Dynamic multiphoton imaging of acellular dermal matrix scaffolds seeded with mesenchymal stem cells in diabetic wound healing

Significantly effective therapies need to be developed for chronic nonhealing diabetic wounds. In this work, the topical transplantation of mesenchymal stem cell (MSC) seeded on an acellular dermal matrix (ADM) scaffold is proposed as a novel therapeutic strategy for diabetic cutaneous wound healing. GFP‐labeled MSCs were cocultured with an ADM scaffold that was decellularized from normal mouse skin. These cultures were subsequently transplanted as a whole into the full‐thickness cutaneous wound site in streptozotocin‐induced diabetic mice. Wounds treated with MSC‐ADM demonstrated an increased percentage of wound closure. The treatment of MSC‐ADM also greatly increased angiogenesis and rapidly completed the reepithelialization of newly formed skin on diabetic mice. More importantly, multiphoton microscopy was used for the intravital and dynamic monitoring of collagen type I (Col‐I) fibers synthesis via second harmonic generation imaging. The synthesis of Col‐I fibers during diabetic wound healing is of great significance for revealing wound repair mechanisms. In addition, the activity of GFP‐labeled MSCs during wound healing was simultaneously traced via two‐photon excitation fluorescence imaging. Our research offers a novel advanced nonlinear optical imaging method for monitoring the diabetic wound healing process while the ADM and MSCs interact in situ. Schematic of dynamic imaging of ADM scaffolds seeded with mesenchymal stem cells in diabetic wound healing using multiphoton microscopy. PMT, photo‐multiplier tube.      

Therapeutic Use of Stem Cell Transplantation for Cell Replacement or Cytoprotective Effect of Microvesicle Released from Mesenchymal Stem Cell

Idiopathic pulmonary fibrosis (IPF) is the most common and severe type of idiopathic interstitial pneumonias (IIP), and which is currently no method was developed to restore normal structure and function. There are several reports on therapeutic effects of adult stem cell transplantations in animal models of pulmonary fibrosis. However, little is known about how mesenchymal stem cell (MSC) can repair the IPF. In this study, we try to provide the evidence to show that transplanted mesenchymal stem cells directly replace fibrosis with normal lung cells using IPF model mice. As results, transplanted MSC successfully integrated and differentiated into type II lung cell which express surfactant protein. In the other hand, we examine the therapeutic effects of microvesicle treatment, which were released from mesenchymal stem cells. Though the therapeutic effects of MV treatment is less than that of MSC treatment, MV treat-ment meaningfully reduced the symptom of IPF, such as collagen deposition and inflammation. These data suggest that stem cell transplantation may be an effective strategy for the treatment of pulmonary fibrosis via replacement and cytoprotective effect of microvesicle released from MSCs.     

Activity of mesenchymal stem cells in therapies for chronic skin wound healing

Chronic or non-healing skin wounds present an ongoing challenge in advanced wound care, particularly as the number of patients increases while technology aimed at stimulating wound healing in these cases remains inefficient. Mesenchymal stem cells (MSCs) have proved to be an attractive cell type for various cell therapies due to their ability to differentiate into various cell lineages, multiple donor tissue types, and relative resilience in ex-vivo expansion, as well as immunomodulatory effects during transplants. More recently, these cells have been targeted for use in strategies to improve chronic wound healing in patients with diabetic ulcers or other stasis wounds. Here, we outline several mechanisms by which MSCs can improve healing outcomes in these cases, including reducing tissue inflammation, inducing angiogenesis in the wound bed, and reducing scarring following the repair process. Approaches to extend MSC life span in implant sites are also examined.     

Injection of synthetic mesenchymal stem cell mitigates osteoporosis in rats after ovariectomy

Osteoporosis is a severe skeletal disorder. Patients have a low bone mineral density and bone structural deterioration. Mounting lines of evidence suggest that inappropriate apoptosis of osteoblasts/osteocytes leads to maladaptive bone remodelling in osteoporosis. It has been suggested that transplantation of stem cells, including mesenchymal stem cells, may alter the trajectory of bone remoulding and mitigate osteoporosis in animal models. However, stem cells needed to be carefully stored and characterized before usage. In addition, there is great batch‐to‐batch variation in stem cell production. Here, we fabricated therapeutic polymer microparticles from the secretome and membranes of mesenchymal stem cells (MSCs). These synthetic MSCs contain growth factors secreted by MSCs. In addition, these particles display MSC surface molecules. In vitro, co‐culture with synthetic MSCs increases the viability of osteoblast cells. In a rat model of ovariectomy‐induced osteoporosis, injection of synthetic MSCs mitigated osteoporosis by reducing cell apoptosis and systemic inflammation, but increasing osteoblast numbers. Synthetic MSC offers a promising therapy to manage osteoporosis.     

