenvironment in vitro showed high indoleamine 2,3 dioxygenase activity. Moreover, macrophages cells grown on graphene collagen cryogels have shown high CD206 (M2 polarization marker) and CD163 (M2 polarization marker) and low CD86 (M1 polarization marker) gene expression demonstrating M2 polarization of macrophages, which may aid in tissue repair. In an organotypic culture, the developed cryogel conduit has supported cellular growth and migration from adult rat spinal cord. Thus, this novel electro-conductive graphene collagen cryogels have potential for suppressing the neuro-inflammation and promoting the neuronal cellular migration and proliferation, which is a major barrier during the spinal cord regeneration.

The Immunomodulatory Potential of Mesenchymal Stem Cells in a Retinal Inflammatory Environment

Retinal degenerative disorders are characterized by a local upregulation of inflammatory factors, infiltration with cells of the immune system, a vascular dysfunction and by the damage of retinal cells. There is still a lack of treatment protocols for these diseases. Mesenchymal stem cell (MSC)-based therapy using immunoregulatory, regenerative and differentiating properties of MSCs offers a promising treatment option. In this study, we analyzed the immunomodulatory properties of mouse bone marrow-derived MSCs after their intravitreal delivery to the inflammatory environment in the eye, caused by the application of pro-inflammatory cytokines IL-1β, TNF-α and IFN-γ. The intravitreal administration of these cytokines induces an increased expression of pro-inflammatory molecules such as IL-1α, IL-6, inducible nitric oxide synthase, TNF-α and vascular endothelial growth factor in the retina. However, a significant decrease in the expression of genes for all these pro-inflammatory molecules was observed after the intravitreal injection of MSCs. We further showed that an increased infiltration of the retina with immune cells, mainly with macrophages, which was observed after pro-inflammatory cytokine application, was significantly reduced after the intravitreal application of MSCs. The similar immunosuppressive effects of MSCs were also demonstrated in vitro in cultures of cytokine-stimulated retinal explants and MSCs. Overall, the results show that intravitreal application of MSCs inhibits the early retinal inflammation caused by pro-inflammatory cytokines, and propose MSCs as a promising candidate for stem cell-based therapy of retinal degenerative diseases.

Enhancing the Therapeutic Potential of Mesenchymal Stem Cells with the CRISPR-Cas System

Mesenchymal stem cells (MSCs), also known as multipotent mesenchymal stromal stem cells, are found in the perivascular space of several tissues. These cells have been subject of intense research in the last decade due to their low teratogenicity, as well as their ability to differentiate into mature cells and to secrete immunomodulatory and trophic factors. However, they usually promote only a modest benefit when transplanted in experimental disease models, one of the limitations for their clinical application. The CRISPR-Cas system, in turn, is highlighted as a simple and effective tool for genetic engineering. This system was tested in clinical trials over a relatively short period of time after establishing its applicability to the edition of the mammalian cell genome. Similar to the research evolution in MSCs, the CRISPR-Cas system demonstrated inconsistencies that limited its clinical application. In this review, we outline the evolution of MSC research and its applicability, and the progress of the CRISPR-Cas system from its discovery to the most recent clinical trials. We also propose perspectives on how the CRISPR-Cas system may improve the therapeutic potential of MSCs, making it more beneficial and long lasting.

Molecular Mechanisms Involved in Neural Substructure Development during Phosphodiesterase Inhibitor Treatment of Mesenchymal Stem Cells

