Mechanisms involved in the therapeutic properties of mesenchymal stem cells

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.

Development and Prospect of Intra-Articular Injection in the Treatment of Osteoarthritis: A Review

Osteoarthritis (OA) is a common degenerative disease that affects the vast majority of the elderly and may eventually embark on the road of the total knee arthroplasty (TKA), although controversy still exists in the medical community about the best therapies for osteoarthritis. Compared with physical therapy, oral analgesics and other non-operative treatments, intra-articular injection is more safe and effective. Moreover, intra-articular injection is much less invasive and has fewer adverse reactions than surgical treatment. This article reviews mechanism, benefits and adverse reactions of corticosteroids (CS), hyaluronic acid (HA), platelet-rich plasma (PRP), mesenchymal stem cell (MSCs), stromal vascular fraction (SVF) and other new therapies (for example: gene therapy). The application prospect of intra-articular injection was analyzed according to the recent progress in drug research.

Evaluation of epithelial progenitor cells and growth factors in a preclinical model of wound healing induced by mesenchymal stromal cells

Background: Skin wounds continue to be a global health problem. Several cellular therapy protocols have been used to improve and accelerate skin wound healing. Here, we evaluated the effect of transplantation of mesenchymal stromal cells (MSC) on the wound re-epithelialization process and its possible relationship with the presence of epithelial progenitor cells (EPC) and the expression of growth factors. Methods: An experimental wound model was developed in C57BL/6 mice. Human MSCs seeded on collagen membranes (CM) were implanted on wounds. As controls, animals with wounds without treatment or treated with CM were established. Histological and immunohistochemical (IH) studies were performed at day 3 post-treatment to detect early skin wound changes associated with the presence of EPC expressing Lgr6 and CD34 markers and the expression of keratinocyte growth factor (KGF) and basic fibroblast growth factor (bFGF). Results: MSC transplantation enhanced skin wound re-epithelialization, as compared with controls. It was associated with an increase in Lgr6⁺ and CD34⁺ cells and the expression of KGF and bFGF in the wound bed. Conclusion: Our results show that cutaneous wound healing induced by MSC is associated with an increase in EPC and growth factors. These preclinical results support the possible clinical use of MSC to treat cutaneous wounds.

Role of stem cell therapies in treating chronic wounds: A systematic review

BACKGROUND

The impairment of cutaneous wound healing results in chronic, non-healing wounds that are caused by altered wound environment oxygenation, tissue injury, and permissive microbial growth. Current modalities for the treatment of these wounds inadequately address the complex changes involved in chronic wound pathogenesis. Consequently, stem cell therapies have emerged as a potential therapeutic modality to promote cutaneous regeneration through trophic and paracrine activity.

AIM

To investigate current literature regarding use of stem cell therapies for the clinical treatment of chronic, non-healing wounds.

METHODS

PubMed, EMBASE, Cochrane Library, Web of Science, and Scopus were queried with combinations of the search terms “mesenchymal stem cells,” “adult stem cells,” “embryonic stem cells,” “erythroid precursor cells,” “stem cell therapies,” and “chronic wounds” in order to find relevant articles published between the years of 2000 and 2019 to review a 20-year experience. Reference lists from the articles were reviewed to identify additional pertinent articles. Retrieved manuscripts (reviews, case reports/series, retrospective/prospective studies, and clinical trials) were evaluated by the authors for their depiction of clinical stem cell therapy use. Data were extracted from the articles using a standardized collection tool.

RESULTS

A total of 43 articles describing the use of stem cell therapies for the treatment of chronic wounds were included in this review. While stem cell therapies have been explored in in vitro and in vivo applications in the past, recent efforts are geared towards assessing their clinical role. A review of the literature revealed that adipose-derived stem cells, bone marrow-derived stem cells, bone marrow-derived mononuclear cells, epidermally-derived mesenchymal stem cells, fibroblast stem cells, keratinocyte stem cells, placental mesenchymal stem cells, and umbilical cord mesenchymal stem cells have all been employed in the treatment of chronic wounds of various etiologies. Most recently, embryonic stem cells have emerged as a novel stem cell therapy with the capacity for multifaceted germ cell layer differentiation. With the capacity for self-renewal and differentiation, stem cells can enrich existing cell populations in chronic wounds in order to overcome barriers impeding the progression of wound healing. Further, stem cell therapies can be utilized to augment cell engraftment, signaling and activity, and resultant patient outcomes.

CONCLUSION

Assessing observed clinical outcomes, potential for stem cell use, and relevant therapeutic challenges allows wound care stakeholders to make informed decisions regarding optimal treatment approaches for their patients’ chronic wounds.

Is Stem Cell Commerce in Small Animal Therapies Scientifically and Morally Justified?

The lack of clear regulations for the use of veterinary stem cells has triggered the commercialization of unproven experimental therapies for companion animal diseases. Adult stem cells have complex biological characteristics that are directly related to the therapeutic application, but several questions remain to be answered. In order to regulate the use of these cells, well-conducted, controlled scientific studies that generate high-quality data should be performed, in order to assess the efficacy and safety of the intended treatment. This paper discusses the scientific challenges of mesenchymal stem cell therapy in veterinary regenerative medicine, and reviews published trials of adipose-tissue-derived stem cells in companion animal diseases that spontaneously occur.

Umbilical Cord Cell Therapy Improves Spatial Memory in Aging Rats

There is a growing interest in the potential of adult stem cells for implementing regenerative medicine in the brain. We assessed the effect of intracerebroventricular (icv) administration of human umbilical cord perivascular cells (HUCPVCs) on spatial memory of senile (27 mo) female rats, using intact senile counterparts as controls. Approximately one third of the animals were injected in the lateral ventricles with a suspension containing 4.8 X 10⁵ HUCPVC in 8 μl per side. The other third received 4.8 X 10⁵ transgenic HUCPVC overexpressing Insulin-like growth factor-1 (IGF-1) and the last third of the rats received no treatment. Spatial memory performance was evaluated using a modified version of the Barnes maze test. In order to evaluate learning ability as well as spatial memory retention, we assessed the time spent (permanence) by animals in goal sector 1 (GS₁) and 3 (GS₃) when the escape box was removed. Fluorescence microscopy revealed the prescence of Dil-labeled HUCPVC in coronal sections of treated brains. The HUCPVC were located in close contact with the ependymal cells with only a few labeled cells migrating into the brain parenchyma. After treatment with naïve or IGF-1 transgenic HUCPVC, permanence in GS₁ and GS₃ increased significantly whereas there were no changes in the intact animals. We conclude that HUCPVC injected icv are effective to improve some components of spatial memory in senile rats. The ready accessibility of HUCPVC constitutes a significant incentive to continue the exploration of their therapeutic potential on neurodegenerative diseases.

Changes in Stemness Properties, Differentiation Potential, Oxidative Stress, Senescence and Mitochondrial Function in Wharton's Jelly Stem Cells of Umbilical Cords of Mothers with Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) has been associated with an increased risk of maternal and neonatal morbidity. The Wharton's jelly (WJ) of the umbilical cord (UC) is a useful indicator of the deleterious effects of hyperglycemia on fetal tissues as it represents the fetus embryologically, physiologically and genetically. We studied WJ mesenchymal stem cells (hWJSCs) from UC from mothers without GDM (Normal; n = 3); insulin-controlled GDM mothers (GDMi; n = 3) and diet-controlled GDM mothers (GDMd; n = 3)]. Cell proliferation, stemness markers, telomerase, osteogenic and chondrogenic differentiation, antioxidant enzymes and gene expression for mitochondrial function (ND2, TFAM, PGC1α, and NDUFB9) were significantly lower in GDMi-hWJSCs and GDMd-hWJSCs compared to normal hWJSCs (P < 0.05). On the other hand, cell cycle inhibitors (p16, p21, p27) and p53 were remarkably up-regulated in GDMi-hWJSCs and GDMd-hWJSCs compared to normal hWJSCs. The results from this study confirmed that maternal hyperglycemia even though managed with insulin or diet, induced changes in the properties of the WJ and its cells. These changes may also be observed in fetal tissues and if true, prevention of the onset of gestational diabetes should be a priority over management. Generation of tissues that simulate those of the fetus such as pancreatic and cardiovascular cells from GDM-hWJSCs by direct differentiation or via induced pluripotent stem cell reprogramming provide possible platforms to evaluate the effects of glucose on specific fetal organ.

