Experimental Study Of PLDR On The Treatment And Radiation Injury Of Orthotopic Implantation Model Of Human Glioma In Embryonic Zebrafish

Objectives:To establish an orthotopic implantation model of human U87R glioma cell lines in embryonic zebrafish, investigate the result of local tumor control, survival time and normal tissue toxicity of pulsed low-dose rate radiotherapy (PLDR) and analysis the result of the blood-brain barrier of PLDR.Methods:48 hpf embryonic Tg(flk:GFP) transgenic Zebrafish were implanted with U87R cell lines in brain. After 24h, successfully established orthotopic implantation models were divided into the following 3 groups: control (n= 25), conventional radiotherapy (RT; n= 25), and PLDR (n= 25). The whole body irradiation was delivered using a 6 MV X-ray linear accelerator and the dose rate was 300MU/min. RT group received 2Gy daily dose and PLDR group received 2Gy daily dose which treated by 10×0.2Gy pulses with 3-minute intervals to achieve an effective low dose rate of 6.7 cGy min-1 for 4 consecutive days. Digital micrographs were taken with a confocal laser scanning microscope, analyzed by Leica LAS-AF Lite software. Data was assayed by ANOVA. A level of P<0.05 was regarded as statistically significant.Results:An orthotopic implantation model of human U87R glioma cell lines in embryonic zebrafish was established successfully. For the local tumor control, PLDR and RT significantly inhibited the growth of U87R orthotopic implantation compared with the control group (P<0.05). The PLDR group also have significantly results than RT group (P<0.05). Median Survival time was 8day、10days and 11 days for the control group, RT and PLDR group (P<0.05) respectively.Rate of the morphological changes of vascular response which representative normal tissue radiation injury of zebrafish was 32% and 20% for the RT and PLDR group (P<0.05).Rate of the tail shape change which representative normal tissue radiation injury of zebrafish was 24% and 16% for the RT and PLDR group (P<0.05). The effect to blood-brain barrier was not found in RT and PLDR group.The disruption of the blood brain barrier in the zebrafish is not observed after tumor’s invasive growth and radiation.Conclusion:Our study established orthotopic implantation model of human U87R glioma cell lines in embryonic zebrafish successfully. For the treatment the experiment showed that PLDR could control U87MG tumors better than conventional RT and PLDR induced much less normal tissue toxicity than RT. Thus, PLDR would be a good modality for glioblastoma treatment.