Stem cells are highly important in biology due to their unique innate ability to self-renew and differentiate into other specialised cells. In a neurological context, treating major injuries such as traumatic brain injury, spinal cord injury and stroke is a strong basis for research in this area. Mesenchymal stem cells (MSC) are a strong candidate because of their accessibility, compatibility if autologous, high yield and multipotency with a potential to generate neural cells. With the use of small-molecule chemicals, the neural induction of stem cells may occur within minutes or hours. Isobutylmethyl xanthine (IBMX) has been widely used in cocktails to induce neural differentiation. However, the key molecular mechanisms it instigates in the process are largely unknown. In this study we showed that IBMX-treated mesenchymal stem cells induced differentiation within 24 h with the unique expression of several key proteins such as Adapter protein crk, hypoxanthine-guanine phosphoribosyltransferase, DNA topoisomerase 2-beta and Cell division protein kinase 5 (CDK5), vital in linking signalling pathways. Furthermore, the increased expression of basic fibroblast growth factor in treated cells promotes phosphatidylinositol 3-kinase (PI3K), mitogen-activated protein kinase (MAPK) cascades and GTPase–Hras interactions. Bioinformatic and pathway analyses revealed upregulation in expression and an increase in the number of proteins with biological ontologies related to neural development and substructure formation. These findings enhance the understanding of the utility of IBMX in MSC neural differentiation and its involvement in neurite substructure development.

Adult mesenchymal stem cells: is there a role for purine receptors in their osteogenic differentiation?

The role played by mesenchymal stem cells (MSCs) in contributing to adult tissue homeostasis and damage repair thanks to their differentiation capabilities has raised a great interest, mainly in bone regenerative medicine. The growth/function of these undifferentiated cells of mesodermal origin, located in specialized structures (niches) of differentiated organs is influenced by substances present in this microenvironment. Among them, ancestral and ubiquitous molecules such as adenine-based purines, i.e., ATP and adenosine, may be included. Notably, extracellular purine concentrations greatly increase during tissue injury; thus, MSCs are exposed to effects mediated by these agents interacting with their own receptors when they act/migrate in vivo or are transplanted into a damaged tissue. Here, we reported that ATP modulates MSC osteogenic differentiation via different P2Y and P2X receptors, but data are often inconclusive/contradictory so that the ATP receptor importance for MSC physiology/differentiation into osteoblasts is yet undetermined. An exception is represented by P2X7 receptors, whose expression was shown at various differentiation stages of bone cells resulting essential for differentiation/survival of both osteoclasts and osteoblasts. As well, adenosine, usually derived from extracellular ATP metabolism, can promote osteogenesis, likely via A2B receptors, even though findings from human MSCs should be implemented and confirmed in preclinical models. Therefore, although many data have revealed possible effects caused by extracellular purines in bone healing/remodeling, further studies, hopefully performed in in vivo models, are necessary to identify defined roles for these compounds in favoring/increasing the pro-osteogenic properties of MSCs and thereby their usefulness in bone regenerative medicine.

Placenta mesenchymal stem cells differentiation toward neuronal-like cells on nanofibrous scaffold

Introduction: Transplantation of stem cells with a nanofibrous scaffold is a promising approach for spinal cord injury therapy. The aim of this work was to differentiate neural-like cells from placenta-derived mesenchymal stem cells (PDMSCs) using suitable induction reagents in three (3D) and two dimensional (2D) culture systems. Methods: After isolation and characterization of PDMSCs, the cells were cultivated on poly-L-lactide acid (PLLA)/poly caprolactone (PCL) nanofibrous scaffold and treated with a neuronal medium for 7 days. Electron microscopy, qPCR, and immunostaining were used to examine the differentiation of PDMSCs (on scaffold and tissue culture polystyrene [TCPS]) and the expression rate of neuronal markers (beta-tubulin, nestin, GFAP, and MAP-2). Results: qPCR analysis showed that beta-tubulin (1.672 fold; P ≤ 0.0001), nestin (11.145 fold; P ≤ 0.0001), and GFAP (80.171; P ≤ 0.0001) gene expressions were higher on scaffolds compared with TCPS. Immunofluorescence analysis showed that nestin and beta-tubulin proteins were recognized in the PDMSCs differentiated on TCPS and scaffold after 7 days in the neuroinductive differentiation medium. Conclusion: Taken together, these results delegated that PDMSCs differentiated on PLLA/PCL scaffolds are more likely to differentiate towards diversity lineages of neural cells. It proposed that PDMSCs have cell subpopulations that have the capability to be differentiated into neurogenic cells.

