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Mesenchymal stem cells (MSCs) can be obtained from almost all tissues and present promising therapeutic effects for metabolic diseases. Human adipose-derived MSCs (hASCs) have recently been widely studied due to their easy access and low immunity. Thus, we intended to figure out the effects and potential mechanism of hASCs on obesity in high-fat-diet (HFD)-induced obese mice. Following 16 weeks of being fed HFD, hASCs were intravenously injected. Two weeks later, body weight, body composition, and energy expenditure were evaluated. Additionally, the phenotypes of macrophages infiltrating adipose tissue were analyzed. The results revealed that hASCs administration significantly reduced adipose tissue weight, adipocyte size, and fat mass and exerted beneficial effects in serum lipid profile. This anti-obesity effect was mediated by the increased O2 consumption, CO2 production, and energy expenditure, which was further evidenced by the upregulation of uncoupling protein-1 (UCP-1) and metabolism-associated genes. Furthermore, hASCs infusion increased the amount of alternatively activated (M2) macrophages in adipose tissue, and the expression of pro-inflammatory cytokines-related genes was reduced. Taken together, these results indicated that hASCs suppressed obesity by increasing UCP-1 expression and enhancing energy expenditure, and this effect might be due to the increased M2 macrophages.

The composite structure composed of carbon fiber reinforced composite and titanium alloy is widely used in aviation and aerospace fields. Due to the different physical properties of these two materials, in the process of lamination, it is easy to appear the pore in the direction of thickness is inconsistent, which is called double-step pore defects (DSPD). The existence of DSPD will undoubtedly have an impact on the connection performance of components, but there is no clear conclusion on the extent of its impact on the connection performance, which restricts the improvement of the pore quality evaluation system, and may cause a waste of resources or leave a safety hazard for aircraft. To solve this problem, the finite element model was established to analyze the initial damage phenomenon of the component with DSPD during bolt tightening. The influence of DSPD on the static strength and fatigue properties of the component was studied by designing experiments, and the failure mechanism was revealed from the perspectives of failure form and damage evolution. The purpose of this study is to provide guidance for the improvement of the evaluation standard and the high quality and stability of the lamination component. [ABSTRACT FROM AUTHOR]

Background. Progressive β-cell dysfunction, a major characteristic of type 2 diabetes (T2D), is closely related to the infiltration of inflammatory macrophages within islets. Mesenchymal stem cells (MSCs) have been identified to alleviate β-cell dysfunction by modulating macrophage phenotype in T2D, but the restoration of β-cells by a single MSC infusion is relatively transient. Decitabine (DAC) has been reported to polarize macrophages towards the anti-inflammatory phenotype at low doses. We therefore investigated whether low-dose decitabine could enhance the antidiabetic effect of MSCs and further promote the restoration of β-cell function. Methods. We induced a T2D mice model by high-fat diets and streptozotocin (STZ) injection. Mice were divided into five groups: the normal group, the T2D group, the DAC group, the MSC group, and the MSC plus DAC group (MD group). We examined the blood glucose and serum insulin levels of mice 1, 2, and 4 weeks after MSC and/or DAC treatment. Dynamic changes in islets and the phenotype of intraislet macrophages were detected via immunofluorescence. In vitro, we explored the effect of MSCs and DAC on macrophage polarization. Results. The blood glucose and serum insulin levels revealed that DAC prolonged the antidiabetic effect of MSCs to 4 weeks in T2D mice. Immunofluorescence staining demonstrated more sustainable morphological and structural amelioration in islets of the MD group than in the MSC group. Interestingly, further analysis showed more alternatively activated macrophages (M2, anti-inflammatory) and fewer classically activated macrophages (M1, proinflammatory) in islets of the MD group 4 weeks after treatment. An in vitro study demonstrated that DAC together with MSCs further polarized macrophages from the M1 to M2 phenotype via the PI3K/AKT pathway. Conclusion. These data unveiled that DAC prolonged the antidiabetic effect of MSCs and promoted sustainable β-cell restoration, possibly by modulating the macrophage phenotype. Our results offer a preferable therapeutic strategy for T2D. [ABSTRACT FROM AUTHOR]

