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Gene-engineered
primary neural stem/progenitor cells for treatment of malignant brain
tumors
Aurelio Lorico, Victor Solodushko, Oystein Fodstad, Germana Rappa
Univ. of South Alabama Cancer Inst., Mobile, AL, Norwegian Radium
Hospital, Oslo, Norway
A major obstacle to the
treatment of malignant brain tumors is their propensity to infiltrate
surrounding tissue and migrate through normal brain, rendering them
unavailable to surgical resection or radio-therapeutic
treatment.
Neural stem/progenitor cells
(NSCs) can migrate through normal brain tissue along non-stereotypical
routes targeting tumor cells.
We have previously developed a
protocol based on adherent culture of NSCs on recombinant fibronectin
to transduce genes into up to 90% NSCs at a multiplicity of infection
of 2 without loss of their stem cell nature or
multipotentiality.
We have now transduced at high
efficiency primary cultures of murine NSCs with SF91-based retroviral
vectors expressing the fluorescent marker, eGFP alone or in
association with the prodrug-activating enzyme, CYP2B6, or with the
anti-angiogenic molecule, endostatin.
We have found that
orthotopically implanted gene-engineered NSCs track and co-localize
with human DS-red-expressing U87Mg glioblastoma cells pre-implanted in
the brains of athymic mice.
To prove that SF91-mediated
expression of CYP2B6 activates cyclophosphamide (CPA) and that
activated CPA metabolites are then released into the culture medium
and kill bystander brain cancer cells, we have exposed parallel
cultures of 3T3/CYP2B6-eGFP and 3T3/eGFP cells (as control) to
different concentrations of CPA for 24 hours.
The conditioned media were then
added to DS-red-labeled U87Mg glioblastoma cells.
24 hours after the addition of
conditioned medium from 3T3/CYP2B6-eGFP, a clear cell killing effect
was observed.
No effect on cell growth was
observed after the addition of conditioned medium from 3T3/eGFP
cells.
Studies are ongoing in our lab
to demonstrate that NSCs, transduced with a retroviral vector
co-expressing endostatin and CYP2B6, can track DS-red-expressing U87Mg
cells in athymic mice and halt their growth upon systemic
administration of CPA.
Copyright © 2005 American
Association for Cancer Research. All rights reserved.
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