An Overview on Stem Cells in Tissue Regeneration

BACKGROUND

Deteriorations in tissues and decline in organ functions, due to chronic diseases or with advancing age or sometimes due to infections or injuries, can severely compromise the quality of life of an individual. Regenerative medicine, a field of medical research focuses on replacing non-functional or dead cells or repairing or regenerating tissues and organs to restore normal functions of an impaired organ. Approaches used in regenerative therapy for achieving the objective employ a number of means which include soluble biomolecules, stem cell transplants, tissue engineering, gene therapy and reprogramming of cells according to target tissue types. Stem cells transplant and tissue regeneration methods for treating various diseases have rapidly grown in usage over the past decades or so. There are different types of stem cells such as mesenchymal, hematopoietic, embryonic, mammary, intestinal, endothelial, neural, olfactory, neural crest, testicular and induced pluripotent stem cells.

METHODS

This review covers the recent advances in tissue regeneration and highlights the application of stem cell transplants in treating many life-threatening diseases or in improving quality of life.

RESULTS

Remarkable progress in stem cell research has established that the cell-based therapy could be an option for treating diseases which could not be cured by conventional medical means till recent. Stem cells play major roles in regenerative medicine with its exceptional characteristics of self-renewal capacity and potential to differentiate into almost all types of cells of a body.

CONCLUSION

Vast number of reports on preclinical and clinical application of stem cells revealed its vital role in disease management and many pharmacological industries around the globe working to achieve effective stem cell based products.

Neurogenesis-on-Chip: Electric field modulated transdifferentiation of human mesenchymal stem cell and mouse muscle precursor cell coculture

A number of bioengineering strategies, using biophysical stimulation, are being explored to guide the human mesenchymal stem cells (hMScs) into different lineages. In this context, we have limited understanding on the transdifferentiation of matured cells to another functional-cell type, when grown with stem cells, in a constrained cellular microenvironment under biophysical stimulation. While addressing such aspects, the present work reports the influence of the electric field (EF) stimulation on the phenotypic and functionality modulation of the coculture of murine myoblasts (C2C12) with hMScs [hMSc:C2C12=1:10] in a custom designed polymethylmethacrylate (PMMA) based microfluidic device with in-built metal electrodes. The quantitative and qualitative analysis of the immunofluorescence study confirms that the cocultured cells in the conditioned medium with astrocytic feed, exhibit differentiation towards neural-committed cells under biophysical stimulation in the range of the endogenous physiological electric field strength (8 ± 0.06  mV/mm). The control experiments using similar culture protocols revealed that while C2C12 monoculture exhibited myotube-like fused structures, the hMScs exhibited the neurosphere-like clusters with SOX2, nestin, βIII-tubulin expression. The electrophysiological study indicates the significant role of intercellular calcium signalling among the differentiated cells towards transdifferentiation. Furthermore, the depolarization induced calcium influx strongly supports neural-like behaviour for the electric field stimulated cells in coculture. The intriguing results are explained in terms of the paracrine signalling among the transdifferentiated cells in the electric field stimulated cellular microenvironment. In summary, the present study establishes the potential for neurogenesis on-chip for the coculture of hMSc and C2C12 cells under tailored electric field stimulation, in vitro.

