Proteasome inhibition-enhanced fracture repair is associated with increased mesenchymal progenitor cells in mice

The ubiquitin/proteasome system controls the stability of Runx2 and JunB, proteins essential for differentiation of mesenchymal progenitor/stem cells (MPCs) to osteoblasts. Local administration of proteasome inhibitor enhances bone fracture healing by accelerating endochondral ossification. However, if a short-term administration of proteasome inhibitor enhances fracture repair and potential mechanisms involved have yet to be exploited. We hypothesize that injury activates the ubiquitin/proteasome system in callus, leading to elevated protein ubiquitination and degradation, decreased MPCs, and impaired fracture healing, which can be prevented by a short-term of proteasome inhibition. We used a tibial fracture model in Nestin-GFP reporter mice, in which a subgroup of MPCs are labeled by Nestin-GFP, to test our hypothesis. We found increased expression of ubiquitin E3 ligases and ubiquitinated proteins in callus tissues at the early phase of fracture repair. Proteasome inhibitor Bortezomib, given soon after fracture, enhanced fracture repair, which is accompanied by increased callus Nestin-GFP+ cells and their proliferation, and the expression of osteoblast-associated genes and Runx2 and JunB proteins. Thus, early treatment of fractures with Bortezomib could enhance the fracture repair by increasing the number and proliferation of MPCs.

Reciprocal impacts of telomerase activity and ADRN/MES differentiation state in neuroblastoma tumor biology

Telomere maintenance and tumor cell differentiation have been separately implicated in neuroblastoma malignancy. Their mechanistic connection is unclear. We analyzed neuroblastoma cell lines and morphologic subclones representing the adrenergic (ADRN) and mesenchymal (MES) differentiation states and uncovered sharp differences in their telomere protein and telomerase activity levels. Pharmacologic conversion of ADRN into MES cells elicited consistent and robust changes in the expression of telomere-related proteins. Conversely, stringent down-regulation of telomerase activity triggers the differentiation of ADRN into MES cells, which was reversible upon telomerase up-regulation. Interestingly, the MES differentiation state is associated with elevated levels of innate immunity factors, including key components of the DNA-sensing pathway. Accordingly, MES but not ADRN cells can mount a robust response to viral infections in vitro. A gene expression signature based on telomere and cell lineage-related factors can cluster neuroblastoma tumor samples into predominantly ADRN or MES-like groups, with distinct clinical outcomes. Our findings establish a strong mechanistic connection between telomere and differentiation and suggest that manipulating telomeres may suppress malignancy not only by limiting the tumor growth potential but also by inducing tumor cell differentiation and altering its immunogenicity.

The Potential Role of Human NME1 in Neuronal Differentiation of Porcine Mesenchymal Stem Cells: Application of NB-hNME1 as a Human NME1 Suppressor

This study aimed to investigate the effects of the human macrophage (MP) secretome in cellular xenograft rejection. The role of human nucleoside diphosphate kinase A (hNME1), from the secretome of MPs involved in the neuronal differentiation of miniature pig adipose tissue-derived mesenchymal stem cells (mp AD-MSCs), was evaluated by proteomic analysis. Herein, we first demonstrate that hNME1 strongly binds to porcine ST8 alpha-N-acetyl-neuraminide alpha-2,8-sialyltransferase 1 (pST8SIA1), which is a ganglioside GD3 synthase. When hNME1 binds with pST8SIA1, it induces degradation of pST8SIA1 in mp AD-MSCs, thereby inhibiting the expression of ganglioside GD3 followed by decreased neuronal differentiation of mp AD-MSCs. Therefore, we produced nanobodies (NBs) named NB-hNME1 that bind to hNME1 specifically, and the inhibitory effect of NB-hNME1 was evaluated for blocking the binding between hNME1 and pST8SIA1. Consequently, NB-hNME1 effectively blocked the binding of hNME1 to pST8SIA1, thereby recovering the expression of ganglioside GD3 and neuronal differentiation of mp AD-MSCs. Our findings suggest that mp AD-MSCs could be a potential candidate for use as an additive, such as an immunosuppressant, in stem cell transplantation.

Effects of Normal Synovial Fluid and Interferon Gamma on Chondrogenic Capability and Immunomodulatory Potential Respectively on Equine Mesenchymal Stem Cells

Synovial fluid contains cytokines, growth factors and resident mesenchymal stem cells (MSCs). The present study aimed to (1) determine the effects of autologous and allogeneic synovial fluid on viability, proliferation and chondrogenesis of equine bone marrow MSCs (BMMSCs) and (2) compare the immunomodulatory properties of equine synovial fluid MSCs (SFMSCs) and BMMSCs after stimulation with interferon gamma (INF-γ). To meet the first aim of the study, the proliferation and viability of MSCs were evaluated by MTS and calcein AM staining assays. To induce chondrogenesis, MSCs were cultured in a medium containing TGF-β1 or different concentrations of synovial fluid. To meet the second aim, SFMSCs and BMMSCs were stimulated with IFN-γ. The concentration of indoleamine-2,3-dioxygenase (IDO) and nitric oxide (NO) were examined. Our results show that MSCs cultured in autologous or allogeneic synovial fluid could maintain proliferation and viability activities. Synovial fluid affected chondrocyte differentiation significantly, as indicated by increased glycosaminoglycan contents, compared to the chondrogenic medium containing 5 ng/mL TGF-β1. After culturing with IFN-γ, the conditioned media of both BMMSCs and SFMSCs showed increased concentrations of IDO, but not NO. Stimulating MSCs with synovial fluid or IFN-γ could enhance chondrogenesis and anti-inflammatory activity, respectively, suggesting that the joint environment is suitable for chondrogenesis.

Effect of Rho-Associated Kinase Inhibitor and Mesenchymal Stem Cell-Derived Conditioned Medium on Corneal Endothelial Cell Senescence and Proliferation

This study aims to obtain sufficient corneal endothelial cells for regenerative application. We examined the combinatory effects of Rho-associated kinase (ROCK) inhibitor Y-27632 and mesenchymal stem cell-derived conditioned medium (MSC-CM) on the proliferation and senescence of rabbit corneal endothelial cells (rCECs). rCECs were cultured in a control medium, a control medium mixed with either Y-27632 or MSC-CM, and a combinatory medium containing Y-27632 and MSC-CM. Cells were analyzed for morphology, cell size, nuclei/cytoplasmic ratio, proliferation capacity and gene expression. rCECs cultured in a combinatory culture medium showed a higher passage number, cell proliferation, and low senescence. rCECs on collagen type I film showed high expression of tight junction. The cell proliferation marker Ki-67 was positively stained either in Y-27632 or MSC-CM-containing media. Genes related to cell proliferation resulted in negligible changes in MKI67, CIP2A, and PCNA in the combinatory medium, suggesting proliferative capacity was maintained. In contrast, all of these genes were significantly downregulated in the other groups. Senescence marker β-galactosidase-positive cells significantly decreased in either MSC-CM and/or Y-27632 mixed media. Senescence-related genes downregulated LMNB1 and MAP2K6, and upregulated MMP2. Cell cycle checkpoint genes such as CDC25C, CDCA2, and CIP2A did not vary in the combinatory medium but were significantly downregulated in either ROCK inhibitor or MSC-CM alone. These results imply the synergistic effect of combinatory culture medium on corneal endothelial cell proliferation and high cell number. This study supports high potential for translation to the development of human corneal endothelial tissue regeneration.

Rspo1-LGR4 axis in BMSCs protects bone against radiation-induced injury through the mTOR-dependent autophagy pathway

While mesenchymal stem cells (MSCs) have been widely used to repair radiation-induced bone damage, the molecular mechanism underlying the effects of MSCs in the maintenance of bone homeostasis under radiation stress remains largely unknown. In this study, the role and mechanisms of R-spondin 1 (Rspo1)-leucine-rich repeat-containing G protein-coupled receptor 4 (LGR4) axis on the initiation of self-defense of bone mesenchymal stem cells (BMSCs) and maintenance of bone homeostasis under radiation stress were investigated. Interestingly, radiation increased levels of Rspo1 and LGR4 in BMSCs. siRNA knockdown of Rspo1 or LGR4 aggravated radiation-induced impairment of self-renewal ability and osteogenic differentiation potential of BMSCs. However, exogenous Rspo1 significantly attenuated radiation-induced depletion of BMSCs, and promoted the lineage shift towards osteoblasts. This alteration was associated with the reversal of mammalian target of rapamycin (mTOR) activation and autophagy decrement. Pharmacological and genetic blockade of autophagy attenuated the radio-protective effects of Rspo1, rendering BMSCs more vulnerable to radiation-induced injury. Then bone radiation injury was induced in C57BL6J mice to further determine the radio-protective effects of Rspo1. In mice, administration of Rspo1 recombinant protein alleviated radiation-induced bone loss. Our results uncover that Rspo1-LGR4-mTOR-autophagy axis are key mechanisms by which BMSCs initiate self-defense against radiation and maintain bone homeostasis. Targeting Rspo1-LGR4 may provide a novel strategy for the intervention of radiation-induced bone damage.

The role of heme oxygenase-1 in hematopoietic system and its microenvironment

Hematopoietic system transports all necessary nutrients to the whole organism and provides the immunological protection. Blood cells have high turnover, therefore, this system must be dynamically controlled and must have broad regeneration potential. In this review, we summarize how this complex system is regulated by the heme oxygenase-1 (HO-1)-an enzyme, which degrades heme to biliverdin, ferrous ion and carbon monoxide. First, we discuss how HO-1 influences hematopoietic stem cells (HSC) self-renewal, aging and differentiation. We also describe a critical role of HO-1 in endothelial cells and mesenchymal stromal cells that constitute the specialized bone marrow niche of HSC. We further discuss the molecular and cellular mechanisms by which HO-1 modulates innate and adaptive immune responses. Finally, we highlight how modulation of HO-1 activity regulates the mobilization of bone marrow hematopoietic cells to peripheral blood. We critically discuss the issue of metalloporphyrins, commonly used pharmacological modulators of HO-1 activity, and raise the issue of their important HO-1-independent activities.

