Promoting Nanoparticle Delivery Efficiency to Tumors by Locally Increasing Blood Flow There

Enhancing the tumor-targeted delivery efficiency of nanoparticles is necessary for improving their therapeutic efficacy, yet how to fulfill this, especially in a practical manner, remains a significant challenge. Noticing that major organs compete effectively with tumors for nanoparticles, we herein carried out meta-analysis on nanoparticle delivery efficiency to major organs and tumors. Notably, in major organs, cellular uptake alone cannot explain why one organ has higher nanoparticle delivery efficiency than another; indeed, blood flow through an organ may facilitate nanoparticle delivery efficiency there as well. Intriguingly, such a facilitative role can be extrapolated to tumors, according to meta-analysis on the relationship of tumor-targeted delivery efficiency of nanoparticles versus blood flow through tumors of different weights. Indeed, using local mild hyperthermia as a model for modalities capable of increasing tumor blood flow, we observed a ∼3-fold increase in tumor-targeted delivery efficiency in the meta-analysis on studies involving both nanoparticles and local mild hyperthermia. This work identifies tumor blood flow as a crucial factor in determining tumor-targeted delivery efficiency of nanoparticles and suggests increasing tumor blood flow as an alternative way to boost tumor-targeted delivery efficiency of nanoparticles.