30. Modulation of Intracellular Calcium Enhances AAV Transduction in the CNS

Recent preclinical studies and clinical trials utilizing recombinant AAV vectors have highlighted vector dose-related toxicity as a potential safety concern. Therefore, strategies to enhance AAV transduction may mitigate this toxicity, as they may allow for administration of lower vector doses. While some strategies rely on modification of the capsid to achieve such, pharmacological modulation of the cellular environment often has the benefit of enhancing AAV transduction independent of capsid serotype. Intracellular calcium is important in the life cycles of several viruses, such as Ebola virus and rotavirus. Several small molecule drugs and biologics exist that can modify intracellular calcium levels in a specific manner. In the current study, we sought to determine if modulation of intracellular calcium levels affects AAV transduction. Increasing intracellular calcium levels using either thapsigargin or ionomycin decreased AAV transduction by an order of magnitude. Conversely, decreasing intracellular calcium levels using the cell permanent calcium chelator BAPTA-AM increased transduction by 10 to 100-fold in a cell independent fashion. In addition, the effects of modification of intracellular calcium are not dependent on AAV serotype. Furthermore, in vivo studies performed in mice demonstrate that BAPTA-AM augments transduction by different AAV serotypes, when administered intracranially. In summary, our results support the preclinical evaluation of drugs and biologics that modulate intracellular calcium in the CNS and evaluate their potential for affecting AAV transduction. Results from ongoing studies in mouse models of disease will be presented.