Directed Differentiation of Human-Induced Pluripotent Stem Cells to Mesenchymal Stem Cells

Application of mesenchymal stem/stromal cells in periodontal regeneration: Opportunities and challenges

Guided tissue regeneration (GTR) has been widely used in the periodontal treatment of intrabony and furcation defects for nearly four decades. The treatment outcomes have shown effectiveness in reducing pocket depth, improving attachment gain and bone filling in periodontal tissue. Although applying GTR could reconstruct the periodontal tissue, the surgical indications are relatively narrow, and some complications and race ethic problems bring new challenges. Therefore, it is challenging to achieve a consensus concerning the clinical benefits of GTR. With the appearance of stem cell-based regenerative medicine, mesenchymal stem/stromal cells (MSCs) have been considered a promising cell resource for periodontal regeneration. In this review, we highlight preclinical and clinical periodontal regeneration using MSCs derived from distinct origins, including non-odontogenic and odontogenic tissues and induced pluripotent stem cells, and discuss the transplantation procedures, therapeutic mechanisms, and concerns to evaluate the effectiveness of MSCs.

Bone marrow mesenchymal stem cell-derived extracellular vesicles promote corneal epithelial repair and suppress apoptosis via modulation of Caspase-3 in vitro

Corneal injuries are the major cause of blindness and visual impairment. Available treatments are limited by their efficacy and side effects. Mesenchymal stem cell-derived extracellular vesicles are presumed as functional equivalents and potential candidates for cell-free therapy. This study reports isolation and characterization of extracellular vesicles from human bone marrow mesenchymal stem cells and evaluates their role in mediating epithelial repair and apoptosis in cultured corneal epithelial cells through scratch assay, PCR, immunofluorescence, and flow cytometry in vitro. The isolated extracellular vesicles were spherical, < 150 nm in diameter, and characterized as CD9+, CD63+, CD81+, TSG101+, and Calnexin-. Further, these vesicles promoted corneal epithelial repair by enhancing proliferation and suppressed apoptosis by regulating the expression of BAD, P53, BCL-2, and cleaved CASPASE-3. Thus, our results suggest that BM-MSC-EVs might have the potential to be used for the treatment of injury-induced corneal epithelial defects. Clinical translation of this work would require further investigations.

Small extracellular vesicles: Multi-functional aspects in non-small cell lung carcinoma

Extracellular vesicles (EVs) impact normal and pathological cellular signaling through bidirectional trafficking. Exosomes, a subset of EVs possess biomolecules including proteins, lipids, DNA fragments and various RNA species reflecting a speculum of their parent cells. The involvement of exosomes in bidirectional communication and their biological constituents substantiate its role in regulating both physiology and pathology, including multiple cancers. Non-small cell lung cancer (NSCLC) is the most common lung cancers (85%) with high incidence, mortality and reduced overall survival. Lack of efficient early diagnostic and therapeutic tools hurdles the management of NSCLC. Interestingly, the exosomes from body fluids similarity with parent cells or tissue offers a potential future multicomponent tool for the early diagnosis of NSCLC. The structural twinning of exosomes with a cell/tissue and the competitive tumor derived exosomes in tumor microenvironment (TME) promotes the unpinning horizons of exosomes as a drug delivery, vaccine, and therapeutic agent. Exosomes in clinical point of view assist to trace: acquired resistance caused by various therapeutic agents, early diagnosis, progression, and surveillance. In an integrated approach, EV biomarkers offer potential cutting-edge techniques for the detection and diagnosis of cancer, though the purification, characterization, and biomarker identification processes for the translational research regarding EVs need further optimization.

Challenges of mesenchymal stem cells in the clinical treatment of COVID-19

The 2019 coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has brought an enormous public health burden to the global society. The duration of the epidemic, the number of infected people, and the widespread of the epidemic are extremely rare in modern society. In the initial stage of infection, people generally show fever, cough, and dyspnea, which can lead to pneumonia, acute respiratory syndrome, kidney failure, and even death in severe cases. The strong infectivity and pathogenicity of SARS-CoV-2 make it more urgent to find an effective treatment. Mesenchymal stem cells (MSCs) are a kind of pluripotent stem cells with the potential for self-renewal and multi-directional differentiation. They are widely used in clinical experiments because of their low immunogenicity and immunomodulatory function. Mesenchymal stem cell-derived exosomes (MSC-Exo) can play a physiological role similar to that of stem cells. Since the COVID-19 pandemic, a series of clinical trials based on MSC therapy have been carried out. The results show that MSCs are safe and can significantly improve patients' respiratory function and prognosis of COVID-19. Here, the effects of MSCs and MSC-Exo in the treatment of COVID-19 are reviewed, and the clinical challenges that may be faced in the future are clarified.

Translating mesenchymal stem cell and their exosome research into GMP compliant advanced therapy products: Promises, problems and prospects

Mesenchymal stem cells (MSCs) are one of the few stem cell types used in clinical practice as therapeutic agents for immunomodulation and ischemic tissue repair, due to their unique paracrine capacity, multiple differentiation potential, active components in exosomes, and effective mitochondria donation. At present, MSCs derived from tissues such as bone marrow and umbilical cord are widely applied in preclinical and clinical studies. Nevertheless, there remain challenges to the maintenance of consistently good quality MSCs derived from different donors or tissues, directly impacting their application as advanced therapy products. In this review, we discuss the promises, problems, and prospects associated with translation of MSC research into a pharmaceutical product. We review the hurdles encountered in translation of MSCs and MSC-exosomes from the research bench to an advanced therapy product compliant with good manufacturing practice (GMP). These difficulties include how to set up GMP-compliant protocols, what factors affect raw material selection, cell expansion to product formulation, establishment of quality control (QC) parameters, and quality assurance to comply with GMP standards. To avoid human error and reduce the risk of contamination, an automatic, closed system that allows real-time monitoring of QC should be considered. We also highlight potential advantages of pluripotent stem cells as an alternative source for MSC and exosomes generation and manufacture.

Comparison of the mesodermal differentiation potential between embryonic stem cells and scalable induced pluripotent stem cells

BACKGROUND

Mesenchymal stem cells (MSCs) have promising potential in clinical application, whereas their limited amount and sources hinder their bioavailability. Embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) have become prominent options in regenerative medicine as both possess the ability to differentiate into MSCs.

METHODS

Recently, our research team has successfully developed human leukocyte antigen (HLA)-homozygous iPSC cell lines with high immune compatibility, covering 13.5% of the Taiwanese population. As we deepen our understanding of the differences between these ESCs and HLA-homozygous iPSCs, our study focused on morphological observations and flow cytometry analysis of specific surface marker proteins during the differentiation of ESCs and iPSCs into MSCs.

RESULTS

The results showed no significant differences between the two pluripotent stem cells, and both of them demonstrated the equivalent ability to further differentiate into adipose, cartilage, and bone cells.

CONCLUSION

Our research revealed that these iPSCs with high immune compatibility exhibit the same differentiation potential as ESCs, enhancing the future applicability of highly immune-compatible iPSCs.

Exosomal miR-9-5p derived from iPSC-MSCs ameliorates doxorubicin-induced cardiomyopathy by inhibiting cardiomyocyte senescence

Doxorubicin (DOX) is a chemotherapeutic agent widely used for tumor treatment. Nonetheless its clinical application is heavily limited by its cardiotoxicity. There is accumulated evidence that transplantation of mesenchymal stem cell-derived exosomes (MSC-EXOs) can protect against Dox-induced cardiomyopathy (DIC). This study aimed to examine the cardioprotective effects of EXOs isolated from human induced pluripotent stem cell-derived MSCs (iPSC-MSCs) against DIC and explore the potential mechanisms. EXOs were isolated from the cultural supernatant of human BM-MSCs (BM-MSC-EXOs) and iPSC-MSCs (iPSC-MSC-EXOs) by ultracentrifugation. A mouse model of DIC was induced by intraperitoneal injection of Dox followed by tail vein injection of PBS, BM-MSC-EXOs, or iPSC-MSC-EXOs. Cardiac function, cardiomyocyte senescence and mitochondrial dynamics in each group were assessed. In vitro, neonatal mouse cardiomyocytes (NMCMs) were subjected to Dox and treated with BM-MSC-EXOs or iPSC-MSC-EXOs. The mitochondrial morphology and cellular senescence of NMCMs were examined by Mitotracker staining and senescence-associated-β-galactosidase assay, respectively. Compared with BM-MSC-EXOs, mice treated with iPSC-MSC-EXOs displayed improved cardiac function and decreased cardiomyocyte mitochondrial fragmentation and senescence. In vitro, iPSC-MSC-EXOs were superior to BM-MSC-EXOs in attenuation of cardiomyocyte mitochondrial fragmentation and senescence caused by DOX. MicroRNA sequencing revealed a higher level of miR-9-5p in iPSC-MSC-EXOs than BM-MSC-EXOs. Mechanistically, iPSC-MSC-EXOs transported miR-9-5p into DOX-treated cardiomyocytes, thereby suppressing cardiomyocyte mitochondrial fragmentation and senescence via regulation of the VPO1/ERK signal pathway. These protective effects and cardioprotection against DIC were largely reversed by knockdown of miR-9-5p in iPSC-MSC-EXOs. Our results showed that miR-9-5p transferred by iPSC-MSC-EXOs protected against DIC by alleviating cardiomyocyte senescence via inhibition of the VPO1/ERK pathway. This study offers new insight into the application of iPSC-MSC-EXOs as a novel therapeutic strategy for DIC treatment.

