Bone marrow derived mesenchymal stem cells from aged mice have reduced wound healing, angiogenesis, proliferation and anti-apoptosis capabilities

Isolation and adipogenic differentiation of murine mesenchymal stem cells harvested from macrophage-depleted bone marrow and adipose tissue

INTRODUCTION AND PURPOSE

Mouse mesenchymal stem cells (MSCs) provide a resourceful tool to study physiological and pathological aspects of adipogenesis. Bone marrow-derived MSCs (BM-MSCs) and adipose tissue-derived MSCs (ASCs) are widely used for these studies. Since there is a wide spectrum of methods available, the purpose is to provide a focused hands-on procedural guide for isolation and characterization of murine BM-MSCs and ASCs and to effectively differentiate them into adipocytes.

METHODS AND RESULTS

Optimized harvesting procedures for murine BM-MSCs and ASCs are described and graphically documented. Since macrophages reside in bone-marrow and fat tissues and regulate the biological behaviour of BM-MSCs and ASCs, we included a procedure to deplete macrophages from the MSC preparations. The identity and stemness of BM-MSCs and ASCs were confirmed by flow cytometry using established markers. Since the composition and concentrations of adipogenic differentiation cocktails differ widely, we present a standardized four-component adipogenic cocktail, consisting of insulin, dexamethasone, 3-isobutyl-1-methylxanthine, and indomethacin to efficiently differentiate freshly isolated or frozen/thawed BM-MSCs and ASCs into adipocytes. We further included visualization and quantification protocols of the differentiated adipocytes.

CONCLUSION

This laboratory protocol was designed as a step-by-step procedure for harvesting murine BM-MSCs and ASCs and differentiating them into adipocytes.

Transplantation of Mesenchymal Stem Cells Derived from Old Rats Improves Healing and Biomechanical Properties of Vaginal Tissue Following Surgical Incision in Aged Rats

Pelvic floor dysfunction encompasses a group of disorders that negatively affect the quality of women's lives. These include pelvic organ prolapse (POP), urinary incontinence, and sexual dysfunction. The greatest risk factors for prolapse are increased parity and older age, with the largest group requiring surgical intervention being post-menopausal women over 65. Prolapse recurrence rates following surgery were reported to be as high as 30%. This may be attributed to ineffective healing in the elderly. Autologous stem cell transplantation during surgery may improve surgical results. In our previous studies, we showed that the transplantation of bone marrow-derived mesenchymal stem cells (MSCs) from young donor rats improved the healing of full-thickness vaginal surgical incision in the vaginal wall of old rats, demonstrated by both histological and functional analysis. In order to translate these results into the clinical reality of autologous MSC transplantation in elderly women, we sought to study whether stem cells derived from old donor animals would provide the same effect. In this study, we demonstrate that MSC transplantation attenuated the inflammatory response, increased angiogenesis, and exhibited a time-dependent impact on MMP9 localization. Most importantly, transplantation improved the restoration of the biomechanical properties of the vagina, resulting in stronger healed vaginal tissue. These results may pave the way for further translational studies focusing on the potential clinical autologous adjuvant transplantation of MSCs for POP repair for the improvement of surgical outcomes.

Stem cell therapy for cardiac regeneration: past, present, and future

Cardiac disorders remain the leading cause of mortality worldwide. Current clinical strategies, including drug therapy, surgical interventions, and organ transplantation offer limited benefits to patients without regenerating the damaged myocardium. Over the past decade, stem cell therapy has generated a keen interest owing to its unique self-renewal and immune privileged characteristics. Furthermore, the ability of stem cells to differentiate into specialized cell types, has made them a popular therapeutic tool against various diseases. This comprehensive review provides an overview of therapeutic potential of different types of stem cells in reference to cardiovascular diseases. Furthermore, it sheds light on the advantages and limitations associated with each cell type. An in-depth analysis of the challenges associated with stem cell research and the hurdles for its clinical translation and their possible solutions have also been elaborated upon. It examines the controversies surrounding embryonic stem cells and the emergence of alternative approaches, such as the use of induced pluripotent stem cells for cardiac therapeutic applications. Overall, this review serves as a valuable resource for researchers, clinicians, and policymakers involved in the field of regenerative medicine, guiding the development of safe and effective stem cell-based therapies to revolutionize patient care.

Senescence-Targeted and NAD+-Dependent SIRT1-Activated Nanoplatform to Counteract Stem Cell Senescence for Promoting Aged Bone Regeneration

Age-related bone defects are a leading cause of disability and mortality in elderly individuals, and targeted therapy to delay the senescence of bone marrow-derived mesenchymal stem cells (MSCs) has emerged as a promising strategy to rejuvenate bone regeneration in aged scenarios. More specifically, activating the nicotinamide adenine dinucleotide (NAD+)-dependent sirtuin 1 (SIRT1) pathway is demonstrated to effectively counteract MSC senescence and thus promote osteogenesis. Herein, based on an inventively identified senescent MSC-specific surface marker Kremen1, a senescence-targeted and NAD+ dependent SIRT1 activated nanoplatform is fabricated with a dual delivery of resveratrol (RSV) (SIRT1 promoter) and nicotinamide riboside (NR, NAD+ precursor). This targeting nanoplatform exhibits a strong affinity for senescent MSCs through conjugation with anti-Kremen1 antibodies and enables specifically responsive release of NR and RSV in lysosomes via senescence-associated β-galactosidase-stimulated enzymatic hydrolysis of the hydrophilic chain. Furthermore, this nanoplatform performs well in promoting aged bone formation both in vitro and in vivo by boosting NAD+, activating SIRT1, and delaying MSC senescence. For the first time, a novel senescent MSC-specific surface marker is identified and aged bone repair is rejuvenated by delaying senescence of MSCs using an active targeting platform. This discovery opens up new insights for nanotherapeutics aimed at age-related diseases.

Aged mesenchymal stem cells and inflammation: from pathology to potential therapeutic strategies

Natural ageing of organisms and corresponding age-related diseases result mainly from stem cell ageing and "inflammaging". Mesenchymal stem cells (MSCs) exhibit very high immune-regulating capacity and are promising candidates for immune-related disease treatment. However, the effect of MSC application is not satisfactory for some patients, especially in elderly individuals. With ageing, MSCs undergo many changes, including altered cell population reduction and differentiation ability, reduced migratory and homing capacity and, most important, defective immunosuppression. It is necessary to explore the relationship between the "inflammaging" and aged MSCs to prevent age-related diseases and increase the therapeutic effects of MSCs. In this review, we discuss changes in naturally ageing MSCs mainly from an inflammation perspective and propose some ideas for rejuvenating aged MSCs in future treatments.

Bone Healing Gone Wrong: Pathological Fracture Healing and Non-Unions-Overview of Basic and Clinical Aspects and Systematic Review of Risk Factors

Bone healing is a multifarious process involving mesenchymal stem cells, osteoprogenitor cells, macrophages, osteoblasts and -clasts, and chondrocytes to restore the osseous tissue. Particularly in long bones including the tibia, clavicle, humerus and femur, this process fails in 2-10% of all fractures, with devastating effects for the patient and the healthcare system. Underlying reasons for this failure are manifold, from lack of biomechanical stability to impaired biological host conditions and wound-immanent intricacies. In this review, we describe the cellular components involved in impaired bone healing and how they interfere with the delicately orchestrated processes of bone repair and formation. We subsequently outline and weigh the risk factors for the development of non-unions that have been established in the literature. Therapeutic prospects are illustrated and put into clinical perspective, before the applicability of biomarkers is finally discussed.

Human Mesenchymal Stem Cells Derived from the Placenta and Chorion Suppress the Proliferation while Enhancing the Migration of Human Breast Cancer Cells

BACKGROUND

Breast cancer is the most frequently diagnosed malignancy among women, resulting from abnormal proliferation of mammary epithelial cells. The highly vascularized nature of breast tissue leads to a high incidence of breast cancer metastases, resulting in a poor survival rate. Previous studies suggest that human mesenchymal stem cells (hMSCs) play essential roles in the growth, metastasis, and drug responses of many cancers, including breast cancer. However, hMSCs from different sources may release different combinations of cytokines that affect breast cancer differently.

METHODS

In this study, we have isolated hMSCs from the placenta (PL-hMSCs) and the chorion (CH-hMSCs) and determined how these hMSCs affect the proliferation, migration, invasion, and gene expression of two human breast cancer cells, MCF-7 and MDA-MB-231, as well as the possible mechanisms underlying those effects.

