Baculoviral vectors as a gene therapy tool for gene delivery into astrocytes

MATÍAS GARCIA FALLIT; MATÍAS L. PIDRE; ANTONELA S. ASAD; JORGE A. PEÑA AGUDELO; SOFÍA SAGRIPANTI; ALEJANDRO J. NICOLA CANDIA; MELANIE PÉREZ KUPER; ABRIL MARCHESINI; LESLIE C. AMORÓS MORALES; NAZARENO GONZALEZ; VICTOR ROMANOWSKI; ADRIANA SEILICOVICH; MARIANA B. VERA; GUILLERMO VIDELA RICHARDSON; CARLA CARUSO; FLAVIA ZANETTI; MARIANELA CANDOLFI

CABA

Encuentro; PRIMER ENCUENTRO DEL CLUB DE LA GLÍA CONO SUR; 2022

Sociedad Neurologica Argentina

In search for better approaches to treat gliomas we developed baculoviral vectors (BVs) to deliver therapeutic transgenes into these brain tumors. Although recombinant adenoviral (AdV) vectors are the gold standard in neuro-oncology due to their robust transduction efficiency and optimal safety profile, they are highly immunogenic and virtually the entire general population has pre-existing anti-AdV immunity, which leads to transient transgene expression. These limitations impair therapeutic efficacy and have led us to search for alternative therapeutic vectors. Since BVs are natural pathogens of insects, no pre-existing immunity against BVs has been reported in humans so far, making it a great candidate for gene delivery to the brain. We evaluated the transduction efficiency and toxicity of BVs in normal and neoplastic astrocytes in vitro and in vivo and compared them with those of AdV. Our hypothesis was that BVs constitute a useful tool for the persistent expression of therapeutic transgenes to treat brain disorders. Therefore, we constructed AdV and BV encoding fluorescent proteins under the control of the cytomegalovirus (CMV) promoter. Using microscopy and flow cytometry, we found that both vectors exert robust transduction efficiency in murine and human glioma cell lines and short cultures derived from biopsies, as well as rat and mouse astrocytes. To assess transduction efficiency and neuropathology in vivo, vectors were injected by stereotactic surgery into the brain of mice with or without intracranial gliomas. Transduction efficiency was comparable with both vectors, as it was immune infiltration at the injection site, with no obvious signs of neurotoxicity. Both vectors efficiently transduced tumor cells and non-neoplastic astrocytes. Transgene expression was detected 7 and 21 days after injection in naïve brain, and it was lost when mice were preimmunized systemically with BVs. Our findings indicate that BVs are excellent tools for transgene delivery in glioma cells and normal astrocytes.