Pre‐treatments enhance the therapeutic effects of mesenchymal stem cells in liver diseases

Liver diseases caused by viral infection, alcohol abuse and metabolic disorders can progress to end‐stage liver failure, liver cirrhosis and liver cancer, which are a growing cause of death worldwide. Although liver transplantation and hepatocyte transplantation are useful strategies to promote liver regeneration, they are limited by scarce sources of organs and hepatocytes. Mesenchymal stem cells (MSCs) restore liver injury after hepatogenic differentiation and exert immunomodulatory, anti‐inflammatory, antifibrotic, antioxidative stress and antiapoptotic effects on liver cells in vivo. After isolation and culture in vitro, MSCs are faced with nutrient and oxygen deprivation, and external growth factors maintain MSC capacities for further applications. In addition, MSCs are placed in a harsh microenvironment, and anoikis and inflammation after transplantation in vivo significantly decrease their regenerative capacity. Pre‐treatment with chemical agents, hypoxia, an inflammatory microenvironment and gene modification can protect MSCs against injury, and pre‐treated MSCs show improved hepatogenic differentiation, homing capacity, survival and paracrine effects in vitro and in vivo in regard to attenuating liver injury. In this review, we mainly focus on pre‐treatments and the underlying mechanisms for improving the therapeutic effects of MSCs in various liver diseases. Thus, we provide evidence for the development of MSC‐based cell therapy to prevent acute or chronic liver injury. Mesenchymal stem cells have potential as a therapeutic to prolong the survival of patients with end‐stage liver diseases in the near future.     

Mesenchymal stem cells induce dermal fibroblast responses to injury

Although bone marrow-derived mesenchymal stem cells have been shown to promote repair when applied to cutaneous wounds, the mechanism for this response remains to be determined. The aim of this study was to determine the effects of paracrine signaling from mesenchymal stem cells on dermal fibroblast responses to injury including proliferation, migration and expression of genes important in wound repair. Dermal fibroblasts were co-cultured with bone marrow-derived mesenchymal stem cells grown in inserts, which allowed for paracrine interactions without direct cell contact. In this co-culture model, bone marrow-derived mesenchymal stem cells regulate dermal fibroblast proliferation, migration and gene expression. When co-cultured with mesenchymal stem cells, dermal fibroblasts show increased proliferation and accelerated migration in a scratch assay. A chemotaxis assay also demonstrated that dermal fibroblasts migrate towards bone marrow-derived mesenchymal stem cells. A PCR array was used to analyze the effect of mesenchymal stem cells on dermal fibroblast gene expression. In response to mesenchymal stem cells, dermal fibroblasts up-regulate integrin alpha 7 expression and down-regulate expression of ICAM1, VCAM1 and MMP11. These observations suggest that mesenchymal stem cells may provide an important early signal for dermal fibroblast responses to cutaneous injury.     

The effects of the DNA methyltranfserases inhibitor 5‐Azacitidine on ageing,oxidative stress and DNA methylation of adipose derived stem cells

Human adipose tissue is a great source of adult mesenchymal stem cells (MSCs) which are recognized from their ability to self‐renew and differentiation into multiple lineages. MSCs have promised a vast therapeutic potential in treatment many diseases including tissue injury and immune disorders. However, their regenerative potential profoundly depends on patients’ age. Age‐related deterioration of MSC is associated with cellular senescence mainly caused by increased DNA methylation status, accumulation of oxidative stress factors and mitochondria dysfunction. We found that DNA methyltransferase (DNMT) inhibitor i.e. 5‐Azacytidine (5‐AZA) reversed the aged phenotype of MSCs. Proliferation rate of cells cultured with 5‐AZA was increased while the accumulation of oxidative stress factors and DNA methylation status were decreased. Simultaneously the mRNA levels of TET proteins involved in demethylation process were elevated in those cells. Moreover, cells treated with 5‐AZA displayed reduced reactive oxygen species (ROS) accumulation, ameliorated superoxide dismutase activity and increased BCL‐2/BAX ratio in comparison to control group. Our results indicates that, treating MSCs with 5‐AZA can be justified therapeutic intervention, that can slow‐down and even reverse aged‐ related degenerative changes in those cells.     

