Fluorescein‑Mediated Sonodynamic Therapy in a Rat Glioma Model
Sonodynamic therapy (SDT) is a novel idea for treating cancer. SDT uses targeted, low-intensity focused ultrasound energy to activate a chemical agent that is usually nontoxic. This nontoxic chemical agent is called a “sonosensitizer.” Although the exact mechanism is still being studied, when the ultrasound activates the sonosensitizer, the resulting biological reaction (e.g., generating a reactive oxygen species) creates an environment that negatively impacts the targeted tumor cells.
In this study, researchers from the University of Virginia, Istituto Neurologico Carlo Besta, and the Focused Ultrasound Foundation sought to investigate whether fluorescein (FL) might be an effective sensitizer for SDT to treat cerebral high-grade glioma, a deadly tumor. FL is a safe, fluorescent xanthene dye that is used during brain tumor surgery to highlight tumoral tissue, as it accumulates specifically within the tumoral environment and washes out of healthy tissues.
In a rat glioma model, the research team compared whether FL was effective for SDT under three different levels of acoustic energy deposition. FL was highly tumor specific, and they found that the SDT treatment significantly inhibited the growth of ectopic gliomas across all three focused ultrasound exposure conditions compared to focused ultrasound or FL alone: the results were still non conclusive for cell death, although the data favor this. Could this treatment be effective in an intracranial glioma model or in human gliomas?