Marrow-derived Multipotent Mesenchymal Stromal Cells Research Articles

The efficacy of cryopreserved ex vivo expanded rat bone marrow-derived multipotent mesenchymal stromal cells in the repair of radiation injuries in rats

At present, applying multipotent mesenchymal stromal cells (MSCs) as cell therapy for radiation damages have gained increasing attention since current medical management remains far from satisfactory. The aim of the study is to examine the efficacy of cryopreserved ex vivo expanded bone marrow-derived MSCs (rBM-MSCs) to the repair of radiation injuries on rat models of total and local radiation exposure. Materials and methods. The MSCs were derived from bone marrow of non-irradiated female albino rats aged 4 months, short-term ex vivo expanded for two passages and cryopreserved under dimethyl sulfoxide cryoprotection for low temperature storage at -70 oC for 6-12 months. The cryopreserved samples from each batch of rBM-MSCs culture were tested for the viability and functional characteristics before being transplanted to rats in experiments in vivo. The acute radiation damages in rats were modeled by total body irradiation (TBI) at doses of 5.5 Gy (TBI 5.5) and 7.0 Gy (TBI 7.0) and locally irradiated in the right hip skin at a dose of 50 Gy. The cryopreserved rBM-MSCs (1.5•106 and 0.5•106 cells/animal) were intravenously transplanted within 24 h following TBI and locally injected (twice 1.5•106 Cells/animals) on days 15 and 21 following thigh irradiation. The efficacy of cryopreserved rBM-MSCs was assessed by survival and hematological study as well as the irradiated skin wound healing assay. Results. The cryopreserved ex vivo expanded rBM-MSCs were characterized by high level of functional activity with cell viability about 80 %, include at least 8.5 % of the colony forming MSCs and MSCs with ability to adipogenic and osteogenic differentiation In TBI 5.5 rats, cryopreserved transplanted rBM-MSCs (1.5·106 cells/animal) prevented acute leukopenia in the first critical days of the radiation injury by increasing the number of leukocytes by 3.7 times on day 2 and contributed to a more complete recovery of hematological disorders by increasing the BM cells number and platelet count on day 22, which led to the increase of the increase of overall survival up to 100 % with a regain of body weight. In TBI 7.0 rats, the lower transplanted dose of rBM-MSCs (0.5•106 cells/animal) was more effective in terms of general recovery and extended the overall survival time for 6 days. The locally injected rBM-MSCs (twice 1.5•106 cells/animals) reduced the severity and promoted the healing of radiation skin wounds according to the results of scoring and wound size assay. Conclusion. The present study confirms that the cryopreserved ex vivo expanded rBM-MSCs were functionally complete for the therapeutic use on rat models of experimental radiation damage and were effective for the recovery of hematopoietic system and severe skin wound after radiation exposure.

Bone Marrow Multipotent Mesenchymal Stromal Cells from Patients with Aplastic Anemia Retain Their Ability to Support Hematopoietic Precursors despite Pronounced Changes in Gene Expression.

The properties of bone marrow-derived multipotent mesenchymal stromal cells (MSC) of patients with aplastic anemia at the onset of the disease are studied insufficiently. The aim of this work was to test the ability of MSC from patients with aplastic anemia to maintain hematopoietic precursors and to analyze the expression of genes associated with hematopoiesis and immune response. The ability of MSC to maintain hematopoietic precursors was determined by counting cobblestone area-forming cells; gene expression was analyzed by quantitative PCR. It was shown that MSC of patients with aplastic anemia preserve their ability to maintain hematopoietic precursors. Pronounced changes in the expression of the VEGFA and ANGPT1 genes were found. MSC from aplastic anemia patients with PNH clone significantly differ from those from aplastic anemia patients without PNH clone in terms of the expression of the SDF1, IL1R, and VEGFA genes. Changes in gene expression can be associated with the pathogenesis of the disease.

