Assembly of targeting complexes driven by a single-chain antibody

Area of Science:

• Biotechnology
• Molecular Biology
• Drug Delivery Systems

Background:

• Recombinant antibodies and fragments targeting cell surface markers offer therapeutic potential.
• Chemical conjugation and lack of internalization hinder antibody-based drug delivery.
• Vascular Endothelial Growth Factor Receptor 2 (VEGFR-2) is a key target for cancer therapies.

Purpose of the Study:

• To convert a non-internalizing single chain variable fragment (scFv) antibody into a versatile targeting protein.
• To develop novel targeting complexes for intracellular delivery of therapeutic agents.
• To investigate targeted DNA delivery using a modified non-internalizing antibody.

Main Methods:

• Engineered a non-internalizing scFv (P4G7) targeting VEGFR-2 into a targeting protein (Hu-P4G7) with a docking tag.
• Assembled targeting complexes by docking S-protein-DNA conjugates to Hu-P4G7.
• Tested DNA delivery into VEGFR-2 expressing cells with and without VEGF.

Main Results:

• Hu-P4G7 and its complexes effectively bound soluble and cellular VEGFR-2.
• Hu-P4G7-based complexes did not deliver DNA into cells without VEGF.
• Selective DNA delivery into VEGFR-2 overexpressing cells was achieved in the presence of VEGF.

Conclusions:

• A non-internalizing scFv can be repurposed as a targeting protein for novel drug delivery systems.
• VEGF can facilitate targeted intracellular delivery by non-internalizing antibody complexes.
• This approach offers a new strategy for targeted intracellular drug delivery, overcoming previous limitations.