Angiogenesis imaging in rats colorectal cancer, induced by SW480, through photoacoustic endoscopy

Abstract

The global incidence of colorectal cancer has increased in recent years. According to the "Global Colorectal Cancer Incidence" report by the International Agency for Research on Cancer (IARC), a subsidiary of the World Health Organization (WHO), which surveyed 184 countries, the incidence of colorectal cancer in Koreans was found to be the highest among the surveyed countries, at 45 cases per 100,000 people. Colorectal cancer has become a common disease, and the importance of research for early diagnosis and treatment is increasingly recognized. Currently, the medical community relies on colonoscopy to diagnose colorectal cancer by checking for the presence of polyps. However, this approach has limitations, as the results can vary depending on the examiner's subjective judgment, and early-stage cancers that are difficult to observe with the naked eye may be challenging to diagnose. In our previous work, we confirmed that photoacoustic ultrasound endoscopy can resolve vessels down to the level of several micrometers2,3. We induced colorectal cancer in rats by injecting SW480 cells into their colons and observed the progression of tumor angiogenesis over time. We synthesized nanoparticles capable of generating photoacoustic signals at a wavelength of 532 nm by attaching a protein that can target SW480 cells to porous silicon nanoparticles (pSiNP) and conjugating them with Evans Blue. Subsequently, we performed imaging on rats injected with these nanoparticles and compared the results with those from rats injected with Evans Blue alone. After the experiments, we confirmed the presence of cancer in the colorectum through surgical observation.