PubMed · 16440648
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M Riminucci. 2005. [Bone stem cells].. https://pubmed.ncbi.nlm.nih.gov/16440648/
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Accumulating evidence indicates that the cellular microenvironment plays a key role in follicular lymphoma (FL) pathogenesis, both within tumor lymph nodes (LNs) and in infiltrated bone marrow where ectopic LN-like reticular cells are integrated within malignant B-cell nodular aggregates. In normal secondary lymphoid organs, specific stromal cell subsets provide a highly specialized microenvironment that supports immune response. In particular, fibroblastic reticular cells (FRCs) mediate immune cell migration, adhesion, and reciprocal interactions. The role of FRCs and their postulated progenitors, that is, bone marrow mesenchymal stem cells (MSCs), in FL remains unexplored. In this study, we investigated the relationships between FRCs and MSCs and their capacity to sustain malignant B-cell growth. Our findings strongly suggest that secondary lymphoid organs contain MSCs able to give rise to adipocytes, chondrocytes, osteoblasts, as well as fully functional B-cell supportive FRCs. In vitro, bone marrow-derived MSCs acquire a complete FRC phenotype in response to a combination of tumor necrosis factor-alpha and lymphotoxin-alpha1beta2. Moreover, MSCs recruit primary FL cells that, in turn, trigger their differentiation into FRCs, making them able to support malignant B-cell survival. Altogether, these new insights into the cross talk between lymphoma cells and their microenvironment could offer original therapeutic strategies.
Angiogenesis plays a significant role in a variety of malignant hematologic diseases, and it is recognized that it has prognostic value. However, the cellular mechanisms by which malignant hematologic cells induce angiogenesis are not well understood. In order to investigate the role of cells from B-cell chronic lymphocytic leukemia (B-CLL) and multiple myeloma (MM) in angiogenesis on human bone marrow endothelial cells (HBMEC), we analyzed the impact of factors secreted by B-CLL cells and by MM cells on HBMEC capillary tube formation on matrigel. It was found that, in addition to the secretion of angiogenic factors VEGF and b-FGF by B-CLL and MM cells, MM cells (but not B-CLL cells) induced a dramatic increase in expression of VEGFR-1 and VEGFR-3 on human bone marrow endothelial cells (HBMEC). It would seem that this increase in VEGFR-3 occurred via the ERK and mTOR pathways, since their respective inhibitors U0126, LY294002 or rapamycin were responsible for a decrease of VEGFR-3. In response to MM cells-increased VEGF receptors on HBMEC, endothelial cell migration was enhanced in a wound artificially produced in a semi-confluent HBMEC culture, a phenomenon which was also down-regulated by the same inhibitors that reversed the increase in VEGF receptors. The present study suggests that, in addition to the classic angiogenic pathway, another mechanism related to an increased expression of VEGFRs on HBMEC might exist in malignant hematopoietic angiogenesis.
AIM: To isolate putative pancreatic stem cells (PSCs) from human adult tissues of pancreas duct using serum-free, conditioned medium. The characterization of surface phenotype of these PSCs was analyzed by flow cytometry. The potential for pancreatic lineage and the capability of beta-cell differentiation in these PSCs were evaluated as well. METHODS: By using serum-free medium supplemented with essential growth factors, we attempted to isolate the putative PSCs which has been reported to express nestin and pdx-1. The Matrigel(TM) was employed to evaluate the differential capacity of isolated cells. Dithizone staining, insulin content/secretion measurement, and immunohistochemistry staining were used to monitor the differentiation. Fluorescence activated cell sorting (FACS) was used to detect the phenotypic markers of putative PSCs. RESULTS: A monolayer of spindle-like cells was cultivated. The putative PSCs expressed pdx-1 and nestin. They were also able to differentiate into insulin-, glucagon-, and somatostatin-positive cells. The spectrum of phenotypic markers in PSCs was investigated; a similarity was revealed when using human bone marrow-derived stem cells as the comparative experiment, such as CD29, CD44, CD49, CD50, CD51, CD62E, PDGFR-alpha, CD73 (SH2), CD81, CD105(SH3). CONCLUSION: In this study, we successfully isolated PSCs from adult human pancreatic duct by using serum-free medium. These PSCs not only expressed nestin and pdx-1 but also exhibited markers attributable to mesenchymal stem cells. Although work is needed to elucidate the role of these cells, the application of these PSCs might be therapeutic strategies for diabetes mellitus.