DNMT3B Is an Oxygen-Sensitive De Novo Methylase in Human Mesenchymal Stem Cells

The application of physiological oxygen (physoxia) concentrations is becoming increasingly commonplace within a mammalian stem cell culture. Human mesenchymal stem cells (hMSCs) attract widespread interest for clinical application due to their unique immunomodulatory, multi-lineage potential, and regenerative capacities. Descriptions of the impact of physoxia on global DNA methylation patterns in hMSCs and the activity of enzymatic machinery responsible for its regulation remain limited. Human bone marrow-derived mesenchymal stem cells (BM-hMSCs, passage 1) isolated in reduced oxygen conditions displayed an upregulation of SOX2 in reduced oxygen conditions vs. air oxygen (21% O2, AO), while no change was noted for either OCT-4 or NANOG. DNA methylation marks 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) showed decreases in 2% O2 environment (workstation) (2% WKS). DNMT3B (DNA methyltransferase 3B) and TET1 (Ten-eleven translocation enzyme 1) displayed reduced transcription in physoxia. Consistent with transcriptional downregulation, we noted increased promoter methylation levels of DNMT3B in 2% WKS accompanied by reduced DNMT3B and TET1 protein expression. Finally, a decrease in HIF1A (Hypoxia-inducible factor 1A) gene expression in 2% WKS environment correlated with protein levels, while HIF2A was significantly higher in physoxia correlated with protein expression levels vs. AO. Together, these data have demonstrated, for the first time, that global 5mC, 5hmC, and DNMT3B are oxygen-sensitive in hMSCs. Further insights into the appropriate epigenetic regulation within hMSCs may enable increased safety and efficacy development within the therapeutic ambitions.

Mesenchymal stem cells alleviate experimental immune-mediated liver injury via chitinase 3-like protein 1-mediated T cell suppression

Liver diseases with different pathogenesis share common pathways of immune-mediated injury. Chitinase-3-like protein 1 (CHI3L1) was induced in both acute and chronic liver injuries, and recent studies reported that it possesses an immunosuppressive ability. CHI3L1 was also expressed in mesenchymal stem cells (MSCs), thus we investigates the role of CHI3L1 in MSC-based therapy for immune-mediated liver injury here. We found that CHI3L1 was highly expressed in human umbilical cord MSCs (hUC-MSCs). Downregulating CHI3L1 mitigated the ability of hUC-MSCs to inhibit T cell activation, proliferation and inflammatory cytokine secretion in vitro. Using Concanavalin A (Con A)-induced liver injury mouse model, we found that silencing CHI3L1 significantly abrogated the hUC-MSCs-mediated alleviation of liver injury, accompanying by weakened suppressive effects on infiltration and activation of hepatic T cells, and secretion of pro-inflammatory cytokines. In addition, recombinant CHI3L1 (rCHI3L1) administration inhibited the proliferation and function of activated T cells, and alleviated the Con A-induced liver injury in mice. Mechanistically, gene set enrichment analysis showed that JAK/STAT signalling pathway was one of the most significantly enriched gene pathways in T cells co-cultured with hUC-MSCs with CHI3L1 knockdown, and further study revealed that CHI3L1 secreted by hUC-MSCs inhibited the STAT1/3 signalling in T cells by upregulating peroxisome proliferator-activated receptor δ (PPARδ). Collectively, our data showed that CHI3L1 was a novel MSC-secreted immunosuppressive factor and provided new insights into therapeutic treatment of immune-mediated liver injury.

Ubiquitin-specific protease 53 promotes osteogenic differentiation of human bone marrow-derived mesenchymal stem cells

The ubiquitin protease pathway plays important role in human bone marrow-derived mesenchymal stem cell (hBMSC) differentiation, including osteogenesis. However, the function of deubiquitinating enzymes in osteogenic differentiation of hBMSCs remains poorly understood. In this study, we aimed to investigate the role of ubiquitin-specific protease 53 (USP53) in the osteogenic differentiation of hBMSCs. Based on re-analysis of the Gene Expression Omnibus database, USP53 was selected as a positive regulator of osteogenic differentiation in hBMSCs. Overexpression of USP53 by lentivirus enhanced osteogenesis in hBMSCs, whereas knockdown of USP53 by lentivirus inhibited osteogenesis in hBMSCs. In addition, USP53 overexpression increased the level of active β-catenin and enhanced the osteogenic differentiation of hBMSCs. This effect was reversed by the Wnt/β-catenin inhibitor DKK1. Mass spectrometry showed that USP53 interacted with F-box only protein 31 (FBXO31) to promote proteasomal degradation of β-catenin. Inhibition of the osteogenic differentiation of hBMSCs by FBXO31 was partially rescued by USP53 overexpression. Animal studies showed that hBMSCs with USP53 overexpression significantly promoted bone regeneration in mice with calvarial defects. These results suggested that USP53 may be a target for gene therapy for bone regeneration.

Ex vivo Ikkβ ablation rescues the immunopotency of mesenchymal stromal cells from diabetics with advanced atherosclerosis

AIMS

Diabetes is a conventional risk factor for atherosclerotic cardiovascular disease and myocardial infarction (MI) is the most common cause of death among these patients. Mesenchymal stromal cells (MSCs) in patients with type 2 diabetes mellitus (T2DM) and atherosclerosis have impaired ability to suppress activated T-cells (i.e. reduced immunopotency). This is mediated by an inflammatory shift in MSC-secreted soluble factors (i.e. pro-inflammatory secretome) and can contribute to the reduced therapeutic effects of autologous T2DM and atherosclerosis-MSC post-MI. The signalling pathways driving the altered secretome of atherosclerosis- and T2DM-MSC are unknown. Specifically, the effect of IκB kinase β (IKKβ) modulation, a key regulator of inflammatory responses, on the immunopotency of MSCs from T2DM patients with advanced atherosclerosis has not been studied.

METHODS AND RESULTS

MSCs were isolated from adipose tissue obtained from patients with (i) atherosclerosis and T2DM (atherosclerosis+T2DM MSCs, n = 17) and (ii) atherosclerosis without T2DM (atherosclerosis MSCs, n = 17). MSCs from atherosclerosis+T2DM individuals displayed an inflammatory senescent phenotype and constitutively expressed active forms of effectors of the canonical IKKβ nuclear factor-κB transcription factors inflammatory pathway. Importantly, this constitutive pro-inflammatory IKKβ signature resulted in an altered secretome and impaired in vitro immunopotency and in vivo healing capacity in an acute MI model. Notably, treatment with a selective IKKβ inhibitor or IKKβ knockdown (KD) (clustered regularly interspaced short palindromic repeats/Cas9-mediated IKKβ KD) in atherosclerosis+T2DM MSCs reduced the production of pro-inflammatory secretome, increased survival, and rescued their immunopotency both in vitro and in vivo.

CONCLUSIONS

Constitutively active IKKβ reduces the immunopotency of atherosclerosis+T2DM MSC by changing their secretome composition. Modulation of IKKβ in atherosclerosis+T2DM MSCs enhances their myocardial repair ability.

Nanostructured Coating of Non-Crystalline Tantalum Pentoxide on Polyetheretherketone Enhances RBMS Cells/HGE Cells Adhesion

PURPOSE

As a dental material, polyetheretherketone (PEEK) is bioinert that does not induce cellular response and bone/gingival tissues regeneration. This study was to develop bioactive coating on PEEK and investigate the effects of coating on cellular response.

MATERIALS AND METHODS

Tantalum pentoxide (TP) coating was fabricated on PEEK surface by vacuum evaporation and responses of rat bone marrow mesenchymal stem (RBMS) cells/human gingival epithelial (HGE) were studied.

RESULTS

A dense coating (around 400 nm in thickness) of TP was closely combined with PEEK (PKTP). Moreover, the coating was non-crystalline TP, which contained many small humps (around 10 nm in size), exhibiting a nanostructured surface. In addition, the roughness, hydrophilicity, surface energy, and protein adsorption of PKTP were remarkably higher than that of PEEK. Furthermore, the responses (adhesion, proliferation, and osteogenic gene expression) of RBMS cells, and responses (adhesion and proliferation) of HGE cells to PKTP were remarkably improved in comparison with PEEK. It could be suggested that the nanostructured coating of TP on PEEK played crucial roles in inducing the responses of RBMS/HGE cells.

CONCLUSION

PKTP with elevated surface performances and outstanding cytocompatibility might have enormous potential for dental implant application.

Mesenchymal stem cell-derived extracellular vesicles promote microglial M2 polarization after subarachnoid hemorrhage in rats and involve the AMPK/NF-κB signaling pathway

Subarachnoid hemorrhage (SAH) is an acute and severe disease with high disability and mortality. Inflammatory reactions have been proven to occur throughout SAH. Extracellular vesicles derived from mesenchymal stem cells (MSCs-EVs) have shown broad potential for the treatment of brain dysfunction and neuroprotective effects through neurogenesis and angiogenesis after stroke. However, the mechanisms of EVs in neuroinflammation during the acute phase of SAH are not well known. Our present study was designed to investigate the effects of MSCs-EVs on neuroinflammation and the polarization regulation of microglia to the M2 phenotype and related signaling pathways after SAH in rats. The SAH model was induced by an improved method of intravascular perforation, and MSCs-EVs were injected via the tail vein. Post-SAH assessments included neurobehavioral tests as well as brain water content, immunohistochemistry, PCR and Western blot analyses. Our results showed that MSCs-EVs alleviated the expression of inflammatory cytokines in the parietal cortex and hippocampus 24 h and 48 h after SAH and that MSCs-EVs inhibited NF-κB and activated AMPK to reduce inflammation after SAH. Furthermore, MSC-EVs regulated the polarization of microglia toward the M2 phenotype by downregulating interleukin-1β, cluster of differentiation 16, cluster of differentiation 11b, and inducible nitric oxide synthase and upregulating the expression of cluster of differentiation 206 and arginase-1. Additionally, MSCs-EVs inhibited the neuroinflammatory response and had neuroprotective effects in the brain tissues of rats after SAH. This study may support their use as a potential treatment strategy for early SAH in the future.