RESULTS

The results showed that the soluble factors derived from PL-hMSCs and CH-hMSCs inhibited the proliferation of MCF-7 and MDA-MB-231 cells but increased the migration of MDA-MB-231 cells. The study of gene expression showed that PL-hMSCs and CH-hMSCs downregulated the expression levels of the protooncogene CyclinD1 while upregulating the expression levels of tumor suppressor genes, P16 and P21 in MCF-7 and MDA-MB-231 cells. Furthermore, hMSCs from both sources also increased the expression levels of MYC, SNAI1, and TWIST, which promote the epithelial-mesenchymal transition and migration of breast cancer cells in both cell lines. The functional study suggests that the suppressive effect of CH-hMSCs and PL-hMSCs on MCF-7 and MDA-MB231 cell proliferation was mediated, at least in part, through IFN-γ.

CONCLUSIONS

Our study suggests that CH-hMSCs and PL-hMSCs inhibited breast cancer cell proliferation by negatively regulating CYCLIND1 expression and upregulating the expression of the P16 and P21 genes. In contrast, hMSCs from both sources enhanced breast cancer cell migration, possibly by increasing the expression of MYC, SNAI1, and TWIST genes in those cells.

Hydrogel patch with pretreated stem cells accelerates wound closure in diabetic rats

Delay in wound healing is a diabetes mellites resulting disorder causing persistent microbial infections, pain, and poor quality of life. This disorder is treated by several strategies using natural biomaterials, growth factors and stem cells molded into various scaffolds which possess the potential to accelerate the closure of impaired diabetic wounds. In this study, we developed a hydrogel patch using chitosan (CS) and polyethylene glycol (PEG) with laden bone marrow-derived mesenchymal stem cells (BMSCs) that were pretreated with fibroblast growth factor 21 (FGF21). The developed hydrogel patches were characterized by scanning electron microscopy and fourier transform infrared (FTIR) spectroscopy. After studying the swelling behavior, growth factor (FGF21) was used to modulate BMSC in the hyperglycemic environment. Later, FGF21 treated BMSC were embedded in CS/PEG hydrogel patch and their wound closure effect was assessed in diabetic rats. The results showed that CS/PEG hydrogel patches have good biocompatibility and possess efficient BMSC recruiting properties. The application of CS/PEG hydrogel patches accelerated wound closure in diabetic rats as compared to the control groups. However, the use of FGF21 pretreated BMSCs laded CS/PEG hydrogel patches further increased the therapeutic efficacy of wound closure in diabetic rats. This study demonstrated that the application of a hydrogel patch of CS/PEG with FGF21 pretreated BMSCs improves diabetic wound healing, but further studies are needed on larger animals before the use of these dressings in clinical trials.

The transplantation of rapamycin-treated senescent human mesenchymal stem cells with enhanced proangiogenic activity promotes neovascularization and ischemic limb salvage in mice

Few therapies can reverse the proangiogenic activity of senescent mesenchymal stromal/stem cells (MSCs). In this study, we investigated the effects of rapamycin on the proangiogenic ability of senescent human umbilical cord MSCs (UCMSCs). An in vitro replicative senescent cell model was established in cultured UCMSCs. We found that late passage (P25 or later) UCMSCs (LP-UCMSCs) exhibited impaired proangiogenic abilities. Treatment of P25 UCMSCs with rapamycin (900 nM) reversed the senescent phenotype and notably enhanced the proangiogenic activity of senescent UCMSCs. In a nude mouse model of hindlimb ischemia, intramuscular injection of rapamycin-treated P25 UCMSCs into the ischemic limb significantly promoted neovascularization and ischemic limb salvage. We further analyzed the changes in the expression of angiogenesis-associated genes in rapamycin-primed MSCs and found higher expression of several genes related to angiogenesis, such as VEGFR2 and CTGF/CCN2, in primed cells than in unprimed MSCs. Taken together, our data demonstrate that rapamycin is a potential drug to restore the proangiogenic activity of senescent MSCs, which is of importance in treating ischemic diseases and tissue engineering.

The promising roles of macrophages in geriatric hip fracture

As aging becomes a global burden, the incidence of hip fracture (HF), which is the most common fracture in the elderly population and can be fatal, is rapidly increasing, and its extremely high fatality rate places significant medical and financial burdens on patients. Fractures trigger a complex set of immune responses, and recent studies have shown that with aging, the immune system shows decreased activity or malfunctions in a process known as immune senescence, leading to disease and death. These phenomena are the reasons why elderly individuals typically exhibit chronically low levels of inflammation and increased rates of infection and chronic disease. Macrophages, which are key players in the inflammatory response, are critical in initiating the inflammatory response, clearing pathogens, controlling the innate and adaptive immune responses and repairing damaged tissues. Tissue-resident macrophages (TRMs) are widely present in tissues and perform immune sentinel and homeostatic functions. TRMs are combinations of macrophages with different functions and phenotypes that can be directly influenced by neighboring cells and the microenvironment. They form a critical component of the first line of defense in all tissues of the body. Immune system disorders caused by aging could affect the biology of macrophages and thus the cascaded immune response after fracture in various ways. In this review, we outline recent studies and discuss the potential link between monocytes and macrophages and their potential roles in HF in elderly individuals.

Updated Living Systematic Review and Meta-analysis of Controlled Trials of Mesenchymal Stromal Cells to Treat COVID-19: A Framework for Accelerated Synthesis of Trial Evidence for Rapid Approval-FASTER Approval

Background

Mesenchymal stromal cells (MSCs) may reduce mortality in patients with COVID-19; however, early evidence is based on few studies with marked interstudy heterogeneity. The second iteration of our living systematic review and meta-analysis evaluates a framework needed for synthesizing evidence from high-quality studies to accelerate consideration for approval.

Methods

A systematic search of the literature was conducted on November 15, 2021, to identify all English-language, full-text, and controlled clinical studies examining MSCs to treat COVID-19 (PROSPERO: CRD42021225431).

Findings

Eleven studies were identified (403 patients with severe and/or critical COVID-19, including 207 given MSCs and 196 controls). All 11 studies reported mortality and were pooled through random-effects meta-analysis. MSCs decreased relative risk of death at study endpoint (RR: 0.50 [95% CI, 0.34-0.75]) and RR of death at 28 days after treatment (0.19 [95% CI], 0.05-0.78) compared to controls. MSCs also decreased length of hospital stay (mean difference (MD: −3.97 days [95% CI, −6.09 to −1.85], n = 5 studies) and increased oxygenation levels at study endpoint compared to controls (MD: 105.62 mmHg O₂ [95% CI, 73.9-137.3,], n = 3 studies). Only 2 of 11 studies reported on all International Society for Cellular Therapy (ISCT) criteria for MSC characterization. Included randomized controlled trials were found to have some concerns (n = 2) to low (n = 4) risk of bias (RoB), while all non-randomized studies were found to have moderate (n = 5) RoB.

Interpretation

Our updated living systematic review concludes that MSCs can likely reduce mortality in patients with severe or critical COVID-19. A master protocol based on our Faster Approval framework appears necessary to facilitate the more accelerated accumulation of high-quality evidence that would reduce RoB, improve consistency in product characterization, and standardize outcome reporting.

Bio-Assisted Synthesis and Characterization of Zinc Oxide Nanoparticles from Lepidium sativum and Their Potent Antioxidant, Antibacterial and Anticancer Activities

Nanotechnology is an emerging area of research that deals with the production, manipulation, and application of nanoscale materials. Bio-assisted synthesis is of particular interest nowadays, to overcome the limitations associated with the physical and chemical means. The aim of this study was to synthesize ZnO nanoparticles (NPs) for the first time, utilizing the seed extract of Lepidium sativum. The synthesized NPs were confirmed through various spectroscopy and imagining techniques, such as XRD, FTIR, HPLC, and SEM. The characterized NPs were then examined for various in vitro biological assays. Crystalline, hexagonal-structured NPs with an average particle size of 25.6 nm were obtained. Biosynthesized ZnO NPs exhibited potent antioxidant activities, effective α-amylase inhibition, moderate urease inhibition (56%), high lipase-inhibition (71%) activities, moderate cytotoxic potential, and significant antibacterial activity. Gene expression of caspase in HepG2 cells was enhanced along with elevated production of ROS/RNS, while membrane integrity was disturbed upon the exposure of NPs. Overall results indicated that bio-assisted ZnO NPs exhibit excellent biological potential and could be exploited for future biomedical applications. particularly in antimicrobial and cancer therapeutics. Moreover, this is the first comprehensive study on Lepidium sativum-mediated synthesis of ZnO nanoparticles and evaluation of their biological activities.