Safety and preliminary efficacy of allogeneic bone marrow-derived multipotent mesenchymal stromal cells for systemic sclerosis: a single-centre, open-label, dose-escalation, proof-of-concept, phase 1/2 study.

Systemic sclerosis remains an orphan life-threatening autoimmune disease. The unique immunomodulatory, proangiogenic, and antifibrotic properties of mesenchymal stromal cells provide a strong rationale for mesenchymal stromal cell-based therapy for systemic sclerosis, and treatment with mesenchymal stromal cells has shown benefits in preclinical models of this disease. The safety of allogeneic bone marrow-derived mesenchymal stromal cell administration in patients with severe systemic sclerosis has not yet been established. We aimed to test the safety and feasibility of a single intravenous injection of intrafamilial allogeneic bone marrow-derived mesenchymal stromal cells to treat severe diffuse systemic sclerosis. We did an open-label, dose-escalation, proof-of-concept, phase 1/2 study at Saint-Louis-Hospital, Paris, France. Eligible patients were aged 18-70 years with severe diffuse systemic sclerosis, who fulfilled the 2013 American College of Rheumatology and European League Against Rheumatism systemic sclerosis criteria, had a minimum modified Rodnan skin score of 15 (range 0-51), had severe lung, heart, or kidney involvement, and had inadequate response or contraindications to conventional immunosuppressive therapy or autologous haematopoietic stem cell transplantation. Patients with severe comorbidities were excluded. The first ten recipients were to receive a single intravenous infusion of 1 × 106 bone marrow-derived mesenchymal stromal cells per kg bodyweight, and the subsequent ten recipients were to be infused with a single dose of 3 × 106 bone marrow-derived mesenchymal stromal cells per kg bodyweight. The primary endpoint was immediate tolerance during infusion and within the first 10 days after infusion, measured as the occurrence of serious adverse events (grade 3 or higher) in all infused patients. Safety was assessed in all participants during the 24-month follow-up period. This study is registered with ClinicalTrials.gov, NCT02213705. Between March 24, 2014, and Jan 6, 2020, 20 cisgender individuals (13 women and seven men) with severe diffuse systemic sclerosis were enrolled. All 20 patients were included in the primary outcome analysis. No infusion-related severe adverse events and three infusion-related adverse events occurred in the first 10 days after treatment; one patient had grade 1 flushing and another patient had grade 1 nausea and grade 2 asthenia. After ten days and up to a median follow-up of 24·1 months (IQR 20·8-24·5), 36 non-treatment-related severe adverse events in 14 (70%) patients and no treatment-related adverse event were reported. A single infusion of allogeneic bone marrow-derived mesenchymal stromal cells was safe in patients with severe diffuse systemic sclerosis. Future placebo-controlled trials will help to definitively ascertain the efficacy of mesenchymal stromal cell-based cell therapy from various tissue sources in larger number of patients with systemic sclerosis. French Ministry of Health, Capucine Association, Fonds de Dotation de l'AFER pour la Recherche Médicale, and Agence Nationale de la Recherche (Infrastructure Program Ecell), France.

Ten-year results of mesenchymal stromal cell transplantation augmented with vascularised bone grafts for advanced osteonecrosis of the femoral head

BackgroundA prospective, open-label clinical trial, in which transplantation of cultured autologous bone marrow-derived multipotent mesenchymal stromal cells in combination with vascularised bone grafts for the treatment of post-collapse extensive osteonecrosis of the femoral head in ten patients, was conducted previously. The aim of this study was to assess the 10-year clinical and radiographic results of that study. MethodsPatients were evaluated for radiographic progression of osteonecrosis of the femoral head using anteroposterior radiographs at 10 years postoperatively. Clinical score and hip function, including the timed up and go test, were also estimated. ResultsOsteoarthritic changes in the affected hip were found in five of the ten patients, two of whom had undergone total hip arthroplasty at 7 and 9 years postoperatively. Five of the six cases (83.3%) in which pre-operative femoral head collapse was less than 3 mm, had no further collapse. On the other hand, all four cases in which pre-operative femoral head collapse was ≥3 mm, showed osteoarthritic changes within 10 years. The average clinical score significantly improved postoperatively and was maintained at 10 years. ConclusionsConsidering that eight of 10 post-collapse cases could avoid total hip arthroplasty conversion with good clinical results for 10 years and five of 6 post-collapse cases (collapse <3 mm) could avoid further collapse and osteoarthritic changes for 10 years, mesenchymal stromal cell transplantation in combination with vascularised bone grafts could be an effective treatment for post-collapse osteonecrosis of the femoral head.