Background: Tissue contraction and the extracellular matrix deposition are part of the pathogenesis of hypertrophic scars. The transcriptional factor NFE2L2 inhibits fibroblast differentiation in idiopathic pulmonary fibrosis and promotes myofibroblast dedifferentiation. Our previous study showed that the transcription factor NFE2L2 was strongly induced on treatment with arsenic trioxide (ATO). Objective: The present study sought to investigate the effect of ATO on myofibroblast formation to determine its potential role in hypertrophic scar treatment. Methods: Small interfering RNA against NFE2L2 was used on treatment with ATO in human skin myofibroblasts. The expression levels of fibrosis markers were assessed by reverse transcription polymerase chain reaction, western blot, and immunofluorescence staining. The transforming growth factor‐β1 (TGF‐β1)/Smad2/3 signaling was detected by western blot. A rabbit ear model was used to evaluate the antifibrotic role of ATO. Results: At the cellular level, ATO abolished fibroblast differentiation in response to TGF‐β1. ATO reduced TGF‐β1‐induced reactive oxygen species accumulation through increased expression of the antioxidant gene HO‐1 in fibroblasts. In addition, ATO promoted the nuclear translocation of NFE2L2 and inhibited the phosphorylation of Smad2/3. In the rabbit ear model, ATO prevented the progression of hypertrophic scar formation. Conclusions: This study provides the first evidence implying that ATO inhibits the formation of myofibroblasts in vivo and in vitro and provides a possible treatment for hypertrophic scars. Tissue contraction and the extracellular matrix deposition are part of the pathogenesis of hypertrophic scars. The present study sought to investigate the effect of arsenic trioxide (ATO) on myofibroblast formation to determine its potential role in hypertrophic scar treatment. This study provides the first evidence implying that ATO inhibits the formation of myofibroblasts in vivo and in vitro and provides a possible treatment for hypertrophic scars. [ABSTRACT FROM AUTHOR]

The transplantation of insulin-producing cells (IPCs) or pancreatic progenitor cells is a theoretical therapy for diabetes with insulin insufficiency. Isolated hepatocytes from newborn rats (within 24 h after birth) were progressively induced into IPCs using 5-aza-2′-deoxycytidine, Trichostatin A, retinoic acid, insulin-transferrin-selenium, and nicotinamide. We transplanted Pdx1+ pancreatic progenitors into STZ-induced diabetic mice and found the decreased blood glucose and increased insulin level in comparison with diabetic model. The dynamic expression profiles of microRNAs (miRNAs) were identified using microarray. We found 67 miRNAs were decreasingly expressed; 52 miRNAs were increasingly expressed; 27 miRNAs were specially inhibited in Stage 1 cells (multipotent progenitor cells); and 58 miRNAs were specially inhibited in Pdx1+ cells (Stage 2). Further analysis showed these miRNAs' targets were associated with genetic recombination, stem cell pluripotency maintenance, cellular structure reorganization and insulin secretion. Enrichment analysis using KEGG pathway showed the differentiation of IPCs from hepatocytes was massively more likely not mediated by canonical Wnt/β-catenin signaling. In addition, the BMP/Smad signaling was involved in this progression. We found the dysregulated miRNAs profiles were inconsistent with cell phenotypes and might be responsible for small molecule-mediated cell differentiation during IPCs induction. [ABSTRACT FROM AUTHOR]