The Application of MSCs-Derived Extracellular Vesicles in Bone Disorders: Novel Cell-Free Therapeutic Strategy

Bone is crucial for supporting the body, protecting other organs, providing minerals, and secreting hormone to regulate other organ's function. Bone disorders result in pain and disability, severely affecting human health, reducing the quality of life and increasing costs to society. With the rapid increase in the aging population worldwide, bone disorders have become one major disease. As a result, efficacious therapies of bone disorders have become the focus of attention worldwide. Mesenchymal stem cells (MSCs) have been widely explored as a new therapeutic method for numerous diseases. Recent evidence suggests that the therapeutic effects of MSCs are mainly mediated by their extracellular vesicles (EV). MSCs-derived extracellular vesicles (MSCs-EV) is indicated as a novel cell-free alternative to cell therapy with MSCs in regenerative medicine. Here, we review the current knowledge of EV and highlight the application studies of MSCs-EV in bone disorders by focusing on osteoarthritis (OA), rheumatoid arthritis (RA), osteoporosis (OP), and bone fracture. Moreover, we discuss the key issues and perspectives of MSCs-EV as a clinical therapeutic strategy for bone diseases.

Adipose Tissue-Derived Stem Cells: The Biologic Basis and Future Directions for Tissue Engineering

Mesenchymal stem cells (MSCs) have been isolated from a variety of tissues using different methods. Active research have confirmed that the most accessible site to collect them is the adipose tissue; which has a significantly higher concentration of MSCs. Moreover; harvesting from adipose tissue is less invasive; there are no ethical limitations and a lower risk of severe complications. These adipose-derived stem cells (ASCs) are also able to increase at higher rates and showing telomerase activity, which acts by maintaining the DNA stability during cell divisions. Adipose-derived stem cells secret molecules that show important function in other cells vitality and mechanisms associated with the immune system, central nervous system, the heart and several muscles. They release cytokines involved in pro/anti-inflammatory, angiogenic and hematopoietic processes. Adipose-derived stem cells also have immunosuppressive properties and have been reported to be "immune privileged" since they show negative or low expression of human leukocyte antigens. Translational medicine and basic research projects can take advantage of bioprinting. This technology allows precise control for both scaffolds and cells. The properties of cell adhesion, migration, maturation, proliferation, mimicry of cell microenvironment, and differentiation should be promoted by the printed biomaterial used in tissue engineering. Self-renewal and potency are presented by MSCs, which implies in an open-source for 3D bioprinting and regenerative medicine. Considering these features and necessities, ASCs can be applied in the designing of tissue engineering products. Understanding the heterogeneity of ASCs and optimizing their properties can contribute to making the best therapeutic use of these cells and opening new paths to make tissue engineering even more useful.

Control of Hyperglycemia Using Differentiated and Undifferentiated Mesenchymal Stem Cells in Rats with Type 1 Diabetes

Due to their ability in self-renewing and differentiation into a wide variety of tissues, mesenchymal stem cells (MSCs) exhibit outstanding potential for regenerative medicine. This study was aimed at investigating different aspects of MSC therapy in controlling hyperglycemia in streptozotocin-induced diabetes rats. Using an islet cell differentiation protocol, bone marrow (BM) MSCs were differentiated into insulin-producing cells (IPCs). The differentiation process was evaluated by immunocytochemistry, reverse transcriptase PCR, and dithizone staining. Diabetic animals in 4 diabetic individual groups received normal saline, BM-MSCs, coadministration of BM-MSCs with supernatant, and IPCs. Blood glucose and insulin levels were monitored during the experiment. Immunohistochemical analysis of the pancreas was performed at the end of the experiment. Administration of BM-MSCs could not reverse glucose and insulin levels in experimental animals as efficiently as cotransplantation of BM-MSCs with supernatant. The effect of coadministration of BM-MSCs with supernatant and transplantation of IPCs on controlling hyperglycemia is comparable. Immunohistochemical analysis showed that number and size of islets per section were significantly increased in groups receiving IPCs and BM-MSC-supernatant compared to the MSC group of animals. In conclusion, coadministration of BM-MSCs with supernatant could be used as efficiently as IPC transplantation in controlling hyperglycemia in diabetic rats.

Mesenchymal stem cells versus curcumin in enhancing the alterations in the cerebellar cortex of streptozocin-induced diabetic albino rats. The role of GFAP, PLC and α-synuclein

BACKGROUND

Diabetes mellitus is the disease, termed either by insulin paucity or resistance and hyperglycemia. The selection of the cerebellum was built on its specific functions. The aim of this study was to investigate a comparison between the possible therapeutic effects of MSCs and curcumin against fluctuations in the cerebellar cortex of STZ-induced diabetic albino rats.

MATERIALS AND METHODS

Forty rats were divided into five groups: control, sham control, streptozotocin-induced diabetes, diabetes and MSCs administered and diabetes and curcumin administered. Light microscopic (H&E), immune-histochemical; Glial fibrillary acidic protein (GFAP), real-time PCR; phospholipase-C (PLC) and α-synuclein, histomorphometric analysis, oxidative / anti-oxidatants; malondialdehyde (MDA)/ superoxide dismutase (SOD) glutathione (GSH) and were made.

RESULTS

The histopathological examination of the STZ-induced diabetic rats revealed alterations in the molecular, purkinje and granular layers. Abnormal organizations, vacuolation, patchy loss of purkinje cells were detected. Some purkinje cells migrated into the granular layer.Hemorrhage in pia mater outspreading to cerebellar layers is discerned. Purkinje cells showed karyorrhexis. The mean value of area percentage for GFAP immune- reactivity revealed 360 % significant increase compared to that of the control group. Also, MDA level was significantly increased while the SOD and GSH levels were significantly lower when compared to the control group. Meanwhile, mean values of PLC demonstrated significant decrease, while α-synuclein levels displayed a significant increment in the diabetic group. Administration of curcumin and MSCs extremely ameliorated the previous alterations.

CONCLUSION

the deleterious alterations on the cerebellar cortex induced by diabetes were obviously improved when treated with either MSCs or curcumin.

Evaluation of Osteogenic/Cementogenic Modulating Potential of PAI-1 Transfected Media for Stem Cells

AIM OF THE STUDY

In vitro evaluation of the effects of plasminogen activator inhibitor-1 (PAI-1) transfected-conditioned media (P-CM) on the differentiation of human periodontal ligament stem cells (hPDLSCs) and human periapical follicular stem cells (hPAFSCs).

MATERIALS AND METHODS

The hPDLSCs and hPAFSCs received from impacted third molars were treated with P-CM and viability, as well as differentiation of the cells were evaluated. Plasmids were constructed according to standard techniques, and all sequences were validated by proper enzyme digestion and sequencing. Chinese hamster ovarian (CHO) cells were transfected with pcDNA3.1-hPAI-1 plasmid to obtain P-CM, followed by western blotting and PAI-1-specific ELISA kit to evaluate the proteins of P-CM. The cell viability of hPDLSCs and hPAFSCs were analyzed using MTT assay after 48 h of incubation. Alizarin red S staining was performed to evaluate the differentiation of hPDLSCs and hPAFSCs. The reverse transcription-polymerase chain reaction was used to observe the expression levels of osteogenic/cementogenic marker genes. The human cytokine antibody array was applied for further analysis of cytokine expression in P-CM.

RESULTS

P-CM significantly promoted the differentiation of hPDLSCs and hPAFSCs and upregulated the expression of osteogenic/cementogenic marker genes in vitro. Furthermore, rhPAI-1 promoted mineralized nodules formation of hPDLSCs and hPAFSCs, and we identified that other proteins, RANTES and IL-6, were highly expressed in P-CM.

CONCLUSIONS

P-CM promoted the differentiation of hPDLSCs and hPAFSCs by upregulating the expression of RANTES and IL-6, and interaction between PAI-1 and RANTES/IL-6 signaling may be involved in P-CM-induced osteogenic/cementogenic differentiation.

Exosomes Isolated From Platelet-Rich Plasma and Mesenchymal Stem Cells Promote Recovery of Function After Muscle Injury

BACKGROUND

Clinical use of platelet-rich plasma (PRP) and mesenchymal stem cells (MSCs) has gained momentum as treatment for muscle injuries. Exosomes, or small cell-derived vesicles, could be helpful if they could deliver the same or better physiological effect without cell transplantation into the muscle.

