Targeted cellular micropharmacies deliver therapeutic agents to the brain

The systemic administration of therapeutic agents, particularly large, charged molecules such as antibodies, has limited efficacy in treating central nervous system (CNS) disorders. In addition, the slow progression of neurodegenerative diseases makes repeated intrathecal injections unfeasible. Alzheimer's disease is characterized by the accumulation of Aβ amyloid plaques. Microglia contribute to the clearance of Aβ, but are inhibited by the expression of CD33. Therefore, antibody blocking of CD33 may enhance the phagocytosis of Aβ by microglial cells, slowing AD progression. Here, we use cells as "targeted cellular micropharmacies" that are retained in the CNS to deliver therapeutic proteins directly into the brain. To achieve this, we genetically engineered CD4 T-cells to express: (1) a chimeric antigen receptor against GD2 to retain the cells in the brain, (2) ectopic FoxP3 to reduce inflammation, (3) secreted IL-2 to promote cell longevity, and (4) secreted anti-CD33 scFv antibody. Our proof-of-concept demonstrates that therapeutic antibodies can be delivered to the brain for at least 8 weeks to treat neurological disorders. Other agents could be similarly delivered into the brain by this platform.