Human neural stem cell secretome relieves endoplasmic reticulum stress-induced apoptosis and improves neuronal functions after traumatic brain injury in a rat model.

Neural stem cell secretome (NSC-S) plays an important role in neuroprotection and recovery. Studies have shown that endoplasmic reticulum stress (ER stress) is involved in the progression of traumatic brain injury (TBI) and is a crucial cause of secondary damage and neuronal death after brain injury. Whether NSC-S is engaged in ER stress and ER stress-mediated neuronal apoptosis post-TBI has not been investigated. In the study, the Feeney SD male rat model was established. The results showed that NSC-S treatment significantly improved the behavior of rats with TBI. In addition, NSC-S relieved ER stress in TBI rats and was observed by transmission electron microscopy and western blot. The specific mechanism was further elucidated that restoration was achieved by alleviating the PERK-eIF2α pathway and thus protecting neurons from apoptosis. Notably, the discovery of calumenin (CALU) in NSC-S by liquid chromatography-tandem mass spectrometry (LC-MS/MS/MS) may be related to the protective effect of NSC-S on ER stress in neurons. Also, the mechanism by which it functions may be related to ubiquitination. In summary, NSC-S improved prognosis and ER stress in TBI rats and might be a promising treatment for relieving TBI.

A ROS-responsive loaded desferoxamine (DFO) hydrogel system for traumatic brain injury therapy.

Traumatic brain injury (TBI) produces excess iron, and increased iron accumulation in the brain leads to lipid peroxidation and reactive oxygen species (ROSs), which can exacerbate secondary damage and lead to disability and death. Therefore, inhibition of iron overload and oxidative stress has a significant role in the treatment of TBI. Functionalized hydrogels with iron overload inhibiting ability and of oxidative stress inhibiting ability will greatly contribute to the repair of TBI. Herein, an injectable, post-traumatic microenvironment-responsive, ROS-responsive hydrogel encapsulated with deferrioxamine mesylate (DFO) was developed. The hydrogel is rapidly formed via dynamic covalent bonding between phenylboronic acid grafted hyaluronic acid (HA-PBA) and polyvinyl alcohol (PVA), and phenylboronate bonds are used to respond to and reduce ROS levels in damaged brain tissue to promote neuronal recovery. The release of DFO from HA-PBA/PVA hydrogels in response to ROS further promotes neuronal regeneration and recovery by relieving iron overload and thus eradicating ROS. In the Feeney model of Sprague Dawley rats, HA-PBA/PVA/DFO hydrogel treatment significantly improved the behavior of TBI rats and reduced the area of brain contusion in rats. In addition, HA-PBA/PVA/DFO hydrogel significantly reduced iron overload to reduce ROS and could effectively promote post-traumatic neuronal recovery. Its effects were also explored, and notably, HA-PBA/PVA/DFO hydrogel can reduce iron overload as well as ROS, thus protecting neurons from death. Thus, this injectable, biocompatible and ROS-responsive drug-loaded hydrogel has great potential for the treatment of TBI. This work suggests a novel method for the treatment of secondary brain injury by inhibiting iron overload and the oxidative stress response after TBI.

Recent advances in nanomedicine development for traumatic brain injury.

Traumatic brain injury (TBI) is one of the major causes of morbidity and mortality worldwide, and it is also a risk factor for neurodegeneration. However, there has not been perceptible progress in treating acute TBI over the last few years, mainly due to the inability of therapeutic drugs to cross the blood-brain barrier (BBB), failing to exert significant pharmacological effects on the brain parenchyma. Recently, nanomedicines are emerging as a powerful tool for the treatment of TBI where nanoscale materials (also called nanomaterials) are employed to deliver therapeutic agents. The advantages of using nanomaterials as a drug carrier include their high solubility and stability, high carrier capacity, site-specific, improved pharmacokinetics, and biodistribution. Keeping these points in consideration, this article reviews the pathophysiology, current treatment options, and emerging nanomedicine strategies for the treatment of TBI. The review will help readers to gain insight into the state-of-the-art of nanomedicine as a new tool for the treatment of TBI.

Human Neural Stem Cell Secretome Inhibits Neuron Heme Uptake and Ferroptosis in Intracerebral Hemorrhage Through Nrf-2 Signaling Pathway.

