Target-selective cytosolic delivery of cargo proteins using the VHH-presented OLE-ZIP capsules

In the pursuit of a new generation of protein pharmaceuticals, the efficient delivery of these therapeutics into cells stands out as a crucial challenge. In this study, we have developed a novel approach utilizing protein capsules modified with VHH antibodies as cytosolic carriers for protein pharmaceuticals. For the protein capsule component, we opted for the OLE-ZIP protein capsules, which can be prepared from the amphiphilic two-helix bundled protein OLE-ZIP using the water-in-oil (w/o) emulsion method. The spacious interior of the OLE-ZIP capsules allows for the stable encapsulation of over 200 molecules of protein pharmaceuticals, such as RNase A and Cre recombinase, in one capsule. By presenting the VHH antibody with an affinity for cell-type-specific receptors such as the epidermal growth factor receptor (EGFR) on the capsule surface, we achieved cell-type selective endocytic uptake in A431 cell lines (high expression level of EGFR) over NHDF and MCF-7 cells (normal expression level of EGFR). This selective uptake was followed by the subsequent release of the encapsulated protein pharmaceuticals into the cytosol of the target cells. Unlike our previous version of the OLE-ZIP protein capsules modified with IgG antibodies, cytosolic delivery of pharmaceutical proteins was little impacted by the presence of other IgGs, which are abundant in the bloodstream. This improved characteristic suggests potential advantages for practical applications, including intravenous administration.