The Hunt Is On! In Pursuit of the Ideal Stem Cell Population for Cartilage Regeneration

Cartilage injury and degeneration are hallmarks of osteoarthritis (OA), the most common joint disease. OA is a major contributor to pain, loss of function, and reduced quality of life. Over the last decade, considerable research efforts have focused on cell-based therapies, including several stem cell-derived approaches to reverse the cartilage alterations associated with OA. Although several tissue sources for deriving cell-based therapies have been identified, none of the resident stem cell populations have adequately fulfilled the promise of curing OA. Indeed, many cell products do not contain true stem cells. As well, issues with aggressive marketing efforts, combined with a lack of evidence regarding efficacy, lead the several national regulatory bodies to discontinue the use of stem cell therapy for OA until more robust evidence becomes available. A review of the evidence is timely to address the status of cell-based cartilage regeneration. The promise of stem cell therapy is not new and has been used successfully to treat non-arthritic diseases, such as hematopoietic and muscle disorders. These fields of regenerative therapy have the advantage of a considerable foundation of knowledge in the area of stem cell repair mechanisms, the role of the stem cell niche, and niche-supporting cells. This foundation is lacking in the field of cartilage repair. So, where should we look for the ideal stem cell to regenerate cartilage? It has recently been discovered that cartilage itself may contain a population of SC-like progenitors. Other potential tissues include stem cell-rich dental pulp and the adolescent growth plate, the latter of which contains chondrocyte progenitors essential for producing the cartilage scaffold needed for bone growth. In this article, we review the progress on stem cell therapies for arthritic disorders, focusing on the various stem cell populations previously used for cartilage regeneration, successful cases of stem cell therapies in muscle and hemopoietic disorders, some of the reasons why these other fields have been successful (i.e., “lessons learned” to be applied to OA stem cell therapy), and finally, novel potential sources of stem cells for regenerating damaged cartilage in vivo.

Potential antimicrobial, antidiabetic, catalytic, antioxidant and ROS/RNS inhibitory activities of Silybum marianum mediated biosynthesized copper oxide nanoparticles

Use of medicinal plants for the biosynthesis of nanoparticles offers several advantages over other synthesis approaches. Plants contain a variety of bioactive compounds that can participate in reduction and capping of nanoparticles. Plant mediated synthesis has the leverage of cost effectiveness, eco-friendly approach and sustained availability. In the current study Silybum marianum, a medicinally valuable plant rich in silymarin content, is used as a reducing and stabilizing agent for the fabrication of nanoparticles. Biosynthesized CuO-NPs were characterized using High Performance Liquid Chromatography (HPLC), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Dynamic Light Scattering (DLS) techniques. Characterization revealed that CuO-NPs having a crystalline structure showed spherical morphology with an average size of 15 nm. HPLC analysis demonstrated conjugation of various silymarin components, especially the presence of silybin A (705.06 ± 1.59 mg g^-1 DW). CuO-NPs exhibited strong bactericidal potency against clinically important pathogenic bacterial strains e.g. Enterobacter aerogenes and Salmonella typhi with an inhibition zone of 18 ± 1.3 mm and 17 ± 1.2 mm, respectively. Synthesized nanoparticles indicated a dose dependent cytotoxic effect against fibroblast cells exhibiting a percentage cell viability of 83.60 ± 1.505% and 55.1 ± 1.80% at 25 μg mL^-1 and 100 μg mL^-1 concentration, respectively. Moreover, CuO-NPs displayed higher antioxidant potential in terms of (TAC: 96.9 ± 0.26 μg AAE/mg), (TRP: 68.8 ± 0.35 μg AAE/mg), (DPPH: 55.5 ± 0.62%), (ABTS: 332.34 μM) and a significant value for (FRAP: 215.40 μM). Furthermore, enzyme inhibition assays also exhibited excellent enzyme inhibition potential against α-amylase (35.5 ± 1.54%), urease (78.4 ± 1.26%) and lipase (80.50.91%), respectively. Overall findings indicated that biosynthesized CuO-NPs possess immense in vitro biological and biomedical properties and could be used as a broad-spectrum agent for a wider range of biomedical applications.

Cellular and Humoral Immunogenicity Investigation of Single and Repeated Allogeneic Tenogenic Primed Mesenchymal Stem Cell Treatments in Horses Suffering From Tendon Injuries

The use of mesenchymal stem cells (MSCs) for the treatment of equine tendon disease is widely investigated because of their regenerative and immunomodulatory potential. However, questions have been raised concerning the immunogenic properties of allogeneic MSCs. Therefore, two studies were conducted to assess the safety of equine allogeneic peripheral blood-derived tenogenic primed MSCs (tpMSCs). The objective was to evaluate if a single and repeated tpMSC administration induced a cellular and humoral immune response in horses suffering from tendon injuries. Horses enrolled in the first study (n = 8) had a surgically induced superficial digital flexor tendon core lesion and were treated intralesionally with tpMSCs. Before and after treatment the cellular immunogenicity was assessed by modified mixed lymphocyte reactions. The humoral immune response was investigated using a crossmatch assay. Presence of anti-bovine serum albumin (BSA) antibodies was detected via ELISA. Horses enrolled in the second study (n = 6) suffered from a naturally occurring tendon injury and were treated twice with tpMSCs. Blood was collected after the second treatment for the same immunological assays. No cellular immune response was found in any of the horses. One out of eight horses in the first study and none of the horses in the second study had anti-tpMSC antibodies. This particular horse had an equine sarcoid and further investigation revealed presence of antibodies against sarcoid cells and epithelial-like stem cells before treatment, which increased after treatment. Additionally, formation of antibodies against BSA was observed. These findings might indicate a non-specific immune response generated after treatment. Serum from the other horses revealed no such antibody formation. These two studies showed that the administration of tpMSCs did not induce a cellular or humoral immune response following an intralesional single or repeated (two consecutive) allogeneic tpMSC treatment in horses with tendon injury, except for one horse. Therefore, a larger field study should confirm these findings and support the safe use of tpMSCs as a therapeutic for horses suffering from tendon injuries.

Strategies to improve regenerative potential of mesenchymal stem cells

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

Age-associated changes in microRNAs affect the differentiation potential of human mesenchymal stem cells: Novel role of miR-29b-1-5p expression

Age-associated osteoporosis is widely accepted as involving the disruption of osteogenic stem cell populations and their functioning. Maintenance of the local bone marrow (BM) microenvironment is critical for regulating proliferation and differentiation of the multipotent BM mesenchymal stromal/stem cell (BMSC) population with age. The potential role of microRNAs (miRNAs) in modulating BMSCs and the BM microenvironment has recently gained attention. However, miRNAs expressed in rapidly isolated BMSCs that are naïve to the non-physiologic standard tissue culture conditions and reflect a more accurate in vivo profile have not yet been reported. Here we directly isolated CD271 positive (+) BMSCs within hours from human surgical BM aspirates without culturing and performed microarray analysis to identify the age-associated changes in BMSC miRNA expression. One hundred and two miRNAs showed differential expression with aging. Target prediction and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed that the up-regulated miRNAs targeting genes in bone development pathways were considerably enriched. Among the differentially up-regulated miRNAs the novel passenger strand miR-29b-1-5p was abundantly expressed as a mature functional miRNA with aging. This suggests a critical arm-switching mechanism regulates the expression of the miR-29b-1-5p/3p pair shifting the normally degraded arm, miR-29b-1-5p, to be the dominantly expressed miRNA of the pair in aging. The normal guide strand miR-29b-1-3p is known to act as a pro-osteogenic miRNA. On the other hand, overexpression of the passenger strand miR-29b-1-5p in culture-expanded CD271+ BMSCs significantly down-regulated the expression of stromal cell-derived factor 1 (CXCL12)/ C-X-C chemokine receptor type 4 (SDF-1(CXCL12)/CXCR4) axis and other osteogenic genes including bone morphogenetic protein-2 (BMP-2) and runt-related transcription factor 2 (RUNX2). In contrast, blocking of miR-29b-1-5p function using an antagomir inhibitor up-regulated expression of BMP-2 and RUNX2 genes. Functional assays confirmed that miR-29b-1-5p negatively regulates BMSC osteogenesis in vitro. These novel findings provide evidence of a pathogenic anti-osteogenic role for miR-29b-1-5p and other miRNAs in age-related defects in osteogenesis and bone regeneration.