Assessment of potential neuropathic changes in cattle after cautery disbudding

Disbudding of calves is a standard husbandry procedure to reduce the risk of injuries to other cattle and to workers. Whereas acute pain resulting from disbudding has been studied extensively, little is known about chronic pain as a potential long-term consequence. The goal of the present study was to investigate possible morphological changes in the cornual nerve as a function of disbudding. Samples were collected from 17 randomly selected bulls and from 21 calves from a prospective clinical study. Among the calves, 13 were disbudded and 8 were sham-disbudded. Out of the disbudded calves, 4 showed signs of chronic pain. In all the animals, the infraorbital nerve was used as a methodological check. Morphological analysis included measuring minimal diameters of the axons present in both the cornual and infraorbital nerves. Sympathetic fibers were identified as based on the presence of Tyroxine hydroxylase (TH). TH-negative fibers were considered afferents. Trigeminal ganglia from the calves were immunostained for glial fibrillary acidic protein (GFAP) and Activating transcription factor 3 (ATF3). R. cornualis and N. infraorbitalis differed in terms of axon diameters and proportion of TH-positive fibers. Weak evidence (p > .091) of a difference in axon diameters between control and disbudded calves was found in R. cornualis, but the proportion of TH-positive fibers was alike in both groups. Average glial envelope and the percentages of ATF3-positive neurons revealed no difference between calves with and without signs of pain. Thus, available evidence is insufficient to support neuropathic changes as a result of disbudding in calves.

There Is No "Stem Cell Mess"

IMPACT STATEMENT

The impact should encourage continued research and clinical trials using mesenchymal stem cells.

Advanced nanotherapies to promote neuroregeneration in the injured newborn brain

Neonatal brain injury affects thousands of babies each year and may lead to long-term and permanent physical and neurological problems. Currently, therapeutic hypothermia is standard clinical care for term newborns with moderate to severe neonatal encephalopathy. Nevertheless, it is not completely protective, and additional strategies to restore and promote regeneration are urgently needed. One way to ensure recovery following injury to the immature brain is to augment endogenous regenerative pathways. However, novel strategies such as stem cell therapy, gene therapies and nanotechnology have not been adequately explored in this unique age group. In this perspective review, we describe current efforts that promote neuroprotection and potential targets that are unique to the developing brain, which can be leveraged to facilitate neuroregeneration.

Mesenchymal stem cells: Cell therapy and regeneration potential

Rapid advances in the isolation of multipotent progenitor cells, routinely called mesenchymal stromal/stem cells (MSCs), from various human tissues and organs have provided impetus to the field of cell therapy and regenerative medicine. The most widely studied sources of MSCs include bone marrow, adipose, muscle, peripheral blood, umbilical cord, placenta, fetal tissue, and amniotic fluid. According to the standard definition of MSCs, these clonal cells adhere to plastic, express cluster of differentiation (CD) markers such as CD73, CD90, and CD105 markers, and can differentiate into adipogenic, chondrogenic, and osteogenic lineages in vitro. However, isolated MSCs have been reported to vary in their potency and self-renewal potential. As a result, the MSCs used for clinical applications often lead to variable or even conflicting results. The lack of uniform characterization methods both in vitro and in vivo also contributes to this confusion. Therefore, the name "MSCs" itself has been increasingly questioned lately. As the use of MSCs is expanding rapidly, there is an increasing need to understand the potential sources and specific potencies of MSCs. This review discusses and compares the characteristics of MSCs and suggests that the variations in their distinctive features are dependent on the source and method of isolation as well as epigenetic changes during maintenance and growth. We also discuss the potential opportunities and challenges of MSC research with the hope to stimulate their use for therapeutic and regenerative medicine.

Generation of functional dopaminergic neurons from human spermatogonial stem cells to rescue parkinsonian phenotypes

Background

Recent progress in the induced generation of dopaminergic (DA) neurons from different types of stem cells or reprogrammed somatic cells holds tremendous potential for the treatment of Parkinson’s disease (PD). However, the lack of a reliable source for cell replacement therapy remains a major limitation in the treatment of human neurological disorders. Additionally, the current protocols for in vitro differentiation or cell reprogramming to generate human DA neurons are laborious, time-consuming, and expensive, and efficient conversion of human spermatogonial stem cells (hSSCs) to functional DA neurons has not yet been achieved.