Placenta Stem/Stromal Cell–Derived Extracellular Vesicles for Potential Use in Lung Repair

Many acute and chronic lung injuries are incurable and rank as the fourth leading cause of death globally. While stem cell treatment for lung injuries is a promising approach, there is growing evidence that the therapeutic efficacy of stem cells originates from secreted extracellular vesicles (EVs). Consequently, EVs are emerging as next‐generation therapeutics. While EVs are extensively researched for diagnostic applications, their therapeutic potential to promote tissue repair is not fully elucidated. By housing and delivering tissue‐repairing cargo, EVs refine the cellular microenvironment, modulate inflammation, and ultimately repair injury. Here, the potential use of EVs derived from two placental mesenchymal stem/stromal cell (MSC) lines is presented; a chorionic MSC line (CMSC29) and a decidual MSC cell line (DMSC23) for applications in lung diseases. Functional analyses using in vitro models of injury demonstrate that these EVs have a role in ameliorating injuries caused to lung cells. It is also shown that EVs promote repair of lung epithelial cells. This study is fundamental to advancing the field of EVs and to unlock the full potential of EVs in regenerative medicine.     

Mesenchymal stem cells in acute lung injury: are they ready for translational medicine?

Acute lung injury (ALI) is a severe clinical condition responsible for high mortality and the development of multiple organ dysfunctions, because of the lack of specific and effective therapies for ALI. Increasing evidence from pre‐clinical studies supports preventive and therapeutic effects of mesenchymal stem cells (MSCs, also called mesenchymal stromal cells) in ALI/ARDS (acute respiratory distress syndrome). Therapeutic effects of MSCs were noticed in various delivery approaches (systemic, local, or other locations), multiple origins (bone marrow or other tissues), or different schedules of administrations (before or after the challenges). MSCs could reduce the over‐production of inflammatory mediators, leucocyte infiltration, tissue injury and pulmonary failure, and produce a number of benefit factors through interaction with other cells in the process of lung tissue repair. Thus, it is necessary to establish guidelines, standard operating procedures and evaluation criteria for translating MSC‐based therapies into clinical application for patients with ALI.     

肿瘤相关间充质干细胞及其靶向治疗的研究进展

间充质干细胞（MSCs）存在于许多组织中,在组织出现损伤时会迁移到受伤部位进行修复。而癌症可以被看作是"永远不会愈合的伤口",在肿瘤微环境中MSCs会被持续募集成为肿瘤微环境的一部分。最近出现了一种肿瘤相关间充质干细胞（TA-MSCs）,它可以激活肿瘤的发生,促进肿瘤的发展与转移。本文讨论了MSCs与TA-MSCs之间的关系;探讨对TA-MSCs的最新认识及其调节癌细胞生存、增殖、迁移与耐药能力。而且,讨论了把TA-MSCs作为癌症治疗上游或者下游的靶点或者用MSCs做载体来传递癌症因子将会发展为癌症治疗的新手段。     

Mallotus philippinensis bark extracts promote preferential migration of mesenchymal stem cells and improve wound healing in mice

In the present study, we report the effects of the ethanol extract from Mallotus philippinensis bark (EMPB) on mesenchymal stem cell (MSC) proliferation, migration, and wound healing in vitro and in a mouse model. Chemotaxis assays demonstrated that EMPB acted an MSC chemoattractant and that the main chemotactic activity of EMPB may be due to the effects of cinnamtannin B-1. Flow cytometric analysis of peripheral blood mononuclear cells in EMPB-injected mice indicated that EMPB enhanced the mobilization of endogenous MSCs into blood circulation. Bioluminescent whole-animal imaging of luciferase-expressing MSCs revealed that EMPB augmented the homing of MSCs to wounds. In addition, the efficacy of EMPB on migration of MSCs was higher than that of other skin cell types, and EMPB treatment improved of wound healing in a diabetic mouse model. The histopathological characteristics demonstrated that the effects of EMPB treatment resembled MSC-induced tissue repair. Taken together, these results suggested that EMPB activated the mobilization and homing of MSCs to wounds and that enhancement of MSC migration may improve wound healing.     