Intracerebral hemorrhage (ICH) is a common subtype of stroke with a very high mortality rate, but there is still no effective cure. Increasing evidence suggests that heme accumulation and neuronal ferroptosis play an important role in secondary injury after ICH. Neural stem cells (NSCs), as seed cells of the central nervous system, have received much attention due to their abundant paracrine product components and low immunogenicity. In this study, we focused on the protective mechanism of neural stem cell secretome (NSC-S) against neuronal ferroptosis in an ICH mouse model using hemin-induced in vitro models and collagenase type IV-induced in vivo models. The results showed that NSC-S could ameliorate neurological deficits and reduce neuronal injury in ICH model mice. In addition, NSC-S reduced heme uptake and ferroptosis in hemin-treated N2a cells in vitro. NSC-S induced the activation of Nrf-2 signaling pathway. However, these effects of NSC-S were abolished by the Nrf-2 inhibitor ML385. Notably, HSPE1 in NSC-S may be associated with the protection of NSC-S against hemin-injured neurons via the Nrf-2 signaling pathway. In summary, NSC-S protects against secondary neuronal injury in ICH via the Nrf-2 signaling pathway. Also, this functionality may be implemented by HSPE1.

Immunomodulatory and Anti-inflammatory effect of Neural Stem/Progenitor Cells in the Central Nervous System.

Neuroinflammation is a critical event that responds to disturbed homeostasis and governs various neurological diseases in the central nervous system (CNS). The excessive inflammatory microenvironment in the CNS can adversely affect endogenous neural stem cells, thereby impeding neural self-repair. Therapies with neural stem/progenitor cells (NSPCs) have shown significant inhibitory effects on inflammation, which is mainly achieved through intercellular contact and paracrine signalings. The intercellular contact between NSPCs and immune cells, the activated CNS- resident microglia, and astrocyte plays a critical role in the therapeutic NSPCs homing and immunomodulatory effects. Moreover, the paracrine effect mainly regulates infiltrating innate and adaptive immune cells, activated microglia, and astrocyte through the secretion of bioactive molecules and extracellular vesicles. However, the molecular mechanism involved in the immunomodulatory effect of NSPCs is not well discussed. This article provides a systematic analysis of the immunomodulatory mechanism of NSPCs, discusses efficient ways to enhance its immunomodulatory ability, and gives suggestions on clinical therapy.

Neural stem cell secretome exerts a protective effect on damaged neuron mitochondria in Parkinson's disease model.

Parkinson's disease (PD) is a common neurodegenerative disease. The main pathological changes are the loss of dopaminergic neurons and the formation of Lewy bodies. There is still no effective cure for PD, and cell replacement therapy has entered a bottleneck period due to tumorigenicity and rejection. Therefore, stem cell secretome has received widespread attention. However, the exploration of the secretome components of neural stem cells (NSCs) is still in its infancy. In this study, 6-hydroxydopamine (6-OHDA) was used to establish a PD rat model in vito and the PC12 cell-damaged model in vitro. The results indicated that the injection of neural stem cell-conditioned medium (NSC-CM) into the striatum and substantia nigra could improve the motor and non-motor deficits of PD rats and rescue the loss of dopaminergic neurons. In addition, NSC-CM alleviated 6-OHDA-induced apoptosis of PC12 cells, reduced the level of oxidative stress, and improved mitochondrial dysfunction in vitro. Parkinson disease protein 7 (Park7) was found in NSC-CM by Liquid chromatography-tandem mass spectrometry (LC-MS/MS), and it may be related to the protective effect of NSC-CM on 6-OHDA-injured neurons through Sirt1 pathway. In conclusion, NSC secretome might provide new ideas for the treatment of PD.

Human Neural Stem Cell Secretome Inhibits Lipopolysaccharide-Induced Neuroinflammation Through Modulating Microglia Polarization by Activating Peroxisome Proliferator-Activated Receptor Gamma.