Biological Characteristics and Optical Reflectance Spectroscopy of Human Placenta Derived Mesenchymal Stem Cells for Application in Regenerative Medicine

Introduction: The efficiency of stem cell isolation, culture, and biological characterization techniques for treatment is facing serious challenges. The purpose of this study was to provide a protocol for isolation and culture of three types of mesenchymal stem cells (MSCs) derived from the human placenta, amniotic membrane, and umbilical cord with high efficiency used for cell therapy. Methods: During this experimental laboratory study, 10 complete placenta samples were prepared from cesarean section mothers. The protocol for isolation and culture of mesenchymal cells from the placenta tissue, umbilical cord, and amniotic membrane was enzymatically optimized. The morphological features of mesenchymal cells were investigated using an inverted microscope and their biological features were measured using flow cytometry. The differentiation potential of the cells was evaluated by measuring their differentiation capacity into osteocytes and adipocytes. The absorption and reflectance features of the cells were recorded by optical spectroscopy. Finally, the data were statistically analyzed. Results: The expression of CD44, CD73, CD90 and CD29 markers in human placenta tissue-derived cells was significant. CD14, CD34 and CD45 markers were not expressed or were slightly expressed. These cells were highly viable and successfully differentiated into osteocytes and adipocytes. MSCs absorbed more light than visible light by showing light absorption peaks at wavelengths of about 435 and 550 nm. Conclusion: The protocol used in this study for isolation and culture of human placenta tissue-derived MSCs had significant efficiency for the production of MSCs for use in cell therapy and tissue engineering.

Tumorigenic Aspects of MSC Senescence-Implication in Cancer Development and Therapy

As an organism ages, many physiological processes change, including the immune system. This process, called immunosenescence, characterized by abnormal activation and imbalance of innate and adaptive immunity, leads to a state of chronic low-grade systemic inflammation, termed inflammaging. Aging and inflammaging are considered to be the root of many diseases of the elderly, as infections, autoimmune and chronic inflammatory diseases, degenerative diseases, and cancer. The role of mesenchymal stromal/stem cells (MSCs) in the inflammaging process and the age-related diseases is not completely established, although numerous features of aging MSCs, including altered immunomodulatory properties, impeded MSC niche supporting functions, and senescent MSC secretory repertoire are consistent with inflammaging development. Although senescence has its physiological function and can represent a mechanism of tumor prevention, in most cases it eventually transforms into a deleterious (para-)inflammatory process that promotes tumor growth. In this review we are going through current literature, trying to explore the role of senescent MSCs in making and/or sustaining a microenvironment permissive to tumor development and to analyze the therapeutic options that could target this process.

Human bone marrow-derived mesenchymal stromal cells cultured in serum-free media demonstrate enhanced antifibrotic abilities via prolonged survival and robust regulatory T cell induction in murine bleomycin-induced pulmonary fibrosis

Background

Mesenchymal stromal cells (MSCs) are a potential therapeutic tool for pulmonary fibrosis. However, ex vivo MSC expansion using serum poses risks of harmful immune responses or unknown pathogen infections in the recipients. Therefore, MSCs cultured in serum-free media (SF-MSCs) are ideal for clinical settings; however, their efficacy in pulmonary fibrosis is unknown. Here, we investigated the effects of SF-MSCs on bleomycin-induced pulmonary inflammation and fibrosis compared to those of MSCs cultured in serum-containing media (S-MSCs).

Methods

SF-MSCs and S-MSCs were characterized in vitro using RNA sequence analysis. The in vivo kinetics and efficacy of SF-MSC therapy were investigated using a murine model of bleomycin-induced pulmonary fibrosis. For normally distributed data, Student’s t test and one-way repeated measures analysis of variance followed by post hoc Tukey’s test were used for comparison between two groups and multiple groups, respectively. For non-normally distributed data, Kruskal–Wallis and Mann–Whitney U tests were used for comparison between groups, using e Bonferroni’s correction for multiple comparisons. All tests were two-sided, and P < 0.05 was considered statistically significant.

Results

Serum-free media promoted human bone marrow-derived MSC expansion and improved lung engraftment of intravenously administered MSCs in recipient mice. SF-MSCs inhibited the reduction in serum transforming growth factor-β1 and the increase of interleukin-6 in both the serum and the bronchoalveolar lavage fluid during bleomycin-induced pulmonary fibrosis. SF-MSC administration increased the numbers of regulatory T cells (Tregs) in the blood and lungs more strongly than in S-MSC administration. Furthermore, SF-MSCs demonstrated enhanced antifibrotic effects on bleomycin-induced pulmonary fibrosis, which were diminished by antibody-mediated Treg depletion.

Conclusions

SF-MSCs significantly suppressed BLM-induced pulmonary inflammation and fibrosis through enhanced induction of Tregs into the lungs and corrected the dysregulated cytokine balance. Therefore, SF-MSCs could be a useful tool for preventing pulmonary fibrosis progression without the demerits of serum use.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02574-5.

Comparison of the Donor Age-Dependent and In Vitro Culture-Dependent Mesenchymal Stem Cell Aging in Rat Model

Clinical experiments suggest that mesenchymal stem cells (MSCs) may be useful for tissue repair therapies or treatment of the autoimmune disorders. There is still lack of consensus concerning the age limit of MSC donors, majority of researchers suggest the autologous MSC therapies of patients not exceeding age limit of 55-60 yrs. The purpose of our study was to compare the selected parameters of MSCs from adipose tissue (adipose stem cell, ASC) collected from young and old rats of ages corresponding to patient's ages 25 yrs. and 80 yrs., respectively. The differences of parameters of ASCs from young and old animals were compared with the differences between ASCs from short-term (3 passage) and long-term (30 passage) in vitro culture. Cell morphology, surface marker expression, growth potential, metabolic activity, β-galactosidase activity, clonogenic potential, angiogenic potential, and differentiation ability of ASCs from young and aged animals and from in vitro cultures at 3rd and 30th passages were compared and analyzed. It may be concluded that ASCs may be applied for autologous transplantations in aged patients. Comparison of ASC aging dynamics depending on host aging or in vitro culture duration suggests that long-term in vitro culture may affect ASCs more than natural aging process of their host. We suggest that ASCs expanded in vitro prior to their clinical use must be carefully screened for the possible aging effects resulting not only from donor age, but from the duration of their in vitro culture.

Xenotransplantation of neonatal porcine bone marrow-derived mesenchymal stem cells improves murine hind limb ischemia through lymphangiogenesis and angiogenesis

BACKGROUND

The clinical utility of stem cell therapy for peripheral artery disease has not been fully discussed, and one obstacle is limited donor supplies. In this study, we attempted to rescue mouse ischemic hind limb by xenotransplantation of neonatal porcine bone marrow-derived mesenchymal stem cells (npBM-MSCs).

METHODS

Neonatal porcine bone marrow-derived mesenchymal stem cells were transplanted to ischemic hind limbs of male C57BL/6J mice (npBM-MSCs group). Mice with syngeneic transplantation of mouse BM-MSCs (mBM-MSCs group) were also prepared for comparison. The angiogenic effects were evaluated by recovery of blood flow on laser Doppler imaging, histologic findings, and genetic and protein levels of angiogenic factors.

RESULTS

Regarding laser Doppler assessments, blood flow in the hind limb was rapidly recovered in the npBM-MSCs group, compared with that in the mBM-MSCs group (P = .016). Compared with the mBM-MSCs group, the npBM-MSCs group had early and prominent lymphangiogenesis [P < .05 on both post-operative days (PODs) 3 and 7] but had similar angiogenesis. Regarding genomic assessments, xenotransplantation of npBM-MSCs enhanced the expressions of both porcine and murine Vegfc in the hind limbs by POD 3. Interestingly, the level of murine Vegfc expression was significantly higher in the npBM-MSCs group than in the mBM-MSCs group on PODs 3 and 7 (P < .001 for both). Furthermore, the secreted VEGFC protein level was higher from npBM-MSCs than from mBM-MSCs (P < .001).

CONCLUSION

Xenotransplantation of npBM-MSCs contributed to the improvement of hind limb ischemia by both angiogenesis and lymphangiogenesis, especially promotion of the latter. npBM-MSCs may provide an alternative to autologous and allogeneic MSCs for stem cell therapy of critical limb ischemia.

Features of a simvastatin-loaded multi-layered co-electrospun barrier membrane for guided bone regeneration

A novel tri-layer membrane consisting of polycaprolactone (PCL) fibrous sheets and structured nanofibers with a gelatin (Gt) shell and a simvastatin-containing PCL core (PCL-Gt/PCL-simvastatin membrane) was prepared. The soft external layer comprised of Gt/PCL-simvastatin, the external layer of PCL and the middle layer of both microfilaments, interwoven together. The membrane was designed to promote osteoinduction and act as a barrier against cells but not against water and molecules in order to promote guided bone regeneration. The structure of the membrane was characterized by scanning electronic microscopy. The in vitro release rates of simvastatin over 32 days were determined by high-performance liquid chromatography. For in vitro biological assays, bone marrow mesenchymal stem cells and human fibroblasts were cultured on the different surfaces of the membrane. Cell adhesion, proliferation, distribution, and differentiation were examined. For in vivo testing, cranial defects were created in rabbits to assess the amount of new bone formed for each membrane. The results revealed that membranes with multi-layered structures showed good cell viability and effective osteoinductive and barrier properties. These results suggest that the novel multi-layered PCL-Gt/PCL-simvastatin membranes have great potential for bone tissue engineering.