Do microRNAs regulate bone marrow stem cell niche physiology?

The adult bone marrow, situated within the bone cavity, comprises three distinct stem cell populations: hematopoietic stem cells (HSCs), mesenchymal stromal/stem cells (MSCs) and endothelial progenitor/stem cells (EPCs). HSCs are a well-characterized population of self-renewing cells that give rise to all blood cells. The definition of MSCs is more complex due to the limited understanding of MSC properties. In general, MSCs are considered multipotent stromal cells that are able to differentiate into various cell types, including osteoblasts, chondrocytes and adipocytes. Compared to HSCs and MSCs, EPCs are a newly discovered population of stem/progenitor cells with the capacity to differentiate into endothelial cells, the cells forming the inner lining of a blood vessel.     

Bone marrow–derived mesenchymal stem cells attenuate tubulointerstitial injury through multiple mechanisms in UUO model

Current evidence supports the use of bone marrow–derived mesenchymal stem cells (MSCs) for a diverse range of clinical applications, and many studies have shown that MSCs have renal-protective effects, but the mechanism is not well understood. Therefore, in this study, we aim to further identify whether MSCs can attenuate renal fibrosis by decreasing tubulointerstitial injury in a unilateral ureteral obstruction (UUO) model. In this study, we cultured MSCs and then transplanted them into a UUO model through the tail vein. Histology, cell proliferation, peritubular capillary (PTC) loss and myofibroblast markers were examined on days 3, 7 and 14 after surgery. We demonstrated that renal interstitial fibrosis in the MSC group was significantly attenuated compared with the UUO and DMEM groups. Moreover, MSC treatment inhibited the loss of PTCs and increased parenchymal cell proliferation. In addition, UUO-induced activation and proliferation of myofibroblasts were suppressed by MSC infusion. Furthermore, MSCs attenuated tubulointerstitial infiltration of macrophages in UUO mice. Tubulointerstitial damage plays a very important role in the progression of chronic kidney disease (CKD). PTC loss, macrophage recruitment, and myofibroblast activation are directly correlated with the development of renal tubulointerstitial fibrosis. Our results suggest that MSC infusion in the UUO model is a promising therapeutic strategy for promoting kidney repair.     

Bone marrow mesenchymal stem cells for post-myocardial infarction cardiac repair: microRNAs as novel regulators

Transplantation of bone marrow-derived mesenchymal stem cells (MSCs) is safe and may improve cardiac function and structural remodelling in patients following myocardial infarction (MI). Cardiovascular cell differentiation and paracrine effects to promote endogenous cardiac regeneration, neovascularization, anti-inflammation, anti-apoptosis, anti-remodelling and cardiac contractility, may contribute to MSC-based cardiac repair following MI. However, current evidence indicates that the efficacy of MSC transplantation was unsatisfactory, due to the poor viability and massive death of the engrafted MSCs in the infarcted myocardium. MicroRNAs are short endogenous, conserved, non-coding RNAs and important regulators involved in numerous facets of cardiac pathophysiologic processes. There is an obvious involvement of microRNAs in almost every facet of putative repair mechanisms of MSC-based therapy in MI, such as stem cell differentiation, neovascularization, apoptosis, cardiac remodelling, cardiac contractility and arrhythmias, and others. It is proposed that therapeutic modulation of individual cardiovascular microRNA of MSCs, either mimicking or antagonizing microRNA actions, will hopefully enhance MSC therapeutic efficacy. In addition, MSCs may be manipulated to enhance functional microRNA expression or to inhibit aberrant microRNA levels in a paracrine manner. We hypothesize that microRNAs may be used as novel regulators in MSC-based therapy in MI and MSC transplantation by microRNA regulation may represent promising therapeutic strategy for MI patients in the future.     