Neuroinflammation is one of the typical events in multiple neurodegenerative diseases, whereas microglia are the critical participants in the pathogenesis of neuroinflammation. Several studies suggest that neural stem cells (NSCs) present immunomodulatory benefits due to their paracrine products, which contain mounting trophic factors. In the current study, the anti-inflammatory effects of NSC secretome (NSC-S) on lipopolysaccharide (LPS)-induced neuroinflammatory models were evaluated in vivo and the underlying mechanism was further investigated in vitro. It was revealed that NSC-S significantly attenuated the severity of LPS-induced behavior disorders and inflammatory response in mice. In vitro studies found that NSC-S significantly promoted the polarization of microglia from proinflammatory M1 to anti-inflammatory M2 phenotype, and reduced the production of proinflammatory cytokines, whereas elevated anti-inflammatory cytokines in BV2 cells. NSC-S promoted peroxisome proliferator-activated receptor gamma (PPAR-γ) pathway activation. However, these effects of NSC-S were abrogated by PPAR-γ inhibitor GW9662. Notably, the fatty acid-binding protein 5 (FABP5) in NSC-S may mediate PPAR-γ activation and inflammation remission. In summary, NSC-S promotes the regression of LPS-induced microglia-mediated inflammation through the PPAR-γ pathway. This function might be achieved through FABP5.

Schwann-like cell conditioned medium promotes angiogenesis and nerve regeneration.

Vascular network reconstruction plays a pivotal role in the axonal regeneration and nerve function recovery after peripheral nerve injury. Increasing evidence indicates that Schwann cells (SCs) can promote nerve function repair, and the beneficial effects attributed to SCs therapy may exert their therapeutic effects through paracrine mechanisms. Recently, the previous research of our group demonstrated the promising neuroregenerative capacity of Schwann-like cells (SCLCs) derived from differentiated human embryonic stem cell-derived neural stem cells (hESC-NSCs) in vitro. Herein, the effects of SC-like cell conditioned medium (SCLC-CM) on angiogenesis and nerve regeneration were further explored. The assays were performed to show the pro-angiogenic effects of SCLC-CM, such as promoted endothelial cell proliferation, migration and tube formation in vitro. In addition, Sprague-Dawley rats were treated with SCLC-CM after sciatic nerve crush injury, SCLC-CM was conducive for the recovery of sciatic nerve function, which was mainly manifested in the SFI increase, the wet weight ratio of gastrocnemius muscle, as well as the number and thickness of myelin. The SCLC-CM treatment reduced the Evans blue leakage and increased the expression of CD34 microvessels. Furthermore, SCLC-CM upregulated the expressions of p-Akt and p-mTOR in endothelial cells. In conclusion, SCLC-CM promotes angiogenesis and nerve regeneration, it is expected to become a new treatment strategy for peripheral nerve injury.

Peroxiredoxin 6 secreted by Schwann-like cells protects neuron against ischemic stroke in rats via PTEN/PI3K/AKT pathway.

Schwann cells can promote the survival of damaged neurons and axon regeneration by secreting or releasing some proteins and factors which may provide effective strategies to the remedy for ischemic stroke. The models of middle cerebral artery occlusion and oxygen-glucose deprivation (OGD) were established. Peroxiredoxin 6 (PRDX6) was found in Schwann-like cell conditioned medium (SCLC-CM) by mass spectrometry. The rehabilitative performance of SCLC-CM on focal cerebral ischemia of rats and on OGD-induced PC12 cells were assessed. SCLC-CM significantly improved neurological recovery, reducing the infarct volume of rats after stroke. PRDX6 could significantly inhibit neuron apoptosis in the OGD injury by mediating oxidative stress and activating the PTEN/PI3K/AKT pathway. In conclusion, PRDX6 secreted by Schwann-like cell protects neuron against focal cerebral ischemia, SCLC-CM might be a new effective early intervention for ischemic stroke.

Microvesicles from Schwann-Like Cells as a New Biomaterial Promote Axonal Growth.