Mesenchymal Stromal Cells Suppress Hepatic Fibrosis Via Modulating the Expression of Fibronectin and Integrin and Inhibiting DNA Fragmentation in Rats

IntroductionLiver fibrosis is currently the 11th most common cause of death worldwide. Because of self-renewal, available sources for isolation, and high differentiation properties, multipotent mesenchymal stromal stem cells are suggested to be potential tool for treatment of liver fibrosis. In this study, we examined the anti-fibrotic and anti-inflammatory activity of bone marrow-derived multipotent mesenchymal stromal stem cells (MSCs) on liver fibrosis induced by carbon tetrachloride on rats relative to silymarin as a standard drug.Material and methodsThis study was performed on 40 male Sprague Dawley rats divided into 4 groups of ten rats each: Group 1 served as controls, Group 2 served as CCl4 (diseased) group, Group 3 served as silymarin treated group and Group 4 served as MSCs treated group. Liver fibrosis was assessed by determination of liver markers and fibrogenesis related genes together with the anti-inflammatory markers in the liver tissue. DNA fragmentation was assessed by Comet assay.ResultsMSCs treatment reduced all liver fibrosis markers as well as the oxidative stress and inflammatory markers. Additionally, MSCs reduced the expression of integrins and fibronectin compared with the control group as well as decreasing DNA fragmentation.ConclusionsTreatment by MSCs significantly ameliorates liver fibrosis in rats. This amelioration was a result of acting on both the anti-inflammatory and anti-fibrotic activity of hepatocytes.

Platelet-rich plasma affects the proliferation of canine bone marrow-derived mesenchymal stromal cells in vitro

BackgroundReported efficacy of platelet-rich plasma (PRP) in regenerative medicine is contradictory. We validated the effects of PRP on proliferation of canine bone marrow-derived multipotent mesenchymal stromal cells (K9BMMSCs) in vitro. PRP was extracted from blood of six dogs with osteoarthritis. K9BMMSCs were established from bone marrow and characterized for CD90 and CD19 expression by immunocytochemistry. Effects of PRP concentrations on viability of matching autologous K9BMMSCs were validated using MTS assay.ResultsPositive CD90 and negative CD19 expression confirmed MSC origin. PRP at 40% volume/volume concentration increased, while PRP at 80 and 100% v/v concentrations suppressed viability of tested K9BMMSCs.ConclusionPRP concentration plays an important role in K9BMMSCs viability, which could affect tissue repairs in vivo.

Extracellular vesicles from bone marrow-derived multipotent mesenchymal stromal cells regulate inflammation and enhance tendon healing