Methods

Primary hSSCs from testicular tissues of patients were exposed to an improved induction system, which consisted mainly of olfactory ensheathing cell conditioned culture medium (OECCM) and a set of defined cell-extrinsic factors and small molecules. Morphological changes were assessed, along with the expression of various DA neuron phenotypic markers (e.g., Tuj-1, TH, Nurr1, DAT) and several critical pro-DA neurogenesis effectors (e.g., EN-1, Pitx3, Foxa2, Lmx1a, Lmx1b, and OTX2). In addition, transcriptome analysis was used to further evaluate the genetic similarity between the artificially differentiated DA neurons and genuine ones. Concomitantly, the functional properties of converted DA neurons including synapse formation, dopamine release, electrophysiological activity, and neuron-specific Ca²⁺ signaling images were determined. Finally, hSSCs in the early stage of induction were evaluated for survival, differentiation, migration, tumorigenicity in the mouse striatum, and improvement of functional deficits in MPTP-induced PD animals.

Results

The hSSC-derived neurons not only acquired neuronal morphological features but also expressed various phenotypic genes and protein characteristic of DA neurons and several effectors critical for pro-DA neurogenesis. Strikingly, as the period of induction was prolonged, expression of the critical molecules for DA neuron epigenetic status gradually increased while hSSC-specific markers sharply decreased. After 3 weeks of induction, the transdifferentiation efficiency reached 21%. In addition, hierarchical clustering analysis showed that the differentiated DA neurons closely resembled genuine ones. Furthermore, the hSSC-derived neurons gained sophisticated functional properties of wild-type DA neurons, and pro-induced hSSCs efficiently survived, migrated, and differentiated into DA neurons without tumorigenesis after transplantation into mouse striatum, leading to improvement of functional deficits in PD animals.

Conclusions

The results showed that, using the present improved straightforward approach, hSSCs could acquire DA neuron morphological features and functional properties and rescue parkinsonian phenotypes. Our strategy for the conversion of hSSCs into DA neurons is very efficient and thus may provide an alternative approach suitable for clinical cell therapy to treat neurodegenerative diseases including PD.

The multifaceted role of mesenchymal stem cells in cancer

Mesenchymal stem cells (MSCs) are multipotent stem cells derived from the mesoderm that give rise to several mesenchymal lineages, including osteoblasts, adipocytes, chondrocytes and myocytes. Their potent ability to home to tumors coupled with their differentiation potential and immunosuppressive function positions MSCs as key regulators of tumor fate. Here we review the existing knowledge on the involvement of MSCs in multiple tumor-promoting processes, including angiogenesis, epithelial-mesenchymal transition, metastasis, immunosuppression and therapy resistance. We also discuss the clinical potential of MSC-based therapy for cancer.

Sonic Hedgehog Effectively Improves Oct4-Mediated Reprogramming of Astrocytes into Neural Stem Cells

Irreversible neuron loss following spinal cord injury (SCI) usually results in persistent neurological dysfunction. The generation of autologous neural stem cells (NSCs) holds great potential for neural replenishment therapies and drug screening in SCI. Our recent studies demonstrated that mature astrocytes from the spinal cord can directly revert back to a pluripotent state under appropriate signals. However, in previous attempts, the reprogramming of astrocytes into induced NSCs (iNSCs) was unstable, inefficient, and frequently accompanied by generation of intermediate precursors. It remained unknown how to further increase the efficiency of astrocyte reprogramming into iNSCs. Here, we show that mature astrocytes could be directly converted into iNSCs by a single transcription factor, Oct4, and that the iNSCs displayed typical neurosphere morphology, authentic NSC gene expression, self-renewal capacity, and multipotency. Strikingly, Oct4-driven reprogramming of astrocytes into iNSCs was potentiated with continuous sonic hedgehog (Shh) stimulation, as demonstrated by a sped-up reprogramming and increased conversion efficiency. Moreover, the iNSC-derived neurons possessed functionality as neurons. Importantly, crosstalk between Sox2/Shh-targeted downstream signals and phosphatidylinositol 3-kinase/cyclin-dependent kinase 2/Smad ubiquitin regulatory factor 2 (PI3K/Cdk2/Smurf2) signaling is likely involved in the mechanisms underlying this cellular event. The highly efficient reprogramming of astrocytes to generate iNSCs will provide an alternative therapeutic approach for SCI using autologous cells.

