| Objectives: The aim of the study is to establish glioma model in rat brain and nude mice subcutaneousness and to study the effect and safety of single photodynamic therapy(PDT) on C6 glioma, using 5-Aminolevulinic acid (ALA), hematoprophyrin (HPD) and ALA +HPD,as well as to explore the mechanisms of PDT,Methods: In the first part of the research, the suspension of C6 glioma cells was stereotaxically injected into the right caudate guided by stereotactic frame.After the rat brain model was established , the examinations such as MRI, HE staining, transmission electron microscope (TEM),brian water(contrast to normal rat brain)were performed at 10 days,15days,20 days and the survival time,immunohistochemical staining of GFAP at the survival time.Then the characteristic of rat brain C6 glioma could be observed.In the second part of the research, the rats were divided randomly into light irradiation group and three PDT(ALA,HPD,ALA+HPD) groups after implanted C6 glioma in the rat brain 15 days,at the same time normal rat brain PDT(HPD)group(control group) was set up.The survival time of the rats,the changes of MRI, brian water,HE staining and TEM were inspected in the five groups after craniotomy and PDT or light irradiation. The effects and mechanisms of PDT were explored after the outcomes comparable between three PDT(ALA,HPD,ALA+HPD) groups and light irradiation. In the third part of the research, when the volume of implantation tumor was grown to 5-7 mm after implanted C6 glioma in double armpit and groin subcutaneousness of the nude mice, the implantation tumors in one side of the nude mice were begun to PDT(ALA,HPD,ALA+HPD) or light irradiation,and all of the contralateral implantation tumors were set up as control groups. divided randomly into light irradiation group and three PDT(ALA,HPD,ALA+HPD) groups.The volume of the implantation tumors in the nude mice subcutaneous was measured by vernier caliper, the tumor suppressive rate was calculated and HE staining were observed at 10 days afterthe nude mice sacrificed.Conbined with the result of PDT on the rat brain C6 glioma,we could furthermore explore the therapeutical effect,safety and mechanisms of PDT. Results:1. The symptom of the rats was emerged to be at 10 days after stereotactic implantation, and were aggravated during 15 to 20 days after stereotactic implantation. The averge diameter of tumor was shown about 1-2 mm at 10 days,3-5 mm at 15 days and 4-8 mm at 20 days after implantation. There were 3 mice survived in the survival time examination group, the tumor volume of 2 mice dropped evidently, and one could not be seen in the MR images. Abundance of blood vessels in the tumor and brain-adjacent-to-tumor, the blur boundary between tumor and nomal brain, high invasiveness of tumor could been inspected in MRI images,the histological sections and TEM. The more volume of the tumor ,the higher the brain water.There was no extracranial metastasis after implantation.2. The averge survival time was 38.5 days for the light irradiation group and above 80 days for the control group and three PDT(ALA, HPD, ALA + HPD) groups after light irradiation or PDT.There was significance difference between the normal brain PDT(HPD) group(control group) ,three PDT(ALA, HPD, ALA + HPD) groups and the pure light irradiation group(P<0.01).3. The tumor volume of MRI in the three PDT(ALA, HPD, ALA + HPD) groups after therapy was shown smaller than before PDT ,and no tumor signs shown at 80 days in the survival time.In the light irradiation group the tumor volume of MRI was gotten very big. There was significance difference between three PDT(ALA, HPD, ALA + HPD) groups and the pure light irradiation group(PO.Ol).4. In the histological sections, slight hemorrhage and necrosis could be examined in the control group within PDT 3 days,and return to nomal after PDT 3 days. In the histological sections congested blood vessels in tumor at 1 day PDT,and no necrosis was examined in light irradiation group. In the histological sections and TEM ,the broken blood vessels and necrosis could be examined in the tumor and around the tumor within 3 days PDT, glial fibrin wrapped around tumor and necrosis after 5 days PDT.5. Brain water was got higher during 3 days in the tumor PDT group and controlgroup,and gotten lower 3 days after PDT. In the light irradiation group brain water was got higher and higher,as far as the rats death.6. Hemorrhage and necrosis could be examined around the C6 glioma in nude mice subcutaneous after PDT(ALA,HPD, ALA+HPD),in the meantime the tumor developed slower than before PDT.In the light irradiation group and all of the contralateral part, a little of hemorrhage and necrosis was examined,but the tumor getting bigger and bigger.7. After PDT(ALA,HPD, ALA+HPD) of the C6 glioma in nude mice subcutaneous 10 days, in the histological sections C6 glioma cells invaded in the interstitial around tumor and no signs of tumor necrosis was examined in light irradiation group and all of the contralateral part.Stale necrosis and haemorrhage could be inspected in the tumor and around the tumor during the three PDT (ALA, HPD, ALA + HPD) groups.Conclusions:1. The rat brain C6 glioma could mimick the human tumor with respect to its development and invasive,but its disadvantage was part of spontaneous regressed . So it is very careful to evaluate therapeutical effect of the model.2. Combined with PDT on the C6 glioma in nude mice subcutaneous, average survival time of the rats with C6 glioma after PDT (ALA, HPD , ALA+HPD) was elongated significantly.The curative effect among three PDT(ALA, HPD, ALA + HPD) groups was no significance difference.3.Most of the C6 glioma cells in rat brain were killed after PDT(ALA, HPD , ALA + HPD),but the growth of C6 glioma cells in nude mice subcutaneousness was suppressed after PDT(ALA, HPD , ALA + HPD).4. The activation of immunocompetence and the microenviromental change around C6 glioma in rat brain might be taken part in killing C6 glioma cells after PDT.5. Transient brain edema could be caused within 3 days after single dose PDT(ALA, HPD, ALA + HPD).
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