How do you optimize in vivo gene delivery for different target tissues?

In vivo delivery optimization considers: vector selection (AAV serotype tropism - AAV9 for CNS, AAV8 for liver; LNPs for hepatocytes), route of administration (systemic IV, local injection, intrathecal), dose determination (balancing efficacy with immunogenicity and toxicity), targeting strategies (engineered capsids, tissue-specific promoters, microRNA de-targeting of off-target tissues), and managing immune responses (capsid immunity, transgene immunity, innate responses). Pre-existing anti-AAV antibodies limit patient eligibility. Durability depends on target cell turnover and episome persistence. Emerging approaches include engineered capsids from directed evolution (AAV-PHP.eB for CNS), LNP optimization for non-liver targets, and transient immunosuppression. Each tissue presents unique barriers - BBB penetration, immune privileged sites, target cell transduction efficiency.