Differentiation of Bone Marrow Mesenchymal Stem Cells into Neural Lineage Cells Induced by bFGF-Chitosan Controlled Release System

Bone marrow mesenchymal stem cells undergo differentiation to different lineages with different efficiencies when induced by different factors. We added a bFGF-chitosan controlled release system (bFGF-CCRS) as an inducer into conditioned medium to facilitate the oriented differentiation of BMSCs into neural lineage cells (eventually mature neurons); furthermore, we synchronized BMSCs to the G0/G1 phase via serum starvation to observe the effect of the inducer on the differentiation direction and efficiency. The nonsynchronized group, chitosan alone (not loaded with bFGF) group, soluble bFGF group, and conditioned medium group served as controls, and we observed the dynamic process of differentiation of BMSCs into neural lineage cells at different time points after the beginning of coculture. We analyzed the binding patterns of bFGF and chitosan and assayed the expression differences of key factors (FGFR1, ERK, and c-fos) and molecular switches (BTG2) that regulate the transformation from cell proliferation to differentiation. We also investigated the potential molecular mechanism of BMSC differentiation into neural lineage cells at a high percentage when induced by bFGF-CCRS.

Forskolin and IBMX Induce Neural Transdifferentiation of MSCs Through Downregulation of the NRSF

Neural differentiation of mesenchymal stem cells is a controversial phenomenon, as it would require transdifferentiation across the mesoderm-ectoderm barrier. However, several laboratories have observed that MSCs are able to be induced to express neural characteristics. Previously, we demonstrated that the cAMP-elevating agents, forskolin and IBMX, induced neural-like differentiation of MSCs, including expression of neural markers and increased sensitivity to neurotransmitters. However, due to the broad range of effects that forskolin and IBMX can elicit through the intracellular second messenger, cAMP, a better mechanistic understanding is required. Here, we show that neural induction by forskolin and IBMX is dependent on downregulation of expression of the master transcriptional regulator, neuron restrictive silencer factor (NRSF), and its downstream target genes. Since silencing of NRSF is known to initiate neural differentiation, it suggests that forskolin and IBMX result in transdifferentiation of MSCs into a neural lineage.

Bioactive Nanofibers Induce Neural Transdifferentiation of Human Bone Marrow Mesenchymal Stem Cells

The combination of biomaterials with stem cells is a promising therapeutic strategy to repair traumatic injuries in the central nervous system, and human bone marrow mesenchymal stem cells (BMSCs) offer a clinically translatable option among other possible sources of stem cells. We report here on the use of a supramolecular bioactive material based on a peptide amphiphile (PA), displaying a laminin-mimetic IKVAV sequence to drive neural transdifferentiation of human BMSCs. The IKVAV-PA self-assembles into supramolecular nanofibers that induce neuroectodermal lineage commitment after 1 week, as evidenced by the upregulation of the neural progenitor gene nestin ( NES) and glial fibrillary acidic protein ( GFAP). After 2 weeks, the bioactive IKVAV-PA nanofibers induce significantly higher expression of neuronal markers β-III tubulin (TUJ-1), microtubule-associated protein-2 (MAP-2), and neuronal nuclei (NEUN), as well as the extracellular matrix laminin (LMN). Furthermore, the human BMSCs exposed to the biomaterial reveal a polarized cytoskeletal architecture and a decrease in cellular size, resembling neuron-like cells. We conclude that the investigated supramolecular biomaterial opens the opportunity to transdifferentiate adult human BMSCs into neuronal lineage.

