Microglia and astrocytes are glial cell types in the brain that interact directly with neurons to maintain neural
tissue homeostasis. We are beginning to understand that glial cell dysfunctions contribute to the early damage
of neural circuits that manifests disease symptoms in many neurodegenerative disorders. Despite the
contributions of glia to CNS disorder progression, we currently have limited approaches to target these cells
preferentially for therapy. Viral vectors are used routinely in preclinical CNS models for cell specific targeting,
but there are limitations with these technologies including poor transduction efficiency in glia, low specificity,
immune activation, and off-target effects. The emergence of comprehensive glial cell specific transcriptomics
information has enabled the identification of unique molecular features on the surface of different glial cells that
can be used to develop innovative targeted non-viral drug delivery approaches. With the overall goal of
developing effective nanoparticle-based strategies to deliver therapies to specific glial cell types to correct
dysfunctions that cause CNS disease, this project’s main objectives are to: 1) optimize dendrimer
nanoparticles with multivalent functionalization of ligands for specific cell surface transporters that are uniquely
and highly expressed on microglia and astrocytes, and 2) test the glial cell specific delivery of mRNA afforded
by these nanoparticles when injected locally into different brain regions or neuroinflammatory states. Our
hypothesis is that intracerebral injection of nanoparticles with multivalent presentation of specific ligands will
enable preferential binding and subsequent uptake of nanoparticles into the glial cells that uniquely express the
transporter for that ligand, thereby enabling highly specific mRNA delivery. In the first aim, we will optimize
dendrimer nanoparticles with multivalent presentation of microglia and astrocyte targeting molecules and
ionizable tertiary amines for mRNA loading. Using an in silico unsupervised analysis of published glia
transcriptomes we have identified specific cell surface transporters that are uniquely and highly expressed on
microglia and astrocytes respectively that can be targeted with known ligands that we can readily conjugate to
dendrimer nanoparticles. We will use several in vitro screening assays to optimize dendrimers for mRNA
loading and delivery. In the second aim, we will test glial cell targeting of dendrimer nanoparticles in the mouse
brain under healthy and neuroinflammation states and use functional delivery of Cre recombinase mRNA in
Ai14 transgenic reporter mice to determine efficacy. Through this project, we will provide new insights into the
biology of transporters and their involvement in trafficking and uptake mechanisms in glia that can be used to
improve drug delivery outcomes. This work will also enable innovations in nanoparticle design for exogenous
targeting of therapies in the CNS that will have broad implications for treating neurological disease.