Complex effect of continuous curcumin exposure on human bone marrow-derived mesenchymal stem cell regenerative properties through matrix metalloproteinase regulation

Curcumin has been reported to be beneficial for cancers, cardiovascular and neurodegenerative diseases, based on its anti-oxidative, anti-inflammation, anti-tumorigenic and neuroprotective properties. With its high-dose application, curcumin toxicity to systemic tissues is a reasonable concern. Here, we report the responses of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) to continuous curcumin exposure. hBM-MSCs were treated with 0.01-100 μmol/L curcumin continuously in vitro for 7 days. 25 μmol/L curcumin or above significantly attenuated hBM-MSC maintenance, whereas 10 μmol/L curcumin reduced hBM-MSC proliferation and hindered their migration with increasing cell apoptosis. Besides, 5 μmol/L curcumin treatment inhibited hBM-MSC adipogenic differentiation, but enhanced osteogenic differentiation, which depended on matrix metalloproteinase (MMP)-13 expression and activity. Furthermore, curcumin treatment reduced MMP1 expression but up-regulated the immunomodulatory gene IDO1 expression. In summary, this study revealed the complex effects of continuous curcumin exposure on hBM-MSC maintenance and regenerative properties through MMP regulation. Given the complex effects of curcumin, its use for biomedical purposes should be carefully considered in treatment length and dosage.

Deimination, Intermediate Filaments and Associated Proteins

Deimination (or citrullination) is a post-translational modification catalyzed by a calcium-dependent enzyme family of five peptidylarginine deiminases (PADs). Deimination is involved in physiological processes (cell differentiation, embryogenesis, innate and adaptive immunity, etc.) and in autoimmune diseases (rheumatoid arthritis, multiple sclerosis and lupus), cancers and neurodegenerative diseases. Intermediate filaments (IF) and associated proteins (IFAP) are major substrates of PADs. Here, we focus on the effects of deimination on the polymerization and solubility properties of IF proteins and on the proteolysis and cross-linking of IFAP, to finally expose some features of interest and some limitations of citrullinomes.

Adhesive Properties of the Hyaluronan Pericellular Coat in Hyaluronan Synthases Overexpressing Mesenchymal Stem Cells

Hyaluronan (HA), a natural component of the extracellular matrix, is supposed to have a regulatory function in the stem cell niche. Bone marrow-derived human mesenchymal stem cells (hMSCs) are known to express all three hyaluronan synthases (HASes), which are responsible for HA production. HA is extruded into the extracellular matrix, but also stays bound to the plasma membrane forming a pericellular coat, which plays a key role during early cell adhesion. Since HAS isoenzymes, HAS1, HAS2 and HAS3, produce HA with different molecular weights, a difference in their role for cell adhesion is expected. Here, we transduced the immortalized hMSC cell line SCP1 to constitutively express eGFP-tagged HASes (SCP1-HAS-eGFP) by lentiviral gene transfer. The overexpression of the HAS-eGFP was shown on RNA and protein levels, HA was determined by ELISA and the stained HA-coat was analyzed using confocal microscopy. Time-lapse microscopy, spreading assay and single cell force spectroscopy using atomic force microscopy were applied to characterize adhesion of the different HAS transduced SCP1 cells. We showed in this study that HAS3 overexpressing cells formed the thickest pericellular coat compared with control or HAS1 and HAS2 transduced cells. Furthermore, SCP1-HAS3-eGFP displayed faster and stronger adhesion compared to cells overexpressing the other synthases or control cells. We conclude that overexpression of HASes in hMSCs differentially modulates their initial adhesive interactions with the substrate. This observation might be helpful in regenerative medicine goals.

Preconditioning of Adipose-Derived Mesenchymal Stem-Like Cells with Eugenol Potentiates Their Migration and Proliferation In Vitro and Therapeutic Abilities in Rat Hepatic Fibrosis

Mesenchymal stem cells (MSCs) have considerable therapeutic abilities in various disorders, including hepatic fibrosis. They may be affected with different culture conditions. This study investigated, on molecular basics, the effect of pretreatment with eugenol on the characteristics of adipose tissue-derived MSCs (ASCs) in vitro and the implication of eugenol preconditioning on the in vivo therapeutic abilities of ASCs against CCl₄-induced hepatic fibrosis in rats. The effect of eugenol on ASCs was assessed using viability, scratch migration and sphere formation assays. Expressions of genes and proteins were estimated by immunofluorescence or qRT-PCR. For the in vivo investigations, rats were divided into four groups: the normal control group, fibrotic (CCl₄) group, CCl₄+ASCs group and CCl₄ + eugenol-preconditioned ASCs (CCl₄+E-ASCs) group. Eugenol affected the viability of ASCs in a concentration- and time-dependent manner. Eugenol improved their self-renewal, proliferation and migration abilities and significantly increased their expression of c-Met, reduced expression 1 (Rex1), octamer-binding transcription factor 4 (Oct4) and nanog genes. Furthermore, E-ASCs showed more of a homing ability than ASCs and improved the serum levels of ALT, AST, albumin, total bilirubin and hyaluronic acid more efficient than ASCs in treating CCl₄-induced hepatic fibrosis, which was confirmed with histopathology. More interestingly, compared to the CCl₄+ASCs group, CCl₄+E-ASCs group showed a lower expression of inducible nitric oxide synthase (iNOS), monocyte chemoattractant protein-1 (MCP-1), cluster of differentiation 163 (CD163) and tumor necrosis factor-α (TNF-α) genes and higher expression of matrix metalloproteinase (MMP)-9 and MMP-13 genes. This study, for the first time, revealed that eugenol significantly improved the self-renewal, migration and proliferation characteristics of ASCs, in vitro. In addition, we demonstrated that eugenol-preconditioning significantly enhanced the therapeutic abilities of the injected ASCs against CCl₄-induced hepatic fibrosis.

Microtubule destabilization caused by silicate via HDAC6 activation contributes to autophagic dysfunction in bone mesenchymal stem cells

BACKGROUND

Silicon-modified biomaterials have been extensively studied in bone tissue engineering. In recent years, the toxicity of silicon-doped biomaterials has gradually attracted attention but requires further elucidation. This study was designed to explore whether high-dose silicate can induce a cytotoxicity effect in bone mesenchymal stem cells (BMSCs) and the role of autophagy in its cytotoxicity and mechanism.

METHODS

Morphologic changes and cell viability of BMSCs were detected after different doses of silicate exposure. Autophagic proteins (LC3, p62), LC3 turnover assay, and RFP-GFP-LC3 assay were applied to detect the changes of autophagic flux following silicate treatment. Furthermore, to identify the potential mechanism of autophagic dysfunction, we tested the acetyl-α-tubulin protein level and histone deacetylase 6 (HDAC6) activity after high-dose silicate exposure as well as the changes in microtubule and autophagic activity after HDAC6 siRNA was applied.

RESULTS

It was found that a high dose of silicate could induce a decrease in cell viability; LC3-II and p62 simultaneously increased after high-dose silicate exposure. A high concentration of silicate could induce autophagic dysfunction and cause autophagosomes to accumulate via microtubule destabilization. Results showed that acetyl-α-tubulin decreased significantly with high-dose silicate treatment, and inhibition of HDAC6 activity can restore microtubule structure and autophagic flux.

CONCLUSIONS

Microtubule destabilization caused by a high concentration of silicate via HDAC6 activation contributed to autophagic dysfunction in BMSCs, and inhibition of HDAC6 exerted a cytoprotection effect through restoration of the microtubule structure and autophagic flux.

Nano-Hydroxyapatite Coating Promotes Porous Calcium Phosphate Ceramic-Induced Osteogenesis Via BMP/Smad Signaling Pathway

BACKGROUND

The hierarchical porous structure and surface topography of calcium phosphate (CaP) bioceramics have a crucial impact on their osteoinductivity.

PURPOSE

To fabricate a biomimetic bone graft with an interconnected porous structure analogous to that of trabecular bone and a bioactive nanostructured surface with excellent osteoinductive potential.

MATERIALS AND METHODS

A biphasic CaP (BCP) substrate with highly porous structure was fabricated by an improved sponge replication method. Surface modification was performed by uniformly depositing a hydroxyapatite (HA) nanoparticle layer to create nHA-coated BCP scaffolds. The effects of these scaffolds on osteogenic differentiation of murine bone marrow-derived stem cells (BMSCs) were investigated in vitro, and their osteoinductivity was further assessed in vivo.

RESULTS

The BCP and nHA-coated BCP scaffolds had similar trabecular bone-like architectures but different surface structures, with mean grain sizes of ~55 nm and ~1 μm, respectively. Compared with the BCP substrate, the nHA-coated BCP scaffolds favored cell adhesion and promoted osteogenic differentiation of BMSCs, as evidenced by upregulated expression of osteogenic genes, enhanced alkaline phosphatase activity, and increased osteocalcin production. This could be attributed to activation of the BMP/Smad signaling pathway, as significantly higher expression levels of BMPRI, Smad1, Smad4, and Smad5 were observed in the nHA-coated BCP group. The nHA-coated BCP scaffold not only maintained scaffold integrity but also induced ectopic bone formation when implanted into rabbit dorsal muscle in vivo for 90 days, whereas the BCP substrate underwent marked biodegradation that led to severe inflammation with no sign of osteogenesis.

CONCLUSION

The present study demonstrates the potential of this biomimetic bone graft with a trabecular framework and nanotopography for use in orthopedic applications.

