Toll-like receptor 4 selective inhibition in medullar microenvironment alters multiple myeloma cell growth.

peer reviewedBone marrow (BM) mesenchymal stromal cells (MSCs) are abnormal in multiple myeloma (MM) and play a critical role by promoting growth, survival, and drug resistance of MM cells. We observed higher Toll-like receptor 4 (TLR4) gene expression in MM MSCs than in MSCs from healthy donors. At the clinical level, we highlighted that TLR4 expression in MM MSCs evolves in parallel with the disease stage. Thus, we reasoned that the TLR4 axis is pivotal in MM by increasing the protumor activity of MSCs. Challenging primary MSCs with TLR4 agonists increased the expression of CD54 and interleukin-6 (IL-6), 2 factors directly implicated in MM MSC-MM cell crosstalk. Then, we evaluated the therapeutic efficacy of a TLR4 antagonist combined or not with conventional treatment in vitro with MSC-MM cell coculture and in vivo with the Vk*MYC mouse model. Selective inhibition of TLR4 specifically reduced the MM MSC ability to support the growth of MM cells in an IL-6-dependent manner and delayed the development of MM in the Vk*MYC mouse model by altering the early disease phase in vivo. For the first time, we demonstrate that specific targeting of the pathological BM microenvironment via TLR4 signaling could be an innovative approach to alter MM pathology development

Pericyte-Like Progenitors Show High Immaturity and Engraftment Potential as Compared with Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) and pericyte progenitors (PPs) are both perivascular cells with similar multipotential properties regardless of tissue of origin. We compared the phenotype and function of the 2 cell types derived from the same bone-marrow samples but expanded in their respective media – pericyte conditions (endothelial cell growth medium 2 [EGM-2]) for PPs and standard medium (mesenchymal stem cell medium [MSM]) for MSCs. After 3 weeks of culture, whatever the expansion medium, all cells showed similar characteristics (MSC markers and adipo-osteo-chondroblastic differentiation potential), although neuronal potential was greater in EGM-2– than MSM-cultured cells. As compared with MSM-cultured MSCs, EGM-2–cultured PPs showed higher expression of the pericyte-specific antigen 3G5 than a-smooth muscle actin. In addition, EGM-2–cultured PPs showed an immature phenotype, with upregulation of stemness OCT4 and SOX2 proteins and downregulation of markers of osteoblastic, chondroblastic, adipocytic and vascular smooth muscle lineages. Despite having less effective in vitro immunosuppression capacities than standard MSCs, EGM-2–cultured PPs had higher engraftment potentials when combined with biomaterials heterotopically-transplanted in Nude mice. Furthermore, these engrafted cells generated more collagen matrix and were preferentially perivascular or lined trabeculae as compared with MSM-cultured MSCs. In conclusion, EGM-2–cultured PPs are highly immature cells with increased plasticity and engraftment potential

Etude des interactions moléculaires à l'aire de contact formée entre les lymphocytes T et les cellules présentatrices d'antigène

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

CD54-Mediated Interaction with Pro-inflammatory Macrophages Increases the Immunosuppressive Function of Human Mesenchymal Stromal Cells

Summary: Mesenchymal stromal cells (MSCs) sense and modulate inflammation and represent potential clinical treatment for immune disorders. However, many details of the bidirectional interaction of MSCs and the innate immune compartment are still unsolved. Here we describe an unconventional but functional interaction between pro-inflammatory classically activated macrophages (M1MΦ) and MSCs, with CD54 playing a central role. CD54 was upregulated and enriched specifically at the contact area between M1MФ and MSCs. Moreover, the specific interaction induced calcium signaling and increased the immunosuppressive capacities of MSCs dependent on CD54 mediation. Our data demonstrate that MSCs can detect an inflammatory microenvironment via a direct and physical interaction with innate immune cells. This finding opens different perspectives for MSC-based cell therapy. : Mesenchymal stromal cells (MSCs) are promising for cell-based therapy in inflammatory disorders by switching off the immune response. Varin and colleagues demonstrate that MSCs and inflammatory macrophages communicate via an unconventional but functional interaction that strongly increases the immunosuppressive capacities of MSCs. This new communication between the innate immune system and MSCs opens new perspectives for MSC-based cell therapy. Keywords: macrophages, bone marrow mesenchymal stromal cells, functional interaction, CD54, immunosuppression, indoleamine 2,3-dioxygenase, cell therap

