Preparations of mesenchymal stromal cells (MSCs) are generally obtained from unfractionated tissue cells, resulting in heterogeneous cell mixtures. Several markers were proposed to enrich these cells, but the majority of these markers are defined for bone marrow (BM). Moreover, the surface markers of freshly isolated MSCs also differ from those of cultured MSCs in addition to a phenotypic variation depending on the MSC source. For tissue engineering applications, it is crucial to start with a well-defined cell population. In this study, we performed immunomagnetic selections with five single surface markers to isolate MSC subpopulations from BM and adipose tissue (AT): CD271, SUSD2, MSCA-1, CD44, and CD34. We determined the phenotype, the clonogenicity, the proliferation, the differentiation capacity, and the immunoregulatory profile of the subpopulations obtained in comparison with unselected cells. We showed that native BM-MSCs can be enriched from the positive fractions of MSCA-1, SUSD2, and CD271 selections. In contrast, we observed that SUSD2 and MSCA-1 were unable to identify MSCs from AT, meaning they are not expressed in situ. Only the CD34(+) selection successfully isolated MSCs from AT. Interestingly, we observed that CD271 selection can define AT cell subsets with particular abilities, but only in lipoaspiration samples and not in abdominoplasty samples. Importantly, we found a population of clear CD34(+) fresh BM-MSCs displaying different properties. A single marker-based selection for MSC enrichment should be more advantageous for cell therapy and would enable the standardization of efficient and safe therapeutic intervention through the use of a well-identified and homogeneous cell population.
BackgroundIn multiple myeloma, bone marrow mesenchymal stromal cells support myeloma cell growth. Previous studies have suggested that direct and indirect interactions between malignant cells and bone marrow mesenchymal stromal cells result in constitutive abnormalities in the bone marrow mesenchymal stromal cells.Design and MethodsThe aims of this study were to investigate the constitutive abnormalities in myeloma bone marrow mesenchymal stromal cells and to evaluate the impact of new treatments.ResultsWe demonstrated that myeloma bone marrow mesenchymal stromal cells have an increased expression of senescence-associated β-galactosidase, increased cell size, reduced proliferation capacity and characteristic expression of senescence-associated secretory profile members. We also observed a reduction in osteoblastogenic capacity and immunomodulatory activity and an increase in hematopoietic support capacity. Finally, we determined that current treatments were able to partially reduce some abnormalities in secreted factors, proliferation and osteoblastogenesis.ConclusionsWe showed that myeloma bone marrow mesenchymal stromal cells have an early senescent profile with profound alterations in their characteristics. This senescent state most likely participates in disease progression and relapse by altering the tumor microenvironment.
Interactions between chronic lymphocytic leukemia (CLL) B cells and the bone marrow (BM) microenvironment play a major function in the physiopathology of CLL. Extracellular vesicles (EVs), which are composed of exosomes and microparticles, play an important role in cell communication. However, little is known about their role in CLL / microenvironment interactions. In the present study, EVs purified by ultracentrifugation from BM mesenchymal stromal cell (BM-MSC) cultures were added to CLL B cells. After their integration into CLL B cells, we observed a decrease of leukemic cell spontaneous apoptosis and an increase in their chemoresistance to several drugs, including fludarabine, ibrutinib, idelalisib and venetoclax after 24 hours. Spontaneous (P=0.0078) and stromal cell-derived factor 1α -induced migration capacities of CLL B cells were also enhanced (P=0.0020). A microarray study highlighted 805 differentially expressed genes between leukemic cells cultured with or without EVs. Of these, genes involved in the B-cell receptor pathway such as CCL3/4, EGR1/2/3, and MYC were increased. Interestingly, this signature presents important overlaps with other microenvironment stimuli such as B-cell receptor stimulation, CLL/nurse-like cells co-culture or those provided by a lymph node microenvironment. Finally, we showed that EVs from MSCs of leukemic patients also rescue leukemic cells from spontaneous or drug-induced apoptosis. However, they induce a higher migration and also a stronger gene modification compared to EVs of healthy MSCs. In conclusion, we show that EVs play a crucial role in CLL B cells/BM microenvironment communication.
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