Effect of mesenchymal stem cells on cytochrome-c release and inflammation in colon cancer induced by 1,2-dimethylhydrazine in Wistar albino rats

Colon cancer is one of the most common causes of deaths by cancer worldwide. Stem cells have immunosuppressive properties that promote tumor targeting and circumvent obstacles currently in gene therapy. Bone marrow stem cells are believed to have anticancer potential. The transplantation of mesenchymal stem cells (MSCs), a type of bone marrow stem cells, has been considered a potential therapy for patients with solid tumors due to their capability to enhance the immune response; MSC transplantation has received renewed interest in recent years. The present study aimed to evaluate the antiapoptotic effects of the MSCs on 1,2-dimethylhydrazine (DMH)-induced inflammation in the rat model of colorectal cancer. The rats were randomly allocated into four groups: control, treated with MSCs, induced by DMH, and induced by DMH and treated with MSCs. The MSCs were intra-rectally injected, and DMH was subcutaneously injected at 20 mg/kg body weight once a week for 15 weeks. The administration of MSCs into rats starting from day 0 of the DMH injection was found to enhance the histopathological picture. The MSC treatment resulted in fewer inflammatory cells than in the DMH group. Therefore, our findings suggest that BMCs have antitumor effects by modulating the cellular redox status and down-regulating the pro-inflammatory genes. Thus, BMCs may provide therapeutic value for colon cancer treatment.     

间充质干细胞在疾病治疗中的应用潜力

间充质干细胞（mesenchymal stem cell,MSCs）是衍生自中胚层的多能细胞,可产生多种间充质谱系,包括成骨细胞、脂肪细胞、成软骨细胞和肌细胞。MSCs还具有分泌多种细胞因子的能力,可促进血管生成、上皮再生等,在再生医学领域具有巨大的潜力。研究证实,MSCs可通过分化为多种细胞类型促进组织再生,加速伤口愈合;通过分泌细胞因子改善组织纤维化;还可通过携带载体药物诱导肿瘤细胞的凋亡,抑制肿瘤的发展。然而MSCs的成纤维化潜能和促进肿瘤生长的能力降低了MSCs应用于临床治疗的安全性。总结了MSCs在肿瘤、慢性难愈合伤口、纤维化等疾病发展过程中的作用,并进一步讨论了MSCs在临床相关疾病治疗中的潜在应用价值及挑战,以期为间充质干细胞的临床应用提供参考。     

Toll-like receptor 9 ligands enhance mesenchymal stem cell invasion and expression of matrix metalloprotease-13

Human mesenchymal stem cells (hMSCs) are multipotent cells that are found in the bone marrow. Inflammation and tissue damage mobilize MSCs and induce their migration towards the damaged site through mechanisms that are not well defined. Toll-like receptor-9 (TLR9) is a cellular receptor for microbial and vertebrate DNA. Stimulation of TLR9 induces inflammatory and invasive responses in TLR9-expressing cells. We studied here the expression of TLR9 in human MSCs and the effects of synthetic TLR9-agonists on their invasion. Constitutive expression of TLR9 was detected in human MSCs but the expression was suppressed when MSCs were induced to differentiate into osteoblasts. Using standard invasion assays and a novel organotypic culture model based on human myoma tissue, we discovered that stimulation with the TLR9 agonistic, CpG oligonucleotides increased the invasion capacity of undifferentiated MSCs. Simultaneously, an increase in MMP-13 synthesis and activity was detected in the CpG-activated MSCs. Addition of anti-MMP-13 antibody significantly diminished the CpG-induced hMSC invasion. We conclude that treatment with TLR9-ligands increases MSC invasiveness, and this process is at least partially MMP-13-mediated.     

Delivery of sTRAIL variants by MSCs in combination with cytotoxic drug treatment leads to p53-independent enhanced antitumor effects

