Biodistribution of P-selectin targeted microbubbles.

Area of Science:

• Biomedical Engineering
• Molecular Imaging
• Oncology

Background:

• P-selectin is a key adhesion molecule upregulated in tumor vasculature.
• Targeted microbubbles (MB) offer a promising strategy for molecular imaging and drug delivery.
• Evaluating the binding efficacy of P-selectin targeted MBs is crucial for their clinical translation.

Purpose of the Study:

• To assess the binding and retention of P-selectin targeted microbubbles (MB) within tumor vasculature.
• To conduct a whole-body imaging and biodistribution study in a preclinical tumor model.

Main Methods:

• Radiolabeling of anti-P-selectin antibodies with Tc-99m using the HYNIC method.
• Avidin-binding of labeled antibodies to lipid-shelled, perfluorocarbon gas-filled MBs.
• Intravenous injection of targeted MBs into mice bearing MDA-MB-231 breast tumors, followed by biodistribution analysis and gamma camera imaging at 5 and 60 minutes.

Main Results:

• Targeted MBs exhibited significantly greater retention in tumor tissue (1.8 ± 0.3% ID/g at 60 min) compared to adjacent skeletal muscle (0.2 ± 0.1% ID/g at 60 min).
• A statistically significant difference (p=0.01) in MB retention was observed between tumor and muscle tissue for the targeted MB group.
• No significant difference in MB retention was found between muscle and tumor for the control group (p=0.17).

Conclusions:

• P-selectin targeted MBs demonstrate significantly enhanced accumulation in tumor tissue compared to surrounding skeletal muscle.
• The study validates the specific binding of P-selectin targeted MBs to tumor vasculature.
• These findings support the potential utility of P-selectin targeted MBs for diagnostic imaging and therapeutic applications in cancer.