Glia Exclusive Gene Therapy

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Abstract Glia are supportive cells in the human brain, comprising microglia, oligodendrocytes, astrocytes, and ependymal cells. Glia are deeply involved in diseases of the nervous system such as Alzheimer’s (AD), autism, pain, affective disorders, and cancers. Different glial cell types play different mechanistic roles in disease formation, driven by specific genes. Modulating glial gene expression via a process called gene therapy could thus be studied as a means of preventing deleterious effects of glia in the brain. However, while significant progress has been made in delivering genes exclusively to neurons, such capabilities are lacking for glia, despite their demonstrated role in disease formation, posing a critical medical need. Although gene delivery to neurons can be achieved using viral vectors, their use to transmit genes to glia in-vivo has been unsuccessful. Here, we propose to design a novel nonviral gene delivery vector targeting microglia or astrocytes exclusively by bioengineering Modified RNAs (ModRNAs). ModRNAs are synthetic RNA molecules known not to trigger an immune response and are strongly expressed in target cells. Currently, ModRNAs enable only days- long expression, impeding long-duration medical applications and lacking cell specificity to glia types. We will engineer glia-type-specific, ModRNAs-based constructs, GliaRNAs, as a platform for glia-exclusive gene therapy, with a customizable expression duration. First, ModRNAs that enable robust and prolonged expression (7-14 days) will be developed (Aim 1). For this purpose, existing ModRNA will be altered, through modifications and by inflicting random mutations of structural components of the molecule, including CAP analog, 3’ untranslated region, coding region, 5’ untranslated region, and the poly-A tail. We will test the expression of these novel GliaRNAs in glial cultures from mice. Next, the vector specificity will be optimized (Aim 2). We will screen for molecular manipulations that enable robust and specific delivery of the GliaRNAs into either microglia or astrocytes (GliaRNA-vectors) and select the best gene delivery vectors, specifically either lipid nanoparticles, antibody-lipid conjugates, or aptamers. As a proof of concept, we will use the new GliaRNA-vector technology to express the green fluorescent protein (GFP) in either astrocytes or microglia in mice brains. The GliaRNA-vector platform will pave the way for genetically healing and modifying different types of glia, opening multiple therapeutic and research avenues in humans by targeting neurodegeneration, autism, pain disorders, mood disorders, and brain cancers.