Cell adhesion and long-term survival of transplanted mesenchymal stem cells: a prerequisite for cell therapy

Lentiviral vector-mediated co-overexpression of VEGF and Bcl-2 improves mesenchymal stem cell survival and enhances paracrine effects in vitro

Mesenchymal stem cell (MSC) transplantation has emerged as a promising therapy for ischemic heart disease; however, the low survival rate of transplanted cells limits their therapeutic efficacy. The aim of this study was to investigate whether the dual genetic modification of vascular endothelial growth factor (VEGF) and B-cell lymphoma-2 (Bcl-2) confers a higher expression level of the target genes, better survival and a stronger paracrine effect in MSCs in an adverse environment than the modification of the individual genes. For this purpse, a lentiviral vector was constructed by using a self-cleaving T2A peptide sequence to link and achieve the co-overexpression of VEGF and Bcl-2. Rat MSCs were transfected to obtain cell lines that exhibited a stable overexpression. An in vitro model of oxygen glucose deprivation (OGD) was applied to mimic the ischemic microenvironment, and cell apoptosis, autophagy and the paracrine effects were then determined. Compared with the MSCs in which individual genes were modified and the control MSCs, the MSCs which were subjected to dual genetic modification had a higher expression level of the target genes, a more rapid proliferation, reduced apoptosis, decreased autophagy and an enhanced paracrine effect. Furthermore, the suppression of autophagy was found to contribute to the inhibition of apoptosis in this in vitro OGD model. On the whole, these data indicate that the co-overexpression of VEGF and Bcl-2 protects MSCs in an ischemic environment by inhibiting apoptosis, suppressing autophagy and enhancing the paracrine effects.

The effect of histone deacetylase inhibitor trichostatin A on porcine mesenchymal stem cell transcriptome

The use of histone deacetylase inhibitors such as trichostatin A (TSA) for epigenetic transformation of mesenchymal stem cells (MSCs), whose nuclei will be transferred into enucleated oocytes, is a novel approach in research involving somatic cell cloning of pigs and other mammalian species. Although the effectiveness of TSA in cloning applications was confirmed, processes and mechanisms underlying achieved effects are not yet fully understood, especially for pig MSCs. To contribute to this knowledge, in this study we performed a comprehensive transcriptome analysis using high-throughput sequencing of pig bone-marrow derived MSCs, both treated and untreated with TSA, and evaluated the effect of TSA administration on their transcription profile after 24 h of in vitro culture. The expression of selected positive and negative mesenchymal surface antigens was also evaluated in these cells by flow cytometry. Subsequently, the stability of induced expression changes was evaluated after another 55-72 h of culture without TSA. The results of this study showed that TSA does not affect the expression of the selected surface antigens related to MSC mesenchymal stemness origin, namely: CD90 (positive marker), CD31 and CD34 (negative markers) and has a wide stimulating effect on MSCs transcription, affecting genes across the whole genome with some minor signs of site-specific acting in regions on SSC2 and SSC6. TSA turned out to have a higher impact on already expressed genes with only minor abilities to induce expression of silenced genes. Genes with expression affected by TSA were related to a wide range of biological processes, however, we found some evidence for specific stimulation of genes associated with development, differentiation, neurogenesis or myogenesis. TSA also seemed to interfere with Wnt signaling pathways by upregulation of several engaged genes. The analysis of cell transcriptome after prolonged culture following the TSA removal, showed that the expression level of majority of genes affected by TSA is restored to the initial level. Nonetheless, the set of about six hundred genes responsible for e.g. adhesion, signal transduction and cell communication was altered even after 55-72 h of culture without TSA. TSA also enhanced expression of some of pluripotency marker genes (FGF2, LIF, TERT) but their expression was stabilized during further culture without TSA. The detailed analysis of factors connected with neuron-like differentiation allowed us to assume that TSA mostly stimulates neurogenic differentiation pathway in the pig MSCs possibly through interaction with Wnt-mediated signaling and thus triggers mechanisms conducive to epigenetic reprograming.

