ORMOSIL nanoparticles as a non-viral gene delivery vector for modeling polyglutamine induced brain pathology

Abstract

Studies have shown the presence of expanded polyQ containing proteins in brain cells related to Huntington disease (HD) and other poly-glutamine disorders. We report the use of organically modified silica (ORMOSIL) nanoparticles as an efficient non-viral gene carrier in an effort to model brain pathology associated with those disorders induced by expanded polyQ peptides. In experiment 1, plasmids expressing Hemaglutinin-tagged polypeptides with 20 glutamine repeats (Q20) or with extended 127-glutamine repeats (Q127) were complexed with ORMOSIL nanoparticles and injected twice (2 weeks apart) into the lateral ventricle of the mouse brain. Fourteen days post-injection of Q127, immunocytochemistry revealed the presence of the characteristic nuclear and cytoplasmic Q127 aggregates in numerous striatal, septal and neocortical neuronal cells as well as ubiquitin-containing aggregates indicative of the neuronal pathology. The mice receiving Q127 showed a marked increase in the reactive GFAP (+) astrocytes in striatum, septum and brain cortex, further indicating the neurodegenerative changes, accompanied by motor impairments. In experiment 2, plasmids Q20 or Q127 were complexed with ORMOSIL and were injected into the brain lateral ventricle or directly into the striatum of adult rats. In both routes of transfection, Q127 induced the appearance of reactive GFAP (+) astrocytes and activated ED1 antigen expressing microglia. An increase in the size of the lateral ventricle was also observed in rats receiving Q127. In transgenic mouse polyQ models, extensive pathologies occur outside the nervous system and the observed brain pathologies could reflect developmental effects of the toxic polyQ proteins. Our experiments show that the nervous tissue restricted expression of poly Q-extended peptides in adult brain is sufficient to evoke neuropathologies associated with HD and other polyQ disorders. Thus, nanotechnology can be employed to model pathological and behavioral aspects of genetic brain diseases in mice as well as in other species, providing a novel research tool for in vivo testing of single or multi-gene therapies.