Polymeric Nanoparticle-Mediated Gene Delivery to Human Astrocytes
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Purpose: Astrocyte tissue-inhibitor of metalloproteinases-1 (TIMP-1) protects neurons during HIV-1-induced apoptosis. However, TIMP-1 levels decrease during chronic inflammation typical of HIV-associated neurocognitive disorders (HAND). We propose that astrocyte-targeted TIMP-1-gene delivery could be a suitable therapeutic for HAND. Nanoparticle (NP)-mediated gene delivery is a viable approach since genes can be delivered to specific brain cell types and NPs are less immunogenic than viral vectors. To test this hypothesis, obtaining a safe and effective gene delivery system is essential. Methods: We tested the gene delivery potential of arginine-based polyethylenimine (PEI) analogs (AnPn) and poly-lactic-co-glycolic-acid (PLGA) in vitro (primary human cells) and in vivo (mice) using a luciferase-reporter plasmid (pLuc). Immunocytochemisty and immunohistochemistry were carried out using antibodies specific to glial fibrillary acidic protein (GFAP), microtubule-associated protein 2 (MAP2), and luciferase. Results: PLGA NPs delivered pLuc across astrocyte plasma membrane but failed to induce protein expression. In parallel, A5P50, a PEI analog, efficiently expressed pLuc in astrocytes. Yet, its neuronal biocompatibility was not optimal. Combining low doses of AnPn with pLuc-loaded-PLGA NPs lead to high gene expression in all cell types including astrocytes. Live imaging indicated that AnPn facilitated PLGA-released-pLuc delivery across the nuclear membrane by an unknown mechanism. Consequently, optimally biocompatible PEI analogs were also synthesized and tested. Conclusions: Our data indicate that AnPn-PLGA combination and new AnPn analogs overcome both neuronal biocompatibility and astrocyte-specific gene expression issues promising clinical translations for HAND treatment in future.