Enhancement of Mitochondrial Transfer by Antioxidants in Human Mesenchymal Stem Cells

Excessive reactive oxygen species is the major component of a harsh microenvironment after ischemia/reperfusion injury in human tissues. Combined treatment of N-acetyl-L-cysteine (NAC) and L-ascorbic acid 2-phosphate (AAP) promoted the growth of human mesenchymal stem cells (hMSCs) and suppressed oxidative stress-induced cell death by enhancing mitochondrial integrity and function in vitro. In this study, we aimed to determine whether NAC and AAP (termed MCA) could enhance the therapeutic potential of hMSCs. We established a coculture system consisting of MCA-treated and H₂O₂-treated hMSCs and investigated the role of tunneling nanotubes (TNTs) in the exchange of mitochondria between the 2 cell populations. The consequences of mitochondria exchange were assessed by fluorescence confocal microscopy and flow cytometry. The results showed that MCA could increase the mitochondrial mass, respiratory capacity, and numbers of TNTs in hMSCs. The “energized” mitochondria were transferred to the injured hMSCs via TNTs, the oxidative stress was decreased, and the mitochondrial membrane potential of the H₂O₂-treated hMSCs was stabilized. The transfer of mitochondria decreased the expression of S616-phosphorylated dynamin-related protein 1, a protein that dictates the fragmentation/fission of mitochondria. Concurrently, MCA also enhanced mitophagy in the coculture system, implicating that damaged mitochondria were eliminated in order to maintain cell physiology.

Bone Marrow Aspirate Concentrate-Enhanced Marrow Stimulation of Chondral Defects

Mesenchymal stem cells (MSCs) from bone marrow play a critical role in osteochondral repair. A bone marrow clot forms within the cartilage defect either as a result of marrow stimulation or during the course of the spontaneous repair of osteochondral defects. Mobilized pluripotent MSCs from the subchondral bone migrate into the defect filled with the clot, differentiate into chondrocytes and osteoblasts, and form a repair tissue over time. The additional application of a bone marrow aspirate (BMA) to the procedure of marrow stimulation is thought to enhance cartilage repair as it may provide both an additional cell population capable of chondrogenesis and a source of growth factors stimulating cartilage repair. Moreover, the BMA clot provides a three-dimensional environment, possibly further supporting chondrogenesis and protecting the subchondral bone from structural alterations. The purpose of this review is to bridge the gap in our understanding between the basic science knowledge on MSCs and BMA and the clinical and technical aspects of marrow stimulation-based cartilage repair by examining available data on the role and mechanisms of MSCs and BMA in osteochondral repair. Implications of findings from both translational and clinical studies using BMA concentrate-enhanced marrow stimulation are discussed.

Activation of cannabinoid receptor type II by AM1241 protects adipose-derived mesenchymal stem cells from oxidative damage and enhances their therapeutic efficacy in myocardial infarction mice via Stat3 activation

The poor survival of cells in ischemic sites diminishes the therapeutic efficacy of stem cell therapy. Previously we and others have reported that Cannabinoid receptor type II (CB2) is protective during heart ischemic injury for its anti-oxidative activity. However, whether CB2 activation could improve the survival and therapeutic efficacy of stem cells in ischemic myocardium and the underlying mechanisms remain elusive. Here, we showed evidence that CB2 agonist AM1241 treatment could improve the functional survival of adipose-derived mesenchymal stem cells (AD-MSCs) in vitro as well as in vivo. Moreover, AD-MSCs adjuvant with AM1241 improved cardiac function, and inhibited cardiac oxidative stress, apoptosis and fibrosis. To unveil possible mechanisms, AD-MSCs were exposed to hydrogen peroxide/serum deprivation to simulate the ischemic environment in myocardium. Results delineated that AM1241 blocked the apoptosis, oxidative damage and promoted the paracrine effects of AD-MSCs. Mechanistically, AM1241 activated signal transducers and activators of transcription 3 (Stat3) through the phosphorylation of Akt and ERK1/2. Moreover, the administration of AM630, LY294002, U0126 and AG490 (inhibitors for CB2, Akt, ERK1/2 and Stat3, respectively) could abolish the beneficial actions of AM1241. Our result support the promise of CB2 activation as an effective strategy to optimize stem cell-based therapy possibly through Stat3 activation.

Jawbone microenvironment promotes periodontium regeneration by regulating the function of periodontal ligament stem cells

During tooth development, the jawbone interacts with dental germ and provides the development microenvironment. Jawbone-derived mesenchymal stem cells (JBMSCs) maintain this microenvironment for root and periodontium development. However, the effect of the jawbone microenvironment on periodontium tissue regeneration is largely elusive. Our previous study showed that cell aggregates (CAs) of bone marrow mesenchymal stem cells promoted periodontium regeneration on the treated dentin scaffold. Here, we found that JBMSCs enhanced not only the osteogenic differentiation of periodontal ligament stem cells (PDLSCs) but also their adhesion to titanium (Ti) material surface. Importantly, the compound CAs of PDLSCs and JBMSCs regenerated periodontal ligament-like fibers and mineralized matrix on the Ti scaffold surface, both in nude mice ectopic and minipig orthotopic transplantations. Our data revealed that an effective regenerative microenvironment, reconstructed by JBMSCs, promoted periodontium regeneration by regulating PDLSCs function on the Ti material.