Transcriptome analysis reveals therapeutic potential of NAMPT in protecting against abdominal aortic aneurysm in human and mouse

Abdominal Aortic Aneurysm (AAA) is a life-threatening vascular disease characterized by the weakening and ballooning of the abdominal aorta, which has no effective therapeutic approaches due to unclear molecular mechanisms. Using single-cell RNA sequencing, we analyzed the molecular profile of individual cells within control and AAA abdominal aortas. We found cellular heterogeneity, with increased plasmacytoid dendritic cells and reduced endothelial cells and vascular smooth muscle cells (VSMCs) in AAA. Up-regulated genes in AAA were associated with muscle tissue development and apoptosis. Genes controlling VSMCs aberrant switch from contractile to synthetic phenotype were significantly enriched in AAA. Additionally, VSMCs in AAA exhibited cell senescence and impaired oxidative phosphorylation. Similar observations were made in a mouse model of AAA induced by Angiotensin II, further affirming the relevance of our findings to human AAA. The concurrence of gene expression changes between human and mouse highlighted the impairment of oxidative phosphorylation as a potential target for intervention. Nicotinamide phosphoribosyltransferase (NAMPT, also named VISFATIN) signaling emerged as a signature event in AAA. NAMPT was significantly downregulated in AAA. NAMPT-extracellular vesicles (EVs) derived from mesenchymal stem cells restored NAMPT levels, and offered protection against AAA. Furthermore, NAMPT-EVs not only repressed injuries, such as cell senescence and DNA damage, but also rescued impairments of oxidative phosphorylation in both mouse and human AAA models, suggesting NAMPT supplementation as a potential therapeutic approach for AAA treatment. These findings shed light on the cellular heterogeneity and injuries in AAA, and offered promising therapeutic intervention for AAA treatment.

Mesenchymal stem cell-derived exosomes: Characteristics and applications in disease pathology and management

Mesenchymal stem cells (MSCs) possess a role in tissue regeneration and homeostasis because of inherent immunomodulatory capacity and the production of factors that encourage healing. There is substantial evidence that MSCs' therapeutic efficacy is primarily determined by their paracrine function including in cancers. Extracellular vesicles (EVs) are basic paracrine effectors of MSCs that reside in numerous bodily fluids and cell homogenates and play an important role in bidirectional communication. MSC-derived EVs (MSC-EVs) offer a wide range of potential therapeutic uses that exceed cell treatment, while maintaining protocell function and having less immunogenicity. We describe characteristics and isolation methods of MSC-EVs, and focus on their therapeutic potential describing its roles in tissue repair, anti-fibrosis, and cancer with an emphasis on the molecular mechanism and immune modulation and clinical trials. We also explain current understanding and challenges in the clinical applications of MSC-EVs as a cell free therapy.

A new strategy for intervertebral disc regeneration: The synergistic potential of mesenchymal stem cells and their extracellular vesicles with hydrogel scaffolds

Intervertebral disc degeneration (IDD) is a disease that severely affects spinal health and is prevalent worldwide. Mesenchymal stem cells (MSCs) and their derived extracellular vesicles (EVs) have regenerative potential and have emerged as promising therapeutic tools for treating degenerative discs. However, challenges such as the harsh microenvironment of degenerated intervertebral discs and EVs' limited stability and efficacy have hindered their clinical application. In recent years, hydrogels have attracted much attention in the field of IDD therapy because they can mimic the physiologic microenvironment of the disc and provide a potential solution by providing a suitable growth environment for MSCs and EVs. This review introduced the biological properties of MSCs and their derived EVs, summarized the research on the application of MSCs and EVs in IDD, summarized the current clinical trial studies of MSCs and EVs, and also explored the mechanism of action of MSCs and EVs in intervertebral discs. In addition, plenty of research elaborated on the mechanism of action of different classified hydrogels in tissue engineering, the synergistic effect of MSCs and EVs in promoting intervertebral disc regeneration, and their wide application in treating IDD. Finally, the challenges and problems still faced by hydrogel-loaded MSCs and EVs in the treatment of IDD are summarized, and potential solutions are proposed. This paper outlines the synergistic effects of MSCs and EVs in treating IDD in combination with hydrogels and aims to provide theoretical references for future related studies.

Roles and mechanisms of umbilical cord mesenchymal stem cells in the treatment of diabetic foot: A review of preclinical and clinical studies

AIMS

Growing preclinical and clinical evidence has suggested the potential method of umbilical cord mesenchymal stem cell (UCMSC) therapy for diabetic foot. Thus, the authors provided an outline of the application of UCMSCs in the treatment of diabetic foot and further summarized the roles and mechanisms of this therapy.

DATA SYNTHESIS

With no time limitations, the authors searched the Web of Science, Cochrane Central Register of Controlled Trials, and PubMed (MEDLINE) databases. 14 studies were included, including 9 preclinical experiments and 5 clinical trials (3 RCTs and 2 single-arm trials).

CONCLUSIONS

The UCMSCs are of great efficacy and safety, and function mainly by reducing inflammation, regulating immunity, promoting growth factors, and enhancing the functions of vascular endothelial cells, fibroblasts, and keratinocytes. As a result, ulcer healing-related biological processes ensue, which finally lead to diabetic foot ulcer healing and clinical symptom improvement. UCMSC treatment enhances diabetic foot ulcer healing and has a safety profile. They function mainly by modulating immunity, promoting growth factor secretion, and enhancing cellular functions. More well-designed preclinical and clinical studies are needed to provide the most optimal protocol, the comprehensive molecular mechanisms, as well as to further evaluate the efficiency and safety profile of UCMSC treatment in diabetic foot patients.

Enhancing the therapeutic efficacy of mesenchymal stem cell transplantation in diabetes: Amelioration of mitochondrial dysfunction-induced senescence

Mesenchymal stem cell (MSC) transplantation offers significant potential for the treatment of diabetes mellitus (DM) and its complications. However, hyperglycemic conditions can induce senescence and dysfunction in both transplanted and resident MSCs, thereby limiting their therapeutic potential. Mitochondrial dysfunction and oxidative stress are key contributors to this process in MSCs exposed to hyperglycemia. As such, strategies aimed at mitigating mitochondrial dysfunction could enhance the therapeutic efficacy of MSC transplantation in DM. In this review, we provide an updated overview of how mitochondrial dysfunction mediates MSC senescence. We present experimental evidence for the molecular mechanisms behind high glucose-induced mitochondrial dysfunction in MSCs, which include impairment of mitochondrial biogenesis, mitochondrial calcium regulation, the mitochondrial antioxidant system, mitochondrial fusion-fission dynamics, mitophagy, and intercellular mitochondrial transfer. Furthermore, we propose potential pharmacological candidates that could improve the efficacy of MSC transplantation by enhancing mitochondrial function in patients with DM and related complications.

Induced pluripotent stem cell-derived extracellular vesicles overexpressing SFPQ protect retinal Müller cells against hypoxia-induced injury

Splicing factor proline/glutamine-rich (SFPQ) is expressed in induced pluripotent stem cells (iPSCs), which are reported to orchestrate hypoxic injury responses and release extracellular vesicles (EVs). Therefore, this study sought to explore the role of iPSC-derived EVs carrying SFPQ in hypoxia-induced injury to retinal Müller cells. We induced oxygen-glucose deprivation/reoxygenation (OGD/R) in Müller cells. SFPQ was overexpressed or knocked down in iPSCs, from which EVs were extracted. Müller cells were co-cultured with EVs, and the results indicated that SFPQ protein was transferred into retinal Müller cells by iPSC-derived EVs. We identified an interaction of SFPQ with HDAC1 in retinal Müller cells. Specifically, SFPQ recruited HDAC1 to downregulate HIF-2α by regulating its acetylation. The in vitro studies suggested that iPSC-derived EVs, SFPQ or HDAC1 overexpression, or HIF-2α silencing diminished cell injury and apoptosis but elevated proliferation in retinal Müller cells. The in vivo studies indicated that iPSC-derived EVs containing SFPQ curtailed apoptosis of retinal Müller cells, thus alleviating retinal ischemia/reperfusion (I/R) injury of rat model. Taken together, iPSC-derived EVs containing SFPQ upregulated HDAC1 to attenuate OGD/R-induced Müller cell injury via downregulation of HIF-2α.

Human mesenchymal stem cells derived from adipose tissue showed a more robust effect than those from the umbilical cord in promoting corneal graft survival by suppressing lymphangiogenesis

BACKGROUND

Mesenchymal stem cells (MSCs) have shown promising potential in allograft survival. However, few reports have focused on comparing the immunosuppressive capacity of MSCs from different sources and administered via different routes in inhibiting transplant rejection. Moreover, virtually nothing is known about the role of MSCs in the regulation of graft neovascularization and lymphangiogenesis. In this study, we compared the efficacy of human adipose MSCs (hAD-MSCs) and human umbilical cord MSCs (hUC-MSCs) in vitro and in corneal transplantation models to explore the underlying molecular mechanisms and provide a powerful strategy for future clinical applications.

METHODS

hAD-MSCs and hUC-MSCs were generated, and their self-renewal and multi-differentiation abilities were evaluated. The inhibitory effect of human MSCs (hMSCs) was examined by T-cell proliferation assays with or without transwell in vitro. Two MSCs from different sources were separately adoptively transferred in mice corneal transplantation (5 × 105 or 1 × 106/mouse) via topical subconjunctival or intravenous (IV) routes. Allograft survival was evaluated every other day, and angiogenesis and lymphomagenesis were quantitatively analyzed by immunofluorescence staining. The RNA expression profiles of hMSCs were revealed by RNA sequencing (RNA-seq) and verified by quantitative real-time PCR (qRT‒PCR), western blotting or ELISA. The function of the differentially expressed gene FAS was verified by a T-cell apoptosis assay.