Schwann cells promote axonal regeneration following peripheral nerve injury. However, in terms of clinical treatment, the therapeutic effects of Schwann cells are limited by their source. The transmission of microvesicles from neuroglia cells to axons is a novel communication mechanism in axon regeneration.To evaluate the effect of microvesicles released from Schwann-like cells on axonal regeneration, neural stem cells derived from human embryonic stem cells differentiated into Schwann-like cells, which presented a typical morphology and characteristics similar to those of schwann cells. The glial markers like MBP, P0, P75NTR, PMP-22, GFAP, HNK-1 and S100 were upregulated, whereas the neural stem markers like NESTIN, SOX1 and SOX2 were significantly downregulated in schwann-like cells. Microvesicles enhanced axonal growth in dorsal root ganglia neurons and regulated GAP43 expression in neuron-like cells (N2A and PC12) through the PTEN/PI3 K/Akt signaling pathway. A 5 mm section of sciatic nerve was transected in Sprague-Dawley rats. With microvesicles transplantation, regenerative nerves were evaluated after 6 weeks. Microvesicles increased sciatic function index scores, delayed gastrocnemius muscle atrophy and elevated ßIII-tubulin-labeled axons in vivo. Schwann-like cells serve as a convenient source and promote axonal growth by secreting microvesicles, which may potentially be used as bioengineering materials for nerve tissue repair.

Human Neural Stem Cell-Conditioned Medium Inhibits Inflammation in Macrophages Via Sirt-1 Signaling Pathway In Vitro and Promotes Sciatic Nerve Injury Recovery in Rats.

Chronic persistent inflammation is thought to impede axon regeneration and cause demyelinating disease also with neuropathic pain, leading to more severe dysfunction after peripheral nerve injury. Increasing evidence indicates that neural stem cells (NSCs) have immunomodulatory effects, and previous studies have shown that many of the beneficial effects attributed to stem cell therapy may exert their therapeutic effects through paracrine mechanisms. In this research, the repairing effect of NSC-conditioned medium (NSC-CM) on sciatic nerve injury and its mechanism of repair were further explored. The present research showed that NSC-CM promoted histopathological and functional recovery after crush injury in rats, and what counts is that NSC-CM inhibited the inflammation of sciatic nerve in the late stage of injury. NSC-CM significantly downregulated the infiltration of proinflammatory factors [tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), and IL-1ß] as well as decreased the CD68 inflammatory macrophages infiltrating in the sciatic nerve. In addition, to study the effect of NSC-CM on the inflammatory state of macrophages in vitro, lipopolysaccharide (LPS) was used to induce the proinflammation of macrophages. The results showed that NSC-CM decreased the expression of macrophage proinflammatory-related proteins (IL-6, IL-1ß, TNF-α, inducible nitric oxide synthase) induced by LPS. The activation of Sirt-1 signaling in macrophages effectively countered the proinflammation induced by LPS in the presence of NSC-CM. Using Sirt-1-specific inhibitor EX527 partially weakened the anti-inflammatory effect of NSC-CM. Altogether, this study demonstrated for the first time that NSC-CM promotes functional recovery after sciatic nerve crush injury in vivo and also inhibits the inflammation in activated macrophages by activating Sirt-1 signaling pathway in vitro.

Regeneration of sciatic nerves by transplanted microvesicles of human neural stem cells derived from embryonic stem cells.

Injured nerves cannot regenerate on their own, and a lack of engraftable human nerves has been a major obstacle in cell-based therapies for regenerating damaged nerves. A monolayer culture approach to obtain adherent neural stem cells from human embryonic stem cells (hESC-NSCs) was established, and the greatest number of stemness characteristics were achieved by the eighth generation of hESC-NSCs (P8 hESC-NSCs). To overcome deficits in cell therapy, we used microvesicles secreted from P8 hESC-NSCs (hESC-NSC-MVs) instead of entire hESC-NSCs. To investigate the therapeutic efficacy of hESC-NSC-MVs in vitro, hESC-NSC-MVs were cocultured with dorsal root ganglia to determine the length of axons. In vivo, we transected the sciatic nerve in SD rats and created a 5-mm gap. A sciatic nerve defect was bridged using a silicone tube filled with hESC-NSC-MVs (45 µg) in the MVs group, P8 hESC-NSCs (1 × 106 single cells) in the cell group and PBS in the control group. The hESC-NSC-MVs group showed better morphological recovery and a significantly greater number of regenerated axons than the hESC-NSCs group 12 weeks after nerve injury. These results indicated that the hESC-NSC-MVs group had the greatest ability to repair and reconstruct nerve structure and function. As a result, hESC-NSC-MVs may have potential for applications in the field of nerve regenerative repair.