Cellularizing hydrogel-based scaffolds to repair bone tissue: How to create a physiologically relevant micro-environment?

Tissue engineering is a promising alternative to autografts or allografts for the regeneration of large bone defects. Cell-free biomaterials with different degrees of sophistication can be used for several therapeutic indications, to stimulate bone repair by the host tissue. However, when osteoprogenitors are not available in the damaged tissue, exogenous cells with an osteoblast differentiation potential must be provided. These cells should have the capacity to colonize the defect and to participate in the building of new bone tissue. To achieve this goal, cells must survive, remain in the defect site, eventually proliferate, and differentiate into mature osteoblasts. A critical issue for these engrafted cells is to be fed by oxygen and nutrients: the transient absence of a vascular network upon implantation is a major challenge for cells to survive in the site of implantation, and different strategies can be followed to promote cell survival under poor oxygen and nutrient supply and to promote rapid vascularization of the defect area. These strategies involve the use of scaffolds designed to create the appropriate micro-environment for cells to survive, proliferate, and differentiate in vitro and in vivo. Hydrogels are an eclectic class of materials that can be easily cellularized and provide effective, minimally invasive approaches to fill bone defects and favor bone tissue regeneration. Furthermore, by playing on their composition and processing, it is possible to obtain biocompatible systems with adequate chemical, biological, and mechanical properties. However, only a good combination of scaffold and cells, possibly with the aid of incorporated growth factors, can lead to successful results in bone regeneration. This review presents the strategies used to design cellularized hydrogel-based systems for bone regeneration, identifying the key parameters of the many different micro-environments created within hydrogels.

Lentiviral transduction and subsequent loading with nanoparticles do not affect cell viability and proliferation in hair-follicle-bulge-derived stem cells in vitro

The application of stem cells in the treatment of various degenerative diseases is highly promising. However, cell-based therapy could be limited by the problem of low viability of grafted cells and uncertainty about their fate. The combination of molecular imaging and contrast-enhanced MRI may give more insight into the survival and behavior of grafted stem cells. We explore hair-follicle-bulge-derived stem cells (HFBSCs) as a potential candidate for autologous cell-based therapy. HFBSCs are transduced with a lentiviral construct with genes coding for bioluminescent (Luc2) and fluorescent (copGFP) reporter proteins, and subsequently loaded with magnetic nanoparticles to enable MRI visualization. Thus, we investigate for the first time if lentiviral transduction and cellular loading with nanoparticles have a cytotoxic effect upon these stem cells. Transduction efficiency, proliferation rate, cell viability and reporter protein co-expression during long-term culture of transduced HFBSCs were studied using fluorescence and bioluminescence microscopy. In addition, the effect of TMSR50 nanoparticles on proliferation and viability was investigated using the MTS assay and bioluminescence microscopy. The amount of TMSR50-loaded HFBSCs needed to reach signal threshold for MRI was assessed using an agarose phantom. Transduction with the Luc2-copGFP construct did not influence senescence, proliferation, doubling time, and differentiation of the HFBSCs. CopGFP expression was visible immediately after transduction and persisted for at least 15 passages, concomitantly with Luc2 expression. Cellular loading with TMSR50 nanoparticles did not affect cell viability and proliferation. The results imply that combined MRI and bioluminescence imaging may enable in vivo localization and long-term monitoring of grafted viable HFBSCs. Copyright © 2016 John Wiley & Sons, Ltd.

Gingival Stromal Cells as an In Vitro Model: Cannabidiol Modulates Genes Linked With Amyotrophic Lateral Sclerosis