HYPOTHESIS

Local delivery of exosomes derived from PRP (PRP-exos) or MSCs (MSC-exos) to injured muscles hastens recovery of contractile function.

STUDY DESIGN

Controlled laboratory study.

METHODS

In a rat model, platelets were isolated from blood, and MSCs were isolated from bone marrow and expanded in culture; exosomes from both were isolated through ultracentrifugation. The tibialis anterior muscles were injured in vivo using maximal lengthening contractions. Muscles were injected with PRP-exos or MSC-exos (immediately after injury and 5 and 10 days after injury); controls received an equal volume of saline. Histological and biochemical analysis was performed on tissues for all groups.

RESULTS

Injury resulted in a significant loss of maximal isometric torque (66% ± 3%) that gradually recovered over 2 weeks. Both PRP-exos and MSC-exos accelerated recovery, with similar faster recovery of contractile function over the saline-treated group at 5, 10, and 15 days after injury (P < .001). A significant increase in centrally nucleated fibers was seen with both types of exosome groups by day 15 (P < .01). Genes involved in skeletal muscle regeneration were modulated by different exosomes. Muscles treated with PRP-exos had increased expression of Myogenin gene (P < .05), whereas muscles treated with MSC-exos had reduced expression of TGF-β (P < .05) at 10 days after muscle injury.

CONCLUSION

Exosomes derived from PRP or MSCs can facilitate recovery after a muscle strain injury in a small-animal model likely because of factors that can modulate inflammation, fibrosis, and myogenesis.

CLINICAL RELEVANCE

Given their small size, low immunogenicity, and ease with which they can be obtained, exosomes could represent a novel therapy for many orthopaedic ailments.

Mechanisms underlying the protective effects of mesenchymal stem cell-based therapy

Mesenchymal stem cells (MSCs) have been extensively investigated for the treatment of various diseases. The therapeutic potential of MSCs is attributed to complex cellular and molecular mechanisms of action including differentiation into multiple cell lineages and regulation of immune responses via immunomodulation. The plasticity of MSCs in immunomodulation allow these cells to exert different immune effects depending on different diseases. Understanding the biology of MSCs and their role in treatment is critical to determine their potential for various therapeutic applications and for the development of MSC-based regenerative medicine. This review summarizes the recent progress of particular mechanisms underlying the tissue regenerative properties and immunomodulatory effects of MSCs. We focused on discussing the functional roles of paracrine activities, direct cell-cell contact, mitochondrial transfer, and extracellular vesicles related to MSC-mediated effects on immune cell responses, cell survival, and regeneration. This will provide an overview of the current research on the rapid development of MSC-based therapies.

Mitochondria transfer enhances proliferation, migration, and osteogenic differentiation of bone marrow mesenchymal stem cell and promotes bone defect healing

Background

Bone marrow-derived mesenchymal stem cell (BMSC) transplantation is considered a promising therapeutic approach for bone defect repair. However, during the transplantation procedure, the functions and viability of BMSCs may be impaired due to extended durations of in vitro culture, aging, and disease conditions of patients. Inspired by spontaneous intercellular mitochondria transfer that naturally occurs within injured tissues to rescue cellular or tissue function, we investigated whether artificial mitochondria transfer into pre-transplant BMSCs in vitro could improve cellular function and enhance their therapeutic effects on bone defect repair in situ.

Methods

Mitochondria were isolated from donor BMSCs and transferred into recipient BMSCs of the same batch and passage. Subsequently, changes in proliferative capacity and cell senescence were evaluated by live cell imaging, Cell Counting Kit-8 assay, cell cycle analysis, Ki67 staining, qPCR and Western blot analysis of c-Myc expression, and β-galactosidase staining. Migration ability was evaluated by the transwell migration assay, wound scratch healing, and cell motility tests. Alkaline phosphatase (ALP) staining, Alizarin Red staining, and combined with qPCR and Western blot analyses of Runx2 and BMP2 were performed to elucidate the effects of mitochondria transfer on the osteogenic potential of BMSCs in vitro. After that, in vivo experiments were performed by transplanting mitochondria-recipient BMSCs into a rat cranial critical-size bone defect model. Micro CT scanning and histological analysis were conducted at 4 and 8 weeks after transplantation to evaluate osteogenesis in situ. Finally, in order to establish the correlation between cellular behavioral changes and aerobic metabolism, OXPHOS (oxidative phosphorylation) and ATP production were assessed and inhibition of aerobic respiration by oligomycin was performed.

Results

Mitochondria-recipient BMSCs exhibited significantly enhanced proliferation and migration, and increased osteogenesis upon osteogenic induction. The in vivo results showed more new bone formation after transplantation of mitochondria-recipient BMSCs in situ. Increased OXPHOS activity and ATP production were observed, which upon inhibition by oligomycin attenuated the enhancement of proliferation, migration, and osteogenic differentiation induced by mitochondria transfer.

Conclusions

Mitochondria transfer is a feasible technique to enhance BMSC function in vitro and promote bone defect repair in situ through the upregulation of aerobic metabolism. The results indicated that mitochondria transfer may be a novel promising technique for optimizing stem cell therapeutic function.

Exosomes: roles and therapeutic potential in osteoarthritis

Exosomes participate in many physiological and pathological processes by regulating cell-cell communication, which are involved in numerous diseases, including osteoarthritis (OA). Exosomes are detectable in the human articular cavity and were observed to change with OA progression. Several joint cells, including chondrocytes, synovial fibroblasts, osteoblasts, and tenocytes, can produce and secrete exosomes that influence the biological effects of targeted cells. In addition, exosomes from stem cells can protect the OA joint from damage by promoting cartilage repair, inhibiting synovitis, and mediating subchondral bone remodeling. This review summarizes the roles and therapeutic potential of exosomes in OA and discusses the perspectives and challenges related to exosome-based treatment for OA patients in the future.

The Emerging Role of Exosomal Non-coding RNAs in Musculoskeletal Diseases

Exosomes are phospholipid bilayer-enclosed membrane vesicles derived and constitutively secreted by various metabolically active cells. They are capable of mediating hetero- and homotypic intercellular communication by transferring multiple cargos from donor cells to recipient cells. Nowadays, non-coding RNAs (ncRNAs) have emerged as novel potential biomarkers or disease-targeting agents in a variety of diseases. However, the lack of effective delivery systems may impair their clinical application. Recently, accumulating evidence demonstrated that ncRNAs could be efficiently delivered to recipient cells using exosomes as a carrier, and therefore can exert a critical role in musculoskeletal diseases including osteoarthritis, rheumatoid arthritis, osteoporosis, muscular dystrophies, osteosarcoma and other diseases. Herein, we present an extensive review of biogenesis, physiological relevance and clinical implication of exosome-derived ncRNAs in musculoskeletal diseases.

Mesenchymal Stem Cells: A New Generation of Therapeutic Agents as Vehicles in Gene Therapy

In recent years, mesenchymal stem cells (MSCs) as a new tool for therapeutic gene delivery in clinics have attracted much attention. Their advantages cover longer lifespan, better isolation, and higher transfection efficiency and proliferation rate. MSCs are the preferred approach for cell-based therapies because of their in vitro self-renewal capacity, migrating especially to tumor tissues, as well as anti-inflammatory and immunomodulatory properties. Therefore, they have considerable efficiency in genetic engineering for future clinical applications in cancer gene therapy and other diseases. For improving therapeutic efficiency, targeted therapy of cancers can be achieved through the sustained release of therapeutic agents and functional gene expression induction to the intended tissues. The development of a new vector in gene therapy can improve the durability of a transgene expression. Also, the safety of the vector, if administered systemically, may resolve several problems, such as durability of expression and the host immune response. Currently, MSCs are prominent candidates as cell vehicles for both preclinical and clinical trials due to the secretion of therapeutic agents in several cancers. In the present study, we discuss the status of gene therapy in both viral and non-viral vectors along with their limitations. Throughout this study, the use of several nano-carriers for gene therapy is also investigated. Finally, we critically discuss the promising advantages of MSCs in targeted gene delivery, tumor inhibition and their utilization as the gene carriers in clinical situations.

