Local presentation of cancer drugs by injectable drug-eluting depots reduces systemic side effects and improves efficacy. However, local depots deplete their drug stores and are difficult to introduce into stiff tissues, or organs, such as the brain, that cannot accommodate increased pressure. We present a method for introducing targetable depots through injection of activated ester molecules into target tissues that react with and anchor themselves to the local extracellular matrix (ECM) and subsequently capture systemically administered small molecules through bioorthogonal click chemistry. A computational model of tissue-anchoring depot formation and distribution was verified by histological analysis and confocal imaging of cleared tissues. ECM-anchored click groups do not elicit any noticeable local or systemic toxicity or immune response and specifically capture systemically circulating molecules at intradermal, intratumoral, and intracranial sites for multiple months. Taken together, ECM anchoring of click chemistry motifs is a promising approach to specific targeting of both small and large therapeutics, enabling repeated local presentation for cancer therapy and other diseases.
Rationale: Within the field of personalized medicine there is an increasing focus on designing flexible, multifunctional drug delivery systems that combine high efficacy with minimal side effects, by tailoring treatment to the individual. Methods: We synthesized a chemically stabilized ~4 nm nucleic acid nanoscaffold, and characterized its assembly, stability and functional properties in vitro and in vivo. We tested its flexibility towards multifunctionalization by conjugating various biomolecules to the four modules of the system. The pharmacokinetics, targeting capability and bioimaging properties of the structure were investigated in mice. The role of avidity in targeted liver cell internalization was investigated by flow cytometry, confocal microscopy and in vivo by fluorescent scanning of the blood and organs of the animals. Results: We have developed a nanoscaffold that rapidly and with high efficiency can self-assemble four chemically conjugated functionalities into a stable, in vivo-applicable system with complete control of stoichiometry and site specificity. The circulation time of the nanoscaffold could be tuned by functionalization with various numbers of polyethylene glycol polymers or with albumin-binding fatty acids. Highly effective hepatocyte-specific internalization was achieved with increasing valencies of tri-antennary galactosamine (triGalNAc) in vitro and in vivo. Conclusion: With its facile functionalization, stoichiometric control, small size and high serum- and thermostability, the nanoscaffold presented here constitutes a novel and flexible platform technology for theranostics.