RESULTS

hAD-MSCs induced stronger immunosuppression in vitro than hUC-MSCs. The inhibitory effect of hUC-MSCs but not hAD-MSCs was mediated by cell-cell contact-dependent mechanisms. Systemic administration of a lower dose of hAD-MSCs showed better performance in prolonging corneal allograft survival than hUC-MSCs, while subconjunctival administration of hMSCs was safer and further prolonged corneal allograft survival. Both types of hMSCs could inhibit corneal neovascularization, while hAD-MSCs showed greater superiority in suppressing graft lymphangiogenesis. RNA-seq analysis and confirmation experiments revealed the superior performance of hAD-MSCs in allografts based on the lower expression of vascular endothelial growth factor C (VEGF-C) and higher expression of FAS.

CONCLUSIONS

The remarkable inhibitory effects on angiogenesis/lymphangiogenesis and immunological transplantation effects support the development of hAD-MSCs as a cell therapy against corneal transplant rejection. Topical administration of hMSCs was a safer and more effective route for application than systemic administration.

Effect of autologous bone marrow derived mesenchymal stem cells in treatment of rheumatoid arthritis

INTRODUCTION

Chronic inflammation causes articular bone and cartilage degeneration in people with rheumatoid arthritis (RA). Despite recent advancements in the management of RA, adverse side effects and ineffective treatments remain a problem. Effective treatment is usually hampered by financial issues. As a result, less expensive medications that reduce both inflammation and bone resorption are required. Mesenchymal stem cells (MSCs) have recently been identified as a potential therapy for RA.

AIM OF THE STUDY

This study aimed to examine the anti-arthritic effect of rat bone marrow-derived mesenchymal stem cells (rBM-MSCs), oligosaccharides (Os), and human placental extract (HPE), individually and combined, on an RA model, using Complete Freund's adjuvant (CFA)-induced arthritis in rats.

MATERIALS AND METHODS

In female rats, RA was induced by injecting CFA in the paw of the hind limb. Rat bone marrow-MSCs, oligosaccharides, and human placental extract (HPE) were given individually and in combination via the intraperitoneal route. A complete blood count (CBC), erythrocyte sedimentation rate (ESR), serum cortisol, urea, uric acid, and other biochemical parameters were measured to determine the safety and efficacy of the different treatments. Histopathological analysis of bone sections was carried out.

RESULTS

Combining oligosaccharides and HPE therapy with the infusion of rat-bone marrow MSCs had beneficial antiarthritic and anti-inflammatory effects in CFA-induced arthritis in rats: overall such triple therapy significantly reduced serum levels of IL-6, IL-10, and TNF-alpha in comparison with all other combinations (all P > 0.05). Meanwhile, the triple therapy did not have negative effects on levels of CBC, serum cortisol, ESR, and liver enzymes (all NS) as well as on renal functions (NS). Also, the histopathological analysis showed significant improvements in the healing and remodelling of osteoporotic lesions in arthritic rats. As shown by counting apoptotic cells as a histopathological substitute for measuring apoptotic or regeneration markers, the lowest count was found in the group treated with a triple therapy of rat bone marrow-derived mesenchymal stem cells (rBM-MSCs), oligosaccharides, and HPE.

CONCLUSION

The combination of rat MSCs, oligosaccharides, and HPE has the potential to be an effective treatment for rheumatoid arthritis.

Hypoxic Preconditioning Enhances Cellular Viability and Migratory Ability: Role of DANCR/miR-656-3p/HIF-1α Axis in Placental Mesenchymal Stem Cells

Preeclampsia (PE) is a common complication of pregnancy characterized by new-onset hypertension, albuminuria, or end-stage organ dysfunction, which is seriously harmful to maternal and infant health. Mesenchymal stem cells (MSCs) are pluripotent stem cells derived from extraembryonic mesoderm. They have the potential for self-renewal, multidirectional differentiation, immunomodulation, and tissue regeneration. Several in vivo and in vitro experiments have confirmed that MSCs can delay the pathological progression of PE and improve maternal and fetal outcomes. However, the major limitations in the application of MSCs are their low-survival rates in ischemic and hypoxic disease areas after transplantation and their low rate of successful migration to the diseased regions. Therefore, enhancing cell viability and migration ability of MSCs in both ischemic and anoxic environments is important. This study aimed to investigate the effects of hypoxic preconditioning on the viability and migration ability of placental mesenchymal stem cells (PMSCs) and their underlying mechanisms. In this study, we found that hypoxic preconditioning enhanced the viability and migration ability of PMSCs, increased the expression of DANCR and hypoxia-inducible factor-1α (HIF-1α), and decreased the expression of miR-656-3p in PMSCs. Inhibiting the expression of HIF-1α and DACNR in PMSCs under hypoxia can inhibit the promotive effect of hypoxic preconditioning on viability and migration ability. In addition, RNA pull down and double luciferase assays confirmed that miR-656-3p could directly bind to DANCR and HIF-1α. In conclusion, our study showed that hypoxia could promote the viability and migration ability of PMSCs through the DANCR/miR-656-3p/HIF-1α axis.

TRAF3IP2 drives mesenchymal stem cell senescence via regulation of NAMPT-mediated NAD biosynthesis

The cellular senescence of mesenchymal stem cells (MSCs) limits their application in regenerative medicine. This study aimed to clarify the role of TNF receptor-associated factor 3 interacting protein 2 (TRAF3IP2), a pro-inflammatory cytoplasmic adaptor protein, in regulating MSC senescence and to explore the potential mechanisms. Methods: MSC senescence was determined by senescence-associated β-galactosidase (SA-β-gal) staining. The expression of TRAF3IP2 and senescence-related proteins was detected by Western blotting. The nicotinamide adenine dinucleotide (NAD+) level and nicotinamide phosphoribosyl transferase (NAMPT) expression in MSCs was measured. Results: Compared with that in MSCs isolated from young donors (YMSCs), the expression of TRAF3IP2 was greatly increased in MSCs derived from aged donors (AMSCs). Overexpression of TRAF3IP2 accelerated YMSC senescence whereas downregulation significantly rescued cellular senescence. The protein level of NAMPT and the level of NAD+ were significantly decreased in AMSCs compared with YMSCs. Mechanistically, TRAF3IP2 induced MSC senescence via downregulation of NAMPT expression and NAD + level by inhibiting the AMPK signaling pathway. These effects were partially reversed by treatment with an AMPK or NAMPT activator. Conclusion: We revealed that TRAF3IP2 accelerated MSC senescence via downregulation of NAMPT-mediated NAD biosynthesis by mediation of the AMPK pathway, highlighting a novel means to rejuvenate senescent MSCs.

The developing role of extracellular vesicles in autoimmune diseases: special attention to mesenchymal stem cell-derived extracellular vesicles

Autoimmune diseases are complex, chronic inflammatory conditions initiated by the loss of immunological tolerance to self-antigens. Nowadays, there is no effective and useful therapy for autoimmune diseases, and the existing medications have some limitations due to their nonspecific targets and side effects. During the last few decades, it has been established that mesenchymal stem cells (MSCs) have immunomodulatory functions. It is proposed that MSCs can exert an important therapeutic effect on autoimmune disorders. In parallel with these findings, several investigations have shown that MSCs alleviate autoimmune diseases. Intriguingly, the results of studies have demonstrated that the effective roles of MSCs in autoimmune diseases do not depend on direct intercellular communication but on their ability to release a wide spectrum of paracrine mediators such as growth factors, cytokines and extracellular vehicles (EVs). EVs that range from 50 to 5,000 nm were produced by almost any cell type, and these nanoparticles participate in homeostasis and intercellular communication via the transfer of a broad range of biomolecules such as modulatory proteins, nucleic acids (DNA and RNA), lipids, cytokines, and metabolites. EVs derived from MSCs display the exact properties of MSCs and can be safer and more beneficial than their parent cells. In this review, we will discuss the features of MSCs and their EVs, EVs biogenesis, and their cargos, and then we will highlight the existing discoveries on the impacts of EVs from MSCs on autoimmune diseases such as multiple sclerosis, arthritis rheumatic, inflammatory bowel disease, Type 1 diabetes mellitus, systemic lupus erythematosus, autoimmune liver diseases, Sjögren syndrome, and osteoarthritis, suggesting a potential alternative for autoimmune conditions therapy.

Gene therapy using genome-edited iPS cells for targeting malignant glioma

Glioblastoma is characterized by diffuse infiltration into the normal brain. Invasive glioma stem cells (GSCs) are an underlying cause of treatment failure. Despite the use of multimodal therapies, the prognosis remains dismal. New therapeutic approach targeting invasive GSCs is required. Here, we show that neural stem cells (NSCs) derived from CRISRP/Cas9-edited human-induced pluripotent stem cell (hiPSC) expressing a suicide gene had higher tumor-trophic migratory capacity compared with mesenchymal stem cells (MSCs), leading to marked in vivo antitumor effects. High migratory capacity in iPSC-NSCs was related to self-repulsive action and pathotropism involved in EphB-ephrinB and CXCL12-CXCR4 signaling. The gene insertion to ACTB provided higher and stable transgene expression than other common insertion sites, such as GAPDH or AAVS1. Ferroptosis was associated with enhanced antitumor immune responses. The thymidylate synthase and dihydroprimidine dehydrogenase expressions predicted the treatment efficacy of therapeutic hiPSC-NSCs. Our results indicate the potential benefit of genome-edited iPS cells based gene therapy for invasive GSCs. Furthermore, the present research concept may become a platform to promote clinical studies using hiPSC.

