title: Isolation and characterization of bone marrow-derived progenitor cells from malignant gliomas.
abstract: BACKGROUND
  Malignant gliomas are highly-vascularised tumours. Neoangiogenesis is a crucial factor in the malignant behaviour of tumour and prognosis of patients. Several mechanisms are suspected to lead to neoangiogenesis, one of them is the recruitment of multipotent progenitor cells towards the tumour. Factors such as Vascular endothelial growth factor-A (VEGF-A) were described to recruit bone marrow-derived endothelial progenitor cells (EPCs) to the glioma stroma and vasculature. Little is known about isolating EPCs from normal or malignant tissues.
  
  
  METHODS
  In this study, we addressed the topic of characterization of tumour-isolated EPCs and re-defined the clonal relationship between EPCs and hematopoietic stem cells (HSCs) in gliomas. We first checked public gene expression data of glioma for putative marker expression, pointing towards a prevalence of EPCs and HSCs in glioma. Immunohistochemical staining of glioma tissue confirmed the higher expression of these progenitor markers in glioma tissue. EPCs and HSCs were consequently isolated and characterized at the phenotypic and functional levels. We applied a new isolation method, for the first time, to specimen from patients with high grade glioma including seven grade IV glioblastoma, five-grade III astrocytoma, and three grade III oligoastrocytoma.
  
  
  RESULTS
  In all samples, we were able to isolate the tumour-derived EPCs, which were positive for characteristic markers: CD31, CD34 and VEGFR2. The EPCs formed capillary networks in vitro and had the ability to take up acetylated low-density lipoprotein. Glioma-derived HSCs were positive for CD34 and CD45, but they were unable to form a capillary network in vitro. These findings on tumour-derived EPCs/HSCs were in concordance with the results, derived from peripheral blood of healthy volunteers.
  
  
  CONCLUSIONS
  In our study, we established a new method for EPC/HSC isolation from human gliomas, defined the contribution of EPCs and HSCs to the tumour tissue, and highlighted the intense in vivo tumour host interaction.
authors.affiliation: Tumour Biological Laboratory, Department of Neurosurgery, Ludwig-Maximilians-University of Munich, Marchioninistr. 15, D81377 Munich, Germany. ketaiguo@gmail.com
authors.forename: Ke-Tai
authors.initials: KT
authors.lastname: Guo
authors.forename: Kathrin
authors.initials: K
authors.lastname: Juerchott
authors.forename: Peng
authors.initials: P
authors.lastname: Fu
authors.forename: Joachim
authors.initials: J
authors.lastname: Selbig
authors.forename: Sabina
authors.initials: S
authors.lastname: Eigenbrod
authors.forename: Jörg-Christian
authors.initials: JC
authors.lastname: Tonn
authors.forename: Christian
authors.initials: C
authors.lastname: Schichor
mesh_terms: D001854:Bone Marrow Cells / Q000166:cytology; D001932:Brain Neoplasms / Q000473:pathology*; D002469:Cell Separation / Q000379:methods*; D042783:Endothelial Cells / Q000166:cytology*; D005910:Glioma / Q000473:pathology*; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D007150:Immunohistochemistry; D009389:Neovascularization, Pathologic / Q000473:pathology; D013234:Stem Cells / Q000166:cytology