Intravital optical imaging for immune cell tracking after photoimmunotherapy with plasmonic gold nanostars.

Bladder cancer has been ranked as one of the most commonly occurring cancers in men and women with approximately half of the diagnoses being the late stage and/or metastatic diseases. We have developed a novel cancer treatment by combining gold nanostar-mediated photothermal therapy with checkpoint inhibitor immunotherapy to treat bladder cancer. Experiment results with a murine animal model demonstrated that our developed photoimmunotherapy therapy is more efficacious than any individual studied treatment. In addition, we used intravital optical imaging with a dorsal skinfold window chamber animal model to study immune responses and immune cell accumulation in a distant tumor following our photoimmunotherapy. The mice used have the CX3CR1-GFP receptor on monocytes, natural killer cells, and dendritic cells allowing us to dynamically track their presence by fluorescence imaging. Our proof-of-principle study results showed that the photoimmunotherapy triggered anti-cancer immune responses to generate anti-cancer immune cells which accumulate in metastatic tumors. Our study results illustrate that intravital optical imaging is an efficient and versatile tool to investigate immune responses and mechanisms of photoimmunotherapy in future studies.