Pooling of Patient-Derived Mesenchymal Stromal Cells Reduces Inter-Individual Confounder-Associated Variation without Negative Impact on Cell Viability, Proliferation and Osteogenic Differentiation

Patient-derived mesenchymal stromal cells (MSCs) play a key role in bone tissue engineering. Various donor-specific factors were identified causing significant variability in the biological properties of MSCs impairing quality of data and inter-study comparability. These limitations might be overcome by pooling cells of different donors. However, the effects of pooling on osteogenic differentiation, proliferation and vitality remain unknown and have, therefore, been evaluated in this study. MSCs of 10 donors were cultivated and differentiated into osteogenic lineage individually and in a pooled setting, containing MSCs of each donor in equal parts. Proliferation was evaluated in expansion (assessment of generation time) and differentiation (quantification of dsDNA content) conditions. Vitality was visualized by a fluorescence-microscopy-based live/dead assay. Osteogenic differentiation was assessed by quantification of alkaline phosphatase (ALP) activity and extracellular calcium deposition. Compared to the individual setting, generation time of pooled MSCs was shorter and proliferation was increased during differentiation with significantly lower variances. Calcium deposition was comparable, while variances were significantly higher in the individual setting. ALP activity showed high variance in both groups, but increased comparably during the incubation period. In conclusion, MSC pooling helps to compensate donor-dependent variability and does not negatively influence MSC vitality, proliferation and osteogenic differentiation.

Let's cross-link: diverse functions of the promiscuous cellular transglutaminase factor XIII-A

Essentials Plasma Factor XIII, a heterodimer of A and B subunits FXIIIA2 B2 , is a transglutaminase enzyme with a well-established role in haemostasis. Cells of bone marrow and mesenchymal lineage express the FXIII-A gene (F13A1) that encodes the cellular form of the transglutaminase, a homodimer of the A subunits, FXIII-A. FXIII-A was presumed to function intracellularly, however, several lines of evidence now indicate that FXIII-A is externalised by an as yet unknown mechanism This review describes the mounting evidence that FXIII-A is a diverse transglutaminase with many intracellular and extracellular substrates that can participate in an array of biological processes SUMMARY: Factor XIII is a tranglutaminase enzyme that catalyzes the formation of ε-(γ-glutamyl)lysyl isopeptide bonds in protein substrates. The plasma form, FXIII-A2 B2 , has an established function in hemostasis, where its primary substrate is fibrin. A deficiency in FXIII manifests as a severe bleeding diathesis, underscoring its importance in this pathway. The cellular form of the enzyme, a homodimer of the A-subunits, denoted FXIII-A, has not been studied in as extensive detail. FXIII-A was generally perceived to remain intracellular, owing to the lack of a classical signal peptide for its release. In the last decade, emerging evidence has revealed that this diverse transglutaminase can be externalized from cells, by an as yet unknown mechanism, and can cross-link extracellular substrates and participate in a number of diverse pathways. The FXIII-A gene (F13A1) is expressed in cells of bone marrow and mesenchymal lineage, notably megakaryocytes, monocytes/macrophages, dendritic cells, chrondrocytes, osteoblasts, and preadipocytes. The biological processes that FXIII-A is coupled with, such as wound healing, phagocytosis, and bone and matrix remodeling, reflect its expression in these cell types. This review describes the mounting evidence that this cellular transglutaminase can be externalized, usually in response to stimuli, and participate in extracellular cross-linking reactions. A corollary of being involved in these biological pathways is the participation of FXIII-A in pathological processes. In conclusion, the functions of this transglutaminase extend far beyond its role in hemostasis, and our understanding of this enzyme in terms of its secretion, regulation and substrates is in its infancy.

Study of the osteogenesis effect of icariside II and icaritin on canine bone marrow mesenchymal stem cells

This study aimed to identify the osteogenesis effect of icariside II (ICSII) and icaritin (ICT) in vitro. Bone marrow mesenchymal stem cells (BMSCs) were treated with ICSII and ICT in order to detect the proliferation and differentiation of BMSCs, the expression of the osteogenesis-related proteins with or without osteogenic medium (OM) and genes, Runt-related transcription factor 2 (Runx-2), osteocalcin (OCN), osteopontin (OPN), osterix, and basic fibroblast growth factor (bFGF), and the phosphorylation levels of mitogen-activated protein kinase (MAPK). We found that the optical density increased and alkaline phosphatase decreased after the BMSCs were treated with different concentrations of ICSII; however, ICT showed an opposing effect. The formation of calcium nodules was observed after the BMSCs were treated with ICSII and ICT. The expression level of osteogenesis-related proteins was enhanced following treatment with both ICSII or ICT, while the expression level of the osteogenesis-related genes Runx-2, OCN, OPN, osterix, and bFGF significantly increased with ICSII treatment (P < 0.05), and only Runx-2 and bFGF significantly increased (P < 0.01) with ICT. The expression of osteogenic differentiation-related proteins (except OPN) following treatment with ICSII + OM or ICT + OM was not notably increased. Both ICSII and ICT elevated the phosphorylation levels of MAPK/ERK, which was attenuated by GDC-0994 (an inhibitor of MAPK/ERK). Collectively, these data indicate that ICSII and ICT facilitate orientation osteogenic differentiation of BMSCs, which is most likely via the MAPK/ERK pathway. OM did not synergistically enhance the osteogenesis effect of ICSII and ICT.

Exosomes Derived from miR-214-Enriched Bone Marrow-Derived Mesenchymal Stem Cells Regulate Oxidative Damage in Cardiac Stem Cells by Targeting CaMKII

Cardiac stem cells (CSCs) have emerged as one of the most promising stem cells for cardiac protection. Recently, exosomes from bone marrow-derived mesenchymal stem cells (BMSCs) have been found to facilitate cell proliferation and survival by transporting various bioactive molecules, including microRNAs (miRs). In this study, we found that BMSC-derived exosomes (BMSC-exos) significantly decreased apoptosis rates and reactive oxygen species (ROS) production in CSCs after oxidative stress injury. Moreover, a stronger effect was induced by exosomes collected from BMSCs cultured under hypoxic conditions (Hypoxic-exos) than those collected from BMSCs cultured under normal conditions (Nor-exos). We also observed greater miR-214 enrichment in Hypoxic-exos than in Nor-exos. In addition, a miR-214 inhibitor or mimics added to modulate miR-214 levels in BMSC-exos revealed that exosomes from miR-214-depleted BMSCs partially reversed the effects of hypoxia-induced exosomes on oxidative damage in CSCs. These data further confirmed that miR-214 is the main effector molecule in BMSC-exos that protects CSCs from oxidative damage. miR-214 mimic and inhibitor transfection assays verified that CaMKII is a target gene of miR-214 in CSCs, with exosome-pretreated CSCs exhibiting increased miR-214 levels but decreased CaMKII levels. Therefore, the miR-214/CaMKII axis regulates oxidative stress-related injury in CSCs, such as apoptosis, calcium homeostasis disequilibrium, and excessive ROS accumulation. Collectively, these findings suggest that BMSCs release miR-214-containing exosomes to suppress oxidative stress injury in CSCs through CaMKII silencing.

Mechanochemical Effects on Extracellular Signal-Regulated Kinase Dynamics in Stem Cell Differentiation

Understanding how key signaling molecules are coregulated by biochemical agents and physical stimuli during stem cell differentiation is critical but often lacking. Due to the important role of extracellular signal-regulated kinase (ERK), this study has examined its temporal dynamics to determine the coregulation of mechanochemical cues on ERK phosphorylation for smooth muscle cell (SMC) differentiation. To assess ERK1/2 activity, a fluorescence resonance energy transfer-based biosensor was transfected into mesenchymal stem cells. The influences of nanopatterned substrates, growth factors, and drugs on ERK activities were related to their effects on SMC differentiation. Results revealed that nanopatterned substrates significantly increased ERK activity in cells, overriding ERK response from administered biochemical factors. The nanopatterned substrates reduced expression of SMC markers after a 48-h biochemical treatment, except for the combination with ERK inhibitor PD98059 treatment, which enhanced expression of mature SMC marker MYH11. Immunofluorescent staining for focal adhesion proteins, vinculin and zyxin, indicated no significant differences in vinculin cluster distribution or dimension, while the location of zyxin changed from adhesion sites of cell periphery on nonpatterned substrate to actin filaments on nanopatterned substrate. The zyxin-reinforced stress fibers likely enhanced the cytoskeletal tension to increase ERK dynamics. Collectively, results suggest that physical stimuli play a dominating role in initial ERK signaling and early-stage differentiation through focal adhesion changes, and the capability of monitoring signaling events in real time could be exploited to guide the engineering of cell microenvironment.

Distinct human α(1,3)-fucosyltransferases drive Lewis-X/sialyl Lewis-X assembly in human cells

In humans, six α(1,3)-fucosyltransferases (α(1,3)-FTs: FT3/FT4/FT5/FT6/FT7/FT9) reportedly fucosylate terminal lactosaminyl glycans yielding Lewis-X (LeX; CD15) and/or sialyl Lewis-X (sLeX; CD15s), structures that play key functions in cell migration, development, and immunity. Prior studies analyzing α(1,3)-FT specificities utilized either purified and/or recombinant enzymes to modify synthetic substrates under nonphysiological reaction conditions or molecular biology approaches wherein α(1,3)-FTs were expressed in mammalian cell lines, notably excluding investigations using primary human cells. Accordingly, although significant insights into α(1,3)-FT catalytic properties have been obtained, uncertainty persists regarding their human LeX/sLeX biosynthetic range across various glycoconjugates. Here, we undertook a comprehensive evaluation of the lactosaminyl product specificities of intracellularly expressed α(1,3)-FTs using a clinically relevant primary human cell type, mesenchymal stem cells. Cells were transfected with modified mRNA encoding each human α(1,3)-FT, and the resultant α(1,3)-fucosylated lactosaminyl glycoconjugates were analyzed using a combination of flow cytometry and MS. The data show that biosynthesis of sLeX is driven by FTs-3, -5, -6, and -7, with FT6 and FT7 having highest potency. FT4 and FT9 dominantly biosynthesize LeX, and, among all FTs, FT6 holds a unique capacity in creating sLeX and LeX determinants across protein and lipid glycoconjugates. Surprisingly, FT4 does not generate sLeX on glycolipids, and neither FT4, FT6, nor FT9 synthesizes the internally fucosylated sialyllactosamine VIM-2 (CD65s). These results unveil the relevant human lactosaminyl glycans created by human α(1,3)-FTs, providing novel insights on how these isoenzymes stereoselectively shape biosynthesis of vital glycoconjugates, thereby biochemically programming human cell migration and tuning human immunologic and developmental processes.