Screening of the best time window for MSC transplantation to treat acute myocardial infarction with SDF-1α antibody-loaded targeted ultrasonic microbubbles: An in vivo study in miniswine

The present study aimed to screen the best time window for the transplantation of bone marrow mesenchymal stem cells (MSCs) after acute myocardial infarction (MI) through targeted ultrasound microbubbles loaded with SDF-1α antibody. Thirty-six MI miniswine were randomly divided into six experimental groups according to the duration after infarction (1 day, 3 days, 1 week, 2 weeks, 3 weeks, and 4 weeks after infarction). MSCs were labeled with BrdU and then injected through the coronary artery in the stem cell transplantation group to detect the number of transplanted MSCs at different time points after MI. Three miniswine were randomly selected as the control group (sham operation: open chest without ligation of the coronary artery). All SDF-1α groups and control groups were injected with a targeted microbubble ultrasound contrast agent. The values of the myocardial perfusion parameters (A, β, and A × β) were determined. A _T, β _T, and (A × β)_T varied with time and peaked 1 week after MI (P < 0.05). The number of transplanted stem cells in the myocardium through coronary injection of MSCs at 1 week was the greatest and consistent with the changing tendency of A _T, β _T, and (A × β)_T (r = 0.658, 0.778, 0.777, P < 0.05). β _T(X), (A × β)_T(X), and the number of transplanted stem cells was used to establish the regression equation as follows: Y = 36.11 + 17.601X; Y = 50.023 + 3.348X (R ² = 0.605, 0.604, P < 0.05). The best time window for transplanting stem cells was 1 week after MI. The myocardial perfusion parameters of the SDF-1α targeted contrast agent can be used to predict the number of transplanted stem cells in the myocardial tissue.

Human menstrual blood-derived stem cells alleviate autoimmune hepatitis via JNK/MAPK signaling pathway in vivo and in vitro

Autoimmune hepatitis (AIH) is a severe globally distributed liver disease that could occur at any age. Human menstrual blood-derived stem cells (MenSCs) have shown therapeutic effect in acute lung injury and liver failure. However, their role in the curative effect of AIH remains unclear. Here, a classic AIH mouse model was constructed through intravenous injection with concanavalin A (Con A). MenSCs were intravenously injected while Con A injection in the treatment groups. The results showed that the mortality by Con A injection was significantly decreased by MenSCs treatment and liver function tests and histological analysis were also ameliorated. The results of phosphoproteomic analysis and RNA-seq revealed that MenSCs improved AIH, mainly by apoptosis and c-Jun N-terminal kinase/mitogen-activated protein signaling pathways. Apoptosis analysis demonstrated that the protein expression of cleaved caspase 3 was increased by Con A injection and reduced by MenSCs transplantation, consistent with the TUNEL staining results. An AML12 co-culture system and JNK inhibitor (SP600125) were used to verify the JNK/MAPK and apoptosis signaling pathways. These findings suggested that MenSCs could be a promising strategy for AIH.

Dedifferentiated fat cells administration ameliorates abnormal expressions of fatty acids metabolism-related protein expressions and intestinal tissue damage in experimental necrotizing enterocolitis

Neonatal necrotizing enterocolitis (NEC) is a serious disease of premature infants that necessitates intensive care and frequently results in life-threatening complications and high mortality. Dedifferentiated fat cells (DFATs) are mesenchymal stem cell-like cells derived from mature adipocytes. DFATs were intraperitoneally administrated to a rat NEC model, and the treatment effect and its mechanism were evaluated. The NEC model was created using rat pups hand fed with artificial milk, exposed to asphyxia and cold stress, and given oral lipopolysaccharides after cesarean section. The pups were sacrificed 96 h after birth for macroscopic histological examination and proteomics analysis. DFATs administration significantly improved the survival rate from 25.0 (vehicle group) to 60.6% (DFAT group) and revealed a significant reduction in macroscopical, histological, and apoptosis evaluation compared with the vehicle group. Additionally, the expression of C-C motif ligand 2 was significantly decreased, and that of interleukin-6 decreased in the DFAT group. DFAT administration ameliorated 93 proteins mainly related to proteins of fatty acid metabolism of the 436 proteins up-/down-regulated by NEC. DFATs improved mortality and restored damaged intestinal tissues in NEC, possibly by improving the abnormal expression of fatty acid-related proteins and reducing inflammation.

Serum starvation affects mitochondrial metabolism of adipose-derived stem/stromal cells

BACKGROUND AIMS

A large part of mesenchymal stromal cell (MSC) regenerative and immunomodulatory action is mediated by paracrine signaling. Hence, an increasing body of evidence acknowledges the potential of MSC secretome in a variety of preclinical and clinical scenarios. Mid-term serum deprivation is a common approach in the pipeline of MSC secretome production. Nevertheless, up to now, little is known about the impact of this procedure on the metabolic status of donor cells.

METHODS

Here, through untargeted differential metabolomics, we revealed an impairment of mitochondrial metabolism in adipose-derived MSCs exposed for 72 h to serum deprivation.

RESULTS

This evidence was further confirmed by the significant accumulation of reactive oxygen species and the reduction of succinate dehydrogenase activity. Probably as a repair mechanism, an upregulation of mitochondrial superoxide dismutase was also induced.

CONCLUSIONS

Of note, the analysis of mitochondrial functionality indicated that, despite a significant reduction of basal respiration and ATP production, serum-starved MSCs still responded to changes in energy demand. This metabolic phenotype correlates with the obtained evidence of mitochondrial elongation and branching upon starvation.

Intravenously Administered Human Umbilical Cord-Derived Mesenchymal Stem Cell (HucMSC) Improves Cardiac Performance following Infarction via Immune Modulation

Overactive inflammatory responses contribute to progressive cardiac dysfunction after myocardial infarction (MI). Mesenchymal stem cell (MSC) has generated significant interest as potent immune modulators that can regulate excessive immune responses. We hypothesized that intravenous (iv) administration of human umbilical cord-derived MSC (HucMSC) exerts systemic and local anti-inflammation effects, leading to improved heart function after MI. In murine MI models, we confirmed that single iv administration of HucMSC ( $30\times {10}^4$ ) improved cardiac performance and prevented adverse remodeling after MI. A small proportion of HucMSC is trafficked to the heart, preferentially in the infarcted region. HucMSC administration increased CD3+ T cell proportion in the periphery while decreased T cell proportion in both infarcted heart and mediastinal lymph nodes (med-LN) at 7-day post-MI, indicating a systematic and local T cell interchange mediated by HucMSC. The inhibitory effects of HucMSC on T cell infiltration in the infarcted heart and med-LN sustained to 21-day post-MI. Our findings suggested that iv administration of HucMSC fostered systemic and local immunomodulatory effects that contributed to the improvement of cardiac performance after MI.

Effects of Ginsenoside Rg1 on the Biological Behavior of Human Amnion-Derived Mesenchymal Stem/Stromal Cells (hAD-MSCs)

Ginsenoside Rg1 (Rg1) is purified from ginseng with various pharmacological effects, which might facilitate the biological behavior of human amnion-derived mesenchymal stem/stromal cells (hAD-MSCs). This study is aimed at investigating the effects of Rg1 on the biological behavior, such as viability, proliferation, apoptosis, senescence, migration, and paracrine, of hAD-MSCs. hAD-MSCs were isolated from human amnions. The effects of Rg1 on the viability, proliferation, apoptosis, senescence, migration, and paracrine of hAD-MSCs were detected by CCK-8, EdU, flow cytometry, SA-β-Gal staining, wound healing, and ELISA assays, respectively. The protein expression levels were detected by western blot. Cell cycle distribution was evaluated using flow cytometry. We found that Rg1 promoted hAD-MSC cycle progression from G0/G1 to S and G2/M phases and significantly increased hAD-MSC proliferation rate. Rg1 activated PI3K/AKT signaling pathway and significantly upregulated the expressions of cyclin D, cyclin E, CDK4, and CDK2 in hAD-MSCs. Inhibition of PI3K/AKT signaling significantly downregulated the expressions of cyclin D, cyclin E, CDK4, and CDK2, prevented cell cycle progression, and reduced hAD-MSC proliferation induced by Rg1. hAD-MSC senescence rate was significantly increased by D-galactose, while the elevated hAD-MSC senescence rate induced by D-galactose was significantly decreased by Rg1 treatment. D-galactose significantly induced the expressions of senescence markers, p16^INK4a, p14^ARF, p21^CIP1, and p53 in hAD-MSCs, while Rg1 significantly reduced the expressions of those markers induced by D-galactose in hAD-MSCs. Rg1 significantly promoted the secretion of IGF-I in hAD-MSCs. Rg1 reduced the hAD-MSC apoptosis rate. However, the difference was not significant. Rg1 had no influence on hAD-MSC migration. Altogether, our results demonstrate that Rg1 can promote the viability, proliferation, and paracrine and relieve the senescence of hAD-MSCs. PI3K/AKT signaling pathway is involved in the promotive effect of Rg1 on hAD-MSC proliferation. The protective effect of Rg1 on hAD-MSC senescence may be achieved via the downregulation of p16^INK4A and p53/p21^CIP1 pathway.

Transfer of Cardiac Mitochondria Improves the Therapeutic Efficacy of Mesenchymal Stem Cells in a Preclinical Model of Ischemic Heart Disease

BACKGROUND

The use of mesenchymal stem cells (MSCs) appears to be a promising therapeutic approach for cardiac repair after myocardial infarction. However, clinical trials have revealed the need to improve their therapeutic efficacy. Recent evidence demonstrated that mitochondria undergo spontaneous transfer from damaged cells to MSCs, resulting in the activation of the cytoprotective and pro-angiogenic functions of recipient MSCs. Based on these observations, we investigated whether the preconditioning of MSCs with mitochondria could optimize their therapeutic potential for ischemic heart disease.

METHODS

Human MSCs were exposed to mitochondria isolated from human fetal cardiomyocytes. After 24 h, the effects of mitochondria preconditioning on the MSCs' function were analyzed both in vitro and in vivo.