Stem Cell Therapy Potency in Personalizing Severe COVID-19 Treatment

Currently, there are no specific and efficient vaccines or drugs for COVID-19, particularly in severe cases. A wide range of variations in the clinical symptoms of different patients attributed to genomic differences. Therefore, personalized treatments seem to play a critical role in improving these symptoms and even similar conditions. Prompted by the uncertainties in the area of COVID-19 therapies, we reviewed the published papers and concepts to gather and provide useful information to clinicians and researchers interested in personalized medicine and cell-based therapy. One novel aspect of this study focuses on the potential application of personalized medicine in treating severe cases of COVID-19. However, it is theoretical, as any real-world examples of the use of genuinely personalized medicine have not existed yet. Nevertheless, we know that stem cells, especially MSCs, have immune-modulatory effects and can be stored for future personalized medicine applications. This theory has been conjugated with some evidence that we review in the present study. Besides, we discuss the importance of personalized medicine and its possible aspects in COVID-19 treatment, then review the cell-based therapy studies for COVID-19 with a particular focus on stem cell-based therapies as a primary personalized tool medicine. However, the idea of cell-based therapy has not been accepted by several scientific communities due to some concerns of lack of satisfactory clinical studies; still, the MSCs and their clinical outcomes have been revealed the safety and potency of this therapeutic approach in several diseases, especially in the immune-mediated inflammatory diseases and some incurable diseases. Promising outcomes have resulted in that clinical studies are going to continue.

MicroRNAs are critical regulators of senescence and aging in mesenchymal stem cells

MicroRNAs (miRNAs) have recently come under scrutiny for their role in various age-related diseases. Similarly, cellular senescence has been linked to disease and aging. MicroRNAs and senescence likely play an intertwined role in driving these pathologic states. In this review, we present the connection between these two drivers of age-related disease concerning mesenchymal stem cells (MSCs). First, we summarize key miRNAs that are differentially expressed in MSCs and other musculoskeletal lineage cells during senescence and aging. Additionally, we also reviewed miRNAs that are regulated via traditional senescence-associated secretory phenotype (SASP) cytokines in MSC. Lastly, we summarize miRNAs that have been found to target components of the cell cycle arrest pathways inherently activated in senescence. This review attempts to highlight potential miRNA targets for regenerative medicine applications in age-related musculoskeletal disease.

Mesenchymal Stromal Cell Therapy in the Management of Perianal Fistulas in Crohn's Disease: An Up-To-Date Review

Crohn’s Disease (CD) is a chronic inflammatory disorder that potentially involves the entire gastrointestinal tract. Perianal fistulizing CD (pCD) is a serious and frequent complication associated with significant morbidities and a heavy negative impact on quality of life. The aim of CD treatment is to induce and maintain disease remission and to promote mucosal repair. Unfortunately, even the best therapeutic regimens in pCD do not have long-term efficacy and cause a significant number of side effects. Therefore, it is mandatory to study new therapeutical options such as the use of mesenchymal stromal cells (MSCs). These cells promote tissue repair via the induction of immunomodulation. The present review aims to analyze the existing updated scientific literature on MSCs adoption in the treatment of pCD to evaluate its efficacy and safety and to compare the use of bone marrow and adipose tissue derived MSCs, type of administration, and dose required for recovery.

Tissue-specific angiogenic and invasive properties of human neonatal thymus and bone MSCs: Role of SLIT3-ROBO1

Although mesenchymal stem/stromal cells (MSCs) are being explored in numerous clinical trials as proangiogenic and proregenerative agents, the influence of tissue origin on the therapeutic qualities of these cells is poorly understood. Complicating the functional comparison of different types of MSCs are the confounding effects of donor age, genetic background, and health status of the donor. Leveraging a clinical setting where MSCs can be simultaneously isolated from discarded but healthy bone and thymus tissues from the same neonatal patients, thereby controlling for these confounding factors, we performed an in vitro and in vivo paired comparison of these cells. We found that both neonatal thymus (nt)MSCs and neonatal bone (nb)MSCs expressed different pericytic surface marker profiles. Further, ntMSCs were more potent in promoting angiogenesis in vitro and in vivo and they were also more motile and efficient at invading ECM in vitro. These functional differences were in part mediated by an increased ntMSC expression of SLIT3, a factor known to activate endothelial cells. Further, we discovered that SLIT3 stimulated MSC motility and fibrin gel invasion via ROBO1 in an autocrine fashion. Consistent with our findings in human MSCs, we found that SLIT3 and ROBO1 were expressed in the perivascular cells of the neonatal murine thymus gland and that global SLIT3 or ROBO1 deficiency resulted in decreased neonatal murine thymus gland vascular density. In conclusion, ntMSCs possess increased proangiogenic and invasive behaviors, which are in part mediated by the paracrine and autocrine effects of SLIT3.

Exosomes derived from atorvastatin-pretreated MSC accelerate diabetic wound repair by enhancing angiogenesis via AKT/eNOS pathway

Background

Mesenchymal stem cell (MSC)-derived exosomes emerge as promising candidates for treating delayed wound healing in diabetes due to the promotion of angiogenesis. Preconditioned MSC with chemical or biological factors could possibly enhance the biological activities of MSC-derived exosomes. The purpose of this research focused on whether exosomes derived from the bone marrow MSC (BMSC) pretreated with atorvastatin (ATV), could exhibit better pro-angiogenic ability in diabetic wound healing or not and its underlying molecular mechanism.

Methods

We isolated exosomes from non-pretreated BMSC (Exos) and ATV pretreated BMSC (ATV-Exos) and evaluated their characterization by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and Western blotting. In vivo, we made full-thickness skin defects in streptozotocin (STZ)-induced diabetic rats and the defects received multiple-point injection with PBS, Exos, or ATV-Exos. Two weeks later, histological analysis was conducted to evaluate the impact of different treatments on wound healing and the neovascularization was measured by micro-CT. In vitro, cell proliferation, migration, tube formation, and vascular endothelial growth factor (VEGF) secretion were measured in human umbilical vein endothelial cells (HUVEC). The role of miRNAs and AKT/eNOS signaling pathway in the promoted angiogenesis of ATV-Exos were assessed with their inhibitors.

Results

No significant difference in morphology, structure, and concentration was observed between ATV-Exos and Exos. In STZ-induced diabetic rats, ATV-Exos exhibited excellent abilities in facilitating the wound regeneration by promoting the formation of blood vessels compared with Exos without influencing liver and kidney function. Meanwhile, ATV-Exos promoted the proliferation, migration, tube formation, and VEGF level of endothelial cells in vitro. And AKT/eNOS pathway was activated by ATV-Exos and the pro-angiogenic effects of ATV-Exo were attenuated after the pathway being blocked. MiR-221-3p was upregulated by ATV-Exos stimulation, and miR-221-3p inhibitor suppressed the pro-angiogenesis effect of ATV-Exos.

Conclusions

Exosomes originated from ATV-pretreated MSCs might serve as a potential strategy for the treatment of diabetic skin defects through enhancing the biological function of endothelial cells via AKT/eNOS pathway by upregulating the miR-221-3p.

Hepatocyte growth factor (HGF) and stem cell factor (SCF) maintained the stemness of human bone marrow mesenchymal stem cells (hBMSCs) during long-term expansion by preserving mitochondrial function via the PI3K/AKT, ERK1/2, and STAT3 signaling pathways

Background

Mesenchymal stem cells (MSCs) have a limited self-renewal ability, impaired multi-differentiation potential, and undetermined cell senescence during in vitro series expansion. To address this concern, we investigated the effects of the microenvironment provided by stem cells from human exfoliated deciduous teeth (SHED) in maintaining the stemness of human bone marrow mesenchymal stem cells (hBMSCs) and identified the key factors and possible mechanisms responsible for maintaining the stemness of MSCs during long-term expansion in vitro.

Methods

The passage 3 (P3) to passage 8 (P8) hBMSCs were cultured in the conditioned medium from SHED (SHED-CM). The percentage of senescent cells was evaluated by β-galactosidase staining. In addition, the osteogenic differentiation potential was analyzed by reverse transcription quantitative PCR (RT-qPCR), Western blot, alizarin red, and alkaline phosphatase (ALP) staining. Furthermore, RT-qPCR results identified hepatocyte growth factor (HGF) and stem cell factor (SCF) as key factors. Thus, the effects of HGF and SCF on mitochondrial function were assessed by measuring the ROS and mitochondrial membrane potential levels. Finally, selected mitochondrial-related proteins associated with the PI3K/AKT, ERK1/2, and STAT3 signaling pathways were investigated to determine the effects of HGF and SCF in preserving the mitochondrial function of hBMSCs during long-term expansion.

