Anti-PEG Single-Chain Variable-Fragment Antibody-Assisted In Vivo Process Decoding of PEGylated Nanomedicines

Area of Science:

• Nanomedicine
• Pharmacokinetics
• Biotechnology

Background:

• Clinical nanomedicine translation is limited by poor understanding of in vivo drug behavior.
• Quantifying encapsulated versus free drug forms in tissues and cells is a critical challenge.
• Polyethylene glycol (PEG) is widely used to improve nanomedicine circulation time.

Purpose of the Study:

• To develop a method for quantifying encapsulated and free drug forms in vivo.
• To map the in vivo process of PEGylated liposomal doxorubicin (sLip/Dox) at high resolution.
• To understand the factors determining sLip/Dox in vivo performance.

Main Methods:

• Development of a versatile anti-PEG single-chain variable-fragment antibody (PEG-scFv) method.
• Quantitative measurement of encapsulated and free drug forms in biofluids (interstitial fluid, cytoplasm).
• In vivo pharmacokinetic profiling of sLip/Dox in bloodstream, liver, and tumor tissues.

Main Results:

• Doxorubicin remained >99% encapsulated in the bloodstream.
• In the liver, drug was mostly interstitial (>80% encapsulated) but released intracellularly in Kupffer cells.
• In tumors, drug access to cells was limited, with most drug remaining interstitial and encapsulated; intracellular release occurred gradually.

Conclusions:

• Cellular internalization rates are critical for the in vivo performance of sLip/Dox, which releases drugs intracellularly.
• The PEG-scFv method provides a broadly applicable tool for dissecting nanomedicine in vivo processes.
• This approach can guide rational nanotherapeutic design and establish dose-effect relationships.