Photodynamic Therapy and dry delivery system for choroidal recvasalarization

2001 Fiscal Year Final Research Report Summary

• Project/Area Number: 11557128
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 展開研究
• Research Field: Ophthalmology
• Research Institution: KYOTO UNIVERSITY
• Principal Investigator: NISHIWAKI Hirokazu Grad. Sch. of Med., KYOTO UNIVERSITY, assistant professor, 医学研究科, 助手 (90303841)
• Co-Investigator(Kenkyū-buntansha): KIRYU Junichi Grad. Sch. of Med., KYOTO UNIVERSITY, Lecturer, 医学研究科, 講師 (80281096) ; TANABE Masayo Grad. Sch. of Med., KYOTO UNIVERSITY, assistant Professor, 医学研究科, 助手 (80243020) ; HONDA Yoshihito Grad. Sch. of Med., KYOTO UNIVERSITY, Professor, 医学研究科, 教授 (90026930)
• Project Period (FY): 1999 – 2001
• Keywords: thermo-sensitive liposone / dny delivery / choroidal recvasalarization / age-related macular degeieration / photodynamic therapy / slit lamp

Research Abstract

We developed a new slit-lamp system "SL-PDT" in cooperation with Topcon Inc. SL-PDT is a modified slit lamp for PDT (photodynamic therapy) and TTT(transpupillary thermotherapy) and it is equipped with three-wavelength laser light Argon laser (490nm) is utilized as the slit light. Diode laser (810nm) is used to deliVer heat to the fundus locally to warm up heat-sensitive liposome and release its contents (carboxyfluorescein or photosensitizer). Diode laser (685nm) is applied simultaneously to activate the released photosensitizer to create free radicals. The fluoresent images are taken with a CCD camera and recorded on S-VHS tapes.
The heat-sensitive liposome was synthesized by the freeze ＆ thaw method from phosopholipids. Carboxyfluorescein was encapsulated within. The phase-transition temperature was adjusted to 41C. After injecting the liposome from rat vein, the diode laser (810nm) was applied to the fundus to release carboxyfluorescein locally and fluorescent images of the rat chori ocapillaris were studied. We also applied this angiography to monkeys. The images of the choroids achieved by this method were different from the conventional ICG angiography (currently clinically available). They can be used to analyze the physiological choroidal circulation in vivo.
The phase-transition temperature of the heat-sensitive liposome can be adjusted by changing the ratio of phospholipids utilized and we synthesized various kinds of liposome with different phase-transition temperature. By using these liposomes we showed the real time monitoring technique ofchoroidal temperature during TTT.
We also performed PDT by.applying therapeutic diode laser (685nm) after injecting photosensitizing agents from rat vein. The retinal vessels of rats can be ccluded photochemically without significant thermal damage to the adjacent tissue. This vessel occlusion model can be utilized to study the mechanism of the'retinal vessel ocdusive diseases in men.
In conclusion, the present method provided detailed information about choroidal circulation. Additionally SL-PDT is useful in investigates the mechanism of PDT and TTT.