The effects of conditioned media generated by polarized macrophages on the cellular behaviours of bone marrow mesenchymal stem cells

Macrophages (Mφs) are involved in a variety of physiological and pathological events including wound healing and tissue regeneration, in which they play both positive and negative roles depending on their polarization state. In this study, we investigated the cellular behaviours of bone marrow mesenchymal stem cells (BMMSCs) after incubation in different conditioned media (CMs) generated by unpolarized Mφs (M0) or polarized Mφs (M1 and M2). Mφ polarization was induced by stimulation with various cytokines, and CMs were obtained from in vitro Mφ cultures termed CM0, CM1 and CM2 based on each Mφ phenotype. We found that CM1 supported the proliferation and adipogenic differentiation of BMMSCs, whereas CM0 had a remarkable effect on cell osteogenic differentiation. To a certain degree, CM2 also facilitated BMMSC osteogenesis; in particular, cells incubated with CM2 exhibited an enhanced capacity to form robust stem cell sheets. Although incubation with CM1 also increased production of extracellular matrix components, such as fibronectin, COL-1 and integrin β1during sheet induction, the sheets generated by CM2-incubated cells were thicker than those generated by CM1-incubated cells (P < 0.001). Our data suggest that each Mφ phenotype has a unique effect on BMMSCs. Fine-tuning Mφ polarization following transplantation may serve as an effective method to modulate the therapeutic potential of BMMSCs.

A role for endothelial nitric oxide synthase in intestinal stem cell proliferation and mesenchymal colorectal cancer

BACKGROUND

Nitric oxide (NO) has been highlighted as an important agent in cancer-related events. Although the inducible nitric oxide synthase (iNOS) isoform has received most attention, recent studies in the literature indicate that the endothelial isoenzyme (eNOS) can also modulate different tumor processes including resistance, angiogenesis, invasion, and metastasis. However, the role of eNOS in cancer stem cell (CSC) biology and mesenchymal tumors is unknown.

RESULTS

Here, we show that eNOS was significantly upregulated in VilCre ERT2 Apc fl/+ and VilCre ERT2 Apc fl/fl mouse intestinal tissue, with intense immunostaining in hyperproliferative crypts. Similarly, the more invasive VilCre ERT2 Apc fl/+ Pten fl/+ mouse model showed an overexpression of eNOS in intestinal tumors whereas this isoform was not expressed in normal tissue. However, none of the three models showed iNOS expression. Notably, when 40 human colorectal tumors were classified into different clinically relevant molecular subtypes, high eNOS expression was found in the poor relapse-free and overall survival mesenchymal subtype, whereas iNOS was absent. Furthermore, Apc fl/fl organoids overexpressed eNOS compared with wild-type organoids and NO depletion with the scavenger carboxy-PTIO (c-PTIO) decreased the proliferation and the expression of stem-cell markers, such as Lgr5, Troy, Vav3, and Slc14a1, in these intestinal organoids. Moreover, specific NO depletion also decreased the expression of CSC-related proteins in human colorectal cancer cells such as β-catenin and Bmi1, impairing the CSC phenotype. To rule out the contribution of iNOS in this effect, we established an iNOS-knockdown colorectal cancer cell line. NO-depleted cells showed a decreased capacity to form tumors and c-PTIO treatment in vivo showed an antitumoral effect in a xenograft mouse model.

CONCLUSION

Our data support that eNOS upregulation occurs after Apc loss, emerging as an unexpected potential new target in poor-prognosis mesenchymal colorectal tumors, where NO scavenging could represent an interesting therapeutic alternative to targeting the CSC subpopulation.

Enhanced Immunosuppressive Properties of Human Mesenchymal Stem Cells Primed by Interferon-γ

Mesenchymal stem cells (MSCs) are of particular interest for the treatment of immune-related diseases owing to their immunosuppressive properties. In this study, we aimed to identify the effect of interferon (IFN)-γ priming on immunomodulation by MSCs and elucidate the possible mechanism underlying their properties for the clinical treatment of allogeneic conflicts. Infusion of MSCs primed with IFN-γ significantly reduced the symptoms of graft-versus-host disease (GVHD) in NOD-SCID mice, thereby increasing survival rate when compared with naïve MSC-infused mice. However, infusion of IFN-γ-primed MSCs in which indoleamine 2,3-dioxygenase (IDO) was downregulated did not elicit this effect. The IDO gene was expressed in MSCs via the IFN-γ-Janus kinase (JAK)-signal transducer and activator of transcription 1 (STAT1) pathway, and the infusion of IDO-over-expressing MSCs increased survival rate in an in vivo GVHD model, similar to infusion of IFN-γ-primed MSCs. These data indicate that IFN-γ production by activated T-cells is correlated with the induction of IDO expression in MSCs via the IFN-γ-JAK-STAT1 pathway, which in turn results in the suppression of T-cell proliferation. Our findings also suggest that cell therapy based on MSCs primed with IFN-γ can be used for the clinical treatment of allogeneic conflicts, including GVHD.

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IFN-γ priming enhances the immunosuppressive properties of human MSCs in in vitro and in vivo models.

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IFN-γ priming induces IDO expression in MSCs via the JAK/STAT1 signaling pathway, but TLR3 activation does not.

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Cell therapy using MSCs primed with IFN-γ could be highly effective in treating allogeneic diseases, including GVHD.

It is necessary to improve the function of mesenchymal stem cells (MSCs) to maximize their treatment potential beyond what is currently achieved in cell therapy studies using naïve heterogeneous MSCs. The preclinical study of a candidate cell therapy based on MSCs primed with interferon-γ as reported in this study, could lay the foundation for the use of cell therapy for the treatment of graft-versus-host disease (GVHD), and is very important for the initiation of clinical trials. Our findings also suggest that cell therapy based on functionally improved MSCs could be used for the clinical treatment of allogeneic conflicts.

Role of the protease corin in chondrogenic differentiation of human bone marrow-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) have the potency to differentiate into chondrocytes, osteocytes and adipocytes. Corin is a cardiac protease that activates the natriuretic peptides, thereby regulating blood volume and pressure. In addition to the heart, corin gene upregulation was reported in bone marrow- and adipose tissue-derived MSCs that underwent osteogenic differentiation. To date, the biological significance of corin expression in MSC differentiation remains unknown. In this study we isolated and cultured human bone marrow-derived MSCs that were capable of undergoing chondrogenic, osteogenic and adipogenic lineage differentiation. By reverse transcription polymerase chain reaction (RT-PCR) and immunostaining, we found that corin expression was upregulated when these MSCs underwent chondrogenic, osteogenic and adipogenic differentiation. The upregulation of corin expression was most significant in the cells undergoing chondrogenic lineage differentiation. Silencing corin gene expression by small hairpin RNA in the MSCs inhibited chondrogenic, but not osteogenic and adipogenic, differentiation. These results suggest a novel function of corin in MSC differentiation and chondrocyte development.

Human Mesenchymal Stem Cells Growth and Osteogenic Differentiation on Piezoelectric Poly(vinylidene fluoride) Microsphere Substrates

The aim of this work was to determine the influence of the biomaterial environment on human mesenchymal stem cell (hMSC) fate when cultured in supports with varying topography. Poly(vinylidene fluoride) (PVDF) culture supports were prepared with structures ranging between 2D and 3D, based on PVDF films on which PVDF microspheres were deposited with varying surface density. Maintenance of multipotentiality when cultured in expansion medium was studied by flow cytometry monitoring the expression of characteristic hMSCs markers, and revealed that cells were losing their characteristic surface markers on these supports. Cell morphology was assessed by scanning electron microscopy (SEM). Alkaline phosphatase activity was also assessed after seven days of culture on expansion medium. On the other hand, osteoblastic differentiation was monitored while culturing in osteogenic medium after cells reached confluence. Osteocalcin immunocytochemistry and alizarin red assays were performed. We show that flow cytometry is a suitable technique for the study of the differentiation of hMSC seeded onto biomaterials, giving a quantitative reliable analysis of hMSC-associated markers. We also show that electrosprayed piezoelectric poly(vinylidene fluoride) is a suitable support for tissue engineering purposes, as hMSCs can proliferate, be viable and undergo osteogenic differentiation when chemically stimulated.

Down-regulation of Noggin and miR-138 coordinately promote osteogenesis of mesenchymal stem cells

Mesenchymal stem cells (MSCs) can differentiate to osteocytes under suitable conditions. In recent years, micro-nucleotides have been progressively used to modulate gene expression in cells due to the consideration of safety. Our present study aimed to investigate whether co-delivery of Noggin-siRNA and antimiR-138 enhances the osteogenic effect of MSCs. Using a murine MSC line, C3H/10T1/2 cells, the delivery efficiency of Noggin-siRNA and antimiR-138 into MSCs was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). Cell phenotype and proliferation capacity was assessed by flow cytometry and MTT assay respectively. The osteogenesis of MSCs was tested by Alkaline Phosphatase (ALP) staining, qRT-PCR, and western blot analyses. Our results demonstrated that the expression of Noggin and miR-138 were significantly silenced in MSCs by Noggin-siRNA and/or antimiR-138 delivery, while the phenotype and proliferation capacity of MSCs were not affected. Down-regulation of Noggin and miR-138 cooperatively promoted osteogenic differentiation of MSCs. The ALP positive cells reached about 83.57 ± 10.18%. Compared with single delivery, the expression of osteogenic related genes, such as Alp, Col-1, Bmp2, Ocn and Runx2, were the highest in cells with co-delivery of the two oligonucleotides. Moreover, the protein level of RUNX2, and the ratios of pSMAD1/5/SMAD1/5 and pERK1/2/ERK1/2 were significantly increased. The activation of Smad, Erk signaling may constitute the underlying mechanism of the enhanced osteogenesis process. Taken together, our study provides a safe strategy for the clinical rehabilitation application of MSCs in skeletal deficiency.

Effect of CXCR3/HO-1 genes modified bone marrow mesenchymal stem cells on small bowel transplant rejection

AIM

To investigate whether bone marrow mesenchymal stem cells (BMMSCs) modified with the HO-1 and CXCR3 genes can augment the inhibitory effect of BMMSCs on small bowel transplant rejection.