Volumetric muscle loss (VML) injury resulted from massive muscle defects and diseases for which there are still no effective therapeutic treatments. This study aimed to investigate the effects of rat adipose-derived mesenchymal stem cells (rASCs) and rASCs-conditioned medium- (CM-) based type I collagen hydrogel on macrophage (MP) transition, myogenesis, and vascularization in the rat VML model. Laser Doppler results demonstrated much higher blood flow in the rASC- and CM-based hydrogel groups. qRT-PCR, hematoxylin and eosin, immunofluorescence, and Sirius Red staining manifested that both rASCs and CM-based hydrogel implantation accelerated muscle repair with upregulated angiogenesis and myogenesis, attenuated inflammation while facilitating M2 transition, and decreased the collagen deposition compared with the hydrogel group. In vitro experiments indicated that factors secreted from polarized M2 MPs could accelerate the migration and tube formation capacities of HUVECs. These results suggested that rASCs exerted immunomodulatory effects on MPs which further enhanced the proangiogenic potential on ECs to promote myogenesis and angiogenesis during muscle repair. These fundamental results support further clinical applications of ASCs for muscle loss injury. [ABSTRACT FROM AUTHOR]

Objective The role of M2 macrophages infusion in dealing with obesity is still little known. In this study, the therapeutic effects of M2 macrophages infusion were investigated. Methods High fat diet (HFD) was used to induce obesity in C57BL/6N mice. 5 × 10 5 M2 macrophages, derived from the bone marrow, were injected into obese mice through the tail vein twice with an interval of one week. Results One week after the second injection, weight of inguinal adipose pad was significantly decreased. Accordingly, the adipocyte size of epididymal and inguinal adipose tissue (EAT and INAT) shrank. To our interest, we found that the infused M2 macrophages were homed to EAT, reversing the disturbed homeostasis of high M1 to low M2 in obese mice. Meanwhile, EAT with remodeled macrophages' homeostasis expressed less MCP-1, accompanying with decreased recruitment of inflammatory CCR2 + CX3CR1 low Ly6C + monocytes from the blood in M2 infusion group. Further, increased M2 in EAT contribute to enhanced expression of UCP1 expression in EAT, which helped to ameliorate insulin resistance and, subsequently, improve the serum level of triglycerides (TG) and low density lipoprotein cholesterol (LDL-c). Conclusions These findings highlighted that M2 macrophages infusion could ameliorate obesity as well as obesity-related insulin resistance, suggesting an effective and healthy weight loss strategy. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSCs) can affect the microenvironment of a wound and thereby accelerate wound healing. Wnt proteins act as key mediators of skin development and participate in the formation of skin appendages such as hair. The mechanisms of action of MSCs and Wnt proteins on skin wounds are largely unknown. Here, we prepared a Wnt7a-containing conditioned medium (Wnt-CM) from the supernatant of cultured human umbilical cord-MSCs (UC-MSCs) overexpressing Wnt7a in order to examine the effects of this CM on cutaneous healing. Our results revealed that Wnt-CM can accelerate wound closure and induce regeneration of hair follicles. Meanwhile, Wnt-CM enhanced expression of extracellular matrix (ECM) components and cell migration of fibroblasts but inhibited the migratory ability and expression of K6 and K16 in keratinocytes by enhancing expression of c-Myc. However, we found that the CM of fibroblasts treated with Wnt-CM (HFWnt-CM-CM) can also promote wound repair and keratinocyte migration; but there was no increase in the number of hair follicles of regeneration. These data indicate that Wnt7a and UC-MSCs have synergistic effects: they can accelerate wound repair and induce hair regeneration via cellular communication in the wound microenvironment. Thus, this study opens up new avenues of research on the mechanisms underlying wound repair. [ABSTRACT FROM AUTHOR]