Mesenchymal stem cell therapy for the treatment of traumatic brain injury: progress and prospects

Traumatic brain injury (TBI) is a major cause of injury-related mortality and morbidity in the USA and around the world. The survivors may suffer from cognitive and memory deficits, vision and hearing loss, movement disorders, and different psychological problems. The primary insult causes neuronal damage and activates astrocytes and microglia which evokes immune responses causing further damage to the brain. Clinical trials of drugs to recover the neuronal loss are not very successful. Regenerative approaches for TBI using mesenchymal stem cells (MSCs) seem promising. Results of preclinical research have shown that transplantation of MSCs reduced secondary neurodegeneration and neuroinflammation, promoted neurogenesis and angiogenesis, and improved functional outcome in the experimental animals. The functional improvement is not necessarily related to cell engraftment; rather, immunomodulation by molecular factors secreted by MSCs is responsible for the beneficial effects of this therapy. However, MSC therapy has a few drawbacks including tumor formation, which can be avoided by the use of MSC-derived exosomes. This review has focused on the research works published in the field of regenerative therapy using MSCs after TBI and its future direction.

Mesenchymal stem cell exosomes in bone regenerative strategies-a systematic review of preclinical studies

The ability of bone for regeneration has long been recognized. However, once beyond a critical size, spontaneous regeneration of bone is limited. Several studies have focused on enhancing bone regeneration by applying mesenchymal stromal/stem cells (MSCs) in the treatment strategies. Despite the therapeutic efficacy of MSCs in bone regeneration, cell-based therapies are impeded by several challenges in maintaining the optimal cell potency and viability during expansion, storage, and final delivery to patients. Recently, there has been a paradigm shift in therapeutic mechanism of MSCs in tissue repair from one based on cellular differentiation and replacement to one based on secretion and paracrine signaling. Among the broad spectrum of trophic factors, extracellular vesicles ​particularly the exosomes have been reported to be therapeutically efficacious in several injury/disease indications, including bone defects and diseases. The current systematic review aims to summarize the results of the existing animal studies which were conducted to evaluate the therapeutic efficacy of MSC exosomes for bone regeneration. Following the Preferred Reporting Items for Systematic Reviews and Meta-analysis ​guidelines, the PubMed and The Cochrane Library database were searched for relevant controlled preclinical animal studies. A total of 23 studies were identified, with the total sample size being 690 rats or mice and 38 rabbits. Generally, MSC exosomes were found to be efficacious for bone regeneration in animal models of bone defects and diseases such as osteonecrosis and osteoporosis. In these studies, MSC exosomes promoted new bone formation with supporting vasculature ​and displayed improved morphological, biomechanical, and histological outcomes, coupled with positive effects on cell survival, proliferation, and migration, osteogenesis, and angiogenesis. Unclear-to-low risk in bias and incomplete reporting in the primary studies highlighted the need for standardization in outcome measurements and reporting. Further studies in large animal models to establish the safety and efficacy would provide useful information on guiding the design of clinical trials.

A nanocomposite hydrogel delivery system for mesenchymal stromal cell secretome

Background

Mesenchymal stromal cell conditioned medium (MSC-CM) contains a cocktail of bioactive factors that act synergistically to induce therapeutic effects. This has been clearly demonstrated by in vivo applications of MSC-CM, but the establishment of controlled delivery systems is an unmet requirement for clinical translation.

Methods

We developed a nanocomposite-hydrogel (NP-H) comprised of poly-L-lactide nanoparticles (NPs) embedded in gelatin/hyaluronic acid (Gel/HA) hydrogel as a delivery vehicle for MSC-CM. First, we optimized the culture conditions for bone marrow-derived MSCs using serum-containing medium (SCM) and serum-free medium (SFM) and characterized the corresponding CM (serum-containing conditioned medium (ScCM) and serum-free conditioned medium (SfCM), respectively) for its potency and xeno markers. Then we prepared a composite matrix followed by physiochemical characterization and functional assays were performed.

Results

Nanocomposite hydrogel displayed an even distribution of NPs along with high porosity (> 60%) and swelling ratios > 1500%, while its protein release pattern corresponded to a mix of degradation and diffusion kinetics. Functional evaluation of the composites was determined using MSCs and human fibroblasts (HFFs). The cells seeded directly onto the composites displayed increasing metabolic activities over time, with ScCM-NP-H groups having maximum activity. The cells treated in vitro with 5% and 10% extracts of ScCM-NP-H and SfCM-NP-H exhibited a dose- and duration-dependent response. Cell activities reduced considerably for all groups, except 10% ScCM-NP-H, which displayed a significant increase over time.

Conclusion

We observed that sustained release of MSC-CM is required to prevent dose-dependent cytotoxicity. The proposed nanocomposite hydrogel for MSC-CM delivery can open up a new array for its clinical application.

Exosomes Derived from Stem Cells from the Apical Papilla Promote Dentine-Pulp Complex Regeneration by Inducing Specific Dentinogenesis

Regenerative endodontic procedures (REPs) are a new option for the treatment of dental pulp or periapical diseases in permanent teeth with open apices. Histologically, the new tissues formed in the root canal after REPs are mainly cementum- or bone-like mineralised tissues, but not the real dentine-pulp complex. Therefore, how to promote dentine-pulp complex regeneration and improve the clinical effects of REPs has become a prominent research topic. Stem cells from apical papilla (SCAP) are derived from the dental papilla that can differentiate into primary odontoblasts and dental pulp cells that produce root dentine and dental pulp. Exosomes are the key regulator for the paracrine activity of stem cells and can influence the function of recipient cells. In this study, SCAP-derived exosomes (SCAP-Exo) were introduced into the root fragment containing bone marrow mesenchymal stem cells (BMMSCs) and transplanted subcutaneously into immunodeficient mice. We observed that dental pulp-like tissues were present and the newly formed dentine was deposited onto the existing dentine in the root canal. Afterwards, the effects of SCAP-Exo on the dentinogenesis of BMMSCs were elucidated in vitro. We found that the gene and protein expression of dentine sialophosphoprotein and mineralised nodule formation in BMMSCs treated with SCAP-Exo were significantly increased. In summary, SCAP-Exo were endocytosed by BMMSCs and obviously improved their specific dentinogenesis. The use of exosomes derived from dental stem cells could comprise a potential therapeutic approach for dentine-pulp complex regeneration in REPs.

Extracellular vesicles derived from different sources of mesenchymal stem cells: therapeutic effects and translational potential

Mesenchymal stem cells (MSCs) were known to have excellent properties in cell therapy. However, the risk of immune rejection associated with cell transplant therapy hampers its use. Extracellular vesicles secreted by MSCs derived from different sources that contain therapeutic molecules such as RNA and proteins, which is a novel strategy for cell-free therapy. Recently, researches show EVs from MSCs (MSC-EVs) of different sources have special functions and effects on different diseases. Here, we collected these researches and compared them to each other. In addition, their potential and possible application in clinical treatment are described.

Stem cell therapy: a potential approach for treatment of influenza virus and coronavirus-induced acute lung injury

Acute lung injury (ALI), an increasingly devastating human disorder, is characterized by a multitude of lung changes arising from a wide variety of lung injuries. Viral infection is the main cause of morbidity and mortality in ALI and acute respiratory distress syndrome (ARDS) patients. In particular, influenza virus, coronavirus, and other respiratory viruses circulate in nature in various animal species and can cause severe and rapidly spread human infections. Although scientific advancements have allowed for rapid progress to be made to understand the pathogenesis and develop therapeutics after each viral pandemic, few effective methods to treat virus-induced ALI have been described. Recently, stem cell therapy has been widely used in the treatment of various diseases, including ALI. In this review, we detail the present stem cell-based therapeutics for lung injury caused by influenza virus and the outlook for the future state of stem cell therapy to deal with emerging influenza and coronaviruses.

Detrusor bioengineering using a cell-enriched compressed collagen hydrogel

OBJECTIVE

The gold standard for bladder regeneration in end-stage bladder disease is the use of intestinal tissue, which is however associated with significant long-term complications. Our study aims to bioengineer functional detrusor muscle combining bladder smooth muscle cells (SMC) and SMC-like adipose-derived stem cells (pADSC) in compressed collagen (CC) hydrogels and to investigate biocompatibility and tissue regeneration of such detrusor-equivalents in a rat detrusorectomy model.