Results

SHED-CM had significantly enhanced the cell proliferation, reduced the senescent cells, and maintained the osteogenesis and pro-angiogenic capacity in P8 hBMSCs during long-term expansion. In addition, hBMSCs treated with 100 ng/ml HGF and 10 ng/ml SCF had reduced ROS levels and preserved mitochondrial membrane potential compared with P8 hBMSCs during long-term expansion. Furthermore, HGF and SCF upregulated the expression of mitochondrial-related proteins associated with the PI3K/AKT, ERK1/2, and STAT3 signaling pathways, possibly contributing to the maintenance of hBMSCs stemness by preserving mitochondrial function.

Conclusion

Both HGF and SCF are key factors in maintaining the stemness of hBMSCs by preserving mitochondrial function through the expression of proteins associated with the PI3K/AKT, ERK1/2, and STAT3 signaling pathways. This study provides new insights into the anti-senescence capability of HGF and SCF, as well as new evidence for their potential application in optimizing the long-term culture of MSCs.

Single and repeated intra-articular injections in the tarsocrural joint with allogeneic and autologous equine bone marrow-derived mesenchymal stem cells are safe, but did not reduce acute inflammation in an experimental interleukin-1β model of synovitis

BACKGROUND

Allogeneic and autologous bone marrow-derived mesenchymal stem cells (BMDMSCs) have been administered in equine joints for their anti-inflammatory effects. However, allogeneic BMDMSC offer multiple clinical and practical advantages. Therefore, it is important to determine the relative effectiveness of allogeneic vs autologous BMDMSCs.

OBJECTIVES

The objective of the study was to compare the inflamed joint response to autologous vs allogeneic BMDMSCs injections, and to determine if either treatment generated an anti-inflammatory effect.

STUDY DESIGN

Randomised controlled study.

METHOD

Bone marrow was harvested from eight horses. Autologous BMDMSCs and pooled allogeneic BMDMSCs were culture expanded, cryopreserved and thawed immediately prior to administration. Ten million autologous BMDMSCs were administered with 75 ng rIL-1β into one tarsocrural joint and the contralateral tarsocrural joint received allogeneic BMDMSC plus 75 ng rIL-1β. Repeat injections were performed with the same treatment administered into the same joint. Four additional horses received 75 ng rIL-1β alone in a single tarsocrural joint. Clinical parameters (lameness, joint circumference and joint effusion) and synovial fluid parameters, including nucleated cell count (NCC), differential cell count, total protein (TP), prostaglandin E₂ (PGE₂ ) and C-reactive protein (CRP), were measured at baseline, 6, 12, 24, 72, 168 and 336 hours post-injection.

RESULTS

No difference was detected between autologous and allogeneic treatment groups with respect to subjective lameness, joint effusion, joint circumference, NCC, TP, differential cell count, CRP or PGE₂ . Neither autologous nor allogeneic treatments resulted in an improvement in clinical or cytological parameters over that elicited by rIL-1β alone.

MAIN LIMITATIONS

A single dose of rIL-1β was evaluated and resulted in a severe synovitis which may have been too severe to observe a BMDMSC-mediated effect.

CONCLUSIONS

This study revealed that allogeneic and autologous BMDMSCs resulted in an equivalent clinical and cytological response. Allogeneic and autologous BMDMSCs were equally ineffective in reducing the inflammatory response from acute rIL-1β-induced joint inflammation in horses.

Epidermal Stem Cells in Wound Healing and Regeneration

Skin stem cells distributed in the basal layer of the epidermis and hair follicles are important cell sources for skin development, metabolism, and injury repair. At present, great progress has been made in the study of epidermal stem cells at the cellular and molecular levels. Stem cell transplantation is reported to promote skin healing, endothelial cell transformation, and vascular formation. Local stem cells can also be transformed into keratinocytes, sebaceous gland, and other skin-associated tissues. However, the mechanism of action of epidermal stem cells on wound healing and regeneration is not completely clear. This review is aimed at briefly summarizing the biological characteristics of epidermal stem cells and their clinical application in wound healing and tissue regeneration. It further discussed the mechanism of action and the development direction in the future.

[Effect of adipose-derived stem cell derived exosomes on angiogenesis after skin flap transplantation in rats]

Objective

To investigate the effect of adipose-derived stem cell derived exosomes (ADSC-Exos) on angiogenesis after skin flap transplantation in rats.

Methods

ADSCs were isolated and cultured by enzymatic digestion from voluntary donated adipose tissue of patients undergoing liposuction. The 3rd generation cells were observed under microscopy and identified by flow cytometry and oil red O staining at 14 days after induction of adipogenesis. After cells were identified as ADSCs, ADSC-Exos was extracted by density gradient centrifugation. And the morphology was observed by transmission electron microscopy, the surface marker proteins (CD63, TSG101) were detected by Western blot, and particle size distribution was measured by nanoparticle size tracking analyzer. Twenty male Sprague Dawley rats, weighing 250-300 g, were randomly divided into ADSC-Exos group and PBS group with 10 rats in each group. ADSC-Exos (ADSC-Exos group) and PBS (PBS group) were injected into the proximal, middle, and distal regions of the dorsal free flaps with an area of 9 cm×3 cm along the long axis in the two groups. The survival rate of the flap was measured on the 7th day, and then the flap tissue was harvested. The tissue morphology was observed by HE staining, and mean blood vessel density (MVD) was measured by CD31 immunohistochemical staining.

Results

ADSCs were identified by microscopy, flow cytometry, and adipogenic induction culture. ADSC-Exos was a round or elliptical membrane vesicle with clear edge and uniform size. It has high expression of CD63 and TSG101, and its size distribution was 30-200 nm, which was in accordance with the size range of Exos. The distal necrosis of the flaps in the ADSC-Exos group was milder than that in the PBS group. On the 7th day, the survival rate of the flaps in the ADSC-Exos group was 64.2%±11.5%, which was significantly higher than that in the PBS group (31.0%±6.6%; t=7.945, P=0.000); the skin appendages in the middle region of the flap in the ADSC-Exos group were more complete, the edema in the proximal region was lighter and the vasodilation was more extensive. MVD of the ADSC-Exos group was (103.3±27.0) /field, which was significantly higher than that of the PBS group [(45.3±16.2)/field; t=3.190, P=0.011].

Conclusion

ADSC-Exos can improve the blood supply of skin flaps by promoting the formation of neovascularization after skin flap transplantation, thereby improve the survival rate of skin flaps in rats.

Osteogenic commitment of Wharton's jelly mesenchymal stromal cells: mechanisms and implications for bioprocess development and clinical application

Background

Orthopaedic diseases are one of the major targets for regenerative medicine. In this context, Wharton’s jelly (WJ) is an alternative source to bone marrow (BM) for allogeneic transplantation since its isolation does not require an invasive procedure for cell collection and does not raise major ethical concerns. However, the osteogenic capacity of human WJ-derived multipotent mesenchymal stromal cells (MSC) remains unclear.

Methods

Here, we compared the baseline osteogenic potential of MSC from WJ and BM cell sources by cytological staining, quantitative real-time PCR and proteomic analysis, and assessed chemical and biological strategies for priming undifferentiated WJ-MSC. Concretely, different inhibitors/activators of the TGFβ1-BMP2 signalling pathway as well as the secretome of differentiating BM-MSC were tested.

Results

Cytochemical staining as well as gene expression and proteomic analysis revealed that osteogenic commitment was poor in WJ-MSC. However, stimulation of the BMP2 pathway with BMP2 plus tanshinone IIA and the addition of extracellular vesicles or protein-enriched preparations from differentiating BM-MSC enhanced WJ-MSC osteogenesis. Furthermore, greater outcome was obtained with the use of conditioned media from differentiating BM-MSC.

Conclusions

Altogether, our results point to the use of master banks of WJ-MSC as a valuable alternative to BM-MSC for orthopaedic conditions.

Dimethyloxaloylglycine-stimulated human bone marrow mesenchymal stem cell-derived exosomes enhance bone regeneration through angiogenesis by targeting the AKT/mTOR pathway

Background

Mesenchymal stem cell (MSC)-derived exosomes have been recognized as new candidate agents for treating critical-sized bone defects; they promote angiogenesis and may be an alternative to cell therapy. In this study, we evaluated whether exosomes derived from bone marrow-derived MSCs (BMSCs) preconditioned with a low dose of dimethyloxaloylglycine (DMOG), DMOG-MSC-Exos, exert superior proangiogenic activity in bone regeneration and the underlying mechanisms involved.