Research in recent years has extensively investigated the therapeutic efficacy of mesenchymal stromal cells in regenerative medicine for many neurodegenerative diseases at preclinical and clinical stages. However, the success rate of stem cell therapy remains less at translational phase. Lack of relevant animal models that potentially simulate the molecular etiology of human pathological symptoms might be a reason behind such poor clinical outcomes associated with stem cell therapy. Apparently, self-renewal and differentiation ability of mesenchymal stem cells may help to study the early developmental signaling pathways connected with the diseases, such as Alzheimer's disease, Amyotrophic lateral sclerosis (ALS), etc., at in vitro level. Cannabidiol, a non-psychotrophic cannabinoid, has been demonstrated as a potent anti-inflammatory and neuroprotective agent in neurological preclinical models. In the present study, we investigated the modulatory role of cannabidiol on genes associated with ALS using human gingiva-derived mesenchymal stromal cells (hGMSCs) as an in vitro model system. Next generation transcriptomic sequencing analysis demonstrated considerable modifications in the expression of genes connected with ALS pathology, oxidative stress, mitochondrial dysfunction, and excitotoxicity in hGMSCs treated with cannabidiol. Our results suggest the efficacy of cannabidiol to delineate the unknown molecular pathways, which may underlie ALS pathology at an early stage using hGMSCs as a compelling in vitro system. J. Cell. Biochem. 118: 819-828, 2017. © 2016 Wiley Periodicals, Inc.

Environmental preconditioning rejuvenates adult stem cells' proliferation and chondrogenic potential

Adult stem cells are a promising cell source for cartilage regeneration. Unfortunately, due to donor age and ex vivo expansion, stem cell senescence becomes a huge hurdle for these cells to be used clinically. Increasing evidence indicates that environmental preconditioning is a powerful approach in promoting stem cells' ability to resist a harsh environment post-engraftment, such as hypoxia and inflammation. However, few reports organize and evaluate the literature regarding the rejuvenation effect of environmental preconditioning on stem cell proliferation and chondrogenic differentiation capacity, which are important variables for stem cell based tissue regeneration. This report aims to identify several critical environmental factors such as oxygen concentration, growth factors, and extracellular matrix and to discuss their preconditioning influence on stem cells' rejuvenation including proliferation and chondrogenic potential as well as underlying molecular mechanisms. We believe that environmental preconditioning based rejuvenation is a simpler and safer strategy to program pre-engraftment stem cells for better survival and enhanced proliferation and differentiation capacity without the undesired effects of some treatments, such as genetic manipulation.

Can the outcomes of mesenchymal stem cell-based therapy for myocardial infarction be improved? Providing weapons and armour to cells

Use of mesenchymal stem cell (MSC) transplantation after myocardial infarction (MI) has been found to have infarct-limiting effects in numerous experimental and clinical studies. However, recent meta-analyses of randomized clinical trials on MSC-based MI therapy have highlighted the need for improving its efficacy. There are two principal approaches for increasing therapeutic effect of MSCs: (i) preventing massive MSC death in ischaemic tissue and (ii) increasing production of cardioreparative growth factors and cytokines with transplanted MSCs. In this review, we aim to integrate our current understanding of genetic approaches that are used for modification of MSCs to enable their improved survival, engraftment, integration, proliferation and differentiation in the ischaemic heart. Genetic modification of MSCs resulting in increased secretion of paracrine factors has also been discussed. In addition, data on MSC preconditioning with physical, chemical and pharmacological factors prior to transplantation are summarized. MSC seeding on three-dimensional polymeric scaffolds facilitates formation of both intercellular connections and contacts between cells and the extracellular matrix, thereby enhancing cell viability and function. Use of genetic and non-genetic approaches to modify MSC function holds great promise for regenerative therapy of myocardial ischaemic injury.

Protective effect of berberine against oxidative stress-induced apoptosis in rat bone marrow-derived mesenchymal stem cells

Bone marrow-derived mesenchymal stem cells (BMSCs) have the potential to be used for the treatment of delayed union, nonunion or persistent bone defects in MSC-based cell therapy. However, implantation of BMSCs into the fracture site is confronted with apoptosis on account of harsh conditions and oxidative stress. In the present study, the anti-apoptotic effects of berberine (BBR) on BMSCs subjected to hydrogen peroxide (H₂O₂) are investigated, and the potential underlying mechanisms are explored. Oxidative injury was induced by exposure to H₂O₂, and cell viability was assessed using a cell counting kit-8 assay. The apoptosis of BMSCs was measured by Hoechst 33258 and Annexin V-fluorescein isothiocyanate/propidium iodide assay. Reactive oxygen species staining and superoxide dismutase (SOD) assay were applied to assess the anti-oxidative effect of BBR. Finally, western blot was performed to measure the expression levels of phosphorylated (p)-Akt, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax) and cleaved caspase-3. In the present study, it was identified that BBR remarkably attenuated H₂O₂-induced apoptotic cell death via quenching ROS production and increasing SOD activity. Further studies indicated that BBR can reduce apoptosis by upregulating the expression level of p-Akt and Bcl-2, and downregulating the expression levels of Bax and cleaved caspase-3. Taken together, the results of the present study demonstrate that pretreatment with BBR could alleviate H₂O₂-induced apoptosis in rat BMSCs in vitro.