Comparison of Stromal Cells of Adipose Tissue From Multiple Myeloma Patients and Healthy Donors

Abstract Abstract 2979 Introduction: Multiple myeloma (MM) is a B-cell neoplasia characterized by the accumulation of malignant plasma cells in the bone marrow (BM) patients causing severe bone disease (with osteolytic lesions, pain, pathological fractures) and cytopenias. These lesions are irreversible, even for patients in complete response to treatment. We have proposed to treat those lesions with mesenchymal stem cells (MSC) of the BM using their ability to differentiate into osteoblasts and to support haematopoiesis. But our previous results demonstrated that MM MSC are abnormal. We thus studied cells from adipose tissue (AT) with similar properties than MSC; the Adipose derived Stromal Cells (ASC). The aim of this study is to demonstrate the normality of ASC in MM context for a potential use in autologous stem cell transplantation. Here we propose the first study comparing ASC issue from MM patients and healthy donors (HD). Patients and Methods: We studied ASC from 15 patients with newly diagnosed MM and 15 HD between 18 and 65 years. All gave their informed consent. The stromal vascular fraction was isolated from subcutaneous AT by and centrifugation. The ASC were sorted by adhesion to the plastic flask and expanded for 3 passages. We then performed the following assays to compare ASC from MM and HD: Results: The cell culture assay of ASC didn't show any difference between MM and HD for all the studied parameters: expansion capacity (HD 470± 45, MM 208±194; p=0.13), cell population doubling (HD 16.0±0.3, MM 15.0±1.3; p=0.17) and progenitor frequency (HD 3.4%±3, MM 3.7%±5.5; p=0.165). ASC phenotype didn't show any significant difference for all the checked markers and confirm their stromal feature: positive for CD90, CD73 and CD105, and negative for CD14 and CD45. The differentiation assay was evaluated for osteogenic, chondrogenic and adipogenic lineages. We did not underline any difference comparing ASC from MM or HD (Table 1). We previously showed that MM MSC secreted increased amount of IL-6, GDF15 and DKK-1 when compared with HD MSC. Interestingly, no difference was observed between MM ASC and HD ASC (Table 2). In the same way, contrary to MM MSC, MM ASC didn't promote the proliferation of MOLP-6 cell line better than HD ASC (proliferation rate: 1.49±0.34 for HD and 1.66±0.80 for MM; p=0.33). Conclusion: To our knowledge, this is the first study to compare ASC from MM patient and HD. These preliminary data suggest that ASC from MM patients are normal and could potentially be used in autologous stem cell transplantation for MM patients. We are currently completing this study by performing haematopoiesis support and microarrays assays. Disclosures: No relevant conflicts of interest to declare. </jats:sec

<scp>CD</scp> 146 expression on mesenchymal stem cells is associated with their vascular smooth muscle commitment

Bone marrow mesenchymal stem cells (MSCs) are plastic adherent cells that can differentiate into various tissue lineages, including osteoblasts, adipocytes and chondrocytes. However, this progenitor property is not shared by all cells within the MSC population. In addition, MSCs vary in their proliferation capacity and expression of markers. Because of heterogeneity of CD146 expression in the MSC population, we compared CD146(−/Low) and CD146(High) cells under clonal conditions and after sorting of the non-clonal cell population to determine whether this expression is associated with specific functions. CD146(−/Low) and CD146(High) bone marrow MSCs did not differ in colony-forming unit-fibroblast number, osteogenic, adipogenic and chondrogenic differentiation or in vitro haematopoietic-supportive activity. However, CD146(−/Low) clones proliferated slightly but significantly faster than did CD146(High) clones. In addition, a strong expression of CD146 molecule was associated with a commitment to a vascular smooth muscle cell (VSMC) lineage characterized by a strong up-regulation of calponin-1 and SM22α expression and an ability to contract collagen matrix. Thus, within a bone marrow MSC population, certain subpopulations characterized by high expression of CD146, are committed towards a VSMC lineage