METHODS

Compressed collagen hydrogels seeded with 1 × 10⁶ or 4 × 10⁶ SMC alone or in combination with pADSC in a 1:1 ratio were investigated. Morphology, phenotype, and viability as well as proteomic secretome analysis were assessed in the 1:1 co-cultures and the respective monocultures. The hydrogels were implanted into rat bladders after partial detrusorectomy. Bladders were harvested 8 weeks after transplantation, and assessed for tissue morphology, detrusor regeneration, neo-vascularization and -innervation.

RESULTS

Co-cultured cells exhibited native SMC morphology, high viability and proliferated to form microtissues in vitro. The pro-angiogenic factors angiogenin, vascular endothelial growth factor (VEGF)-A and -D were increased in the secretome of the pADSC samples. After 8 weeks of in vivo, the regenerated bladder wall showed a multilayered structure containing all bladder wall components. The overall performance of the bladder wall regeneration of CC seeded with 4 × 10⁶ cells was significantly better than with 1 × 10⁶ cells and the combination SMC:pADCS performed slightly better than SMC alone.

CONCLUSION

Compressed collagen possesses an adequate regenerative potential to promote regeneration of bladder wall tissue in vivo. Seeded with a combination of pADSC and SMC this may well be the first step towards a functional bladder reconstruction especially in patients suffering of end-stage bladder diseases.

Humoral factors secreted from adipose tissue-derived mesenchymal stem cells ameliorate atherosclerosis in Ldlr-/- mice

AIMS

Atherosclerosis is a chronic inflammatory disease of the vasculature. Mesenchymal stem cells (MSCs) exert immunomodulatory and immunosuppressive effects by secreting humoral factors; however, the intravascular MSC administration presents a risk of vascular occlusion. Here, we investigated both the effect of conditioned medium from cultured MSCs (MSC-CM) on atherosclerosis and the underlying mechanism.

METHODS AND RESULTS

Low-density lipoprotein receptor-deficient (Ldlr-/-) mice were fed a high-fat diet and received intravenous injections of either MSC-CM from adipose tissue-derived MSCs or control medium 2×/week for 13 weeks. MSC-CM treatment decreased the atherosclerotic plaque area in the aorta and aortic root of Ldlr-/- mice by 41% and 30%, respectively, with no change in serum lipoprotein levels. Histopathologically, the MSC-CM treatment decreased the expression of cell adhesion molecules (CAMs) and the accumulation of macrophages on the vascular walls. Extracellular vesicles (EVs) and supernatant (MSC-CM supernatant) were separated from the MSC-CM by ultracentrifugation. In tumour necrosis factor-α stimulated human aortic endothelial cells (HAOECs), both the MSC EVs and MSC-CM supernatant decreased CAM expression by inhibiting the mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NFκB) pathways. In macrophages, the MSC-CM supernatant decreased the lipopolysaccharide-induced increases in M1 marker expression by inhibiting both the MAPK and NFκB pathways and increased the expression of M2 markers by activating the signal transducer and activator of transcription 3 pathway. In co-culture, inflamed HAOECs pretreated with MSC-CM supernatant and MSC EVs exhibited decreased monocyte adhesion to HAOECs. In addition, the neutralization of hepatocyte growth factor (HGF) in MSC-CM or MSC-CM supernatant attenuated their abilities to suppress monocyte adhesion to HAOECs in co-culture.

CONCLUSION

MSC-CM ameliorated atherosclerosis in Ldlr-/- mice and suppressed CAM expression and macrophage accumulation in the vascular walls. Humoral factors, including HGF and EVs from MSCs, hold promise as therapeutic agents to reduce the residual risk of coronary artery diseases.

The effects of 17 Beta-Estradiol primed mesenchymal stem cells on the biology of co-cultured neutrophil

OBJECTIVES

Mesenchymal stem cells (MSCs) can influence immune effector cells. It is proved that MSCs respond to various Toll-like receptor (TLR) ligands, which could ultimately result in changes in their immunomodulatory effects. Neutrophils play an essential role in the first line defense system and their function can be regulated by MSCs. Estrogen is a female hormone that contributes to sex differences in several immune-related diseases. With regard to the stated facts, this research aims to elucidate the effects of estrogen treatment on the ability of TLR4-primed MSCs to regulate neutrophil functions.

METHODS

Following isolation and characterization, MSCs were stimulated with LPS as a TLR4 ligand and subsequently incubated with different concentrations (0, 10, 20 and 40 nM) of estrogen for 48 hrs. Then, MSCs were co-cultured with neutrophils to investigate the vitality and function of the co-cultured neutrophils.

RESULTS

Our results indicated that TLR4-primed MSCs could decrease the viability and neutral red uptake potential of co-cultured neutrophils. Furthermore, neutrophils co-cultured with TLR4-primed MSCs exhibited a decrease in the respiratory burst intensity after being challenged with opsonized yeast. Interestingly, treating TLR4-primed MSCs with estrogen reversed the observed alterations in neutrophil functions.

CONCLUSION

It appears that estrogen can alter the interaction between MSCs and neutrophils.

The PI3k/Akt pathway is associated with angiogenesis, oxidative stress and survival of mesenchymal stem cells in pathophysiologic condition in ischemia

Ischemic diseases are characterized by reduced blood supply to a tissue or an organ due to obstruction of blood vessels. The most serious and most common ischemic diseases include ischemic heart disease, ischemic stroke, and critical limb ischemia. Revascularization is the first choice of therapy, but the cell therapy is being introduced as a possible way of treatment for no-option patients. One of the possibilities of cell therapy is the use of mesenchymal stem cells (MSCs). MSCs are easily isolated from bone marrow and can be defined as non-hematopoietic multipotent adult stem cells population with a defined capacity for self-renewal and differentiation into cell types of all three germ layers depending on their origin. Since 1974, when Friedenstein and coworkers (Friedenstein et al. 1974) first time isolated and characterized MSCs, MSC-based therapy has been shown to be safe and effective. Nevertheless, many scientists and clinical researchers want to improve the success of MSCs in regenerative therapy. The secret of successful cell therapy may lie, along with the homing, in secretion of biologically active molecules including cytokines, growth factors, and chemokines known as MSCs secretome. One of the intracellular signalling mechanism includes the activity of phosphatidylinositol-3-kinase (phosphoinositide 3-kinase) (PI3K) - protein kinase B (serine-threonine protein kinase Akt) (Akt) pathway. This PI3K/Akt pathway plays key roles in many cell types in regulating cell proliferation, differentiation, apoptosis, and migration. Pre-conditioning of MSCs could improve efficacy of signalling mechanism.

Mesenchymal stem cell-laden, personalized 3D scaffolds with controlled structure and fiber alignment promote diabetic wound healing

The management of diabetic wounds remains a major therapeutic challenge in clinics. Herein, we report a personalized treatment using 3D scaffolds consisting of radially or vertically aligned nanofibers in combination with bone marrow mesenchymal stem cells (BMSCs). The 3D scaffolds have customizable sizes, depths, and shapes, enabling them to fit a variety of type 2 diabetic wounds. In addition, the 3D scaffolds are shape-recoverable in atmosphere and water following compression. The BMSCs-laden 3D scaffolds are capable of enhancing the formation of granulation tissue, promoting angiogenesis, and facilitating collagen deposition. Further, such scaffolds inhibit the formation of M1-type macrophages and the expression of pro-inflammatory cytokines IL-6 and TNF-α and promote the formation of M2-type macrophages and the expression of anti-inflammatory cytokines IL-4 and IL-10. Taken together, BMSCs-laden, 3D nanofiber scaffolds with controlled structure and alignment hold great promise for the treatment of diabetic wounds. STATEMENT OF SIGNIFICANCE: In this study, we developed 3D radially and vertically aligned nanofiber scaffolds to transplant bone marrow mesenchymal stem cells (BMSCs). We personalized 3D scaffolds that could completely match the size, depth, and shape of diabetic wounds. Moreover, both the radially and vertically aligned nanofiber scaffolds could completely recover their shape and maintain structural integrity after repeated loads with compressive stresses. Furthermore, the BMSCs-laden 3D scaffolds are able to promote granulation tissue formation, angiogenesis, and collagen deposition, and switch the immune responses to the pro-regenerative direction. These 3D scaffolds consisting of radially or vertically aligned nanofibers in combination with BMSCs offer a robust, customizable platform potentially for a significant improvement of managing diabetic wounds.