Methods

To investigate the effects of these exosomes, scratch wound healing, cell proliferation, and tube formation assays were performed in human umbilical vein endothelial cells (HUVECs). To test the effects in vivo, a critical-sized calvarial defect rat model was established. Eight weeks after the procedure, histological/histomorphometrical analysis was performed to measure bone regeneration, and micro-computerized tomography was used to measure bone regeneration and neovascularization.

Results

DMOG-MSC-Exos activated the AKT/mTOR pathway to stimulate angiogenesis in HUVECs. This contributed to bone regeneration and angiogenesis in the critical-sized calvarial defect rat model in vivo.

Conclusions

Low doses of DMOG trigger exosomes to exert enhanced proangiogenic activity in cell-free therapeutic applications.

Stromal cell-derived factor-1 (CXCL12) and its role in bone and muscle biology

Musculoskeletal disorders are the leading cause of disability worldwide; two of the most prevalent of which are osteoporosis and sarcopenia. Each affect millions in the aging population across the world and the associated morbidity and mortality contributes to billions of dollars in annual healthcare cost. Thus, it is important to better understand the underlying pathologic mechanisms of the disease process. Regulatory chemokine, CXCL12, and its receptor, CXCR4, are recognized to be essential in the recruitment, localization, maintenance, development and differentiation of progenitor stem cells of the musculoskeletal system. CXCL12 signaling results in the development and functional ability of osteoblasts, osteoclasts, satellite cells and myoblasts critical to maintaining musculoskeletal homeostasis. Interestingly, one suggested pathologic mechanism of osteoporosis and sarcopenia is a decline in the regenerative capacity of musculoskeletal progenitor stem cells. Thus, because CXCL12 is critical to progenitor function, a disruption in the CXCL12 signaling axis might play a distinct role in these pathological processes. Therefore, in this article, we perform a review of CXCL12, its physiologic and pathologic function in bone and muscle, and potential targets for therapeutic development.

Engineering the vasculature for islet transplantation

The microvasculature in the pancreatic islet is highly specialized for glucose sensing and insulin secretion. Although pancreatic islet transplantation is a potentially life-changing treatment for patients with insulin-dependent diabetes, a lack of blood perfusion reduces viability and function of newly transplanted tissues. Functional vasculature around an implant is not only necessary for the supply of oxygen and nutrients but also required for rapid insulin release kinetics and removal of metabolic waste. Inadequate vascularization is particularly a challenge in islet encapsulation. Selectively permeable membranes increase the barrier to diffusion and often elicit a foreign body reaction including a fibrotic capsule that is not well vascularized. Therefore, approaches that aid in the rapid formation of a mature and robust vasculature in close proximity to the transplanted cells are crucial for successful islet transplantation or other cellular therapies. In this paper, we review various strategies to engineer vasculature for islet transplantation. We consider properties of materials (both synthetic and naturally derived), prevascularization, local release of proangiogenic factors, and co-transplantation of vascular cells that have all been harnessed to increase vasculature. We then discuss the various other challenges in engineering mature, long-term functional and clinically viable vasculature as well as some emerging technologies developed to address them. The benefits of physiological glucose control for patients and the healthcare system demand vigorous pursuit of solutions to cell transplant challenges. STATEMENT OF SIGNIFICANCE: Insulin-dependent diabetes affects more than 1.25 million people in the United States alone. Pancreatic islets secrete insulin and other endocrine hormones that control glucose to normal levels. During preparation for transplantation, the specialized islet blood vessel supply is lost. Furthermore, in the case of cell encapsulation, cells are protected within a device, further limiting delivery of nutrients and absorption of hormones. To overcome these issues, this review considers methods to rapidly vascularize sites and implants through material properties, pre-vascularization, delivery of growth factors, or co-transplantation of vessel supporting cells. Other challenges and emerging technologies are also discussed. Proper vascular growth is a significant component of successful islet transplantation, a treatment that can provide life-changing benefits to patients.

Gestational Tissue-Derived Human Mesenchymal Stem Cells Use Distinct Combinations of Bioactive Molecules to Suppress the Proliferation of Human Hepatoblastoma and Colorectal Cancer Cells

Background

Cancer has been considered a serious global health problem and a leading cause of morbidity and mortality worldwide. Despite recent advances in cancer therapy, treatments of advance stage cancers are mostly ineffective resulting in poor survival of patients. Recent evidences suggest that multipotent human mesenchymal stem cells (hMSCs) play important roles in growth and metastasis of several cancers by enhancing their engraftment and inducing tumor neovascularization. However, the effect of hMSCs on cancer cells is still controversial because there are also evidences demonstrating that hMSCs inhibited growth and metastasis of some cancers.

Methods

In this study, we investigated the effects of bioactive molecules released from bone marrow and gestational tissue-derived hMSCs on the proliferation of various human cancer cells, including C3A, HT29, A549, Saos-2, and U251. We also characterized the hMSC-derived factors that inhibit cancer cell proliferation by protein fractionation and mass spectrometry analysis.

Results

We herein make a direct comparison and show that the effects of hMSCs on cancer cell proliferation and migration depend on both hMSC sources and cancer cell types and cancer-derived bioactive molecules did not affect the cancer suppressive capacity of hMSCs. Moreover, hMSCs use distinct combination of bioactive molecules to suppress the proliferation of human hepatoblastoma and colorectal cancer cells. Using protein fractionation and mass spectrometry analysis, we have identified several novel hMSC-derived factors that might be able to suppress cancer cell proliferation.

Conclusion

We believe that the procedure developed in this study could be used to discover other therapeutically useful molecules released by various hMSC sources for a future in vivo study.

Banking Mesenchymal Stromal Cells from Umbilical Cord Tissue: Large Sample Size Analysis Reveals Consistency Between Donors

Mesenchymal stromal cells (MSCs) have emerged as candidate cells with therapeutic potential to treat different pathologies. The underlying mechanism is paracrine signaling. The cells secrete proteins that can impact inflammation, apoptosis, angiogenesis, and cell proliferation. All are important in wound healing and tissue regeneration. Although the bone marrow has been the most widely used source of MSCs, umbilical cord tissue (CT) presents a source that is just starting to be used in the clinic, yet can be obtained with more ease and easily stored. Here, we characterize CT‐MSCs obtained from multiple donors by analyzing cell surface proteins, differentiation capacity, and proteome profile. Analysis of low, medium, and high passage cells indicates that the morphology and proliferation rate stay constant and with the exception of cluster of differentiation (CD) 105 at late passage, there are no changes in the cell surface protein characteristics, indicating the population does not change with passage. TNF‐stimulated gene 6 protein was measured in a subset of samples and variable expression was observed, but this did not impact the ability of the cells to enhance skin regeneration. In conclusion, CT‐MSC represents a consistent, easily accessible source of cells for cell therapy. stem cells translational medicine2019;8:1041–1054

Cx601 (darvadstrocel) for the treatment of perianal fistulizing Crohn's disease

Introduction: Given the well-documented difficulty to treat perianal fistulizing Crohn's disease (pCD), with 40% of patients experiencing recurrence even after reiterative surgery and advanced medical therapy, research in this field has focused on the role of mesenchymal stem cells (MSC). Areas covered: The aim of this article is to furnish an overview of the pathogenetic mechanisms, clinical applications and evidences for the use of MSC for pCD with particular focus on adipose-derived allogenic MSC including darvadstrocel. Expert Opinion: The effect of MSC on fistula healing is probably mediated by their anti-inflammatory properties more than by their ability to engraft and trans-differentiate in the healthy tissue. A holistic treatment of pCD, addressing different pathophysiological factors, may represent the key for an improvement in the healing rate. In this setting, MSC might play a role as 'augmentation' therapy in combination with more conventional treatments. Whether MSC have benefit in non-complex fistula in biological naïve patients, in complex fistula with many tracts and/or in rectovaginal fistulas, are unexplored fields that need further investigation. A central registry of pCD patients undergoing treatment with MSC should be created in order to elucidate the efficacy, safety and costs of stem cells treatment on long term follow up.