METHODS

Lewis rat BMMSCs were cultured in vitro. Third-passage BMMSCs were transduced with the CXCR3/HO-1 genes or the HO-1 gene alone. The rats were divided into six groups and rats in the experimental group were pretreated with BMMSCs 7 d prior to small bowel transplant. Six time points (instant, 1 d, 3 d, 7 d, 10 d, and 14 d) (n = 6) were chosen for each group. Hematoxylin-eosin staining was used to observe pathologic rejection, while immunohistochemistry and Western blot were used to detect protein expression. Flow cytometry was used to detect T lymphocytes and enzyme linked immunosorbent assay was used to detect cytokines.

RESULTS

The median survival time of BMMSCs from the CXCR3/HO-1 modified group (53 d) was significantly longer than that of the HO-1 modified BMMSCs group (39 d), the BMMSCs group (26 d), and the NS group (control group) (16 d) (P < 0.05). Compared with BMMSCs from the HO-1 modified BMMSCs, BMMSCs, and NS groups, rejection of the small bowel in the CXCR3/HO-1 modified group was significantly reduced, while the weight of transplant recipients was also significantly decreased (P < 0.05). Furthermore, IL-2, IL-6, IL-17, IFN-γ, and TNF-α levels were significantly decreased and the levels of IL-10 and TGF-β were significantly increased (P < 0.05).

CONCLUSION

BMMSCs modified with the CXCR3 and HO-1 genes can abrogate the rejection of transplanted small bowel more effectively and significantly increase the survival time of rats that receive a small bowel transplant.

Macrophage type modulates osteogenic differentiation of adipose tissue MSCs

Since the reconstruction of large bone defects remains a challenge, knowledge about the biology of bone healing is desirable to develop novel strategies for improving the treatment of bone defects. In osteoimmunology, macrophages are the central component in the early stage of physiological response after bone injury and bone remodeling in the late stage. During this process, a switch of macrophage phenotype from pro-inflammatory (M1) to anti-inflammatory (M2) is observed. An appealing option for bone regeneration would be to exploit this regulatory role for the benefit of osteogenic differentiation of osteoprogenitor cells (e.g., mesenchymal stem cells; MSCs) and to eventually utilize this knowledge to improve the therapeutic outcome of bone regenerative treatment. In view of this, we focused on the in vitro interaction of different macrophage subtypes with adipose tissue MSCs to monitor the behavior (i.e. proliferation, differentiation and mineralization) of the latter in dedicated co-culture models. Our data show that co-culture of MSCs with M2 macrophages, but not with M1 macrophages or M0 macrophages, results in significantly increased MSC mineralization caused by soluble factors. Specifically, M2 macrophages promoted the proliferation and osteogenic differentiation of MSCs, while M0 and M1 macrophages solely stimulated the osteogenic differentiation of MSCs in the early and middle stages during co-culture. Secretion of the soluble factors oncostatin M (OSM) and bone morphogenetic protein 2 (BMP-2) by macrophages showed correlation with MSC gene expression levels for OSM-receptor and BMP-2, suggesting the involvement of both signaling pathways in the osteogenic differentiation of MSCs.

miR-214 suppresses the osteogenic differentiation of bone marrow-derived mesenchymal stem cells and these effects are mediated through the inhibition of the JNK and p38 pathways

In this study, we sought to investigate the expression of microRNA (miR)-214 on the osteogenic differentiation of bone marrow‑derived mesenchymal stem cells (BMSCs) and explore the possible underlying mechanisms. We found that the overexpression of miR‑214 effectively promoted the adipocyte differentiation of BMSCs in vitro, reduced alkaline phosphatase (ALP) activity and the gene expression of collagen type I (Col I), osteocalcin (OCN) and osteopontin (OPN) in the BMSCs. We further found that the overexpression of miR‑214 suppressed the protein expression of fibroblast growth factor (FGF), phosphorylated c‑Jun N-terminal kinase (p-JNK) and phosphorylated p38 (p-p38) in the BMSCs. The downregulation of miR‑214 promoted the osteogenic differentiation of BMSCs, and increased ALP activity and Col I, OCN and OPN gene expression in the BMSCs. It also increased FGF p-JNK and p-p38 protein expression in the BMSCs. The use of JNK inhibitor (SP600125) enhanced the inhibitory effects of miR‑214 overexpression on osteogenic differentiation, ALP activity, and Col I, OCN and OPN gene expression in the BMSCs. Lastly, the use of p38 inhibitor (SB202190) also enhanced the inhibitory effects of miR‑214 overexpression on ALP activity, and Col I, OCN and OPN gene expression in the BMSCs. These results provide a mechanism responsible for the suppressive effects of miR‑214 on the osteogenic differentiation of BMSCs involving the inhibition of the JNK and p38 pathways.

The In Vitro and In Vivo Response to MMP-Sensitive Poly(Ethylene Glycol) Hydrogels

Enzyme-sensitive hydrogels are a promising class of materials for cell encapsulation and tissue engineering because their ability to be degraded by cell-secreted factors. However, it is well known that nearly all synthetic biomaterials elicit a foreign body response (FBR) upon implantation. Therefore, this study aimed to evaluate the in vitro and in vivo response to an enzyme-sensitive hydrogel. Hydrogels were formed from poly(ethylene glycol) with the peptide crosslinker, C-VPLS↓LYSG-C, which is susceptible to matrix metalloproteinases 2 and 9. We evaluated the hydrogel by exogenously delivered enzymes, encapsulated mesenchymal stem cells as a tissue engineering relevant cell type, and by macrophage-secreted factors in vitro and for the FBR through macrophage attachment in vitro and in a subcutaneous mouse model. These hydrogels rapidly degraded upon exposure to exogenous MMP-2 and to lesser degree with MMP-9. Encapsulated mesenchymal stem cells were capable of degrading the hydrogels via matrix metalloproteinases. Inflammatory macrophages were confirmed to attach to the hydrogels, but were not capable of rapidly degrading the hydrogels. In vivo, these hydrogels remained intact after 4 weeks and exhibited a classic FBR with inflammatory cells at the hydrogel surface and a fibrous capsule. In summary, these findings suggest that while this MMP-2/9 sensitive hydrogel is readily degraded in vitro, it does not undergo rapid degradation by the FBR. Thus, the long term stability of these hydrogels in vivo coupled with the ability for encapsulated cells to degrade the hydrogel makes them promising materials for tissue engineering.

High glucose microenvironments inhibit the proliferation and migration of bone mesenchymal stem cells by activating GSK3β

Diabetes mellitus involves metabolic changes that can impair bone repair. Bone mesenchymal stem cells (BMSCs) play an important role in bone regeneration. However, the bone regeneration ability of BMSCs is inhibited in high glucose microenvironments. It can be speculated that this effect is due to changes in BMSCs' proliferation and migration ability, because the recruitment of factors with an adequate number of MSCs and the microenvironment around the site of bone injury are required for effective bone repair. Recent genetic evidence has shown that the Cyclin D1 and the CXC receptor 4 (CXCR-4) play important roles in the proliferation and migration of BMSCs. In this study we determined the specific role of glycogen synthase kinase-3β (GSK3β) in the proliferation and migration of BMSCs in high glucose microenvironments. The proliferation and migration ability of BMSCs were suppressed under high glucose conditions. We showed that high glucose activates GSK3β but suppresses CXCR-4, β-catenin, LEF-1, and cyclin D1. Inhibition of GSK3β by LiCl led to increased levels of β-catenin, LEF-1, cyclin D1, and CXCR-4 expression. Our data indicate that GSK3β plays an important role in regulating the proliferation and migration of BMSCs by inhibiting cyclin D1 and CXCR-4 under high glucose conditions.

Melatonin reverses flow shear stress-induced injury in bone marrow mesenchymal stem cells via activation of AMP-activated protein kinase signaling

Tissue-engineered heart valves (TEHVs) are a promising treatment for valvular heart disease, although their application is limited by high flow shear stress (FSS). Melatonin has a wide range of physiological functions and is currently under clinical investigation for expanded applications; moreover, extensive protective effects on the cardiovascular system have been reported. In this study, we investigated the protection conferred by melatonin supplementation against FSS-induced injury in bone marrow mesenchymal stem cells (BMSCs) and elucidated the potential mechanism in this process. Melatonin markedly reduced BMSC apoptotic death in a concentration-dependent manner while increasing the levels of transforming growth factor β (TGF-β), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) and B-cell lymphoma 2 (Bcl2), and decreasing those of Bcl-2-associated X protein (Bax), p53 upregulated modulator of apoptosis (PUMA), and caspase 3. Notably, melatonin exerted its protective effects by upregulating the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK), which promotes acetyl-CoA carboxylase (ACC) phosphorylation. Further molecular experiments revealed that luzindole, a nonselective antagonist of melatonin receptors, blocked the anti-FSS injury (anti-FSSI) effects of melatonin. Inhibition of AMPK by Compound C also counteracted the protective effects of melatonin, suggesting that melatonin reverses FSSI in BMSCs through the AMPK-dependent pathway. Overall, our findings indicate that melatonin contributes to the amelioration of FSS-induced BMSC injury by activating melatonin receptors and AMPK/ACC signaling. Our findings may provide a basis for the design of more effective strategies that promote the use of TEHCs in patients.