BackgroundExtracellular vesicles from bone marrow-derived multipotent mesenchymal stromal cells (BMSC-EVs) can play important roles in the repair of injured tissues. However, no reports have investigated the role and underlying mechanisms of BMSCs-EVs in the tendon repair process. We hypothesized that BMSC-EVs may play a role in modulating inflammation during tendon healing and improving tendon repair in a rat model of patellar tendon injury.MethodsFirst, we created window defects in the patellar tendons of Sprague–Dawley rats. Rats (n = 16) were then randomly assigned to three groups: BMSC-EVs group, Fibrin group, and control group. Rats in the BMSC-EVs group were treated with BMSC-EVs and fibrin glue (25 µg in 10 µL). Rats in the fibrin group were treated with fibrin only, and those in the control group received no treatment. Histopathology, immunohistochemistry, and gene expression analyses were performed at 2 and 4 weeks after surgery.ResultsAt 4 weeks, tendons treated with BMSC-EVs showed regularly aligned and compact collagen fibers as compared with the disrupted scar-like healing in rats in the fibrin and control groups. The expression of genes related to tendon matrix formation and tenogenic differentiation: collagen (COL)-1a1, scleraxis (SCX), and tenomodulin (TNMD) was significantly higher in the BMSC-EVs group than in the other two groups. With histopathology, we observed significantly higher numbers of CD146+ tendon stem cells and fewer numbers of apoptotic cells and C–C chemokine receptor type 7 (CCR7)-positive proinflammatory macrophages in the BMSC-EVs group. BMSC-EVs treatment also led to an increase in the expression of anti-inflammatory mediators (IL-10 and IL-4) at 2 weeks after surgery.ConclusionsOverall, our findings show that the local administration of BMSC-EVs promotes tendon healing by suppressing inflammation and apoptotic cell accumulation and increasing the proportion of tendon-resident stem/progenitor cells. These findings provide a basis for the potential clinical use of BMSC-EVs in tendon repair.

HLA-DR expression in clinical-grade bone marrow-derived multipotent mesenchymal stromal cells: a two-site study

BackgroundContrary to the minimal criteria proposed by the International Society for Cell and Gene Therapy for defining multipotent mesenchymal stromal cells (MSC), human leukocyte antigen (HLA)-DR expression is largely unpredictable in ex vivo-expanded clinical-grade cultures. Although activation of MSC in culture does not appear to affect their functionality, a large study investigating the impact of HLA-DR expression on cell identity and potency is still missing in the literature.MethodsA retrospective analysis of HLA-DR expression in 130 clinical batches of bone marrow (BM)-MSC from two independent Good Manufacturing Practice-compliant production facilities was performed in order to identify the consequences on critical quality attributes as well as potential activation cues and dynamics of MSC activation in culture.ResultsHLA-DR+ cells in culture were confirmed to maintain fibroblastic morphology, mesenchymal phenotype identity, multipotency in vitro, and immunomodulatory capacity. Interestingly, the use of either human sera or platelet lysate supplements resulted in similar results.ConclusionsHLA-DR expression should be considered informative rather than as a criterion to define MSC. Further work is still required to understand the impact of HLA-DR expression in the context of product specifications on BM-MSC qualities for clinical use in specific indications.

Comparative Analysis of Secretome of Human Umbilical Cord- and Bone Marrow-Derived Multipotent Mesenchymal Stromal Cells

Production of cytokines and growth factors by cultured human umbilical cord tissue- and bone marrow-derived multipotent mesenchymal stromal cells was measured by multiplex analysis. In most cases, the concentrations of bioactive factors in the culture medium conditioned by umbilical cord-derived cells was ten- to hundred-times higher than in the medium conditioned by bone marrow-derived cells. These results suggest that both multipotent mesenchymal stromal cells from the umbilical cord and cell-free products can have more pronounced therapeutic effect in comparison with mesenchymal stromal cells obtained from "adult" sources.

The effects of different doses of thymulin in vivo and in vitro on some biological properties of bone marrow-derived multipotent mesenchymal stromal cells in mice of different strains

The effects of different doses of thymulin in vivo and in vitro on some biological properties of bone marrow-derived multipotent mesenchymal stromal cells in mice of different strains

Sternal bone marrow derived equine multipotent mesenchymal stromal cells (MSCs): investigations considering the sampling site and the use of different culture media.

