Protein Nanocarrier for Targeted Intracellular Delivery of Functional Antibodies
Lukianov, Cyril Igorevich
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The cell membrane remains a formidable barrier for antibody-based therapies, and efficient intracellular delivery of functional antibodies may be critical for modulating intracellular signaling mechanisms and protein-protein interactions involved in various disorders. This study utilized protein engineering techniques to develop a novel nanocarrier that is capable of delivering functional antibodies to the intracellular environment. Each nanocarrier contains six SPAB antibody-binding domains, and is therefore capable of delivering up to six antibodies. The interaction between the SPAB domain of the nanocarrier and the heavy chain constant region of the antibody is noncovalent, thus allowing the nanocarrier to bind different functional antibodies with the same affinity. Three iRGD domains were integrated into the nanocarrier structure to allow for selective targeting of integrin-overexpressing cells. We successfully expressed the protein monomers, assembled the functional nanocarrier, and investigated its antibody-binding properties. Results of cellular uptake studies involving HeLa, MCF-7, as well as SK-BR-3 cancer cell lines indicate significant cellular uptake of antibody-loaded nanocarrier as compared to soluble antibody control. Without any modification of the carrier, we also used HER2 targeting antibodies to direct the carriers preferentially into HER2-positive SK-BR-3 cells. In addition to efficient cellular uptake, the highly biocompatible and modular nature of our nanocarrier makes it ideal for expanding the scope of antibody-based therapeutics to the intracellular environment.