RESULTS

We found that cardiac mitochondria-preconditioning improved the proliferation and repair properties of MSCs in vitro. Mechanistically, cardiac mitochondria mediate their stimulatory effects through the production of reactive oxygen species, which trigger their own degradation in recipient MSCs. These effects were further confirmed in vivo, as the mitochondria preconditioning of MSCs potentiated their therapeutic efficacy on cardiac function following their engraftment into infarcted mouse hearts.

CONCLUSIONS

The preconditioning of MSCs with the artificial transfer of cardiac mitochondria appears to be promising strategy to improve the efficacy of MSC-based cell therapy in ischemic heart disease.

Matricellular Protein SMOC2 Potentiates BMP9-Induced Osteogenic Differentiation in Mesenchymal Stem Cells through the Enhancement of FAK/PI3K/AKT Signaling

Mesenchymal stem cells (MSCs) can self-renew and differentiate into multiple lineages, making MSC transplantation a promising option for bone regeneration. Both matricellular proteins and growth factors play an important role in regulating stem cell fate. In this study, we investigated the effects of matricellular protein SMOC2 (secreted modular calcium-binding protein 2) on bone morphogenetic protein 9 (BMP9) in mouse embryonic fibroblasts (MEFs) and revealed a possible molecular mechanism underlying this process. We found that SMOC2 was detectable in MEFs and that exogenous SMOC2 expression potentiated BMP9-induced osteogenic markers, matrix mineralization, and ectopic bone formation, whereas SMOC2 knockdown inhibited these effects. BMP9 increased the levels of p-FAK and p-AKT, which were either enhanced or reduced by SMOC2 and FAK silencing, respectively. BMP9-induced osteogenic markers were increased by SMOC2, and this increase was partially abolished by silencing FAK or LY290042. Furthermore, we found that general transcription factor 2I (GTF2I) was enriched at the promoter region of SMOC2 and that integrin β1 interacted with SMOC2 in BMP9-treated MEFs. Our findings demonstrate that SMOC2 can promote BMP9-induced osteogenic differentiation by enhancing the FAK/PI3K/AKT pathway, which may be triggered by facilitating the interaction between SMOC2 and integrin β1.

Comparative analysis of mesenchymal stem/stromal cells derived from human induced pluripotent stem cells and the cognate umbilical cord mesenchymal stem/stromal cells

Mesenchymal stem/stromal cells (MSCs) show tremendous potential for regenerative medicine due to their self-renewal, multi-differentiation and immunomodulatory capabilities. Largely studies had indicated conventional tissue-derived MSCs have considerable limited expandability and donor variability which hinders further application. Induced pluripotent stem cell (iPSCs)-derived MSCs (iMSCs) have created exciting source for standardized cellular therapy. However, the cellular and molecular differences between iMSCs and the cognate tissue-derived MSCs remains poorly explored. In this study, we first successfully reprogrammed human umbilical cords-derived mesenchymal stem/stromal cells (UMSCs) into iPSCs by using the cocktails of mRNA. Subsequently, iPSCs were further differentiated into iMSCs in xeno-free induction medium. Then, iMSCs were compared with the donor matched UMSCs by assessing proliferative state, differentiation capability, immunomodulatory potential through immunohistochemical analysis, flow cytometric analysis, transcriptome sequencing analysis, and combine with coculture with immune cell population. The results showed that iMSCs exhibited high expression of MSCs positive-makers CD73, CD90, CD105 and lack expression of negative-maker cocktails CD34, CD45, CD11b, CD19, HLA-DR; also successfully differentiated into osteocytes, chondrocytes and adipocytes. Further, the iMSCs were similar with their parental UMSCs in cell proliferative state detected by the CCK-8 assay, and in cell rejuvenation state assessed by β-Galactosidase staining and telomerase activity related mRNA and protein analysis. However, iMSCs exhibited similarity to resident MSCs in Homeobox (Hox) genes expression profile and presented better neural differentiation potential by activation of NESTIN related pathway. Moreover, iMSCs owned enhanced immunosuppression capacity through downregulation pools of pro-inflammatory factors, including IL6, IL1B etc. and upregulation anti-inflammatory factors NOS1, TGFB etc. signals. In summary, our study provides an attractive cell source for basic research and offers fundamental biological insight of iMSCs-based therapy.

Immunomodulatory and Regenerative Effects of MSC-Derived Extracellular Vesicles to Treat Acute GVHD

The development of human mesenchymal stromal/stem cell (MSC)-based therapy has focused on exploring biological nanoparticles secreted from MSCs. There is emerging evidence that the immunomodulatory and regenerative effects of MSCs can be recapitulated by extracellular vesicles released from MSCs (MSC-EVs). Off-the-shelf allogeneic human MSC products are clinically available to treat acute graft-versus-host disease (GVHD), but real-world data have revealed the limitations of these products as well as their feasibility, safety, and efficacy. MSC-EVs may have advantages over parental MSCs as drugs because of their distinguished biodistribution and importantly dose-dependent therapeutic effects. Recent research has shed light on the role of microRNAs in the mode-of-action of MSC-EVs. A group of specific microRNAs alone or in combination with membrane proteins, membrane lipids, and soluble factors present in MSC-EVs play key roles in the regulation of GVHD. In this concise review, we review the regulation of T-cell-mediated adaptive immunity and antigen-presenting cell-mediated innate immunity by MSC-EVs and the direct regenerative effects on damaged cells in association with the immunopathology of GVHD.

Effects of Low-Intensity Pulsed Ultrasound on the Migration and Homing of Human Amnion-Derived Mesenchymal Stem Cells to Ovaries in Rats With Premature Ovarian Insufficiency

Premature ovarian insufficiency (POI) can cause multiple sequelae and is currently incurable. Mesenchymal stem cell (MSC) transplantation might provide an effective treatment method for POI. However, the clinical application of systemic MSC transplantation is limited by the low efficiency of cell homing to target tissue in vivo, including systemic MSC transplantation for POI treatment. Thus, exploration of methods to promote MSC homing is necessary. This study was to investigate the effects of low-intensity pulsed ultrasound (LIPUS) on the migration and homing of transplanted human amnion–derived MSCs (hAD-MSCs) to ovaries in rats with chemotherapy-induced POI. For LIPUS treatment, hAD-MSCs were exposed to LIPUS or sham irradiation. Chemokine receptor expressions in hAD-MSCs were detected by polymerase chain reaction (PCR), Western blot, and immunofluorescence assays. hAD-MSC migration was detected by wound healing and transwell migration assays. Cyclophosphamide-induced POI rat models were established to evaluate the effects of LIPUS on the homing of systemically transplanted hAD-MSCs to chemotherapy-induced POI ovaries in vivo. We found that hAD-MSCs expressed chemokine receptors. The LIPUS promoted the expression of chemokine receptors, especially CXCR4, in hAD-MSCs. SDF-1 induced hAD-MSC migration. The LIPUS promoted hAD-MSC migration induced by SDF-1 through SDF-1/CXCR4 axis. SDF-1 levels significantly increased in ovaries induced by chemotherapy in POI rats. Pretreating hAD-MSCs with LIPUS increased the number of hAD-MSCs homing to ovaries in rats with chemotherapy-induced POI to some extent. However, the difference was not significant. Both hAD-MSC and LIPUS-pretreated hAD-MSC transplantation reduced ovarian injuries and improved ovarian function in rats with chemotherapy-induced POI. CXCR4 antagonist significantly reduced the number of hAD-MSCs- and LIPUS-pretreated hAD-MSCs homing to POI ovaries, and further reduced their efficacy in POI treatment. According to these findings, pretreating MSCs with LIPUS before transplantation might provide a novel, convenient, and safe technique to explore for improving the homing of systemically transplanted MSCs to target tissue.

Comprehensive immune cell analysis of human menstrual-blood-derived stem cells therapy to concanavalin A hepatitis

Autoimmune hepatitis is an autoimmune disease with increasing occurrence worldwide. The most common and convenient mouse model is the concanavalin A (ConA) mouse model. Human menstrual-blood-derived stem cells (MenSCs) have shown great potential as a type of mesenchymal stem cell for treating various diseases. Time-of-flight mass cytometry was performed in phosphate-buffered saline control (NC) group and ConA injection with or without MenSCs treatment groups, and conventional flow cytometry was used for further validation. The serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels and H&E staining depicted that MenSCs treatment could significantly alleviate ConA-induced hepatitis. The t-distributed stochastic neighbor embedding (t-SNE) analysis of nine liver samples displayed favorable cell clustering, and the NC group was significantly different from the other two groups. The proportions of CD69⁺ T cells, NKT cells, and PD-L1⁺ macrophages were notably increased by ConA injection, while MenSCs could decrease ConA-induced macrophage percentage and M1 polarization in the liver tissue. The analysis of proinflammatory factors carried out by cytometric bead array demonstrated that tumor necrosis factor alpha (TNF-α), interleukin (IL)-17A, IL-12p70, IL-6, IL-2, IL-1b, and interferon gamma (IFN-γ) were upregulated after ConA injection and then rapidly decreased at 12 h. MenSCs also played an important role in downregulating these cytokines. Here, we described the comprehensive changes in leukocytes in the liver tissue of ConA-induced hepatitis at 12 h after ConA injection and found that MenSCs rescued ConA-induced hepatitis mostly by inhibiting macrophages and M1 polarization in mouse liver.