Mesenchymal stem cells (MSCs) are able to infiltrate tumor tissues and thereby effectively deliver gene therapeutic payloads. Here, we engineered murine MSCs (mMSCs) to express a secreted form of the TNF-related apoptosis-inducing ligand (TRAIL), which is a potent inducer of apoptosis in tumor cells, and tested these MSCs, termed MSC.sTRAIL, in combination with conventional chemotherapeutic drug treatment in colon cancer models. When we pretreated human colorectal cancer HCT116 cells with low doses of 5-fluorouracil (5-FU) and added MSC.sTRAIL, we found significantly increased apoptosis as compared with single-agent treatment. Moreover, HCT116 xenografts, which were cotreated with 5-FU and systemically delivered MSC.sTRAIL, went into remission. Noteworthy, this effect was protein 53 (p53) independent and was mediated by TRAIL-receptor 2 (TRAIL-R2) upregulation, demonstrating the applicability of this approach in p53-defective tumors. Consequently, when we generated MSCs that secreted TRAIL-R2-specific variants of soluble TRAIL (sTRAIL), we found that such engineered MSCs, labeled MSC.sTRAIL^DR5, had enhanced antitumor activity in combination with 5-FU when compared with MSC.sTRAIL. In contrast, TRAIL-resistant pancreatic carcinoma PancTu1 cells responded better to MSC.sTRAIL^DR4 when the antiapoptotic protein XIAP (X-linked inhibitor of apoptosis protein) was silenced concomitantly. Taken together, our results demonstrate that TRAIL-receptor selective variants can potentially enhance the therapeutic efficacy of MSC-delivered TRAIL as part of individualized and tumor-specific combination treatments.     

Therapeutic potential of adult bone marrow‐derived mesenchymal stem cells in diseases of the skeleton

Mesenchymal stem cells (MSCs) are the most popular among the adult stem cells in tissue engineering and regenerative medicine. Since their discovery and functional characterization in the late 1960s and early 1970s, MSCs or MSC‐like cells have been obtained from various mesodermal and non‐mesodermal tissues, although majority of the therapeutic applications involved bone marrow‐derived MSCs. Based on its mesenchymal origin, it was predicted earlier that MSCs only can differentiate into mesengenic lineages like bone, cartilage, fat or muscle. However, varied isolation and cell culturing methods identified subsets of MSCs in the bone marrow which not only differentiated into mesenchymal lineages, but also into ectodermal and endodermal derivatives. Although, true pluripotent status is yet to be established, MSCs have been successfully used in bone and cartilage regeneration in osteoporotic fracture and arthritis, respectively, and in the repair of cardiac tissue following myocardial infarction. Immunosuppressive properties of MSCs extend utility of MSCs to reduce complications of graft versus host disease and rheumatoid arthritis. Homing of MSCs to sites of tissue injury, including tumor, is well established. In addition to their ability in tissue regeneration, MSCs can be genetically engineered ex vivo for delivery of therapeutic molecule(s) to the sites of injury or tumorigenesis as cell therapy vehicles. MSCs tend to lose surface receptors for trafficking and have been reported to develop sarcoma in long‐term culture. In this article, we reviewed the current status of MSCs with special emphasis to therapeutic application in bone‐related diseases. J. Cell. Biochem. 111: 249–257, 2010. © 2010 Wiley‐Liss, Inc.     

Hepatogenic differentiation of mesenchymal stem cells in a rat model of thioacetamide-induced liver cirrhosis

Implantation of bone-marrow-derived MSCs (mesenchymal stem cells) has emerged as a potential treatment modality for liver failure, but in vivo differentiation of MSCs into functioning hepatocytes and its therapeutic effects have not yet been determined. We investigated MSC differentiation process in a rat model of TAA (thioacetamide)-induced liver cirrhosis. Male Sprague-Dawley rats were administered 0.04% TAA-containing water for 8 weeks, MSCs were injected into the spleen for transsplenic migration into the liver, and liver tissues were examined over 3 weeks. Ingestion of TAA for 8 weeks induced micronodular liver cirrhosis in 93% of rats. Injected MSCs were diffusely engrafted in the liver parenchyma, differentiated into CK19 (cytokeratin 19)- and thy1-positive oval cells and later into albumin-producing hepatocyte-like cells. MSC engraftment rate per slice was measured as 1.0-1.6%. MSC injection resulted in apoptosis of hepatic stellate cells and resultant resolution of fibrosis, but did not cause apoptosis of hepatocytes. Injection of MSCs treated with HGF (hepatocyte growth factor) in vitro for 2 weeks, which became CD90-negative and CK18-positive, resulted in chronological advancement of hepatogenic cellular differentiation by 2 weeks and decrease in anti-fibrotic activity. Early differentiation of MSCs to progenitor oval cells and hepatocytes results in various therapeutic effects, including repair of damaged hepatocytes, intracellular glycogen restoration and resolution of fibrosis. Thus, these results support that the in vivo hepatogenic differentiation of MSCs is related to the beneficial effects of MSCs rather than the differentiated hepatocytes themselves.