Aims/Introduction Moderate elevation of glucose level has been shown to effectively promote β-cell replication in various models in vitro and in normal rodents. Here, we aimed to test the effect of moderately elevated glucose on β-cell mass expansion and islet function recovery in diabetic animal models. Materials and Methods A single high dose of streptozotocin was given to induce insulin-deficient diabetes in adult male Sprague-Dawley rats. Then, 48 h after streptozotocin injection, newly diabetic rats were randomly divided into three groups: (i) no treatment to maintain hyperglycemia; (ii) daily exogenous long-acting human insulin analog injection that maintained mild hyperglycemia (15 mmol/L < blood glucose < 18 mmol/L); (iii) daily exogenous long-acting human insulin analog injection to restore normoglycemia (blood glucose <8 mmol/L) as a control. Islet function, β-cell regeneration and β-cell replication were monitored during the entire analysis period. Results A single high dose of streptozotocin induced massive loss of β-cells, resulting in irreversible hyperglycemia. Mild hyperglycemia markedly promoted β-cell proliferation, leading to robust β-cell regeneration. Importantly, rats that maintained mild hyperglycemia showed nearly normal glucose-stimulated insulin secretion, glucose disposal and random blood glucose levels, suggesting almost full restoration of the islet function. Normalization of blood glucose levels profoundly blunted β-cell replication, regeneration and islet function recovery observed in mild hyperglycemia. Conclusions Our research provides a feasible approach to stimulate in situ β-cell regeneration in diabetic rats, offering new perspectives for diabetes therapy. [ABSTRACT FROM AUTHOR]

Background. The purpose of this study was to evaluate the effects of ASCs on full-thickness skin grafts. Specifically, we investigated the anti-inflammatory effects of ASCs that are mediated via regulation of the phenotypes of activated macrophages. Methods. ASCs were isolated, cultured, and injected under full-thickness skin grafts in 15 rats (ASC group). An additional 15 rats served as controls (PBS group). Skin graft survival assessment and vascularization detection were assessed with H&E staining and laser Doppler blood flowmetry (LDF). The effects of ASCs on angiogenesis, anti-inflammation, collagen accumulation-promoting, and antiscarring were assessed. Results. We found that the skin graft survival rate was significantly increased in the ASC group. The neovascularization, collagen deposition, collagen type I to type III ratio, and levels of VEGF and TGF-β3 in the ASC group were markedly higher than those in the PBS group at day 14. Additionally, in the ASC group, the levels of iNOS, IL-1β, and TNF-α were remarkably decreased, whereas the levels of IL-10 and Arg-1 were substantially increased. Conclusions. Our results confirm that ASCs transplantation can effectively improve full-thickness skin graft survival. Additionally, the anti-inflammatory role of ASCs may indirectly contribute to skin graft survival via its effect on macrophage polarization. [ABSTRACT FROM AUTHOR]

Insulin resistance, a major characteristic of type 2 diabetes (T2D), is closely associated with adipose tissue macrophages (ATMs) that induce chronic low-grade inflammation. Recently, mesenchymal stem cells (MSCs) have been identified in alleviation of insulin resistance. However, the underlying mechanism still remains elusive. Thus, we aimed to investigate whether the effect of MSCs on insulin resistance was related to macrophages phenotypes in adipose tissues of T2D rats. In this study, human umbilical cord-derived MSCs (UC-MSCs) infusion produced significantly anti-diabetic effects and promoted insulin sensitivity in T2D rats that were induced by a high-fat diet combined with streptozotocin and directed ATMs into an alternatively activated phenotype (M2, anti-inflammatory). In vitro, MSC-induced M2 macrophages alleviated insulin resistance caused by classically activated macrophages (M1, pro-inflammatory). Further analysis showed that M1 stimulated UC-MSCs to increase expression of interleukin (IL)-6, a molecule which upregulated IL4R expression, promoted phosphorylation of STAT6 in macrophages, and eventually polarized macrophages into M2 phenotype. Moreover, the UC-MSCs effect on macrophages was largely abrogated by small interfering RNA (siRNA) knockdown of IL-6. Together, our results indicate that UC-MSCs can alleviate insulin resistance in part via production of IL-6 that elicits M2 polarization. Additionally, human obesity and insulin resistance were associated with increased pro-inflammatory ATMs infiltration. Thus, MSCs may be a new treatment for obesity-related insulin resistance and T2D concerning macrophage polarized effects. S tem C ells 2016;34:627-639 [ABSTRACT FROM AUTHOR]