Fabrication of Tβ4-Exosome-releasing artificial stem cells for myocardial infarction therapy by improving coronary collateralization

Currently, stem cell transplantations in cardiac repair are limited owing to disadvantages, such as immunological rejection and poor cell viability. Although direct injection of exosomes can have a curative effect similar to that of stem cell transplantation, high clearance hinders its application in clinical practice. Previous reports suggested that induction of coronary collateralization can be a desired method of adjunctive therapy for someone who had missed the optimal operation time to attenuate myocardial ischemia. In this study, to mimic the paracrine and biological activity of stem cells, we developed artificial stem cells that can continuously release Tβ4-exosomes (Tβ4-ASCs) by encapsulating specific exosomes within microspheres using microfluidics technology. The results show that Tβ4-ASCs can greatly promote coronary collateralization in the periphery of the myocardial infarcted area, and its therapeutic effect is superior to that of directly injecting the exosomes. In addition, to better understand how it works, we demonstrated that the Tβ4-ASC-derived exosomes can enhance the angiogenic capacity of coronary endothelial cells (CAECs) via the miR-17-5p/PHD3/Hif-1α pathway. In brief, as artificial stem cells, Tβ4-ASCs can constantly release functional exosomes and stimulate the formation of collateral circulation after myocardial infarction, providing a feasible and alternative method for clinical revascularization.

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Inspired by the paracrine of stem cells, we fabricated artificial stem cells (Tβ4-ASCs) by loading engineered Tβ4-exosomes with microspheres using microfluidics technology.

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Tβ4-ASCs stimulate the formation of coronary collateralization in myocardial infarcted area through a slowly sustained release of engineered Tβ4-exosomes.

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Tβ4-ASCs improve coronary collateralization via the miR-17-5p/PHD3/Hif-1α signaling pathway.

Human umbilical cord mesenchymal stem cells derived extracellular vesicles regulate acquired immune response of lupus mouse in vitro

Systemic lupus erythematosus (SLE) is an autoimmune disease involving multiple systems. Immunopathology believes that abnormal T cell function and excessive production of autoantibodies by B cells are involved in multi-organ damage. Human umbilical cord mesenchymal stem cells (hUCMSCs) therapies have endowed with promise in SLE, while the function of MSC-derived extracellular vesicles (MSC-EVs) was still unclear. Extracellular vesicles (EVs) are subcellular components secreted by a paracellular mechanism and are essentially a group of nanoparticles. EVs play a vital role in cell-to-cell communication by acting as biological transporters. New evidence has shown beneficial effects of MSC-EVs on autoimmune diseases, such as their immunomodulatory properties. In this study, we investigated whether hUCMSCs derived extracellular vesicles (hUCMSC-EVs) could regulate abnormal immune responses of T cells or B cells in SLE. We isolated splenic mononuclear cells from MRL/lpr mice, a classical animal model of SLE. PBS (Phosphate-buffered saline), 2 × 10⁵ hUCMSCs, 25 µg/ml hUCMSC-EVs, 50 µg/ml hUCMSC-EVs were co-cultured with 2 × 10⁶ activated splenic mononuclear cells for 3 days in vitro, respectively. The proportions of CD4⁺ T cell subsets, B cells and the concentrations of cytokines were detected. Both hUCMSCs and hUCMSC-EVs inhibited CD4⁺ T cells, increased the production of T helper (Th)17 cells, promoted the production of interleukin (IL)-17 and transforming growth factor beta1 (TGF-β1) (P < 0.05), although they had no significant effects on Th1, Th2, T follicular helper (Tfh), regulatory T (Treg) cells and IL-10 (P > 0.05); only hUCMSCs inhibited CD19⁺ B cells, promoted the production of interferon-gamma (IFN-γ) and IL-4 (P < 0.05). hUCMSCs exert immunoregulatory effects on SLE at least partially through hUCMSC-EVs in vitro, therefore, hUCMSC-EVs play novel and potential regulator roles in SLE.

Potential Cell-Based and Cell-Free Therapy for Patients with COVID-19

Since it was first reported, the novel coronavirus disease 2019 (COVID-19) remains an unresolved puzzle for biomedical researchers in different fields. Various treatments, drugs, and interventions were explored as treatments for COVID. Nevertheless, there are no standard and effective therapeutic measures. Meanwhile, mesenchymal stem cell (MSC) therapy offers a new approach with minimal side effects. MSCs and MSC-based products possess several biological properties that potentially alleviate COVID-19 symptoms. Generally, there are three classifications of stem cell therapy: cell-based therapy, tissue engineering, and cell-free therapy. This review discusses the MSC-based and cell-free therapies for patients with COVID-19, their potential mechanisms of action, and clinical trials related to these therapies. Cell-based therapies involve the direct use and injection of MSCs into the target tissue or organ. On the other hand, cell-free therapy uses secreted products from cells as the primary material. Cell-free therapy materials can comprise cell secretomes and extracellular vesicles. Each therapeutic approach possesses different benefits and various risks. A better understanding of MSC-based and cell-free therapies is essential for supporting the development of safe and effective COVID-19 therapy.

Direct administration of mesenchymal stem cell-derived mitochondria improves cardiac function after infarction via ameliorating endothelial senescence

Mitochondrial dysfunction is considered to be a key contributor to the development of heart failure. Replacing injured mitochondria with healthy mitochondria to restore mitochondrial bioenergy in myocardium holds great promise for cardioprotection after infarction. This study aimed to investigate whether direct transplantation of exogenous mitochondria derived from mesenchymal stem cells (MSC-mt) is beneficial and superior in protecting cardiac function in a mouse model of myocardial infarction (MI) compared to mitochondria derived from skin fibroblast (FB-mt) and to explore the underlying mechanisms from their effects on the endothelial cells. The isolated MSC-mt presented intact mitochondrial morphology and activity, as determined by electron microscopy, JC-1 mitochondrial membrane potential assay, and seahorse assay. Direct injection of MSC-mt into the peri-infarct region in a mouse MI model enhanced blood vessel density, inhibited cardiac remodeling and apoptosis, thus improving heart function compared with FB-mt group. The injected MSC-mt can be tracked in the endothelial cells. In vitro, the fluorescence signal of MSC-mt can be detected in human umbilical vein endothelial cells (HUVECs) by confocal microscopy and flow cytometry after coculture. Compared to FB-mt, MSC-mt more effectively protected the HUVECs from oxidative stress-induced apoptosis and reduced mitochondrial production of reactive oxygen species. MSC-mt presented superior capacity in inducing tube formation, enhancing SCF secretion, ATP content and cell proliferation in HUVECs compared to FB-mt. Mechanistically, MSC-mt administration alleviated oxidative stress-induced endothelial senescence via activation of ERK pathway. These findings suggest that using MSCs as sources of mitochondria is feasible and that proangiogenesis could be the mechanism by which MSC-mt transplantation attenuates MI. MSC-mt transplantation might serve as a new therapeutic strategy for treating MI.

Interferon-γ enhances the immunosuppressive ability of canine bone marrow-derived mesenchymal stem cells by activating the TLR3-dependent IDO/kynurenine pathway

BACKGROUND

The immunomodulatory function of mesenchymal stem cells (MSCs) has been considered to be vital for MSC-based therapies. Many works have been devoted to excavate effective strategies for enhancing the immunomodulation effect of MSCs. Nonetheless, canine MSC-mediated immunomodulation is still poorly understood.

METHODS AND RESULTS

The inflammatory microenvironment was simulated through the employment of interferon-γ (IFN-γ) in a culture system. Compared with unstimulated cBMSCs, IFN-γ stimulation increased the mRNA levels of Toll-like receptor 3 (TLR3) and indoleamine 2, 3-dioxygenase 1 (IDO-1), and simultaneously enhanced the secretion of immunosuppressive molecules, including interleukin (IL)-10, hepatocyte growth factor (HGF), and kynurenine in cBMSCs. IFN-γ stimulation significantly enhanced the ability of cBMSCs and their supernatant to suppress the proliferation of murine spleen lymphocytes. Lymphocyte subtyping evaluation revealed that cBMSCs and their supernatant diminished the percentage of CD3⁺CD4⁺ and CD3⁺CD8⁺ lymphocytes compared with the control group, with a decreasing CD4⁺/CD8⁺ ratio. Notably, exposure to IFN-γ decreased the CD4⁺/CD8⁺ ratio more effectively than unstimulated cells or supernatant. Additionally, IFN-γ-stimulation increased the mRNA levels of the Th1 cytokines TNF-α, and remarkably decreased the mRNA level of the Th2 cytokine IL-4 and IL-10.

CONCLUSION

Our findings substantiate that IFN-γ stimulation can enhance the immunomodulatory properties of cBMSCs by promoting TLR3-dependent activation of the IDO/kynurenine pathway, increasing the secretion of immunoregulatory molecules and strengthening interactions with T lymphocytes, which may provide a meaningful strategy for the clinical application of cBMSCs in immune-related diseases.

Metformin Ameliorates Senescence of Adipose-Derived Mesenchymal Stem Cells and Attenuates Osteoarthritis Progression via the AMPK-Dependent Autophagy Pathway

Osteoarthritis (OA) is one of the most serious age-related diseases worldwide that drastically affects the quality of life of patients. Despite advancements in the treatment of arthritis, especially with adipose-derived mesenchymal stem cells (ADSCs), senescence-induced alterations in ADSCs negatively affect the treatment outcomes. This study was aimed at mechanistically exploring whether metformin could ameliorate the senescence of ADSCs and at exploring the effect of metformin-preconditioned ADSCs in an experimental OA mouse model. In this study, an H2O2-induced mouse ADSC senescent model was established. Cell proliferation, senescence, and autophagy were investigated in vitro. Moreover, the effects of intra-articular injection of metformin-preconditioned ADSCs were investigated in vivo. Metformin could promote autophagy and activate the AMPK/mTOR pathway in ADSCs. The metformin-enhanced autophagy could improve the survival and reduce the senescence of ADSCs. The protective effects of metformin against senescence were partially blocked by 3-methyladenine and compound C. Injection of metformin-preconditioned ADSCs slowed OA progression and reduced OA pain in mice. The results suggest that metformin activates the AMPK/mTOR-dependent autophagy pathway in ADSCs against H2O2-induced senescence, while metformin-preconditioned ADSCs can potentially inhibit OA progression.

