Endothelial Differentiation of Hematopoietic Stem and Progenitor Cells from Patients with Multiple Myeloma

Abstract

Purpose: Vasculogenesis is a physiologic process typical of fetal development in which new blood vessels develop from undifferentiated precursors (or angioblasts). In tumors, near angiogenesis, vasculogenesis contributes to the formation of the microvascular plexus that is important for diffusion. Here, we show that hematopoietic stem and progenitor cells (HSPC) of multiple myeloma (MM) patients are able to differentiate into cells with endothelial phenotype on exposure to angiogenic cytokines. Experimental Design: Circulating HSPCs were purified with an anti-CD133 antibody from patients with newly diagnosed MM before autologous transplantation and exposed to vascular endothelial growth factor (VEGF), fibroblast growth factor-2 and insulin-like growth factor in a 3-week culture. Results: HSPCs gradually lost CD133 expression and acquired VEGF receptor-2, factor VIII–related antigen, and vascular endothelial-cadherin expression. The expression pattern overlapped with paired MM endothelial cells (MMEC). During culture, cells adhered to fibronectin, spread, and acquired an endothelial cell shape. Differentiated HSPCs also became capillarogenic in the Matrigel assay with maximal activity at the third week of culture. Bone marrow biopsies revealed HSPCs inside the neovessel wall in patients with MM but not in those with monoclonal gammopathy of undetermined significance. Conclusions: In patients with MM, but not in those with monoclonal gammopathy of undetermined significance, HSPCs contribute to the neovessel wall building together with MMECs. Therefore, besides angiogenesis, HSPC-linked vasculogenesis contributes to neovascularization in MM patients. Tentatively, we hypothesize that in HSPC cultures a multipotent cell population expressing low VEGF receptor-2 levels corresponds to the endothelial progenitor cell precursor and seems to be the MMEC precursor.

Validation of PDGFRβ and c-Src tyrosine kinases as tumor/vessel targets in patients with multiple myeloma: preclinical efficacy of the novel, orally available inhibitor dasatinib

“…Because PDGFR␤ is usually undetectable in quiescent microvascular ECs, 48,49 these findings emphasize the importance of epigenetic changes (ie, increased expression of PDGF-BB and PDGFR␤, at both mRNA and protein levels in MMECs) in promoting the "angiogenic switch" that occurs in the early stages of MM, and also potentially governs the MM cell resistance to drug-induced apoptosis in patients with progressive disease (ie, relapsed/refractory MM). 6,10 Intriguingly, a recent study demonstrated that PDGFR␤ is expressed on early hematopoietic/endothelial cell precursors (ie, hemangioblasts), and PDGF-BB is sufficient to promote their EC 51 hence sustaining an active "vasculogenic/ angiogenic phase," as the disease evolves. 7 Moreover, our data indicate that the constitutive autophosphorylation of pp60c-Src at tyrosine (Y)-418 in MM patient-derived tumor/ECs may further represent a robust read-out of SFKs activity during the clinical assessment of dasatinib in MM.…”

Spontaneous origin from human embryonic stem cells of liver cells displaying conjoint meso-endodermal phenotype with hepatic functions

“…To study the differentiation capacity of hESC-MECs, we induced osteogenic, adipogenic and endothelial lineages by established protocols over 3 weeks in vitro (supplementary material Fig. S4) (Dan et al, 2006;Inada et al, 2008b;Ria et al, 2008). The hESC-MECs generated osteocytes, adipocytes and endothelial-like cells, which is similar to the differentiation ability of fetal human liver stem cells (Inada et al, 2008b).…”

“…For endothelial differentiation (Ria et al, 2008), cells were cultured on fibronectin (Sigma, St Louis, MO). For endoderm differentiation, cells were cultured in RPMI 1640 medium without serum for 2 days, 0.2% serum for 2 days and 2% serum for 2 weeks, with activin A (100 ng/ml), a-FGF (100 ng/ml), HGF (20 ng/ml), OSM (20 ng/ml), DKK-1 (20 ng/ml) (R&D Systems), trichostatin A (100 nM/ml), and c-secretase inhibitor X (Calbiochem, La Jolla, CA) (supplementary material Table S3).…”

Deciphering the Key Features of Malignant Tumor Microenvironment for Anti-cancer Therapy

“…The activated TAMs can release various niche factors, such as growth factors, chemokines, and proteolytic enzymes to promote TME formation. Bone marrow-derived monocytes and macrophages contribute to vasculogenesis in multiple myeloma, and bone marrow macrophages from multiple myeloma patients can form a capillarylike network and contribute to the malignancy of multiple myeloma [89,90]. In addition, Tie2-expressing monocytes have nonredundant function to promote tumor angiogenesis and genesis of TME in mice [88].…”