Modulation of human multipotent and pluripotent stem cells using surface nanotopographies and surface-immobilised bioactive signals: A review

The ability to control the interactions of stem cells with synthetic surfaces is proving to be effective and essential for the quality of passaged stem cells and ultimately the success of regenerative medicine. The stem cell niche is crucial for stem cell self-renewal and differentiation. Thus, mimicking the stem cell niche, and here in particular the extracellular matrix (ECM), in vitro is an important goal for the expansion of stem cells and their applications. Here, surface nanotopographies and surface-immobilised biosignals have been identified as major factors that control stem cell responses. The development of tailored surfaces having an optimum nanotopography and displaying suitable biosignals is proposed to be essential for future stem cell culture, cell therapy and regenerative medicine applications. While early research in the field has been restricted by the limited availability of micro- and nanofabrication techniques, new approaches involving the use of advanced fabrication and surface immobilisation methods are starting to emerge. In addition, new cell types such as induced pluripotent stem cells (iPSCs) have become available in the last decade, but have not been fully understood. This review summarises significant advances in the area and focuses on the approaches that are aimed at controlling the behavior of human stem cells including maintenance of their self-renewal ability and improvement of their lineage commitment using nanotopographies and biosignals. More specifically, we discuss developments in biointerface science that are an important driving force for new biomedical materials and advances in bioengineering aiming at improving stem cell culture protocols and 3D scaffolds for clinical applications. Cellular responses revolve around the interplay between the surface properties of the cell culture substrate and the biomolecular composition of the cell culture medium. Determination of the precise role played by each factor, as well as the synergistic effects amongst the factors, all of which influence stem cell responses is essential for future developments. This review provides an overview of the current state-of-the-art in the design of complex material surfaces aimed at being the next generation of tools tailored for applications in cell culture and regenerative medicine.

STATEMENT OF SIGNIFICANCE

This review focuses on the effect of surface nanotopographies and surface-bound biosignals on human stem cells. Recently, stem cell research attracts much attention especially the induced pluripotent stem cells (iPSCs) and direct lineage reprogramming. The fast advance of stem cell research benefits disease treatment and cell therapy. On the other hand, surface property of cell adhered materials has been demonstrated very important for in vitro cell culture and regenerative medicine. Modulation of cell behavior using surfaces is costeffective and more defined. Thus, we summarise the recent progress of modulation of human stem cells using surface science. We believe that this review will capture a broad audience interested in topographical and chemical patterning aimed at understanding complex cellular responses to biomaterials.

Oncostatin M-Preconditioned Mesenchymal Stem Cells Alleviate Bleomycin-Induced Pulmonary Fibrosis Through Paracrine Effects of the Hepatocyte Growth Factor

Mesenchymal stem cells (MSCs) are widely considered for treatment of pulmonary fibrosis based on the anti‐inflammatory, antifibrotic, antiapoptotic, and regenerative properties of the cells. Recently, elevated levels of oncostatin M (OSM) have been reported in the bronchoalveolar lavage fluid of a pulmonary fibrosis animal model and in patients. In this work, we aimed to prolong engrafted MSC survival and to enhance the effectiveness of pulmonary fibrosis transplantation therapy by using OSM‐preconditioned MSCs. OSM‐preconditioned MSCs were shown to overexpress type 2 OSM receptor (gp130/OSMRβ) and exhibited high susceptibility to OSM, resulting in upregulation of the paracrine factor, hepatocyte growth factor (HGF). Moreover, OSM‐preconditioned MSCs enhanced cell proliferation and migration, attenuated transforming growth factor‐β1‐ or OSM‐induced extracellular matrix production in MRC‐5 fibroblasts through paracrine effects. In bleomycin‐induced lung fibrotic mice, transplantation of OSM‐preconditioned MSCs significantly improved pulmonary respiratory functions and downregulated expression of inflammatory factors and fibrotic factors in the lung tissues. Histopathologic examination indicated remarkable amelioration of the lung fibrosis. LacZ‐tagged MSCs were detected in the lung tissues of the OSM‐preconditioned MSC‐treated mice 18 days after post‐transplantation. Taken together, our data further demonstrated that HGF upregulation played an important role in mediating the therapeutic effects of transplanted OSM‐preconditioned MSCs in alleviating lung fibrosis in the mice. Stem Cells Translational Medicine2017;6:1006–1017