Objective. To evaluate the therapeutic effects of G-CSF administration after intraosseous (IO) resuscitation in hemorrhagic shock (HS) combined with cutaneous injury rats. Methods. The rats were randomly divided into four groups: (1) HS with resuscitation (blank), (2) HS with resuscitation + G-CSF (G-CSF, 200 μg/kg body weight, subcutaneous injection), (3) HS with resuscitation + normal saline solution injection (normal saline), and (4) HS + G-CSF injection without resuscitation (Unres/G-CSF). To estimate the treatment effects, the vital signs of alteration were first evaluated, and then wound closure rates and homing of MSCs and EPCs to the wound skins and vasculogenesis were measured. Besides, inflammation and vasculogenesis related mRNA expressions were also examined. Results. IO infusion hypertonic hydroxyethyl starch (HHES) exhibited beneficial volume expansion roles and G-CSF administration accelerated wound healing 3 days ahead of other groups under hemorrhagic shock. Circulating and the homing of MSCs and EPCs at wound skins were significantly elevated at 6 h after G-CSF treatment. Inflammation was declined since 3 d while angiogenesis was more obvious in G-CSF treated group on day 9. Conclusions. These results suggested that the synergistical application of HHES and G-CSF has life-saving effects and is beneficial for improving wound healing in HS combined with cutaneous injury rats. [ABSTRACT FROM AUTHOR]

Bone marrow-derived mesenchymal stem cells (BM-MSCs) have properties that make them promising for the treatment of chronic nonhealing wounds. The major challenge is ensuring an efficient, safe, and painless delivery of BMMSCs. Tissue-engineered skin substitutes have considerable benefits in skin damage resulting from chronic nonhealing wounds. Here, we have constructed a three-dimensional biomimetic scaffold known as collagen-chitosan sponge scaffolds (CCSS) using the cross-linking and freeze-drying method. Scanning electron microscopy images showed that CCSS had an interconnected network pore configuration about 100 μm and exhibited a suitable swelling ratio for maintaining morphological stability and appropriate biodegradability to improve biostability using swelling and degradation assays. Furthermore, BM-MSCs were seeded in CCSS using the two-step seeding method to construct tissueengineered skin substitutes. In addition, in this three-dimensional biomimetic CCSS, BM-MSCs secreted their own collagen and maintain favorable survival ability and viability. Importantly, BM-MSCs exhibited a significant upregulated expression of proangiogenesis factors, including HIF-1α, VEGF, and PDGF following hypoxia pretreatment. In vivo, hypoxia pretreatment of the skin substitute observably accelerated wound closure via the reduction of inflammation and enhanced angiogenesis in diabetic rats with hindlimb ischemia. Thus, hypoxia pretreatment of the skin substitutes can serve as ideal bioengineering skin substitutes to promote optimal diabetic skin wound healing. [ABSTRACT FROM AUTHOR]

Wound reepithelialization is a cooperative multifactorial process dominated by keratinocyte migration, proliferation, and differentiation that restores the intact epidermal barrier to prevent infection and excessive moisture loss. However, in wounds that exhibit impaired wound healing, such as chronic nonhealing wounds or hypertrophic scars, the reepithelialization process has failed. Thus, it is necessary to explore a suitable way to mitigate these abnormalities to promote reepithelialization and achieve wound healing. Mesenchymal stem cells (MSCs) have the capacity for self-renewal as well as potential multipotency. These cells play important roles in many biological processes, including anti-inflammation, cell migration, proliferation, and differentiation, and signal pathway activation or inhibition. The mechanism of the involvement of MSCs in reepithelialization is still not fully understood. An abundance of evidence has shown that MSCs participate in reepithelialization by inhibiting excessive inflammatory responses, secreting important factors, differentiating into multiple skin cell types, and recruiting other host cells. This review describes the evidence for the roles that MSCs appear to play in the reepithelialization process. [ABSTRACT FROM AUTHOR]