Preconditioning of bone marrow-derived mesenchymal stem cells highly strengthens their potential to promote IL-6-dependent M2b polarization

Background

During the last decade, mesenchymal stem cells (MSCs) have gained much attention in the field of regenerative medicine due to their capacity to differentiate into different cell types and to promote immunosuppressive effects. However, the underlying mechanism of MSC-mediated immunoregulation is not fully understood so far. Macrophages are distinguished in classical activated, pro-inflammatory M1 and alternatively activated M2 cells, which possess different functions and transcriptional profiles with respect to inflammatory responses. As polarization is not fixed, macrophage functional plasticity might be modulated by the microenvironment allowing them to rapidly react to danger signals and maintaining tissue homeostasis.

Methods

Murine MSCs were preconditioned with IL-1ß and IFN-ɣ to enhance their immunosuppressive capacity regarding macrophage polarization under M1- and M2a-polarizing conditions. Macrophage polarization was analyzed by real-time PCR, flow cytometry, and cytokine detection in culture supernatants. The role of MSC-derived nitric oxide (NO), prostaglandin E2 (PGE2), and IL-6 in this process has been evaluated using siRNA transfection and IL-6 receptor-deficient macrophages, respectively.

Results

Preconditioned, but not unprimed, MSCs secreted high levels of NO, IL-6, and PGE2. Co-culture with macrophages (M0) in the presence of M1 inducers (LPS + IFN-ɣ) led to significant reduction of CD86 and iNOS protein in macrophages and diminished TNF-α secretion. Additionally, CD86 and iNOS protein expression as well as NO and IL-10 secretion were markedly increased under M2a-polarizing culture conditions (IL-4). MSC-dependent macrophage polarization did not depend on direct cell-cell contact. Co-culturing in the presence of LPS and IFN-ɣ resulted in the upregulation of M2a, M2b, and M2c marker genes, whereas in the presence of IL-4 only M2b markers were significantly increased. In turn, IL-10-producing regulatory M2b cells significantly inhibited IFN-ɣ expression in CD4⁺ T lymphocytes. Finally, we show that MSC-mediated macrophage polarization strongly depends on IL-6, whereas a minor role for NO and PGE2 was found.

Conclusions

Preconditioning of MSCs highly strengthens their capacity to regulate macrophage features and to promote immunosuppression. Repression of M1 polarization during inflammation and M2b polarization under anti-inflammatory conditions strongly depend on functional IL-6 signaling in macrophages. The potential benefit of preconditioned MSCs and IL-6 should be considered for future clinical treatment.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-1039-2) contains supplementary material, which is available to authorized users.

Critical Role of Tumor Necrosis Factor Signaling in Mesenchymal Stem Cell-Based Therapy for Autoimmune and Inflammatory Diseases

Mesenchymal stem cells (MSCs) have been broadly used as a therapy for autoimmune disease in both animal models and clinical trials. MSCs inhibit T effector cells and many other immune cells, while activating regulatory T cells, thus reducing the production of pro-inflammatory cytokines, including tumor necrosis factor (TNF), and repressing inflammation. TNF can modify the MSC effects via two TNF receptors, i.e., TNFR1 in general mediates pro-inflammatory effects and TNFR2 mediates anti-inflammatory effects. In the central nervous system, TNF signaling plays a dual role, which enhances inflammation via TNFR1 on immune cells while providing cytoprotection via TNFR2 on neural cells. In addition, the soluble form of TNFR1 and membrane-bound TNF also participate in the regulation to fine-tune the functions of target cells. Other factors that impact TNF signaling and MSC functions include the gender of the host, disease course, cytokine concentrations, and the length of treatment time. This review will introduce the fascinating progress in this aspect of research and discuss remaining questions and future perspectives.