Molecular evidence of the amelioration of toluene induced encephalopathy by human breast milk mesenchymal stem cells

Toluene was widely used volatile organic compound that accumulates in tissues with high lipid content. Stem cells have been proposed as an increasingly attractive approach for repair of damaged nervous system, we aimed to evaluate the ability of breast milk mesenchymal stem cells (MSc) to ameliorate toluene-induced encephalopathy. Sixty adult male albino rats were assigned to 3 groups, control, toluene, and toluene/breast milk-MSc. Neurological assessment was evaluated as well as serum levels of glial fibrillary acidic protein (GFAP), tumor necrosis factor-alpha (TNF-α), nerve growth factor (NGF), vascular endothelial growth factor (VEGF), tissue dopamine and oxidative markers. Gene expression of peroxisome Proliferator-Activated Receptor-Gamma (PPAR-ɣ), nuclear factor-kappaB (NF-kB), and interleukin-6 (IL-6) were evaluated. Moreover, histological and immunohistochemical investigation were done. Results revealed that toluene caused cerebral injury, as evidenced by a significant increase in serum GFAP, TNF-α, malondialdehyde (MDA) and nitric oxide (NO), a significant decrease in serum NGF, tissue dopamine and oxidative markers, besides, a non-significant change in VEGF. Toluene also caused changes in normal cerebral structure and cellular degeneration, including a significant decrease in the total number of neurons and thickness of frontal cortex. Meninges showing signs of inflammation with inflammatory cell infiltration and exudation, a significant decrease in MBP immunoreactivity, and increase in the percent of high motility group box protein-1 (HMGB1) positive cells. PPAR- ɣ, NF-kB, and IL-6 gene expression were all considerably elevated by toluene. These changes were greatly improved by breast milk MSc. Therefore, we conclude that breast milk MSc can attenuate toluene-induced encephalopathy.

In vitro generation of transplantable insulin-producing cells from canine adipose-derived mesenchymal stem cells

Canine mesenchymal stem cells (cMSCs) have potential applications for regenerative therapy, including the generation of insulin-producing cells (IPCs) for studying and treating diabetes. In this study, we established a useful protocol for generating IPCs from canine adipose mesenchymal stem cells (cAD-MSCs). Subsequently, in vitro preservation of pluronic F127-coated alginate (ALGPA)-encapsulated cAD-MSC-derived IPCs was performed to verify ready-to-use IPCs. IPCs were induced from cAD-MSCs with the modulated three-stepwise protocol. The first step of definitive endoderm (DE) induction showed that the cooperation of Chir99021 and Activin A created the effective production of Sox17-expressed DE cells. The second step for pancreatic endocrine (PE) progenitor induction from DE indicated that the treatment with taurine, retinoic acid, FGF2, EGF, TGFβ inhibitor, dorsomorphin, nicotinamide, and DAPT showed the significant upregulation of the pancreatic endocrine precursor markers Pdx1 and Ngn3. The last step of IPC production, the combination of taurine, nicotinamide, Glp-1, forskolin, PI3K inhibitor, and TGFβ inhibitor, yielded efficiently functional IPCs from PE precursors. Afterward, the maintenance of ALGPA-encapsulated cAD-MSC-derived IPCs with VSCBIC-1, a specialized medium, enhanced IPC properties. Conclusion, the modulated three-stepwise protocol generates the functional IPCs. Together, the encapsulation of cAD-MSC-derived IPCs and the cultivation with VSCBIC-1 enrich the maturation of generated IPCs.

Periodontal tissue regeneration by transplantation of autologous adipose tissue-derived multi-lineage progenitor cells

Periodontitis is a chronic inflammatory disease that destroys tooth-supporting periodontal tissue. Current periodontal regenerative therapies have unsatisfactory efficacy; therefore, periodontal tissue engineering might be established by developing new cell-based therapies. In this study, we evaluated the safety and efficacy of adipose tissue-derived multi-lineage progenitor cells (ADMPC) autologous transplantation for periodontal tissue regeneration in humans. We conducted an open-label, single-arm exploratory phase I clinical study in which 12 periodontitis patients were transplanted with autologous ADMPCs isolated from subcutaneous adipose tissue. Each patient underwent flap surgery during which autologous ADMPCs were transplanted into the bone defect with a fibrin carrier material. Up to 36 weeks after transplantation, we performed a variety of clinical examinations including periodontal tissue inspection and standardized dental radiographic analysis. A 36-week follow-up demonstrated no severe transplantation-related adverse events in any cases. ADMPC transplantation reduced the probing pocket depth, improved the clinical attachment level, and induced neogenesis of alveolar bone. Therapeutic efficiency was observed in 2- or 3-walled vertical bone defects as well as more severe periodontal bone defects. These results suggest that autologous ADMPC transplantation might be an applicable therapy for severe periodontitis by inducing periodontal regeneration.

Discovery and Application of Postnatal Nucleus Pulposus Progenitors Essential for Intervertebral Disc Homeostasis and Degeneration

Intervertebral disc degeneration (IDD) results from the dysfunction of nucleus pulposus (NP) cells and the exhaustion of NP progenitors (ProNPs). The cellular applications of NP cells during IDD are currently limited due to the lack of in vivo studies showing whether NP cells are heterogeneous and contain ProNPs throughout postnatal stages. In this study, single-cell RNA sequencing of purified NP cells is used to map four molecularly defined populations and urotensin II receptor (UTS2R)-expressing postnatal ProNPs is identified, which are markedly exhausted during IDD, in mouse and human specimens. The lineage tracing shows that UTS2R⁺ ProNPs preferentially resides in the NP periphery with its niche factor tenascin-C and give rise to functional NP cells. It is also demonstrated that transplanting UTS2R⁺ ProNPs with tenascin-C into injured intervertebral discs attenuate the progression of IDD. The study provides a novel NP cell atlas, identified resident ProNPs with regenerative potential, and revealed promising diagnostic and therapeutic targets for IDD.

Different isoforms of growth hormone (20 kD-GH and 22 kD-GH) shows different biological activities in mesenchymal stem cell (MSC)

There are two main types of growth hormone (GH) in the circulatory system. One is 22 kD-GH, which is the predominant isoform in the circulating system, 90% GH is present as a 22 kD protein, and 10% of GH is present as a 20 kD protein. Amino acid sequences are identical between 20 kD-GH and 22 kD-GH protein, except that 20 kD-GH lacks 15 amino acid residues 32 to 46. Studies have shown that GH has many important biological effects on mesenchymal stem cells (MSCs). However, so far, the cellular characteristics of the two types of GH have not been studied in BM-MSCs. Furthermore, the biological activity of 20 kD-GH has not been explored in BM-MSCs. For this, in the current work, BM-MSCs were used as in vitro cell model. We have carried out the current research using a series of experimental techniques (such as Western-blot and indirect immunofluorescence). Firstly, we explored the cell behavior of two types of GH in the Bm-MSC model and found that they showed different biological characteristics; Secondly, we investigated the biological characteristics of 20 kD-GH and 22 kD-GH, and results showed that 22 kD-GH and 20 kD-GH exhibited different signaling profiles; Thirdly, we found that the 20 kD-GH and 22 kD-GH Gexhibited different regulatory effects on the osteogenic differentiation of BM-MSCs. The current research lays a solid foundation for further studies on the regulatory effects of GH on MSCs.

Electrostatic Charge-Mediated Apoptotic Vesicle Biodistribution Attenuates Sepsis by Switching Neutrophil NETosis to Apoptosis

Mesenchymal stem cell (MSC) therapy can attenuate organ damage and reduce mortality in sepsis; however, the detailed mechanism is not fully elucidated. In this study, it is shown that MSC-derived apoptotic vesicles (apoVs) can ameliorate multiple organ dysfunction and improve survival in septic mice. Mechanistically, it is found that tail vein-infused apoVs mainly accumulate in the bone marrow of septic mice via electrostatic charge interactions with positively charged neutrophil extracellular traps (NETs). Moreover, apoVs switch neutrophils NETosis to apoptosis via the apoV-Fas ligand (FasL)-activated Fas pathway. In summary, these findings uncover a previously unknown role of apoVs in sepsis treatment and an electrostatic charge-directed target therapeutic mechanism, suggesting that cell death is associated with disease development and therapy.

Apelin-13 Pretreatment Promotes the Cardioprotective Effect of Mesenchymal Stem Cells against Myocardial Infarction by Improving Their Survival

Although mesenchymal stem cell- (MSC-) based therapy has shown promising results for myocardial infarction (MI), low cell survival heavily limits its beneficial effects. Apelin plays an essential regulatory role in cell proliferation. This study was aimed at determining whether Apelin-13 pretreatment could improve the survival of MSCs in the ischemic heart and enhance their cardioprotective efficacy against MI. MSCs were pretreated with or without Apelin-13 for 24 hours and then exposed to serum deprivation and hypoxia (SD/H) for 48 hours. The mitochondrial morphology of MSCs was assessed by MitoTracker staining. The apoptosis of MSCs was determined by TUNEL staining. The level of mitochondrial reactive oxygen species (ROS) of MSCs was detected by Mito-Sox staining. MSCs and Apelin-13-pretreated MSCs were transplanted into the peri-infarct region in a mouse MI model. Apelin-13 pretreatment protected MSCs against SD/H-induced mitochondrial fragmentation and apoptosis. Apelin-13 pretreatment reduced ROS generation induced by SD/H in MSCs. Furthermore, Apelin-13 pretreatment enhanced the angiogenesis of MSCs under SD/H conditions. Mechanistically, Apelin-13 pretreatment inhibited SD/H-induced MSC apoptosis by downregulating mitochondrial fission via activation of the ERK pathway, and these effects were partially abrogated by ERK inhibitor U0126. Apelin-13 pretreatment promoted the survival of MSCs in the ischemic heart. Moreover, transplantation with Apelin-13-pretreated MSCs improved heart function and increased angiogenesis accompanied by decreased fibrosis compared with MSC transplantation at 28 days following MI. These findings reveal that pretreatment with Apelin-13 improves MSCs survival and enhances their therapeutic efficacy for MI. Our study provides a novel approach to improve MSC-based therapy for cardiovascular disease.

