This experiment was conducted by using the diffuse optical spectroscopy based on near-infrared light. The near-infrared light in the water window was used to see the change of molecular concentration in the living tissue. The experiment subject was New Zealand rabbits weighing 3 ± 0.3 kg. VX2 tumor cells were injected into the inside of the chest wall of rabbits. The concentration of indocyanine green (ICG) has been observed once every three days, after the size of the pleural tumor grew up over 1cm. We used five different wavelengths (732, 758, 805, 840, and 880 nm) with known ICG spectrum. The distance between light source and detector probes was fixed by 1 cm. The probes were placed on the skin right above the tumor with an aid of laparoscope. ICG was injected into rabbits via ear vein. The diffused light was measured through the tumor with time course using a spectrometer. These measured data enabled us to observe the change of ICG concentration in real time with respect to the baseline without ICG. ICG was present longer in tumor compared to normal tissue. This phenomenon is thought to be due to the excessive angiogenesis in the tumor tissue. Since this method can be applied to other cases easily, it is thought that there is a possibility of cancer screening with less cost and simple equipment.
Conjunctival squamous cell carcinoma (SCC) is an uncommon disease. However, SCC has recently become an important clinical problem due the identification of a significantly high incidence of SCC among a group of black African patients with AIDS. However, basic research concerning SCC, including both intraepithelial and invasive squamous neoplasia, is limited due to the lack of an ocular tumor animal model. Specifically, current ocular imaging and treatment modalities are insufficient for investigating currently available small animal models, because the conjunctival space is not comparable to that of humans. We describe the development of a reproducible model of subconjunctival squamous carcinoma in moderate-sized immunocompetent rabbits. Under optical coherence tomography guidance, 1×10 7 VX2 carcinoma cells are inoculated into the subconjunctival space of 3 to 4-kg New Zealand white rabbits. Malignant tumor involvement developed on the subconjunctival space after an average of 1 to 2 weeks. This subconjunctival tumor model induction method will likely facilitate a broad range of investigation of subconjunctival cancer diagnostics and therapeutics.