Neural Stem Cells Derived Directly from Adipose Tissue

Neural stem cells (NSCs) are characterized as self-renewing cell populations with the ability to differentiate into the multiple tissue types of the central nervous system. These cells can differentiate into mature neurons, astrocytes, and oligodendrocytes. This category of stem cells has been shown to be a promisingly effective treatment for neurodegenerative diseases and neuronal injury. Most treatment studies with NSCs in animal models use embryonic brain-derived NSCs. This approach presents both ethical and feasibility issues for translation to human patients. Adult tissue is a more practical source of stem cells for transplantation therapies in humans. Some adult tissues such as adipose tissue and bone marrow contain a wide variety of stem cell populations, some of which have been shown to be similar to embryonic stem cells, possessing many pluripotent properties. Of these stem cell populations, some are able to respond to neuronal growth factors and can be expanded in vitro, forming neurospheres analogous to cells harvested from embryonic brain tissue. In this study, we describe a method for the collection and culture of cells from adipose tissue that directly, without going through intermediates such as mesenchymal stem cells, results in a population of NSCs that are able to be expanded in vitro and be differentiated into functional neuronal cells. These adipose-derived NSCs display a similar phenotype to those directly derived from embryonic brain. When differentiated into neurons, cells derived from adipose tissue have spontaneous spiking activity with network characteristics similar to that of neuronal cultures.

Genetically‑modified stem cells in treatment of human diseases: Tissue kallikrein (KLK1)‑based targeted therapy (Review)

The tissue kallikrein-kinin system (KKS) is an endogenous multiprotein metabolic cascade which is implicated in the homeostasis of the cardiovascular, renal and central nervous system. Human tissue kallikrein (KLK1) is a serine protease, component of the KKS that has been demonstrated to exert pleiotropic beneficial effects in protection from tissue injury through its anti-inflammatory, anti-apoptotic, anti-fibrotic and anti-oxidative actions. Mesenchymal stem cells (MSCs) or endothelial progenitor cells (EPCs) constitute populations of well-characterized, readily obtainable multipotent cells with special immunomodulatory, migratory and paracrine properties rendering them appealing potential therapeutics in experimental animal models of various diseases. Genetic modification enhances their inherent properties. MSCs or EPCs are competent cellular vehicles for drug and/or gene delivery in the targeted treatment of diseases. KLK1 gene delivery using adenoviral vectors or KLK1 protein infusion into injured tissues of animal models has provided particularly encouraging results in attenuating or reversing myocardial, renal and cerebrovascular ischemic phenotype and tissue damage, thus paving the way for the administration of genetically modified MSCs or EPCs with the human tissue KLK1 gene. Engraftment of KLK1-modified MSCs and/or KLK1-modified EPCs resulted in advanced beneficial outcome regarding heart and kidney protection and recovery from ischemic insults. Collectively, findings from pre-clinical studies raise the possibility that tissue KLK1 may be a novel future therapeutic target in the treatment of a wide range of cardiovascular, cerebrovascular and renal disorders.

Preparation of NGF encapsulated chitosan nanoparticles and its evaluation on neuronal differentiation potentiality of canine mesenchymal stem cells

Sustained and controlled release of neurotrophic factors in target tissue through nanomaterial based delivery system could be a better strategy for nerve tissue regeneration. The present study aims to prepare the nerve growth factor (NGF) encapsulated chitosan nanoparticles (NGF-CNPs) and its evaluation on neuronal differentiation potentiality of canine bone marrow derived mesenchymal stem cells (cBM-MSCs). The NGF-CNPs were prepared by ionotropic gelation method with tripolyphosphate (TPP) as an ionic cross-linking agent. Observations on physiochemical properties displayed the size of nanoparticles as 80-90 nm with positive zeta potential as well as an ionic interaction between NGF and nanoparticle. NGF loading efficiency was found to be 61% while its sustained release was observed by an in vitro release kinetics study. These nanoparticles were found to be cytocompatible to cBM-MSCs when supplemented at a concentration upto 4 mg/ml in culture media. The NGF-CNP supplemented culture media was able to transdifferentiate the preinduced cBM-MSCs into neurons in a better way than unbound NGF supplementation. Further, it was also noticed that NGF-CNPs were able to transdifferentiate cBM-MSCs without any chemical based preinduction. In conclusion, our findings propose that NGF-CNPs are capable of releasing bioactive NGF with the ability to transdifferentiate mesenchymal stem cells into neurons, suggesting its potential future application in nerve tissue regeneration.