Microvesicles Derived from Human Embryonic Neural Stem Cells Inhibit the Apoptosis of HL-1 Cardiomyocytes by Promoting Autophagy and Regulating AKT and mTOR via Transporting HSP-70.

Myocardial reperfusion injury (MRI) induced by cardiomyocyte apoptosis plays an important role in the pathogenesis of a variety of cardiovascular diseases. New MRI treatments involving stem cells are currently being developed because these cells may exert their therapeutic effects primarily through paracrine mechanisms. Microvesicles (MVs) are small extracellular vesicles that have become the key mediators of intercellular communication. MVs derived from stem cells have been reported to play an important role in MRI. In this article, we attempted to explore the mechanisms by which MVs derived from human embryonic neural stem cells (hESC-NSC-derived MVs) rescue MRI. hESCs were differentiated into NSCs, and MVs were isolated from their supernatants by ultracentrifugation. H2O2 was used to induce apoptosis in HL-1 cardiomyocytes. Cell viability was detected by using the CCK-8 assay, apoptosis was detected by Annexin V-FITC/PI staining, and apoptosis-related proteins and signalling pathway-related proteins were detected by western blot analysis. Autophagic flux was measured using the tandem fluorescent mRFG-GFP-LC3 assay. Transmission electron microscopy and western blot analysis were adopted to evaluate autophagy levels. hESC-NSC-derived MVs increased the autophagy and inhibited the apoptosis of HL-1 cells exposed to H2O2 for 3 h in a dose-dependent manner. Additionally, hESC-NSC-derived MVs contained high levels of heat shock protein 70 (HSP-70), which can increase the level of HSP-70 in cells. Moreover, the same effect could be achieved by heat shock preconditioning of HL-1 cells overexpressing HSP-70. The benefits of NSC-MVs may be due to the involvement of AKT and mTOR signalling pathways. Importantly, hESC-NSC-derived MVs stimulated the activation of the AKTand mTOR signalling pathway in those cells by transporting HSP-70. Our results suggest that hESC-NSC-derived MVs inhibit the apoptosis of HL-1 cardiomyocytes by promoting autophagy and regulating AKT and mTOR via transporting HSP-70. However, this hypothesis requires in vivo confirmation.

Human hair keratins promote the regeneration of peripheral nerves in a rat sciatic nerve crush model.

Axon regeneration and functional recovery after peripheral nerve injury remains a clinical challenge. Injury leads to axonal disintegration after which Schwann cells (SCs) and macrophages re-engage in the process of regeneration. At present, biomaterials are regarded as the most promising way to repair peripheral nerve damage. As a natural material, keratin has a wide range of sources and has good biocompatibility and biodegradability. Here, a keratin was extracted from human hair by reducing method and a keratin sponge with porous structure was obtained by further processing. The results suggested that keratin can promote cell adhesion, proliferation, migration as well as the secretion of neurotrophic factors by SCs and the regulation of the expression of macrophage inflammatory cytokines in vitro. We report for the first time that human hair keratin can promote the extension of axon in DRG neurons. The motor deficits caused by a sciatic nerve crush injury were alleviated by keratin sponge dressing in vivo. Thus, keratin has been identified as a valuable biomaterial that can enhance peripheral nerve regeneration.

Microvesicles released from human embryonic stem cell derived-mesenchymal stem cells inhibit proliferation of leukemia cells.

Human embryonic stem cell derived-mesenchymal stem cells (hESC­MSCs) are able to inhibit proliferation of leukemia cells. Microvesicles released from human embryonic stem cell derived-mesenchymal stem cells (hESC­MSC­MVs) might play an important part in antitumor activity. Microvesicles were isolated by ultracentrifugation and identified under a scanning electron microscopy and transmission electron microscope separately. After 48-h cocultured with hESC­MSCs and hESC­MSC­MVs, the number of K562 and HL60 was counted and tumor cell viability was measured by CCK8 assay. The expression of proteins Bcl-2 and Bax were estimated by western blotting. Transmission electron microscope and western blot analysis were adopted to evaluate the autophagy level. Results showed that both hESC­MSCs and hESC­MSC­MVs inhibited proliferation of leukemia cells in a concentration-dependent manner. hESC­MSC­MVs reduced the ratio of Bcl/Bax, enhanced the protein level of Beclin-1 and LC3-II conversion, thus upregulating autophagy and apoptosis. In conclusion, microvesicles released from human embryonic stem cell derived-mesenchymal stem cells inhibited tumor growth and stimulated autophagy and excessive autophagy might induce apoptosis.