3D ordered structures beyond microscale with targeted modification are catching increasing attention due to its application as tissue scaffolds. Especially scaffolds with necessary growth factors at designated locations are meaningful for induced cell differentiation and tissue formation. However, few fabrication methods can address the challenge of introducing bioactive species to the interior targeted places during the preparation process. Herein, for the first time macroscopic supramolecular assembly is applied to obtain such 3D ordered structures and established a proof-of-concept idea of complex scaffold with targeted modification. Taking strip-like polydimethylsilicon building block as a model system, microscaled multilayered structures have been fabricated with parallel aligned building blocks in each layer. The morphology can be adjusted in a flexible way by tuning the number of layer, the space between two adjacent building blocks, and the position and orientation of each PDMS. The as-prepared 3D structures are demonstrated biocompatible and potential as scaffolds for 3D cell culture. Moreover, bioactive species can be in situ incorporated into designated locations within the 3D structure precisely. In this way, a novel strategy is provided to address the current challenges in fabricating complex 3D tissue scaffolds with localized protein for future induced cell differentiation. [ABSTRACT FROM AUTHOR]

Background/Aims: Mesenchymal stem cell (MSC) based therapies may be useful for treating acute respiratory distress syndrome (ARDS), but the underlying mechanisms are incompletely understood. We investigated the impact of human umbilical cord Wharton's jelly-derived MSC (hUC-MSC) secreted factors on alveolar epithelial cells under septic conditions and determined the relevant intracellular signaling pathways. Methods: Human alveolar epithelial cells (AEC) and primary human small airway epithelial cells (SAEC) were subjected to lipopolysaccharide (LPS) with or without the presence of hUC-MSC-conditioned medium (CM). Proliferation and migration of AEC and SAEC were determined via an MTT assay, a wound healing assay and a transwell migration assay (only for AEC). Protein phosphorylation was determined by western blot and the experiments were repeated in presence of small-molecule inhibitors. The hMSC-secretory proteins were identified by LC-MS/MS mass spectrometry. Results: MSC-CM enhanced proliferation and migration. Activation of JNK and P38, but not ERK, was required for the proliferation and migration of AEC and SAEC. Pretreatment of AEC or SAEC with SP600125, an inhibitor of JNK1 or SB200358, an inhibitor of P38, significantly reduced cell proliferation and migration. An array of proteins including TGF-beta receptor type-1, TGF-beta receptor type-2, Ras-related C3 botulinum toxin substrate 1 and Ras-related C3 botulinum toxin substrate 2 which influencing the proliferation and migration of AEC and SAEC were detected in MSC-CM. Conclusion: Our data suggest MSC promote epithelial cell repair through releasing a repertoire of paracrine factors via activation of JNK and P38 MAPK. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Within the last few years, it has become evident that LPS-preconditioned mesenchymal stromal cells (LPS pre-MSCs) show enhanced paracrine effects, including increased trophic support and improved regenerative and repair properties. MSCs may release large amounts of exosomes for cell-to-cell communication and maintain a dynamic and homeostatic microenvironment for tissue repair. The present study assesses the therapeutic efficacy and mechanisms of LPS-preconditioned MSC-derived exosomes (LPS pre-Exo) for chronic inflammation and wound healing.Methods: We extracted exosomes from the supernatant of LPS pre-MSCs using a gradient centrifugation method. In vitro, THP-1 cells were cultured with high glucose (HG, 30 mM) as an inflammatory model and treated with LPS pre-Exo for 48 h. The expression of inflammation-related cytokines was detected by real-time RT-PCR, and the distribution of macrophage subtype was measured by immunofluorescence. Next, the miRNA expression profiles of LPS pre-Exo were evaluated using miRNA microarray analysis. The molecular signaling pathway responsible for the regenerative potential was identified by western blotting. In vivo, we established a cutaneous wound model in streptozotocin-induced diabetic rats, and LPS pre-Exo were injected dispersively into the wound edge. The curative effects of LPS pre-Exo on inflammation and wound healing were observed and evaluated.Results: LPS pre-Exo have a better ability than untreated MSC-derived exosomes (un-Exo) to modulate the balance of macrophages due to their upregulation of the expression of anti-inflammatory cytokines and promotion of M2 macrophage activation. Microarray analysis of LPS pre-Exo identified the unique expression of let-7b compared with un-Exo, and the let-7b/TLR4 pathway served as potential contributor to macrophage polarization and inflammatory ablation. Further investigation of the mechanisms that control let-7b expression demonstrated that a TLR4/NF-κB/STAT3/AKT regulatory signaling pathway plays a critical role in the regulation of macrophage plasticity. Knockdown of AKT in THP-1 cells similarly abolished the immunomodulatory effect of LPS pre-Exo. In vivo, LPS pre-Exo greatly alleviated inflammation and enhanced diabetic cutaneous wound healing.Conclusion: LPS pre-Exo may have improved regulatory abilities for macrophage polarization and resolution of chronic inflammation by shuttling let-7b, and these exosomes carry much immunotherapeutic potential for wound healing. [ABSTRACT FROM AUTHOR]

