Isolation & Characterization of Brain Tumor Stem Cells (BTSC) in Human Glioblastomas (GBs)
JC Martinez, MV Toledo, C Sanfeliu, S Sacristan, R Samaniego. Hospital Ramon y Cajal, Madrid, Spain; Universidad de Alcala, Madrid, Spain; IIBB, CSIC-IDIBAPS, Barcelona, Spain; Hospital U G Maraon, Madrid, Spain
Background: Recent studies are suggesting that gliomas, develop from a subset of cells with self-renewal capacity stem-like cells. GB research, is showing evidences that brain tumor stem-cells (BTSC) drive tumorigenesis. BTSC isolated from GBs transplanted into immunodeficient animals generate GBs. However transplanted GBs cell lines devoid of BTSC do not generate tumors. BTSC are identified by their capacity to form neurospheres in culture, that express progenitor/ stem cell markers, like CD133, Nestin, Wnt, CXCR4, etc. Furthermore, BTSC expressing CD133 have been shown to be more resistant to radiation, being responsible of radiation treatment failure. Most studies were done in vitro or in animal models. We have addressed whether a population of BTSC exists in human GBs, that can be characterized phenotypically, to study patterns of expresssion & get insights into the biology of GBs.
Design: GBs disaggregated to single cells, were cultured with EGF & hFGF. Neuroespheres were harvested at 6 weeks. After centrifugation, the pellet was fixed, paraffin embedded and sectioned. Neuroespheres & original GB specimens from which they were generated, were immunostained with CD133, Nestin, Wnt1, CXCR4 & VEGFR3.
Results: CD133, Nestin, Wnt1, CXCR4 & VEGFR3 were expressed by neuroespheres with variable intensity, consistent with their heterogeneous nature. GBs displayed expression of these antigens by groups of neoplastic cells identified as BTSC with the following patters: -Frequent expression by perivascular cells, neoplastic vessels & perinecrotic palisades. -Increased expression by infiltrating marginal cells, versus the central tumoral areas. -High levels at the most anaplastic areas.
Conclusions: The patterns of expression of the BTSC subpopulation in GBs argues for their role as cancer driving cells. 1) The expression of stem/progenitor markers support their property as self-renewal neoplastic elements. 2) The perivascular and endothelial proliferating cells location of BTSC, argues for a role in neoplastic angiogenesis, a hallmark of glioma anaplasia. 3) The high levels of BTSC observed at infiltrating margins and perinecrotic palisades, are in keep with their suggested invasive function. This raises the importance of using BTSC as therapeutic targets to improve treatment success.
Tuesday, March 10, 2009 9:30 AM
Poster Session III # 195, Tuesday Morning