Promotion of Survival and Engraftment of Transplanted Adipose Tissue-Derived Stromal and Vascular Cells by Overexpression of Manganese Superoxide Dismutase

Short-term persistence of transplanted cells during early post-implant period limits clinical efficacy of cell therapy. Poor cell survival is mainly due to the harsh hypoxic microenvironment transplanted cells face at the site of implantation and to anoikis, driven by cell adhesion loss. We evaluated the hypothesis that viral-mediated expression of a gene conferring hypoxia resistance to cells before transplant could enhance survival of grafted cells in early stages after implant. We used adipose tissue as cell source because it consistently provides high yields of adipose-tissue-derived stromal and vascular cells (ASCs), suitable for regenerative purposes. Luciferase positive cells were transduced with lentiviral vectors expressing either green fluorescent protein as control or human manganese superoxide dismutase (SOD2). Cells were then exposed in vitro to hypoxic conditions, mimicking cell transplantation into an ischemic site. Cells overexpressing SOD2 displayed survival rates significantly greater compared to mock transduced cells. Similar results were also obtained in vivo after implantation into syngeneic mice and assessment of cell engraftment by in vivo bioluminescent imaging. Taken together, these findings suggest that ex vivo gene transfer of SOD2 into ASCs before implantation confers a cytoprotective effect leading to improved survival and engraftment rates, therefore enhancing cell therapy regenerative potential.

The Preclinical Research Progress of Stem Cells Therapy in Parkinson's Disease

Parkinson's disease (PD) is a type of degenerative disorder of the basal ganglia, causing tremor at rest, muscle rigidity hypokinesia, and dementia. The effectiveness of drug treatments gradually diminishes because the conversion to dopamine within the brain is increasingly disrupted by the progressive degeneration of the dopaminergic terminals. After long-term treatment, most patients with PD suffer from disability that cannot be satisfactorily controlled. To solve these issues, stem cells have recently been used for cell therapy of PD. In this review, the characteristics of different stem cells and their therapeutic effects on PD treatment will be discussed.

3D spheroid culture enhances survival and therapeutic capacities of MSCs injected into ischemic kidney

Three‐dimensional (3D) cell culture has been reported to increase the therapeutic potentials of mesenchymal stem cells (MSCs). In this study, we aimed to investigate the therapeutic effects of 3D spheroids of human adipose‐derived MSCs for acute kidney injury (AKI). In vitro studies indicated that 3D spheroids of MSCs produced higher levels of extracellular matrix proteins (including collagen I, fibronectin and laminin), and exhibited stronger anti‐apoptotic and anti‐oxidative capacities than two‐dimensional (2D) cultured cells. Furthermore, 3D culture increased the paracrine secretion of cytokines by MSCs, including angiogenic factors (VEGF and basic fibroblast growth factor), anti‐apoptotic factors (epidermal growth factor and hepatocyte growth factor), the anti‐oxidative factor insulin‐like growth factor and the anti‐inflammatory protein tumour necrosis factor‐alpha stimulated gene/protein 6. Consistent with in vitro experiments, 3D spheroids of MSCs showed enhanced survival and paracrine effects in vivo. More importantly, when injected into the kidney of model rats with ischemia‐reperfusion (I/R)‐induced AKI, 3D spheroids were more beneficial in protecting the I/R kidney against apoptosis, reducing tissue damage, promoting vascularization and ameliorating renal function compared with 2D cultured cells. Therefore, the 3D culture strategy improved the therapeutic effects of MSCs, and might be promising for AKI treatment.

Application of mesenchymal stem cells in digestive system diseases

Mesenchymal stem cells (MSCs) have the capacity of multipotent differentiation and the property of immunomodulation. MSCs have been widely used in digestive system disease research because of their advantageous characteristics such as homing to areas of inflammation or tumour tissue, anti-inflammation, high plasticity, absence of immunologic rejection, being easy to be isolated, and being convenient for the expression of exogenous genes. In this article, we will review the application of mesenchymal stem cells in digestive system diseases including caustic esophagus injury, reflux esophagitis, gastric ulcer, radioactive intestinal injury, severe acute pancreatitis, inflammatory bowel disease, nonalcoholic steatohepatitis, acute liver failure, hepatic fibrosis, autoimmune liver diseases, liver cirrhosis, esophageal cancer, gastric cancer, colon cancer, liver cancer, and pancreatic cancer.