Porous Ga-In Bimetallic Oxide Nanofibers with Controllable Structures for Ultrasensitive and Selective Detection of Formaldehyde.

The design of appropriate composite materials with unique surface structures is an important strategy to achieve ideal chemical gas sensing. In this paper, efficient and selective detection of formaldehyde vapor has been realized by a gas sensor based on porous GaxIn2-xO3 nanofibers assembled by small building blocks. By tuning the Ga/In atomic ratios in the materials, crystallite phase, nanostructure, and band gap of as-obtained GaxIn2-xO3 nanofibers can be rationally altered. This further offers a good opportunity to optimize the gas sensing performances. In particular, the sensor based on porous Ga0.6In1.4O3 nanofibers assembled by small nanoparticles (∼4.6 nm) exhibits best sensing performances. Toward 100 ppm formaldehyde, its highest response (Ra/Rg = 52.4, at 150 °C) is ∼4 times higher than that of the pure In2O3 (Ra/Rg = 13.0, at 200 °C). Meanwhile, it has superior ability to selectively detect formaldehyde against other interfering volatile organic compound gases. The significantly improved sensing performance makes the Ga0.6In1.4O3 sensor very promising for selective detection of formaldehyde.

Changes in mesenchymal stem cells following long-term culture in vitro.

Mesenchymal stem cells (MSCs), which can be isolated from umbilical cords and induced to differentiate into multiple cell types in vitro, represent an ideal source for cell and gene therapy. MSCs are typically expanded in culture prior to their therapeutic application. However, similar to other types of stem cell, MSCs undergo senescence following a certain number of cell expansion passages in vitro, and eventually stop proliferating. The objective of the present study was to measure the changes that occur over successive passages of MSCs during long­term in vitro culture, and to detect the effect of aging on MSC morphology, phenotype, proliferation, cell cycle, differentiation, intracellular reactive oxygen species (ROS) levels and gene expression. To understand the importance of oxidative stress in the aging of adult stem cells, the current study established a cell model of H2O2­induced MSC premature senescence. Analysis of the biological characteristics of human umbilical cord MSCs during replicative and premature senescence revealed the importance of extrinsic factors in the aging of stem cells, particularly ROS. The findings of the present study suggest that cellular senescence, a state of irreversible growth arrest, can be triggered by ROS. Thus, it is important to improve the extrinsic culture environment of MSCs to retain the phenotype of expanded cells and delay the process of senescence prior to their clinical application.

miR-21: A gene of dual regulation in breast cancer.

Breast cancer is characterized by an elevated capacity for tumor invasion and lymph node metastasis, but the cause remains to be determined. Recent studies suggest that microRNAs (miRNAs) can regulate the evolution of malignant behavior by regulating multiple target genes. A key oncomir in carcinogenesis is miR-21, which is consistently upregulated in a wide range of cancers. However, few functional studies are available for miR-21, and few targets have been identified. In this study, we explored the role of miR-21 in human breast cancer cells and searched for miR-21 targets.Total RNA from breast cancer tissue and corresponding adjacent normal tissue was extracted and used to detect miR-21 expression by quantificational real-time polymerase chain reaction (qRT-PCR), followed by analysis of the correlation between gonad hormone indices in peripheral blood and miR-21 expression in cancerous tissues from the same patients. Cell proliferation, colony formation, migration and invasion were then examined to determine the role of miR-21 in regulating breast cancer cells. Finally, western blotting was performed to determine if miR-21 regulated expression of signal transducers and activators of transcription 3 (STAT3), and assays of cell proliferation, colony formation, migration and invasion were performed to examine the role of STAT3 in regulation of breast cancer cells. We found that expression of miR-21 increased from normal through benign to cancerous breast tissues. Enhanced miR-21 expression was associated with serum levels of follicle-stimulating hormone, estradiol, ß-human chorionic gonadotropin, testosterone and prolactin in patients with breast cancer. Furthermore, cell proliferation, colony formation, migration and invasion were increased after overexpression of miR-21 in breast cancer cells and reduced by miR-21 suppression. In addition, we identified a putative miR-21 binding site in the 3'-untranslated region of the STAT3 gene using an online bioinformatical tool. We found that protein expression of STAT3 was significantly downregulated when breast cancer cells were transfected with miR-21 mimics, and was significantly upregulated in breast cancer cells transfected with a miR-21 inhibitor. Finally, we found that cell proliferation, colony formation, migration and invasion were decreased by treatment with 2.5 nM of Stattic, an inhibitor of STAT3 activation. Our data suggest that miR-21 expression is increased in breast cancer and plays an important role as a tumor gene by targeting STAT3, which may act as a double-response controller in breast cancer.