Efficacy of Stem Cell Therapy for Tendon Disorders: A Systematic Review

Background:

Stem cell therapy is an emerging treatment for tendon disorders.

Purpose:

To systematically review the efficacy of stem cell therapy for patients with tendon disorders.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

MEDLINE/PubMed, EMBASE, CINAHL, CENTRAL, PEDro, and SPORTDiscus; trial registers; and gray literature were searched to identify randomized controlled trials (RCTs) and non-RCTs, cohort studies, and case series with 5 or more cases. Studies investigating any type of stem cell therapy for patients with tendon disorders were eligible if they included patient-reported outcome measures or assessed tendon healing. Risk of bias was assessed through use of the Cochrane risk of bias tools.

Results:

This review included 8 trials (289 patients). All trials had moderate to high risk of bias (level 3 or 4 evidence). In Achilles tendon disorders, 1 trial found that allogenic-derived stem cells led to a faster recovery compared with platelet-rich plasma. Another study found no retears after bone marrow–derived stem cell therapy was used in addition to surgical treatment. There were 4 trials that studied the efficacy of bone marrow–derived stem cell therapy for rotator cuff tears. The controlled trials reported superior patient-reported outcomes and better tendon healing. A further 2 case series found that stem cell therapy improved patient-reported outcomes in patients with patellar tendinopathy and elbow tendinopathy.

Conclusion:

Level 3 evidence is available to support the efficacy of stem cell therapy for tendon disorders. The findings of available studies are at considerable risk of bias, and evidence-based recommendations for the use of stem cell therapy for tendon disorders in clinical practice cannot be made at this time. Stem cell injections should not be used in clinical practice given the lack of knowledge about potentially serious adverse effects.

Dual Role of Autophagy in Regulation of Mesenchymal Stem Cell Senescence

During their development and overall life, mesenchymal stem cells (MSCs) encounter a plethora of internal and external stress signals and therefore, they need to put in action homeostatic changes in order to face these stresses. To this aim, similar to other mammalian cells, MSCs are endowed with two crucial biological responses, autophagy and senescence. Sharing of a number of stimuli like shrinkage of telomeres, oncogenic and oxidative stress, and DNA damage, suggest an intriguingly close relationship between autophagy and senescence. Autophagy is at first reported to suppress MSC senescence by clearing injured cytoplasmic organelles and impaired macromolecules, yet recent investigations also showed that autophagy can promote MSC senescence by inducing the production of senescence-associated secretory proteins (SASP). These apparently contrary contributions of autophagy may mirror an intricate image of autophagic regulation on MSC senescence. We here tackle the pro-senescence and anti-senescence roles of autophagy in MSCs while concentrating on some possible mechanistic explanations of such an intricate liaison. Clarifying the autophagy/senescence relationship in MSCs will help the development of more effective and safer therapeutic strategies.

Mesenchymal Stem Cell Exosomes for Cartilage Regeneration: A Systematic Review of Preclinical In Vivo Studies

Clinical and animal studies have demonstrated efficacy of mesenchymal stem/stromal cells (MSCs) in cartilage repair. Although MSCs were originally predicated to mediate tissue repair through cellular differentiation and cell replacement, it is now recognized that MSCs exert most of their paracrine effects on tissue repair through the release of extracellular vesicles (EVs). In particular, 50-200 nm small EVs that also include exosomes carry a rich cargo of lipids, nucleic acids, and proteins, and have been reported to be therapeutically efficacious in various disease indications, including osteochondral injuries and osteoarthritis (OA). This systematic review aimed to assess the preclinical studies that used MSC exosomes for cartilage repair. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, PubMed and Cochrane Library databases were searched for relevant controlled preclinical animal studies. A total of 13 studies were identified, with the total sample size being 434. This included 378 (87.1%) mice or rats and 56 (12.9%) rabbits. According to Systematic Review Centre for Laboratory Animal Experimentation risk of bias assessment, all the studies presented with unclear-to-low risk in bias. In general, MSC exosomes were found to be efficacious in promoting repair and regeneration of osteochondral defects and alleviating OA degeneration. In most studies, exosome-treated animals displayed increased cellular proliferation, enhanced matrix deposition, and improved histological scores. Having assessed the relevant preclinical animal studies reported to date, this systematic review shows the therapeutic benefit of MSC exosome therapy in cartilage repair. Standardization of animal models and outcome measurements would be needed to facilitate more robust analysis and improve the validity of the results in future studies.

Emerging Therapeutic Potential of Mesenchymal Stem/Stromal Cells in Preeclampsia

PURPOSE OF REVIEW

Preeclampsia is a dangerous pregnancy condition affecting both the mother and offspring. It is a multifactorial disease with poorly understood pathogenesis, lacking effective treatments. Maternal immune response, inflammation and oxidative stress leading to endothelial dysfunction are the most prominent pathogenic processes implicated in preeclampsia development. Here, we give a detailed overview of the therapeutic applications and mechanisms of mesenchymal stem/stromal cells (MSCs) as a potential new treatment for preeclampsia.

RECENT FINDINGS

MSCs have gained growing attention due to low immunogenicity, easy cultivation and expansion in vitro. Accumulating evidence now suggests that MSCs act primarily through their secretomes facilitating paracrine signalling that leads to potent immunomodulatory, pro-angiogenic and regenerative therapeutic effects. MSCs have been studied in different animal models of preeclampsia demonstrating promising result, which support further investigations into the therapeutic effects and mechanisms of MSC-based therapies in preeclampsia, steering these therapies into clinical trials.

Stammzellen in der Regenerativen Medizin – Translationale Hürden und Möglichkeiten zur Überwindung

Der Einsatz von mesenchymalen Stammzellen in der regenerativen Medizin wird immer populärer. Nichtsdestotrotz ist ihre Anwendung im klinischen Alltag noch immer limitiert. Zahlreiche ethische, rechtliche und translationale Probleme sowie Ungewissheit bzgl. der Sicherheit hemmen noch immer die Entstehung von entsprechenden Therapien aus vielversprechenden wissenschaftlichen Ansätzen.

Diese Arbeit soll die Hauptprobleme bei der Translation von stammzellbasierten Therapien aus der Grundlagenforschung und Präklinik in den klinischen Alltag darstellen, sowie Ansätze aufzeigen, diese zu überwinden.

Why Should Growth Hormone (GH) Be Considered a Promising Therapeutic Agent for Arteriogenesis? Insights from the GHAS Trial

Despite the important role that the growth hormone (GH)/IGF-I axis plays in vascular homeostasis, these kind of growth factors barely appear in articles addressing the neovascularization process. Currently, the vascular endothelium is considered as an authentic gland of internal secretion due to the wide variety of released factors and functions with local effects, including the paracrine/autocrine production of GH or IGF-I, for which the endothelium has specific receptors. In this comprehensive review, the evidence involving these proangiogenic hormones in arteriogenesis dealing with the arterial occlusion and making of them a potential therapy is described. All the elements that trigger the local and systemic production of GH/IGF-I, as well as their possible roles both in physiological and pathological conditions are analyzed. All of the evidence is combined with important data from the GHAS trial, in which GH or a placebo were administrated to patients suffering from critical limb ischemia with no option for revascularization. We postulate that GH, alone or in combination, should be considered as a promising therapeutic agent for helping in the approach of ischemic disease.

Multi-peptide presentation and hydrogel mechanics jointly enhance therapeutic duo-potential of entrapped stromal cells

The native extracellular matrix (ECM) contains a host of matricellular proteins and bioactive factors that regulate cell behavior, and many ECM components have been leveraged to guide cell fate. However, the large size and chemical characteristics of these constituents complicate their incorporation into biomaterials without interfering with material properties, motivating the need for alternative approaches to regulate cellular responses. Mesenchymal stromal cells (MSCs) can promote osseous regeneration in vivo directly or indirectly through multiple means including (1) secretion of proangiogenic and mitogenic factors to initiate formation of a vascular template and recruit host cells into the tissue site or (2) direct differentiation into osteoblasts. As MSC behavior is influenced by the properties of engineered hydrogels, we hypothesized that the biochemical and biophysical properties of alginate could be manipulated to promote the dual contributions of encapsulated MSCs toward bone formation. We functionalized alginate with QK peptide to enhance proangiogenic factor secretion and RGD to promote adhesion, while biomechanical-mediated osteogenic cues were controlled by modulating viscoelastic properties of the alginate substrate. A 1:1 ratio of QK:RGD resulted in the highest levels of both proangiogenic factor secretion and mineralization in vitro. Viscoelastic alginate outperformed purely elastic gels in both categories, and this effect was enhanced by stiffness up to 20 kPa. Furthermore, viscoelastic constructs promoted vessel infiltration and bone regeneration in a rat calvarial defect over 12 weeks. These data suggest that modulating viscoelastic properties of biomaterials, in conjunction with dual peptide functionalization, can simultaneously enhance multiple aspects of MSC regenerative potential and improve neovascularization of engineered tissues.