Aspiration of equine sternal bone marrow is required for the cultivation of bone marrow‐derived multipotent mesenchymal stromal cells (BM‐MSCs) for regenerative therapies. For bone marrow aspiration as well as for MSC cultivation, there is a need to optimize techniques and protocols to enhance MSC harvest at minimized culture times. In a comparative study bone marrow aspirates from sternebra 4 and 5 were collected at two different positions within the sternebrae, either from 10 mm or from 30 mm dorsal from the ventral margin of the sternebrae. Accuracy of the puncture depth was confirmed by ultrasonography and computed tomography. Isolated MSCs were cultivated using media supplemented with three alternative sera, i.e. fetal calf serum, standardized horse serum and autologous serum. Due to morphological characteristics (spherical shape, only thin layer of hyaline cartilage at the ventral site, reliable bone marrow aspiration from only 10 mm intraosseous depth), sternebra 5 appeared most suitable for bone marrow aspiration. Cultivation and expansion of BM‐MSCs was most efficient using fetal calf serum.

Human mesenchymal stromal cells reduce influenza A H5N1-associated acute lung injury in vitro and in vivo

Influenza can cause acute lung injury. Because immune responses often play a role, antivirals may not ensure a successful outcome. To identify pathogenic mechanisms and potential adjunctive therapeutic options, we compared the extent to which avian influenza A/H5N1 virus and seasonal influenza A/H1N1 virus impair alveolar fluid clearance and protein permeability in an in vitro model of acute lung injury, defined the role of virus-induced soluble mediators in these injury effects, and demonstrated that the effects are prevented or reduced by bone marrow-derived multipotent mesenchymal stromal cells. We verified the in vivo relevance of these findings in mice experimentally infected with influenza A/H5N1. We found that, in vitro, the alveolar epithelium's protein permeability and fluid clearance were dysregulated by soluble immune mediators released upon infection with avian (A/Hong Kong/483/97, H5N1) but not seasonal (A/Hong Kong/54/98, H1N1) influenza virus. The reduced alveolar fluid transport associated with down-regulation of sodium and chloride transporters was prevented or reduced by coculture with mesenchymal stromal cells. In vivo, treatment of aged H5N1-infected mice with mesenchymal stromal cells increased their likelihood of survival. We conclude that mesenchymal stromal cells significantly reduce the impairment of alveolar fluid clearance induced by A/H5N1 infection in vitro and prevent or reduce A/H5N1-associated acute lung injury in vivo. This potential adjunctive therapy for severe influenza-induced lung disease warrants rapid clinical investigation.

High Content Imaging of Early Morphological Signatures Predicts Long Term Mineralization Capacity of Human Mesenchymal Stem Cells upon Osteogenic Induction.

Human bone marrow-derived multipotent mesenchymal stromal cells, often referred to as mesenchymal stem cells (MSCs), represent an attractive cell source for many regenerative medicine applications due to their potential for multi-lineage differentiation, immunomodulation, and paracrine factor secretion. A major complication for current MSC-based therapies is the lack of well-defined characterization methods that can robustly predict how they will perform in a particular in vitro or in vivo setting. Significant advances have been made with identifying molecular markers of MSC quality and potency using multivariate genomic and proteomic approaches, and more recently with advanced techniques incorporating high content imaging to assess high-dimensional single cell morphological data. We sought to expand upon current methods of high dimensional morphological analysis by investigating whether short term cell and nuclear morphological profiles of MSCs from multiple donors (at multiple passages) correlated with long term mineralization upon osteogenic induction. Using the combined power of automated high content imaging followed by automated image analysis, we demonstrated that MSC morphology after 3 days was highly correlated with 35 day mineralization and comparable to other methods of MSC osteogenesis assessment (such as alkaline phosphatase activity). We then expanded on this initial morphological characterization and identified morphological features that were highly predictive of mineralization capacities (>90% accuracy) of MSCs from additional donors and different manufacturing techniques using linear discriminant analysis. Together, this work thoroughly demonstrates the predictive power of MSC morphology for mineralization capacity and motivates further studies into MSC morphology as a predictive marker for additional in vitro and in vivo responses.