Post-Injury Neuroprotective Effects of the Thalidomide Analog 3,6'-Dithiothalidomide on Traumatic Brain Injury

Traumatic brain injury (TBI) is a major cause of mortality and disability worldwide. Long-term deficits after TBI arise not only from the direct effects of the injury but also from ongoing processes such as neuronal excitotoxicity, inflammation, oxidative stress and apoptosis. Tumor necrosis factor-α (TNF-α) is known to contribute to these processes. We have previously shown that 3,6′-dithiothalidomide (3,6′-DT), a thalidomide analog that is more potent than thalidomide with similar brain penetration, selectively inhibits the synthesis of TNF-α in cultured cells and reverses behavioral impairments induced by mild TBI in mice. In the present study, we further explored the therapeutic potential of 3,6′-DT in an animal model of moderate TBI using Sprague-Dawley rats subjected to controlled cortical impact. A single dose of 3,6′-DT (28 mg/kg, i.p.) at 5 h after TBI significantly reduced contusion volume, neuronal degeneration, neuronal apoptosis and neurological deficits at 24 h post-injury. Expression of pro-inflammatory cytokines in the contusion regions were also suppressed at the transcription and translation level by 3,6′-DT. Notably, neuronal oxidative stress was also suppressed by 3,6′-DT. We conclude that 3,6′-DT may represent a potential therapy to ameliorate TBI-induced functional deficits.

Relationship between senescence in macaques and bone marrow mesenchymal stem cells and the molecular mechanism

The relationship between bone marrow mesenchymal stem cells (BMSCs) and aging, as well as the antiaging effects of BMSCs, was observed. An aging macaque BMSC model was established. We isolated BMSCs from young and aged macaques and used RT-PCR and Western blot to confirm the aging-related mRNAs and their expression, revealing that TERT, SIRT1 and SIRT6 expression was decreased in the aged BMSCs. The morphology, immunophenotype, differentiation potential, proliferation potential, and antiaging effects of aged and young BMSCs on 293T cells were compared. The expression of aging-related genes and the difference between the secreted cytokines in natural aging and induced aging BMSCs were observed. The transcriptome of peripheral blood mononuclear cells from macaques was analyzed by high-throughput sequencing. Finally, the transcriptional characteristics and regulatory mechanisms of gene transcription in aging macaques were investigated.

Overexpression of ERBB4 rejuvenates aged mesenchymal stem cells and enhances angiogenesis via PI3K/AKT and MAPK/ERK pathways

The age-related functional exhaustion limits potential efficacy of mesenchymal stem cells (MSC) in treating cardiovascular disease. Therefore, rejuvenation of aged MSC in the elderly population is of great interest. We have previously reported that Erb-B2 receptor tyrosine kinase 4 ( ERBB4) plays a critical role in regulating MSC survival under hypoxia. The aim of this study was to investigate whether ERBB4 rejuvenates aged MSC and how ERBB4 enhances therapeutic efficacy of aged MSC in treating myocardial infarction (MI). Compared with vector aged MSC (aged-MSC), ERBB4-engineered aged MSC (ER4-aged-MSC) conferred resistance to oxidative stress-induced cell death and ameliorated the senescent phenotype in vitro. Four weeks after MI, the ER4-aged-MSC group exhibited enhanced blood vessel density, reduced cardiac remodeling and apoptosis with improved heart function compared with the aged-MSC group. Overexpression of ERBB4 caused an increase in phosphorylated v-akt murine thymoma viral oncogene homolog 1 (AKT), and phosphorylated ERK expression under hypoxia. ER4-aged-MSC secreted higher levels of angiopoietin, epithelial neutrophil activating peptide 78, VEGF, and fibroblast growth factor 2, and enhanced tube formation in HUVEC. The impact of ERBB4 on protein expression, proangiogenesis, cell behavior, and cytokine secretion was abolished by inhibiting PI3K/AKT and MAPK/ERK signaling pathway.-Liang, X., Ding, Y., Lin, F., Zhang, Y., Zhou, X., Meng, Q., Lu, X., Jiang, G., Zhu, H., Chen, Y., Lian, Q., Fan, H., Liu, Z. Overexpression of ERBB4 rejuvenates aged mesenchymal stem cells and enhances angiogenesis via PI3K/AKT and MAPK/ERK pathways.

Effect of age on biomaterial-mediated in situ bone tissue regeneration

Emerging studies show the potential application of synthetic biomaterials that are intrinsically osteoconductive and osteoinductive as bone grafts to treat critical bone defects. Here, the biomaterial not only assists recruitment of endogenous cells, but also supports cellular activities relevant to bone tissue formation and function. While such biomaterial-mediated in situ tissue engineering is highly attractive, success of such an approach relies largely on the regenerative potential of the recruited cells, which is anticipated to vary with age. In this study, we investigated the effect of the age of the host on mineralized biomaterial-mediated bone tissue repair using critical-sized cranial defects as a model system. Mice of varying ages, 1-month-old (juvenile), 2-month-old (young-adult), 6-month-old (middle-aged), and 14-month-old (elderly), were used as recipients. Our results show that the bio-mineralized scaffolds support bone tissue formation by recruiting endogenous cells for all groups albeit with differences in an age-related manner. Analyses of bone tissue formation after 2 and 8 weeks post-treatment show low mineral deposition and reduced number of osteocalcin and tartrate-resistant acid phosphatase (TRAP)-expressing cells in elderly mice.

STATEMENT OF SIGNIFICANCE

Tissue engineering strategies that promote tissue repair through recruitment of endogenous cells will have a significant impact in regenerative medicine. Previous studies from our group have shown that biomineralized materials containing calcium phosphate minerals can contribute to neo-bone tissue through recruitment and activation of endogenous cells. In this study, we investigated the effect of age of the recipient on biomaterial-mediated bone tissue repair. Our results show that the age of the recipient mouse had a significant impact on the quality and quantity of the engineered neo-bone tissues, in which delayed/compromised bone tissue formation was observed in older mice. These findings are in agreement with the clinical observations that age of patients is a key factor in bone repair.

Adipose mesenchymal stem cell-derived exosomes stimulated by hydrogen peroxide enhanced skin flap recovery in ischemia-reperfusion injury

BACKGROUND

Mesenchymal stem cell (MSC)-derived exosomes have been recognized as new candidates for the treatment of ischemic disease or injury and may be an alternative treatment for cell therapy. This aim of the study was to evaluate whether exosomes derived from adipose mesenchymal stem cell (ADSC) can protect the skin flap during ischemia-reperfusion (I/R) injury and induce neovascularization.

METHODS

To investigate the effects of exosomes in the I/R injury of flap transplantation in vivo, flaps were subjected to 6 h of ischemia by ligating the left superficial inferior epigastric vessels (SIEA) followed by blood perfusion. Exosomes derived from normal ADSC (ADSC-exos) and exosomes derived from ADSC preconditioned with H₂O₂ (H₂O₂-ADSC-exos) were injected into the flaps. Then, the blood perfusion unit (BPU) of the flaps was measured by Laser Doppler Perfusion Imaging (LDPI) and microvessel density was determined by the endothelial with cell marker CD31 with Immunohistochemistry (IHC) staining. Inflammatory cell infiltration of the skin flap and apoptosis were detected by hematoxylin & eosin staining (H&E) and the TdT-mediated biotinylated dUTP nick end-labeling (TUNEL) technique.

RESULTS

In vivo, exosomes significantly increased flap survival and capillary density compared to I/R on postoperative day 5, and decreased the inflammatory reaction and apoptosis in the skin flap (P < 0.05). Furthermore, H₂O₂-ADSC-exos had better outcomes compared to normal exosomes (P < 0.05). ADSC-exos could significantly increase human umbilical vein endothelial cell (HUVEC) proliferation (P < 0.05), but no statistic difference was found in exosomes derived from different microenvironments (P > 0.05). HUVEC co-cultured with H₂O₂-ADSC-exos increased the migration ratio and generated more cord-like structures compared to ADSC-exos and the control group (P < 0.05).

CONCLUSION

ADSC-exos can enhance skin flap survival, promote neovascularization and alleviate the inflammation reaction and apoptosis in the skin flap after I/R injury. The use of a specific microenvironment for in vitro stem cell culture, such as one containing a low concentration of H₂O₂, will facilitate the development of customized exosomes for cell-free therapeutic applications in skin flap transplantation.

Effect of donor age on the proliferation and multipotency of canine adipose-derived mesenchymal stem cells

Research into adipose tissue-derived mesenchymal stem cells (AD-MSCs) has demonstrated the feasibility of their use in clinical applications due to their ease of isolation and abundance in adipose tissue. We isolated AD-MSCs from young and old dogs, and the cells were subjected to sequential sub-passaging from passage 1 (P1) to P7. Canine AD-MSCs (cAD-MSCs) were examined for proliferation kinetics, expression of molecules associated with self-renewal, expression of cell surface markers, and differentiation potentials at P3. Cumulative population doubling level was significantly higher in cAD-MSCs of young donors than in those of old donors. In addition, expressions of CD73, CD80, Oct3/4, Nanog, cell survival genes and differentiation potentials were significantly higher in young donors than in old donors. The present study suggests that donor age should be considered when developing cell-based therapies for clinical application of cAD-MSCs.