A novel antifibrotic strategy utilizing conditioned media obtained from miR-150-transfected adipose-derived stem cells: validation of an animal model of liver fibrosis

The limitations of stem cells have led researchers to investigate the secretome, which is the secretory materials in stem cells, since the principal mechanism of action of stem cells is mediated by the secretome. In this study, we determined the antifibrotic potential of the secretome released from miR-150-transfected adipose-derived stromal cells (ASCs). The secretome released from ASCs that were transfected with antifibrotic miR-150 was obtained (referred to as the miR-150 secretome). To validate the antifibrotic effects of the miR-150 secretome, we generated in vitro and in vivo models of liver fibrosis by treating human hepatic stellate cells (LX2 cells) with thioacetamide (TAA) and subcutaneous injection of TAA into mice, respectively. In the in vitro model, more significant reductions in the expression of fibrosis-related markers, such as TGFβ, Col1A1, and α-SMA, were observed by using the miR-150 secretome than the control secretome, specifically in TAA-treated LX2 cells. In the in vivo model, infusion of the miR-150 secretome into mice with liver fibrosis abrogated the increase in serum levels of systemic inflammatory cytokines, such as IL-6 and TNF-α, and induced increased expression of antifibrotic, proliferation, and antioxidant activity markers in the liver. Our in vitro and in vivo experiments indicate that the miR-150 secretome is superior to the naive secretome in terms of ameliorating liver fibrosis, minimizing systemic inflammatory responses, and promoting antioxidant enzyme expression. Therefore, we conclude that miR-150 transfection into ASCs has the potential to induce the release of secretory materials with enhanced antifibrotic, proliferative, and antioxidant properties.

A mixture of molecules produced by genetically modified stem cells could help repair the damage associated with liver fibrosis. Fat-derived adipose stem cells (ASCs) secrete proteins and nucleic acids that can facilitate tissue regeneration, but the natural mixture of molecules secreted (the ‘secretome’) is insufficient to reverse advanced fibrosis. Researchers led by Say-June Kim of the Catholic University of Korea, Seoul, South Korea, have boosted the potency of this cell-derived treatment by engineering ASCs to produce an RNA called miR-150. This RNA inhibits biological processes that drive fibrosis. Experiments in cultured cells and a mouse model of fibrosis confirmed that miR-150 consistently improved the ASC secretome’s capacity to control liver fibrosis and minimize systemic inflammatory responses. This approach could thus offer a safe strategy for promoting tissue regeneration and preventing liver failure.

The proangiogenic effects of extracellular vesicles secreted by dental pulp stem cells derived from periodontally compromised teeth

Background

Although dental pulp stem cells (DPSCs) isolated from periodontally compromised teeth (P-DPSCs) have been demonstrated to retain pluripotency and regenerative potential, their use as therapeutics remains largely unexplored. In this study, we investigated the proangiogenic effects of extracellular vesicles (EVs) secreted by P-DPSCs using in vitro and in vivo testing models.

Methods

Patient-matched DPSCs derived from periodontally healthy teeth (H-DPSCs) were used as the control for P-DPSCs. Conditioned media (CMs) derived from H-DPSCs and P-DPSCs (H-CM and P-CM), CMs derived from both cell types pretreated with the EV secretion blocker GW4869 (H-GW and P-GW), and EVs secreted by H-DPSCs and P-DPSCs (H-EVs and P-EVs) were prepared to test their proangiogenic effects on endothelial cells (ECs). Cell proliferation, migration, and tube formation were assessed using the Cell Counting Kit-8 (CCK-8), transwell/scratch wound healing, and Matrigel assays, respectively. Specifically, quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and western blot analysis were used to examine the expression levels of angiogenesis-related genes/proteins in ECs in response to EV-based incubation. Finally, a full-thickness skin defect model was applied to test the effects of EVs on wound healing and new vessel formation.

Results

Both H-CM and P-CM promoted EC angiogenesis, but the proangiogenic effects were compromised when ECs were incubated in H-GW and P-GW, wherein the EV secretion was blocked by pretreatment with GW4869. In EV-based incubations, although both H-EVs and P-EVs were found to enhance the angiogenesis-related activities of ECs, P-EVs exerted a more robust potential to stimulate EC proliferation, migration, and tube formation. In addition, P-EVs led to higher expression levels of angiogenesis-related genes/proteins in ECs than H-EVs. Similarly, both P-EVs and H-EVs were found to accelerate wound healing and promote vascularization across skin defects in mice, but wounds treated with P-EVs resulted in a quicker healing outcome and enhanced new vessel formation.

Conclusions

The findings of the present study provide additional evidence that P-DPSCs derived from periodontally diseased teeth represent a potential source of cells for research and therapeutic use. Particularly, the proangiogenic effects of P-EVs suggest that P-DPSCs may be used to promote new vessel formation in cellular therapy and regenerative medicine.

Human umbilical cord mesenchymal stem cell-derived and dermal fibroblast-derived extracellular vesicles protect dermal fibroblasts from ultraviolet radiation-induced photoaging in vitro

Ultraviolet B (UVB) radiation is a major cause of aging in dermal fibroblasts. Human umbilical cord mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) show antioxidant activity. In this study, the anti-aging effects of MSC-EVs on dermal fibroblast photoaging induced by UVB radiation were evaluated, and the effects of extracellular vesicles derived from dermal fibroblasts (Fb-EVs) were compared. Human umbilical cord mesenchymal stem cells and human dermal fibroblasts were cultured, and MSC-EVs and Fb-EVs were isolated and characterized. Human dermal fibroblasts were cultured in the absence or presence of different concentrations of EVs 24 hours prior to UVB radiation exposure. Cell proliferation and cell cycle were evaluated, and senescent cells and intracellular ROS were detected. The expressions of matrix metalloproteinase-1 (MMP-1), extracellular matrix protein collagen type 1 (Col-1), and antioxidant proteins such as glutathione peroxidase 1 (GPX-1), superoxide dismutase (SOD), and catalase were also analyzed. Pretreatment with MSC-EVs or Fb-EVs significantly inhibited the production of ROS induced by UVB radiation, increased dermal fibroblast proliferation, protected cells against UVB-induced cell death and cell cycle arrest, and remarkably decreased the percentage of aged cells. Pretreatment with MSC-EVs or Fb-EVs promoted the expressions of GPX-1 and Col-1 and decreased the expression of MMP-1. Both MSC-EVs and Fb-EVs protected dermal fibroblasts from UVB-induced photoaging, likely through their antioxidant activity.

Extracellular vesicles: Potential role in osteoarthritis regenerative medicine

Osteoarthritis (OA) is a prevalent whole joint disease characterised by cartilage degradation, subchondral bone sclerosis and bone remodelling, and synovium inflammation, leading to pain, deformity, and cartilage dysfunction. Currently, there is no appropriate therapy for OA, and available treatments simply aim to reduce pain and swelling. Exosomes are membrane-bound extracellular vesicles secreted by almost all cells, receiving increasing interest because of their effect in cell-to-cell communication. Increasing evidence suggests that exosomes play an important role in cartilage physiological and pathological effects. This article reviews the potential role of exosomes in OA regenerative medicine. Special attention is given to mesenchymal stem cells-derived exosomes due to the extensive research on their cartilage repair property and their function as miRNA cargo. More investigations are needed for the effects of exosomes from synovial fluid and chondrocytes in joints. A better understanding of the mechanisms will contribute to a novel and promising therapy for OA patients.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

A better understanding of the role of extracellular vesicles in regenerative medicine will contribute to a novel and promising therapy for OA patients.