Possibility of Using Mesenchymal Stromal Cells to Restore Lymph Flow in Experimental Phlebothrombosis.

The possibility of formation of lymphatic vessels after introduction of autologous bone marrow-derived multipotent mesenchymal stromal cells transfected with GFP gene into thrombosed femoral vein was studied by fluorescent microscopy. Vascular thrombosis caused by ligation of the great vein with subsequent injection of thrombin solution was accompanied by blockade of regional lymph flow. The cells injected into thrombosed vein directly participate in the formation of new lymphatic vessels in the paravasal tissue surrounding the vein, its tissue region, and around regional lymph nodes. This is seen from bright specific fluorescence of individual cells in the walls of lymphatic vessels and all vascular layers and valves in UV light.

Hypoxic Preconditioning Increases Survival and Pro-Angiogenic Capacity of Human Cord Blood Mesenchymal Stromal Cells In Vitro.

Hypoxic preconditioning was shown to improve the therapeutic efficacy of bone marrow-derived multipotent mesenchymal stromal cells (MSCs) upon transplantation in ischemic tissue. Given the interest in clinical applications of umbilical cord blood-derived MSCs, we developed a specific hypoxic preconditioning protocol and investigated its anti-apoptotic and pro-angiogenic effects on cord blood MSCs undergoing simulated ischemia in vitro by subjecting them to hypoxia and nutrient deprivation with or without preceding hypoxic preconditioning. Cell number, metabolic activity, surface marker expression, chromosomal stability, apoptosis (caspases-3/7 activity) and necrosis were determined, and phosphorylation, mRNA expression and protein secretion of selected apoptosis and angiogenesis-regulating factors were quantified. Then, human umbilical vein endothelial cells (HUVEC) were subjected to simulated ischemia in co-culture with hypoxically preconditioned or naïve cord blood MSCs, and HUVEC proliferation was measured. Migration, proliferation and nitric oxide production of HUVECs were determined in presence of cord blood MSC-conditioned medium. Cord blood MSCs proved least sensitive to simulated ischemia when they were preconditioned for 24 h, while their basic behavior, immunophenotype and karyotype in culture remained unchanged. Here, “post-ischemic” cell number and metabolic activity were enhanced and caspase-3/7 activity and lactate dehydrogenase release were reduced as compared to non-preconditioned cells. Phosphorylation of AKT and BAD, mRNA expression of BCL-XL, BAG1 and VEGF, and VEGF protein secretion were higher in preconditioned cells. Hypoxically preconditioned cord blood MSCs enhanced HUVEC proliferation and migration, while nitric oxide production remained unchanged. We conclude that hypoxic preconditioning protects cord blood MSCs by activation of anti-apoptotic signaling mechanisms and enhances their angiogenic potential. Hence, hypoxic preconditioning might be a translationally relevant strategy to increase the tolerance of cord blood MSCs to ischemia and improve their therapeutic efficacy in clinical applications.

Intravenous administration of bone marrow-derived multipotent mesenchymal stromal cells enhances the recruitment of CD11b+ myeloid cells to the lungs and facilitates B16-F10 melanoma colonization

The discovery that the regenerative properties of bone marrow multipotent mesenchymal stromal cells (BM-MSCs) could collaterally favor neoplastic progression has led to a great interest in the function of these cells in tumors. However, the effect of BM-MSCs on colonization, a rate-limiting step of the metastatic cascade, is unknown. In this study, we investigated the effect of BM-MSCs on metastatic outgrowth of B16-F10 melanoma cells. In in vitro experiments, direct co-culture assays demonstrated that BM-MSCs stimulated the proliferation of B16-F10 cells in a dose-dependent manner. For in vivo experiments, luciferase-expressing B16-F10 cells were injected through tail vein and mice were subsequently treated with four systemic injections of BM-MSCs. In vivo bioluminescent imaging during 16 days demonstrated that BM-MSCs enhanced the colonization of lungs by B16-F10 cells, which correlated with a 2-fold increase in the number of metastatic foci. Flow cytometry analysis of lungs demonstrated that although mice harboring B16-F10 metastases displayed more endothelial cells, CD4 T and CD8 T lymphocytes in the lungs in comparison to metastases-free mice, BM-MSCs did not alter the number of these cells. Interestingly, BM-MSCs inoculation resulted in a 2-fold increase in the number of CD11b+ myeloid cells in the lungs of melanoma-bearing animals, a cell population previously described to organize “premetastatic niches” in experimental models. These findings indicate that BM-MSCs provide support to B16-F10 cells to overcome the constraints that limit metastatic outgrowth and that these effects might involve the interplay between BM-MSCs, CD11b+ myeloid cells and tumor cells.