The effects of α-zearalanol on the proliferation of bone-marrow-derived mesenchymal stem cells and their differentiation into osteoblasts

The aim of this study was to explore the effects of α-zearalanol (α-ZAL) on the proliferation of mouse bone-marrow-derived mesenchymal stem cells (BMSCs) and their differentiation into osteoblasts. Six- to eight-week-old BALB/C mice were used either as recipients or as bone marrow donors. BMSCs were isolated and collected using a differential adhesion method, with use of 10 % fetal bovine serum and Iscove's modified Dulbecco's medium. After the third generation, the BMSCs were randomly placed into the following subgroups: a control group, an osteogenic medium (OM) group, a 17β-estradiol group, an α-ZAL 10(-7) mol/L group, an α-ZAL 10(-6) mol/L group, and an α-ZAL 10(-5) mol/L group. Flow cytometry was used to identify the BMSCs collected from the bone marrow. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test was performed, and markers of the osteoblasts were measured in the different subgroups. In addition, expression of osteoprotegerin and expression of receptor activator of nuclear factor κB ligand were examined using Western blot. In contrast to the control and OM groups, BMSCs in the α-ZAL groups exhibited long fusiform shapes, and contact inhibition was observed when the cells were closely packed. After induction, the BMSCs grew well and exhibited triangular, star, polygonal, or irregular shapes. Clumps and multiple cells were evident. The trends of the proliferation and differentiation for the control, OM, 17β-estradiol, and α-ZAL groups were similar. Compared with the control and OM groups, in the α-ZAL groups the expression levels of alkaline phosphatase, procollagen type I N-terminal propeptide, bone morphogenetic protein 2, and osteocalcin were significantly increased (p < 0.05). In addition, α-ZAL inhibited osteoclastogenesis by increasing the expression of osteoprotegerin and decreasing the expression of nuclear factor κB ligand. In conclusion, α-ZAL can increase the proliferation of BMSCs and their differentiation into osteoblasts and can effectively suppress osteoclastogenesis.

Apelin: an endogenous peptide essential for cardiomyogenic differentiation of mesenchymal stem cells via activating extracellular signal-regulated kinase 1/2 and 5

Growing evidence has shown that apelin/APJ system functions as a critical mediator of cardiac development as well as cardiovascular function. Here, we investigated the role of apelin in the cardiomyogenic differentiation of mesenchymal stem cells derived from Wharton's jelly of human umbilical cord in vitro. In this research, we used RNA interference methodology and gene transfection technique to regulate the expression of apelin in Wharton's jelly-derived mesenchymal stem cells and induced cells with a effective cardiac differentiation protocol including 5-azacytidine and bFGF. Four weeks after induction, induced cells assumed a stick-like morphology and myotube-like structures except apelin-silenced cells and the control group. The silencing expression of apelin in Wharton's jelly-derived mesenchymal stem cells decreased the expression of several critical cardiac progenitor transcription factors (Mesp1, Mef2c, NKX2.5) and cardiac phenotypes (cardiac α-actin, β-MHC, cTnT, and connexin-43). Meanwhile, endogenous compensation of apelin contributed to differentiating into cells with characteristics of cardiomyocytes in vitro. Further experiment showed that exogenous apelin peptide rescued the cardiomyogenic differentiation of apelin-silenced mesenchymal stem cells in the early stage (1-4 days) of induction. Remarkably, our experiment indicated that apelin up-regulated cardiac specific genes in Wharton's jelly-derived mesenchymal stem cells via activating extracellular signal-regulated kinase (ERK) 1/2 and 5.

Deregulation of arginase induces bone complications in high-fat/high-sucrose diet diabetic mouse model

A balanced diet is crucial for healthy development and prevention of musculoskeletal related diseases. Diets high in fat content are known to cause obesity, diabetes and a number of other disease states. Our group and others have previously reported that activity of the urea cycle enzyme arginase is involved in diabetes-induced dysregulation of vascular function due to decreases in nitric oxide formation. We hypothesized that diabetes may also elevate arginase activity in bone and bone marrow, which could lead to bone-related complications. To test this we determined the effects of diabetes on expression and activity of arginase, in bone and bone marrow stromal cells (BMSCs). We demonstrated that arginase 1 is abundantly present in the bone and BMSCs. We also demonstrated that arginase activity and expression in bone and bone marrow is up-regulated in models of diabetes induced by HFHS diet and streptozotocin (STZ). HFHS diet down-regulated expression of healthy bone metabolism markers (BMP2, COL-1, ALP, and RUNX2) and reduced bone mineral density, bone volume and trabecular thickness. However, treatment with an arginase inhibitor (ABH) prevented these bone-related complications of diabetes. In-vitro study of BMSCs showed that high glucose treatment increased arginase activity and decreased nitric oxide production. These effects were reversed by treatment with an arginase inhibitor (ABH). Our study provides evidence that deregulation of l-arginine metabolism plays a vital role in HFHS diet-induced diabetic complications and that these complications can be prevented by treatment with arginase inhibitors. The modulation of l-arginine metabolism in disease could offer a novel therapeutic approach for osteoporosis and other musculoskeletal related diseases.

Human urokinase-type plasminogen activator gene-modified bone marrow-derived mesenchymal stem cells attenuate liver fibrosis in rats by down-regulating the Wnt signaling pathway

AIM: To evaluate the therapeutic effects of bone marrow-derived mesenchymal stem cells (BMSCs) with human urokinase-type plasminogen activator (uPA) on liver fibrosis, and to investigate the mechanism of gene therapy.

METHODS: BMSCs transfected with adenovirus-mediated human urokinase plasminogen activator (Ad-uPA) were transplanted into rats with CCl₄-induced liver fibrosis. All rats were sacrificed after 8 wk, and their serum and liver tissue were collected for biochemical, histopathologic, and molecular analyzes. The degree of liver fibrosis was assessed by hematoxylin and eosin or Masson’s staining. Western blot and quantitative reverse transcription-polymerase chain reaction were used to determine protein and mRNA expression levels.

RESULTS: Serum levels of alanine aminotransferase, aminotransferase, total bilirubin, hyaluronic acid, laminin, and procollagen type III were markedly decreased, whereas the levels of serum albumin were increased by uPA gene modified BMSCs treatment. Histopathology revealed that chronic CCl4-treatment resulted in significant fibrosis while uPA gene modified BMSCs treatment significantly reversed fibrosis. By quantitatively analysing the fibrosis area of liver tissue using Masson staining in different groups of animals, we found that model animals with CCl₄-induced liver fibrosis had the largest fibrotic area (16.69% ± 1.30%), while fibrotic area was significantly decreased by BMSCs treatment (12.38% ± 2.27%) and was further reduced by uPA-BMSCs treatment (8.31% ± 1.21%). Both protein and mRNA expression of β-catenin, Wnt4 and Wnt5a was down-regulated in liver tissues following uPA gene modified BMSCs treatment when compared with the model animals.

CONCLUSION: Transplantation of uPA gene modified BMSCs suppressed liver fibrosis and ameliorated liver function and may be a new approach to treating liver fibrosis. Furthermore, treatment with uPA gene modified BMSCs also resulted in a decrease in expression of molecules of the Wnt signaling pathway.

Serine/Threonine Kinase MLK4 Determines Mesenchymal Identity in Glioma Stem Cells in an NF-κB-dependent Manner

Activation of nuclear factor κB (NF-κB) induces mesenchymal (MES) transdifferentiation and radioresistance in glioma stem cells (GSCs), but molecular mechanisms for NF-κB activation in GSCs are currently unknown. Here, we report that mixed lineage kinase 4 (MLK4) is overexpressed in MES but not proneural (PN) GSCs. Silencing MLK4 suppresses self-renewal, motility, tumorigenesis, and radioresistance of MES GSCs via a loss of the MES signature. MLK4 binds and phosphorylates the NF-κB regulator IKKα, leading to activation of NF-κB signaling in GSCs. MLK4 expression is inversely correlated with patient prognosis in MES, but not PN high-grade gliomas. Collectively, our results uncover MLK4 as an upstream regulator of NF-κB signaling and a potential molecular target for the MES subtype of glioblastomas.

Extracellular Protease Inhibition Alters the Phenotype of Chondrogenically Differentiating Human Mesenchymal Stem Cells (MSCs) in 3D Collagen Microspheres

Matrix remodeling of cells is highly regulated by proteases and their inhibitors. Nevertheless, how would the chondrogenesis of mesenchymal stem cells (MSCs) be affected, when the balance of the matrix remodeling is disturbed by inhibiting matrix proteases, is incompletely known. Using a previously developed collagen microencapsulation platform, we investigated whether exposing chondrogenically differentiating MSCs to intracellular and extracellular protease inhibitors will affect the extracellular matrix remodeling and hence the outcomes of chondrogenesis. Results showed that inhibition of matrix proteases particularly the extracellular ones favors the phenotype of fibrocartilage rather than hyaline cartilage in chondrogenically differentiating hMSCs by upregulating type I collagen protein deposition and type II collagen gene expression without significantly altering the hypertrophic markers at gene level. This study suggests the potential of manipulating extracellular proteases to alter the outcomes of hMSC chondrogenesis, contributing to future development of differentiation protocols for fibrocartilage tissues for intervertebral disc and meniscus tissue engineering.

The Macrophage Polarization Regulates MSC Osteoblast Differentiation in vitro

Bone repair is a complex yet highly organized process involving interactions between various cell types and the extracellular environment. Macrophages are not only activated in inflammation during early phases of repair processes, but they are also present in bone throughout the whole bone repair process. Bone marrow derived mesenchymal stem cells (MSCs) represent an attractive therapeutic for bone fracture with their expansion potential, osteogenic capability, and potential for injury. However, less is known about the interaction between macrophage and MSC during bone repair and regeneration. This study was aimed to investigate whether macrophages in different statuses can regulate MSC osteoblast differentiation in vitro. Using in vitro cell coculture of macrophage and MSC, it was shown that macrophage polarization can regulate MSC osteoblast differentiation. This was evidenced by increased alkaline phosphatase (ALP), osteogenic markers, and bone mineralization in M2 macrophage cocultured MSC but decreased in M1 counterpart. These results might be mediated by pro-regenerative cytokines, such as TGF-β, VEGF, and IFG-1, produced by M2 macrophages and detrimental inflammation cytokines, such as IL-6, IL-12, and TNF-α, produced by M1 macrophages. Taken together, this shows that macrophage polarization could be crucial for maintaining bone homeostasis and promoting bone repair by regulating the MSC osteoblast differentiation.