ABSTRACT Although advancements have been made with traditional therapies, the treatment of chronic nonhealing wounds still remains a tough challenge. In the past two decades, mesenchymal stem cell (MSC)-based therapy has emerged as a promising therapeutic strategy for nonhealing wounds because of their characteristics including self-renewal and a multidirectional differentiation ability and their easy collection and weak immunogenicity. There is a growing body of basic scientific studies that shed light on the functional mechanism of MSCs in modulating nonhealing wounds. Furthermore, critical advances have been achieved using MSC-based therapy in preclinical animal models as well as in clinics trials. In this present review, we summarize the mechanisms of MSCs and highlight the important preclinical and clinical trials of MSC therapy for nonhealing wounds. In particular, the combination of MSCs transplantation and tissue-engineered skin is addressed as a new strategy to optimize the delivery efficiency and therapeutic potential. Additionally, the current drawbacks of MSC therapy and the potential to further optimize the use of MSCs are implied. [ABSTRACT FROM AUTHOR]

Human umbilical cord–derived mesenchymal stem cells (UC-MSCs) are multipotent, primitive, and have been widely used for skin tissue engineering. Their transdifferentiation is determined by the local microenvironment. In this study, we investigated the potential epidermal differentiation of UC-MSCs and the formation of epidermis substitutes in a 3-dimensional (3D) microenvironment, which was fabricated by UC-MSCs embedded into collagen–chitosan scaffolds (CCSs) combined with an air–liquid interface (ALI) culture system. Using fluorescence microscope, we observed that UC-MSCs were spindle-shaped and evenly distributed in the scaffold. Methyl thiazolyl blue tetrazolium bromide assay and Live/Dead assay indicated that the CCSs have good biocompatibility with UC-MSCs. Immunohistochemistry and western blotting assay showed that UC-MSCs on the surface of the CCSs were positive for the epidermal markers cytokeratin 19 and involucrin at 14 days. In addition, hematoxylin–eosin staining indicated that multilayered epidermis substitutes were established. The constructed epidermis substitutes were applied to treat full-thickness wounds in rats and proved to promote wound healing. In conclusion, manipulating the 3D microenvironment is a novel method for inducing the epidermal differentiation of MSCs to engineer epidermal substitutes, which provides an alternative strategy for skin tissue engineering. [ABSTRACT FROM AUTHOR]

