title: Decellularized matrix from tumorigenic human mesenchymal stem cells promotes neovascularization with galectin-1 dependent endothelial interaction.
abstract: BACKGROUND
  Acquisition of a blood supply is fundamental for extensive tumor growth. We recently described vascular heterogeneity in tumours derived from cell clones of a human mesenchymal stem cell (hMSC) strain (hMSC-TERT20) immortalized by retroviral vector mediated human telomerase (hTERT) gene expression. Histological analysis showed that cells of the most vascularized tumorigenic clone, -BD11 had a pericyte-like alpha smooth muscle actin (ASMA+) and CD146+ positive phenotype. Upon serum withdrawal in culture, -BD11 cells formed cord-like structures mimicking capillary morphogenesis. In contrast, cells of the poorly tumorigenic clone, -BC8 did not stain for ASMA, tumours were less vascularized and serum withdrawal in culture led to cell death. By exploring the heterogeneity in hMSC-TERT20 clones we aimed to understand molecular mechanisms by which mesenchymal stem cells may promote neovascularization.
  
  
  RESULTS
  Quantitative qRT-PCR analysis revealed similar mRNA levels for genes encoding the angiogenic cytokines VEGF and Angiopoietin-1 in both clones. However, clone-BD11 produced a denser extracellular matrix that supported stable ex vivo capillary morphogenesis of human endothelial cells and promoted in vivo neovascularization. Proteomic characterization of the -BD11 decellularized matrix identified 50 extracellular angiogenic proteins, including galectin-1. siRNA knock down of galectin-1 expression abrogated the ex vivo interaction between decellularized -BD11 matrix and endothelial cells. More stable shRNA knock down of galectin-1 expression did not prevent -BD11 tumorigenesis, but greatly reduced endothelial migration into -BD11 cell xenografts.
  
  
  CONCLUSIONS
  Decellularized hMSC matrix had significant angiogenic potential with at least 50 angiogenic cell surface and extracellular proteins, implicated in attracting endothelial cells, their adhesion and activation to form tubular structures. hMSC -BD11 surface galectin-1 expression was required to bring about matrix-endothelial interactions and for xenografted hMSC -BD11 cells to optimally recruit host vasculature.
authors.affiliation: Molecular Endocrinology Laboratory KMEB, Department of Endocrinology and Metabolism, Odense University Hospital, University of Southern Denmark, Odense, Denmark. jorge.burns@unimore.it
authors.forename: Jorge S
authors.initials: JS
authors.lastname: Burns
authors.forename: Malthe
authors.initials: M
authors.lastname: Kristiansen
authors.forename: Lars P
authors.initials: LP
authors.lastname: Kristensen
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Larsen
authors.forename: Maria O
authors.initials: MO
authors.lastname: Nielsen
authors.forename: Helle
authors.initials: H
authors.lastname: Christiansen
authors.forename: Jan
authors.initials: J
authors.lastname: Nehlin
authors.forename: Jens S
authors.initials: JS
authors.lastname: Andersen
authors.forename: Moustapha
authors.initials: M
authors.lastname: Kassem
mesh_terms: D042683:Angiopoietin-1 / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D005260:Female; D037483:Galectin 1 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D013058:Mass Spectrometry; D059630:Mesenchymal Stem Cells / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D018613:Microscopy, Confocal; D009389:Neovascularization, Pathologic / Q000378:metabolism* / Q000473:pathology*; D040901:Proteomics; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: D042683:Angiopoietin-1; D037483:Galectin 1; D034741:RNA, Small Interfering; D042461:Vascular Endothelial Growth Factor A