Structurally-diverse, PPARγ-activating environmental toxicants induce adipogenesis and suppress osteogenesis in bone marrow mesenchymal stromal cells.

Environmental obesogens are a newly recognized category of endocrine disrupting chemicals that have been implicated in contributing to the rising rates of obesity in the United States. While obesity is typically regarded as an increase in visceral fat, adipocyte accumulation in the bone has been linked to increased fracture risk, lower bone density, and osteoporosis. Exposure to environmental toxicants that activate peroxisome proliferator activated receptor γ (PPARγ), a critical regulator of the balance of differentiation between adipogenesis and osteogenesis, may contribute to the increasing prevalence of osteoporosis. However, induction of adipogenesis and suppression of osteogenesis are separable activities of PPARγ, and ligands may selectively alter these activities. It currently is unknown whether suppression of osteogenesis is a common toxic endpoint of environmental PPARγ ligands. Using a primary mouse bone marrow culture model, we tested the hypothesis that environmental toxicants acting as PPARγ agonists divert the differentiation pathway of bone marrow-derived multipotent mesenchymal stromal cells towards adipogenesis and away from osteogenesis. The toxicants tested included the organotins tributyltin and triphenyltin, a ubiquitous phthalate metabolite (mono-(2-ethylhexyl) phthalate, MEHP), and two brominated flame retardants (tetrabromobisphenol-a, TBBPA, and mono-(2-ethylhexyl) tetrabromophthalate, METBP). All of the compounds activated PPARγ1 and 2. All compounds increased adipogenesis (lipid accumulation, Fabp4 expression) and suppressed osteogenesis (alkaline phosphatase activity, Osx expression) in mouse primary bone marrow cultures, but with different potencies and efficacies. Despite structural dissimilarities, there was a strong negative correlation between efficacies to induce adipogenesis and suppress osteogenesis, with the organotins being distinct in their exceptional ability to suppress osteogenesis. As human exposure to a mixture of toxicants is likely, albeit at low doses, the fact that multiple toxicants are capable of suppressing bone formation supports the hypothesis that environmental PPARγ ligands represent an emerging threat to human bone health.

Inflammatory Chemokines MIP-1δ and MIP-3α Are Involved in the Migration of Multipotent Mesenchymal Stromal Cells Induced by Hepatoma Cells.

