Can targeted nanoparticles distinguish cancer metastasis from inflammation?

Targeting ligands have been widely used to increase the intratumoral accumulation of nanoparticles and their uptake by cancer cells. However, these ligands aim at targets that are often also upregulated in inflamed tissues. Here, we assessed the ability of targeted nanoparticles to distinguish metastatic cancer from sites of inflammation. Using common targeting ligands and a 60-nm liposome as a representative nanoparticle, we generated three targeted nanoparticle (NP) variants that targeted either fibronectin, folate, or αvβ3 integrin, whose deposition was compared against that of standard untargeted NP. Using fluorescently labeled NPs and ex vivo fluorescence imaging of organs, we assessed the deposition of the NPs into the lungs of mice modeling 4 different biological landscapes, including healthy lungs, aggressive metastasis in lungs, dormant/latent metastasis in lungs, and lungs with general pulmonary inflammation. Among the four NP variants, fibronectin-targeting NP and untargeted NP exhibited the highest deposition in lungs harboring aggressive metastases. However, the deposition of all targeted NP variants in lungs with metastasis was similar to the deposition in lungs with inflammation. Only the untargeted NP was able to exhibit higher deposition in metastasis than inflammation. Moreover, flow-cytometry analysis showed all NP variants accumulated predominantly in immune cells rather than cancer cells. For example, the number of NP+ macrophages and dendritic cells was 16-fold greater than NP+ cancer cells in the case of fibronectin-targeting NP. Overall, targeted NPs were unable to distinguish cancer metastasis from general inflammation, which may have clinical implications to the nanoparticle-mediated delivery of cancer drugs.