Differentiation of Induced Pluripotent Stem Cells Into Chondrocytes: Methods and Applications for Disease Modeling and Drug Discovery

Induced pluripotent stem cell (iPSC) technology allows pathomechanistic and therapeutic investigation of human heritable disorders affecting tissue types whose collection from patients is difficult or even impossible. Among them are cartilage diseases. Over the past decade, iPSC-chondrocyte disease models have been shown to exhibit several key aspects of known disease mechanisms. Concurrently, an increasing number of protocols to differentiate iPSCs into chondrocytes have been published, each with its respective (dis)advantages. In this review we provide a comprehensive overview of the different differentiation approaches, the hitherto described iPSC-chondrocyte disease models and mechanistic and/or therapeutic insights that have been derived from their investigation, and the current model limitations. Key lessons are that the most appropriate differentiation approach is dependent upon the cartilage disease under investigation and that further optimization is still required to recapitulate the in vivo cartilage. © 2022 American Society for Bone and Mineral Research (ASBMR).

Characteristics and regulation of mesenchymal stem cell plasticity by the microenvironment — specific factors involved in the regulation of MSC plasticity

Mesenchymal stem cells (MSCs), multipotent stromal cells, have attracted extensive attention in the field of regenerative medicine and cell therapy due to the capacity of self-renewal, multilineage differentiation, and immune regulation. MSCs have different cellular effects in different diseases, and even have markedly different curative effects with different tissue sources, indicating the plasticity of MSCs. The phenotypes, secreted factors, and proliferative, migratory, differentiating, and immunomodulatory effects of MSCs depend on certain mediators present in their microenvironment. Understanding microenvironmental factors and their internal mechanisms in MSC responses may help in subsequent prediction and improvement of clinical benefits. This review highlighted the recent advances in MSC plasticity in the physiological and pathological microenvironment and multiple microenvironmental factors regulating MSC plasticity. It also highlighted some progress in the underlying molecular mechanisms of MSC remodeling in the microenvironment. It might provide references for the improvement in vitro culture of MSCs, clinical application, and in vivo induction.

Mesenchymal Stem Cell-Derived Exosome Therapy of Microbial Diseases: From Bench to Bed

Microbial diseases are a global health threat, leading to tremendous casualties and economic losses. The strategy to treat microbial diseases falls into two broad categories: pathogen-directed therapy (PDT) and host-directed therapy (HDT). As the typical PDT, antibiotics or antiviral drugs directly attack bacteria or viruses through discerning specific molecules. However, drug abuse could result in antimicrobial resistance and increase infectious disease morbidity. Recently, the exosome therapy, as a HDT, has attracted extensive attentions for its potential in limiting infectious complications and targeted drug delivery. Mesenchymal stem cell-derived exosomes (MSC-Exos) are the most broadly investigated. In this review, we mainly focus on the development and recent advances of the application of MSC-Exos on microbial diseases. The review starts with the difficulties and current strategies in antimicrobial treatments, followed by a comprehensive overview of exosomes in aspect of isolation, identification, contents, and applications. Then, the underlying mechanisms of the MSC-Exo therapy in microbial diseases are discussed in depth, mainly including immunomodulation, repression of excessive inflammation, and promotion of tissue regeneration. In addition, we highlight the latest progress in the clinical translation of the MSC-Exo therapy, by summarizing related clinical trials, routes of administration, and exosome modifications. This review will provide fundamental insights and future perspectives on MSC-Exo therapy in microbial diseases from bench to bedside.

Cryo-Temperature Pretreatment Increases the Pro-Angiogenic Capacity of Three-Dimensional Mesenchymal Stem Cells via the PI3K-AKT Pathway

To increase the potential and effectiveness of three-dimensional (3D) mesenchymal stem cells (MSCs) for clinical applications, this study explored the effects of short cryo-temperature pretreatment on MSC function. Adipose-derived MSCs (A-MSCs) were cultured via the ordinary monolayer method and 3D hanging drop spheroid method. When the cells adhered to the wall or formed a spheroid, they were subjected to hypothermic stress at 4°C for 1 h and then divided into three recovery periods at 37°C, specifically 0, 12, and 24 h. The control group was not subjected to any treatment throughout the study. Monolayer and 3D spheroid A-MSCs were analyzed via RNA sequencing after hypothermic stress at 4°C for 1 h. Subsequently, each group of cells was collected and subjected to phenotype identification via flow cytometry, and mRNA expression was detected via reverse transcription-quantitative polymerase chain reaction analysis. Western blot analysis was performed to analyze the PI3K-AKT signaling pathway in A-MSCs. The effects of A-MSCs on angiogenesis in vivo were examined using a chick chorioallantoic membrane assay. Transwell assays were performed to determine whether the culture supernatant from each group could induce the chemotaxis of human umbilical vein endothelial cells (HUVECs). Three-dimensional spheroid culture did not change the phenotype of A-MSCs. The expression of fibroblast growth factors, hepatocyte growth factors, and other angiogenesis-related factors in A-MSCs was upregulated. A-MSCs subjected to hypothermic stress promoted angiogenesis under both monolayer and 3D spheroid cultures. Moreover, the chemotaxis of HUVECs to the 3D spheroid culture supernatant increased substantially. Short cryo-temperature pretreatment could stimulate 3D spheroid A-MSCs and activate the PI3K-AKT pathway. This approach has the advantages of promoting angiogenesis and maintaining cell viability.

Bone Marrow Mesenchymal Stem Cells Overexpressing HIF-1α Prevented the Progression of Glucocorticoid-Induced Avascular Osteonecrosis of Femoral Heads in Mice

Glucocorticoid (GC)-induced avascular osteonecrosis of femoral head (AOFH) is a devastating complication, and no cures are currently available for it. Previous studies have demonstrated that implantation of bone marrow mesenchymal stem cells (BMMSCs) may prevent the progression of pre-collapse AOFH. Based on previous observations, we hypothesized that GCs induce AOFH via the COX-2 (cyclooxygenase-2)-PGE-2 (prostaglandin E2)-HIF-1α (hypoxia-inducible factor-1α) axis, and that modification of BMMSCs may improve the efficacy of their implantation. BMMSCs isolated from wild-type (WT) mice were treated with dexamethasone (Dex) and the results showed that Dex repressed the expression of COX-2. Femoral head samples harvested from both WT and COX-2 knock-out (COX-2^-/-) mice were subjected to micro-computed tomography and histological examinations. Compared with their WT littermates, COX-2^-/- mice had larger trabecular separations, diminished microvasculature, and reduced HIF-1α expression in their femoral heads. In vitro angiogenesis assays with tube formation and fetal metatarsal sprouting demonstrated that Dex repressed angiogenesis and PGE-2 antagonized its effects. An AOFH model was successfully established in C57BL/6J mice. In vitro experiment showed that BMMSCs infected with Lentivirus encoding HIF-1α (Lenti-HIF-1α) resulted in a robust increase in the production of HIF-1α protein. Implantation of BMMSCs overexpressing HIF-1α into femoral heads of AOFH mice significantly reduced osteonecrotic areas and enhanced bone repair, thus largely preserving the structural integrity of femoral heads. Our studies provide strong rationales for early intervention with core decompression and implantation of modified BMMSCs for GC-induced AOFH, which may spare patients from expensive and difficult surgical procedures.

OUP accepted manuscript

Mesenchymal stem cells (MSCs) are a promising cellular vehicle for transferring anti-cancer factors to malignant tumors. Currently, a variety of anti-cancer agents, including the tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), have been loaded into MSCs derived from a range of sources through different engineering methods. These engineered MSCs exhibit enormous therapeutic potential for various cancers. To avoid the intrinsic defects of MSCs derived from tissues and the potential risk of viral vectors, TRAIL was site-specifically integrated into the ribosomal DNA (rDNA) locus of human-induced pluripotent stem cells (iPSCs) using a non-viral rDNA-targeting vector and transcription activator-like effector nickases (TALENickases). These genetically modified human iPSCs were differentiated into an unlimited number of homogeneous induced MSCs (TRAIL-iMSCs) that overexpressed TRAIL in both culture supernatants and cell lysates while maintaining MSC-like characteristics over continuous passages. We found that TRAIL-iMSCs significantly induced apoptosis in A375, A549, HepG2, and MCF-7 cells in vitro. After intravenous infusion, TRAIL-iMSCs had a prominent tissue tropism for A549 or MCF-7 xenografts and significantly inhibited tumor growth through the activation of apoptotic signaling pathways without obvious side effects in tumor-bearing mice models. Altogether, our results showed that TRAIL-iMSCs have strong anti-tumor effects in vitro and in vivo on a range of cancers. This study allows for the development of an unlimited number of therapeutic gene-targeted MSCs with stable quality and high homogeneity for cancer therapy, thus highlighting a universal and safe strategy for stem cell-based gene therapy with high potential for clinical applications.