Interplay of Substrate Conductivity, Cellular Microenvironment, and Pulsatile Electrical Stimulation toward Osteogenesis of Human Mesenchymal Stem Cells in Vitro

The influences of physical stimuli such as surface elasticity, topography, and chemistry over mesenchymal stem cell proliferation and differentiation are well investigated. In this context, a fundamentally different approach was adopted, and we have demonstrated the interplay of inherent substrate conductivity, defined chemical composition of cellular microenvironment, and intermittent delivery of electric pulses to drive mesenchymal stem cell differentiation toward osteogenesis. For this, conducting polyaniline (PANI) substrates were coated with collagen type 1 (Coll) alone or in association with sulfated hyaluronan (sHya) to form artificial extracellular matrix (aECM), which mimics the native microenvironment of bone tissue. Further, bone marrow derived human mesenchymal stem cells (hMSCs) were cultured on these moderately conductive (10(-4)-10(-3) S/cm) aECM coated PANI substrates and exposed intermittently to pulsed electric field (PEF) generated through transformer-like coupling (TLC) approach over 28 days. On the basis of critical analysis over an array of end points, it was inferred that Coll/sHya coated PANI (PANI/Coll/sHya) substrates had enhanced proliferative capacity of hMSCs up to 28 days in culture, even in the absence of PEF stimulation. On the contrary, the adopted PEF stimulation protocol (7 ms rectangular pulses, 3.6 mV/cm, 10 Hz) is shown to enhance osteogenic differentiation potential of hMSCs. Additionally, PEF stimulated hMSCs had also displayed different morphological characteristics as their nonstimulated counterparts. Concomitantly, earlier onset of ALP activity was also observed on PANI/Coll/sHya substrates and resulted in more calcium deposition. Moreover, real-time polymerase chain reaction results indicated higher mRNA levels of alkaline phosphatase and osteocalcin, whereas the expression of other osteogenic markers such as Runt-related transcription factor 2, Col1A, and osteopontin exhibited a dynamic pattern similar to control cells that are cultured in osteogenic medium. Taken together, our experimental results illustrate the interplay of multiple parameters such as substrate conductivity, electric field stimulation, and aECM coating on the modulation of hMSC proliferation and differentiation in vitro.

Alleviation of apoptosis of bone marrow-derived mesenchymal stem cells in the acute injured kidney by heme oxygenase-1 gene modification

Bone marrow-derived mesenchymal stem cells (BMSCs) transplantation is beneficial for the treatment of acute kidney injury (AKI), but the poor survival of BMSCs limits the repair effect. The oxidative stress in the AKI microenvironment is regarded as the main reason. Considering the potent anti-oxidant ability of heme oxygenase-1 (HO-1), HO-1 overexpression in BMSCs can be expected to improve the survival of BMSCs and correspondingly enhance the AKI repair effect. Here, BMSCs are transfected with pLV-HO-1/eGFP and pLV-eGFP by the lentivirus vector to get HO-1-BMSCs and eGFP-BMSCs, respectively. Ischemia/reperfusion-AKI kidney homogenate supernatant (KHS) is prepared for treating BMSCs, eGFP-BMSCs and HO-1-BMSCs. AKI-KHS results in a high inhibitory rate of BMSCs growth and a high proportion of TUNEL positive BMSCs, while HO-1 overexpression inverses this phenomenon and re-establishes the antioxidant and oxidant balance in HO-1-BMSCs. Phosphorylations of p53 and p38 mitogen-activated protein kinases (p38 MAPK) in HO-1-BMSCs decrease. Lower levels of monocyte chemotactic protein 1, tumor necrosis factor-α and interleukin 1β are also observed in supernatant of HO-1-BMSCs. The in vivo study shows that HO-1 overexpression sharply decreases the apoptosis of BMSCs in the injured kidney, and correspondingly the renal function of the AKI rats improves significantly. In conclusion, BMSCs with HO-1 overexpression suggests a better survival in the I/R-AKI microenvironment and a better kidney repair effect. The anti-oxidant effect via the inactivations of the downstream p53 and p38MAPK in BMSCs and the anti-inflammation could be the mechanisms. It provides a novel approach for the cell-based AKI-therapy.

Modulation of Bone-Specific Tissue Regeneration by Incorporating Bone Morphogenetic Protein and Controlling the Shell Thickness of Silk Fibroin/Chitosan/Nanohydroxyapatite Core-Shell Nanofibrous Membranes

The presence of both osteoconductive and osteoinductive factors is important in promoting stem cell differentiation toward the osteogenic lineage. In this study, we prepared silk fibroin/chitosan/nanohydroxyapatite/bone morphogenetic protein-2 (SF/CS/nHAP/BMP-2, SCHB2) nanofibrous membranes (NFMs) by incorporating BMP-2 in the core and SF/CS/nHAP as the shell layer of a nanofiber with two different shell thicknesses (SCHB2-thick and SCHB-thin). The physicochemical properties of SCHB2 membranes were characterized and compared with those of SF/CS and SF/CS/nHAP NFMs. When tested in release studies, the release rate of BMP-2 and the concentration of BMP-2 in the release medium were higher for SCHB2-thin NFMs because of reduced shell thickness. The BMP-2 released from the nanofiber retained its osteoinductive activity toward human-bone-marrow-derived mesenchymal stem cells (hMSCs). Compared with SF/CS and SF/CS/nHAP NFMs, the incorporation of BMP-2-promoted osteogenic differentiation of hMSCs and the SCHB-thin NFM is the best scaffold during in vitro cell culture. Gene expression analysis by real-time quantitative polymerase chain reaction detected the evolution of both early and late marker genes of bone formation. The relative mRNA expression is in accordance with the effect of BMP-2 incorporation and shell thickness, while the same was reconfirmed through the quantification of bone marker protein osteocalcin. In vivo experiments were carried out by subcutaneously implanting hMSC-seeded SCHB2-thin NFMs and acellular controls on the back sides of nude mice. Immunohistochemical and histological staining confirmed ectopic bone formation and osteogenesis of hMSCs in SCHB2-thin NFMs. In conclusion, the SCHB2-thin NFM could be suggested as a promising scaffold for bone tissue engineering.

The Use of Autologous Mesenchymal Stem Cells for Cell Therapy of Patients with Amyotrophic Lateral Sclerosis in Belarus

We studied a new method of treatment of amyotrophic lateral sclerosis with autologous mesenchymal stem cells. Autologous mesenchymal stem cells were injected intravenously (intact cells) or via lumbar puncture (cells committed to neuronal differentiation). Evaluation of the results of cell therapy after 12-month follow-up revealed slowing down of the disease progression in 10 patients in comparison with the control group consisting of 15 patients. The cell therapy was safe for the patients.

Melatonin reverses H2 O2 -induced premature senescence in mesenchymal stem cells via the SIRT1-dependent pathway

Mesenchymal stem cells (MSCs) represent an attractive source for stem cell-based regenerative therapy, but they are vulnerable to oxidative stress-induced premature senescence in pathological conditions. We previously reported antioxidant and antiarthritic effects of melatonin on MSCs against proinflammatory cytokines. In this study, we hypothesized that melatonin could protect MSCs from premature senescence induced by hydrogen peroxide (H2 O2 ) via the silent information regulator type 1 (SIRT1)-dependent pathway. In response to H2 O2 at a sublethal concentration of 200 μm, human bone marrow-derived MSCs (BM-MSCs) underwent growth arrest and cellular senescence. Treatment with melatonin before H2 O2 exposure cannot significantly prevent premature senescence; however, treatment with melatonin subsequent to H2 O2 exposure successfully reversed the senescent phenotypes of BM-MSCs in a dose-dependent manner. This result was made evident by improved cell proliferation, decreased senescence-associated β-galactosidase activity, and the improved entry of proliferating cells into the S phase. In addition, treatment with 100 μm melatonin restored the osteogenic differentiation potential of BM-MSCs that was inhibited by H2 O2 -induced premature senescence. We also found that melatonin attenuated the H2 O2 -stimulated phosphorylation of p38 mitogen-activated protein kinase, decreased expression of the senescence-associated protein p16(INK) (4α) , and increased SIRT1. Further molecular experiments revealed that luzindole, a nonselective antagonist of melatonin receptors, blocked melatonin-mediated antisenescence effects. Inhibition of SIRT1 by sirtinol counteracted the protective effects of melatonin, suggesting that melatonin reversed the senescence in cells through the SIRT1-dependent pathway. Together, these findings lay new ground for understanding oxidative stress-induced premature senescence and open perspectives for therapeutic applications of melatonin in stem cell-based regenerative medicine.

Cold exposure stimulates lipid metabolism, induces inflammatory response in the adipose tissue of mice and promotes the osteogenic differentiation of BMMSCs via the p38 MAPK pathway in vitro

This study was to explore the effect of long-term cold exposure on morphological changes of WAT and BAT, metabolic changes and inflammatory responses in vivo. We also investigated the effect of cold exposure on the osteogenic differentiation of BMMSCs and the mechanism involved in vitro. At the end of the animal experiments, WAT and BAT were isolated and analyzed by HE staining. The results showed that both temperature and exposure time were associated with the degree of WAT browning. Then, peripheral blood samples were collected and centrifuged to obtain serum. Serum biochemical analysis was performed. After exposure to cold air for 21 d, cyclic adenosine monophosphate (cAMP) level in BAT was greatly upregulated. cAMP in WAT and glycerol levels were slightly increased. Cold exposure decreased triglyceride (TG) level and increased the levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C). Whereas, high-density lipoprotein cholesterol (HDL-C) and free fatty acid (FFA) levels remains unchanged. Moreover, leptin and adiponectin (ADP) levels were remarkably downregulated. Tumor necrosis factor (TNF)-α and interleukin (IL)-6 concentrations were significantly elevated. Furthermore, the results showed that cold exposure significantly elevated runt-related transcription factor 2 (Runx2), bone sialoprotein (BSP), osteopontin (OPN) and collagen I levels and promoted the phosphorylation of p38 MAPK. However, the inducing effects were greatly inhibited by p38 MAPK inhibitor SB203580. These data suggest that long-term cold exposure activate BAT, increase lipolysis rate and enhance inflammatory response in mice. Furthermore, cold exposure promoted the osteogenic differentiation of BMMSCs partially via the p38 MAPK pathway.