Targeted delivery of doxorubicin toward 4 T1 cells via in situ binding between maleimide functionalized AS1411 - NH₂ aptamer and endogenous albumin

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Drug Delivery Systems

Background:

• Targeted drug delivery aims to enhance therapeutic efficacy and minimize side effects.
• Albumin's natural circulation in the bloodstream presents an opportunity for targeted delivery strategies.
• The Trojan horse strategy leverages endogenous albumin for in situ binding and targeted delivery of therapeutic agents.

Purpose of the Study:

• To develop and evaluate a novel Trojan horse drug delivery system.
• To utilize an AS1411-NH2 aptamer-PEG-albumin conjugate for targeted delivery of doxorubicin (DOX).
• To assess the in vitro and in vivo efficacy and toxicity of the developed drug delivery system.

Main Methods:

• Conjugation of AS1411 aptamer with Mal-PEG3.5-NHS ester, followed by binding to human/mouse serum albumin.
• Confirmation of conjugate formation and albumin attachment using agarose gel electrophoresis and SDS-PAGE.
• Assessment of doxorubicin loading capacity and in situ complex formation (DOX-Apt-PEG-HSA/MSA).
• Characterization using Dynamic Light Scattering (DLS) and evaluation of drug release profiles.
• In vitro validation through MTT assays, live/dead staining, flow cytometry, apoptosis/necrosis assays, and fluorescence imaging.
• In vivo efficacy assessment in 4T1 tumor-bearing mice, including tumor volume measurements, histological studies, and fluorescence imaging.

Main Results:

• Successful formation and characterization of the DOX-Apt-PEG-HSA/MSA complex with appropriate size and charge.
• Demonstrated pH-sensitive drug release profile and stability of the complex.
• Validated in vitro functionality, cellular internalization, and cytotoxic effects of the DOX-Apt-PEG composite.
• In vivo studies showed significant tumor shrinkage (4/6 mice) and tumor ablation (2/6 mice) in 4T1 tumor-bearing mice.
• Histological analysis and fluorescence imaging confirmed targeted accumulation in tumors, leading to necrosis, with reduced off-target organ accumulation and toxicity.

Conclusions:

• The developed aptamer-PEG-albumin Trojan horse system effectively delivers doxorubicin to tumors.
• This targeted delivery approach significantly enhances anti-tumor efficacy while minimizing systemic toxicity.
• The study validates the potential of this novel nanocarrier for advanced cancer therapy.