Transplantation of mesenchymal stem cells and their derivatives effectively promotes liver regeneration to attenuate acetaminophen-induced liver injury

Acetaminophen (APAP)-induced injury is a common clinical phenomenon that not only occurs in a dose-dependent manner but also occurs in some idiosyncratic individuals in a dose-independent manner. APAP overdose generally results in acute liver injury via the initiation of oxidative stress, endoplasmic reticulum (ER) stress, autophagy, liver inflammation, and microcirculatory dysfunction. Liver transplantation is the only effective strategy for treating APAP-induced liver failure, but liver transplantation is inhibited by scarce availability of donor liver grafts, acute graft rejection, lifelong immunosuppression, and unbearable costs. Currently, N-acetylcysteine (NAC) effectively restores liver functions early after APAP intake, but it does not protect against APAP-induced injury at the late stage. An increasing number of animal studies have demonstrated that mesenchymal stem cells (MSCs) significantly attenuate acute liver injury through their migratory capacity, hepatogenic differentiation, immunoregulatory capacity, and paracrine effects in acute liver failure (ALF). In this review, we comprehensively discuss the mechanisms of APAP overdose-induced liver injury and current therapies for treating APAP-induced liver injury. We then comprehensively summarize recent studies about transplantation of MSC and MSC derivatives for treating APAP-induced liver injury. We firmly believe that MSCs and their derivatives will effectively promote liver regeneration and liver injury repair in APAP overdose-treated animals and patients. To this end, MSC-based therapies may serve as an effective strategy for patients who are waiting for liver transplantation during the early and late stages of APAP-induced ALF in the near future.

Modulation of the in vitro angiogenic potential of human mesenchymal stromal cells from different tissue sources

Mesenchymal stromal cells (MSCs) have been widely exploited for the treatment of several conditions due to their intrinsic regenerative and immunomodulatory properties. MSC have demonstrated to be particularly relevant for the treatment of ischemic diseases, where MSC-based therapies can stimulate angiogenesis and induce tissue regeneration. Regardless of the condition targeted, recent analyses of MSC-based clinical trials have demonstrated limited benefits indicating a need to improve the efficacy of this cell product. Preconditioning MSC ex vivo through microenvironment modulation was found to improve MSC survival rate and thus prolong their therapeutic effect. This workstudy aims at enhancing the in vitro angiogenic capacity of a potential MSC-based medicinal product by comparing different sources of MSC and culture conditions. MSC from three different sources (bone marrow [BM], adipose tissue [AT], and umbilical cord matrix [UCM]) were cultured with xenogeneic-/serum-free culture medium under static conditions and their angiogenic potential was studied. Results indicated a higher in vitro angiogenic capacity of UCM MSC, compared with cells derived from BM and AT. Physicochemical preconditioning of UCM MSC through a microcarrier-based culture platform and low oxygen concentration (2% O₂ , compared with atmospheric air) increased the in vitro angiogenic potential of the cultured cells. Envisaging the clinical manufacturing of an allogeneic, off-the-shelf MSC-based product, preconditioned UCM MSC maintain the angiogenic gene expression profile upon cryopreservation and delivery processes in the conditions of our study. These results are expected to contribute to the development of MSC-based therapies in the context of angiogenesis.

Therapeutic Potential of Mesenchymal Stem Cells for Cancer Therapy

Mesenchymal stem cells (MSCs) are among the most frequently used cell type for regenerative medicine. A large number of studies have shown the beneficial effects of MSC-based therapies to treat different pathologies, including neurological disorders, cardiac ischemia, diabetes, and bone and cartilage diseases. However, the therapeutic potential of MSCs in cancer is still controversial. While some studies indicate that MSCs may contribute to cancer pathogenesis, emerging data reported the suppressive effects of MSCs on cancer cells. Because of this reality, a sustained effort to understand when MSCs promote or suppress tumor development is needed before planning a MSC-based therapy for cancer. Herein, we provide an overview on the therapeutic application of MSCs for regenerative medicine and the processes that orchestrates tissue repair, with a special emphasis placed on cancer, including central nervous system tumors. Furthermore, we will discuss the current evidence regarding the double-edged sword of MSCs in oncological treatment and the latest advances in MSC-based anti-cancer agent delivery systems.

Carosella E, Benkirane-Jessel N, Moreau P, Rouas-Freiss N, Bensoussan D, Huselstein C. Are the Immune Properties of Mesenchymal Stem Cells from Wharton's Jelly Maintained during Chondrogenic Differentiation?

Background: Umbilical mesenchymal stem/stromal cells (MSCs), and especially those derived from Wharton’s jelly (WJ), are a promising engineering tool for tissue repair in an allogeneic context. This is due to their differentiation capacity and immunological properties, like their immunomodulatory potential and paracrine activity. Hence, these cells may be considered an Advanced Therapy Medicinal Product (ATMP). The purpose of this work was to differentiate MSCs from WJ (WJ-MSCs) into chondrocytes using a scaffold and to evaluate, in vitro, the immunomodulatory capacities of WJ-MSCs in an allogeneic and inflammatory context, mimicked by IFN-γ and TNF-α priming during the chondrogenic differentiation. Methods: Scaffolds were made from hydrogel composed by alginate enriched in hyaluronic acid (Alg/HA). Chondrogenic differentiation, immunological function, phenotype expression, but also secreted soluble factors were the different parameters followed during 28 days of culture. Results: During chondrocyte differentiation, even in an allogeneic context, WJ-MSCs remained unable to establish the immunological synapse or to induce T cell alloproliferation. Moreover, interestingly, paracrine activity and functional immunomodulation were maintained during cell differentiation. Conclusion: These results show that WJ-MSCs remained hypoimmunogenic and retained immunomodulatory properties even when they had undergone chondrocyte differentiation.

Comparative Analysis of Adipose-Derived Stromal Cells and Their Secretome for Auricular Cartilage Regeneration

Adipose-derived stromal cells (ADSCs) can repair auricular cartilage defects. Furthermore, stem cell secretome may also be a promising biological therapeutic option, which is equal to or even superior to the stem cell. We explored the therapeutic efficacies of ADSCs and their secretome in terms of rabbit auricular cartilage regeneration. ADSCs and their secretome were placed into surgically created auricular cartilage defects. After 4 and 8 weeks, the resected auricles were histopathologically and immunohistochemically examined. We used real-time PCR to determine the levels of genes expressing collagen type II, transforming growth factor-β1 (TGF-β1), and insulin-like growth factor-1 (IGF-1). ADSCs significantly improved auricular cartilage regeneration at 4 and 8 weeks, compared to the secretome and PBS groups, as revealed by gross examination, histopathologically and immunohistochemically. ADSCs upregulated the expression of collagen type II, TGF-β1, and IGF-1 more so than did the secretome or PBS. The expression levels of collagen type II and IGF-1 were significantly higher at 8 weeks than at 4 weeks after ADSC injection. Although ADSCs thus significantly enhanced new cartilage formation, their secretome did not. Therefore, ADSCs may be more effective than their secretome in the repair of auricular cartilage defect.

Porous bio-click microgel scaffolds control hMSC interactions and promote their secretory properties

Human mesenchymal stem/stromal cells (hMSCs) are known to secrete numerous cytokines that signal to endogenous cells and aid in tissue regeneration. However, the role that biomaterial scaffolds can play in controlling hMSC secretory properties has been less explored. Here, microgels were co-assembled with hMSCs using three different microgel populations, with large (190 ± 100 μm), medium (110 ± 60 μm), and small (13 ± 6 μm) diameters, to create distinct porous environments that influenced hMSC clustering. Cells embedded in large diameter microgel networks resided in large clusters (~40 cells), compared to small clusters (~6 cells) observed in networks using medium diameter microgels and primarily single cells in small diameter microgel networks. Using a cytokine microarray, an overall increase in secretion was observed in scaffolds that promoted hMSC clustering, with over 60% of the measured cytokines most elevated in the large diameter microgel networks. N-cadherin interactions were identified as partially mediating these differences, so the microgel formulations were modified with an N-cadherin epitope, HAVDI, to mimic cell-cell interactions. Results revealed increased secretory properties for hMSCs in HAVDI functionalized scaffolds, even the non-clustered cells in small diameter microgel networks. Together, these results demonstrate opportunities for microgel-based scaffold systems for hMSC delivery and tailoring of porous materials properties to promote their secretory potential.