Endothelial dysfunction induced by unordered metabolism results in vascular reconstruction challenges in diabetic lower limb ischemia (DLLI). Mesenchymal stem cells (MSCs) are multipotent secretory cells that are suitable for clinical DLLI treatment, but their use has been hampered by poor survival after injection. Hypoxia can significantly enhance the capacity of MSCs to secrete angiogenic factors. We investigated transient hypoxia pretreatment of MSCs to facilitate revascularization in DLLI. Rat bone marrow MSCs (BM-MSCs) were cultured at different oxygen concentrations for varying time periods. The results indicated that transient pretreatment (5% O2, 48 h) not only increased the expression of VEGF-1α, ANG, HIF-1α and MMP-9 in BM-MSCs as assessed by real-time RT-PCR, but also increased the expression of Bcl-2 as determined by western blotting. The transplantation of pretreated BM-MSCs into rats with DLLI demonstrated accelerated vascular reconstruction when assayed by angiography and immunohistochemistry. CM-Dil-labeled tracer experiments indicated that the survival of BM-MSCs was significantly improved, with approximately 5% of the injected cells remaining alive at 14 days. The expression levels of VEGF-1α, MMP-9 and VEGF-R were significantly increased, and the expression of pAKT was up-regulated in ischemic muscle. Double immunofluorescence studies confirmed that the pretreated BM-MSCs promoted the proliferation and inhibited the apoptosis of endothelial cells. In vitro, pretreated BM-MSCs increased the migratory and tube forming capacity of endothelial cells (ECs). Hypoxia pretreatment of BM-MSCs significantly improved angiogenesis in response to tissue ischemia by ameliorating endothelial cell dysfunction and is a promising therapeutic treatment for DLLI. [ABSTRACT FROM AUTHOR]

Bone marrow–derived mesenchymal stem cells (BM-MSCs)have great therapeutic potential for the repair of diabetic lower-limb ischemia because of their proangiogenic properties. However, cells transplanted into an ischemic environment have reduced cell survival rates and impaired angiogenic capacity in vivo. We explored hypoxia pretreatment as a method to promote BM-MSC survival by inducing autophagy. Our results showed that hypoxic pretreatment has no effect on the phenotype or differentiation capacity of BM-MSCs; however, hypoxia increased viability and reduced apoptosis in cells treated with lipopolysaccharide. Immunofluorescence and western blot results showed that hypoxia pretreatment enhances cell autophagy mediated by elevated expression of hypoxia inducible factor-1α (HIF-1α). The AMPK/mTOR (adenosine monophosphate–activated protein kinase/mammalian target of rapamycin) signaling pathway was also activated in BM-MSCs during hypoxia-enhanced autophagy. It is important to note that hypoxia pretreatment in BM-MSCs significantly enhanced cell survival and promoted angiogenesis in the lower limb of ischemic diabetic rats. In conclusion, hypoxia pretreatment enhances survival in BM-MSCs, promoting angiogenesis by increasing autophagy and significantly decreasing apoptosis. Therefore, modulation of autophagy with hypoxic pretreatment may provide a novel strategy to improve MSC-based therapies. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Multiple MSC infusions could reverse hyperglycemia in T2D rats. [•] Multiple MSC infusions could restore the injured pancreatic islets in T2D rats. [•] The effect of multiple-MSC infusions was strong at early-phase. [•] Cytokines of MSCs are responsible for the anti-diabetes effects. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSCs) hold great therapeutic potential. However, MSCs undergo replication senescence during the in vitro expansion process. Wharton's jelly from the human umbilical cord harbors a large number of MSCs. In this study, we hypothesized that Wharton's jelly would be beneficial for in vitro expansion of MSCs. Wharton's jelly extract (WJEs), which is mainly composed of extracellular matrix and cytokines, was prepared as coating substrate. Human MSCs were isolated and cultured on WJE-coated plates. Although the proliferation capacity of cells was not augmented by WJE in early phase culture, adynamic growth in late-phase culture was clearly reduced, suggesting that the replicative senescence of MSCs was efficiently slowed by WJE. This was confirmed by β-galactosidase staining and telomere length measurements of MSCs in late-phase culture. In addition, the decreased differentiation ability of MSCs after long-term culture was largely ameliorated by WJE. Reactive oxygen species (ROS), p53, and p16INK4a/pRb expression increased with passaging. Analysis at the molecular level revealed that WJE-based culture efficiently suppressed the enhancement of intracellular ROS, p53, and p16INK4a/pRb in MSCs. These data demonstrated that WJE provided an ideal microenvironment for MSCs culture expansion in vitro preserved MSC properties by delaying MSCs senescence, and allowed large numbers of MSCs to be obtained for basic research and clinical therapies. [ABSTRACT FROM AUTHOR]