Cytotoxic effects of 4-methylimidazole on bone marrow mesenchymal stem cells in vitro.

4-Methylimidazole (4-MI) is found in a great number of food products. The National Toxicology Program (NTP) revealed that 4-MI is carcinogenic and can also cause anemia and weight loss. Mesenchymal stem cells (MSCs) are able to support hematopoiesis and migrate to the site of tumors. To investigate whether 4-MI has an impact on MSCs, we have measured the ability of cell (osteoblast, adipocyte) proliferation, apoptosis, cell cycle, gene expression, migration and differentiation between control group and the 4-MI group. The results showed that higher concentrations of 4-MI (≥150 µg/ml) had significant effects on BMSCs viability while lower concentrations (≤100 µg/ml) had no significant effects on cell proliferation, apoptosis, migration, differentiation, and expression of relevant marker genes of hematopoietic cytokines, including TPO, SCF, VEGF and FLt3. The results also indicated that 4-MI (≤100 µg/ml) may have no significant effect on the biological characteristics of MSCs. Low concentration of 4-MI in foods and beverages have no toxic effect on BMSCs. The anemia and weight loss of animals caused by 4-MI may not be due to its effect on BMSCs.

Umbilical cord-derived mesenchymal stem cells promote proliferation and migration in MCF-7 and MDA-MB-231 breast cancer cells through activation of the ERK pathway.

Mesenchymal stem cells (MSCs) are known to migrate to tumor tissues and to play an important role in cancer progression. However, the effects of MSCs on tumor progression remain controversial. The purpose of the present study was to detect the effects of human umbilical cord-derived MSCs (hUC­MSCs) on the human breast cancer cell lines MDA-MB­231 and MCF-7 in vitro and the underlying mechanisms. MSCs were isolated and identified from umbilical cord tissues. MDA-MB­231 and MCF-7 cells were treated with conditioned medium (CM) from 10 and 20% umbilical cord MSCs (UC-MSCs), and the resulting changes in proliferation and migration were investigated. The 3-(4,5-dimethyl-2-thiazolyl)­2,5-diphenyl­2-H-tetrazolium bromide (MTT) and plate clone formation assays were used to assess the effect on proliferation, and the effects of CM on MDA-MB-231 and MCF-7 migration were assessed through scratch wound and Transwell migration assays. The expression of cell proliferation- and metastasis-related genes and proteins and activation of the ERK signaling pathway were analyzed by RT-PCR and western blot assays. UC-MSCs are characteristically similar to bone marrow MSCs (BM-MSCs) and exhibit multipotential differentiation capability (i.e., osteoblasts and adipocytes). The MTT, plate clone formation, scratch wound and Transwell migration assay results revealed that 10 and 20% CM promoted the proliferation and migration to higher levels than those observed in the control group. Our findings showed that UC-MSC-CM inhibited E-cadherin expression, increased the expression of N-cadherin and proliferating cell nuclear antigen (PCNA) and enhanced the expression of ZEB1, a transcription factor involved in epithelial­to­mesenchymal transition (EMT), through activation of the ERK pathway. U0126, an inhibitor of ERK, reversed the effects of UC-MSC-CM on breast cancer cell proliferation and migration. We conclude that UC-MSCs promote the proliferation and migration of breast cancer cell lines via activation of the ERK pathway.