Cell "vaults" are natural nano-capsules in cells that scientists use to monitor gene activity. These structures consist of 78 copies of the main vault protein (MVP), which binds with weak non-covalent interactions, allowing the vaults to "breathe" and let small molecules through. Scientists synthesize them in genetically modified yeast and infuse them with molecules such as the tumor-fighting immune signaling molecule CCL21. Vault Pharma is planning a clinical trial on advanced cancer patients later this year, which would be the first time synthetic vaults would enter the human body. The method uses the INT domain from the VPARP protein to target foreign molecules to the interior of the vaults. In a November 2023 preprint study, the vaults successfully delivered AAV viruses into cells, where they released the genetic cargo and evaded antibodies, solving the problem of AAV immunity. Vaults have demonstrated functionality in both cells and the test tube, for example with a fluorescent protein or the enzyme luciferase.[1][2][3]