In vivo, bone marrow-derived multipotent mesenchymal stromal cells (MSC) have been identified at sites of tumors, suggesting that specific signals mobilize and activate MSC to migrate to areas surrounding tumors. The signals and migratory mechanisms that guide MSC are not well understood. Here, we investigated the migration of human MSC induced by conditioned medium of Huh-7 hepatoma cells (Huh-7 CM). Using a transwell migration system, we showed that human MSC migration was increased in the presence of Huh-7 CM. Using a human cytokine antibody array, we detected increased levels of MIP-1δ and MIP-3α in Huh-7 CM. Recombinant chemokines MIP-1δ and MIP-3α induced MSC migration. Anti-MIP-1δ and anti-MIP-3α antibodies added to Huh-7 CM decreased MSC migration, further suggesting that MIP-1δ and MIP-3α were implicated in the Huh-7 CM-induced MSC migration. By real-time polymerase chain reaction, we observed an absence of chemokine receptors CCR2 and CXCR2 and low expression of CCR1, CCR5, and CCR6 in MSC. Expression of these chemokine receptors was not regulated by Huh-7 CM. Furthermore, matrix metalloproteinase 1 (MMP-1) expression was strongly increased in MSC after incubation with Huh-7 CM, suggesting that MSC migration depends on MMP-1 activity. The signaling pathway MAPK/ERK was activated by Huh-7 CM but its inhibition by PD98059 did not impair Huh-7 CM-induced MSC migration. Further, long-term incubation of MSC with MIP-1δ increased α-smooth muscle actin expression, suggesting its implication in the Huh-7 CM-induced evolvement of MSC into myofibroblasts. In conclusion, we report that two inflammatory cytokines, MIP-1δ and MIP-3α, are able to increase MSC migration in vitro. These cytokines might be responsible for migration and evolvement of MSC into myofibroblasts around tumors.

Tetraspanin CD9 determines invasiveness and tumorigenicity of human breast cancer cells.

Interaction of breast cancer cells (BCCs) with stromal components is critical for tumor growth and metastasis. Here, we assessed the role of CD9 in adhesion, migration and invasiveness of BCCs. We used co-cultures of BCCs and bone marrow-derived multipotent mesenchymal stromal cells (MSCs), and analyzed their behavior and morphology by dynamic total internal reflection fluorescence, confocal and scanning electron microscopy. 83, 16 and 10% of contacts between MDA-MB-231 (MDA), MA-11 or MCF-7 cells and MSCs, respectively, resulted in MSC invasion. MDA cells developed long magnupodia, lamellipodia and dorsal microvilli, whereas long microvilli emerged from MA-11 cells. MCF-7 cells displayed large dorsal ruffles. CD9 knockdown and antibody blockage in MDA cells inhibited MSC invasion by 95 and 70%, respectively, suggesting that CD9 is required for this process. Remarkably, CD9-deficient MDA cells displayed significant alteration of their plasma membrane, harboring numerous peripheral and dorsal membrane ruffles instead of intact magnupodium/lamellipodium and microvillus, respectively. Such modification might explain the delayed adhesion, and hence MSC invasion. In agreement with this hypothesis, CD9-knockdown suppressed the metastatic capacity of MDA cells in mouse xenografts. Our data indicate that CD9 is implicated in BCC invasiveness and metastases by cellular mechanisms that involve specific CD9+ plasma membrane protrusions of BCCs.

Effect of Metformin on Viability, Morphology, and Ultrastructure of Mouse Bone Marrow-Derived Multipotent Mesenchymal Stromal Cells and Balb/3T3 Embryonic Fibroblast Cell Line.

Metformin, a popular drug used to treat diabetes, has recently gained attention as a potentially useful therapeutic agent for treating cancer. In our research metformin was added to in vitro cultures of bone marrow-derived multipotent mesenchymal stromal cells (BMSCs) and Balb/3T3 fibroblast at concentration of 1 mM, 5 mM, and 10 mM. Obtained results indicated that metformin negatively affected proliferation activity of investigated cells. The drug triggered the formation of autophagosomes and apoptotic bodies in all tested cultures. Additionally, we focused on determination of expression of genes involved in insulin-like growth factor 2 (IGF2) signaling pathway. The most striking finding was that the mRNA level of IGF2 was constant in both BMSCs and Balb/3T3. Further, the analysis of IGF2 concentration in cell supernatants showed that it decreased in BMSC cultures after 5 and 10 mM metformin treatments. In case of Balb/3T3 the concentration of IGF2 in culture supernatants decreased after 1 and 5 mM and increased after 10 mM of metformin. Our results suggest that metformin influences the cytophysiology of somatic cells in a dose- and time-dependent manner causing inhibition of proliferation and abnormalities of their morphology and ultrastructure.