Therapeutic effects of Holmium-166 chitosan complex in rat brain tumor model

This study examined the effectiveness of Holmium-166 (Ho-166) chitosan complex therapy for a malignant glioma. Cultured C6 glioma cells (100,000 in 5 μl) were injected into the caudate/putamen of 200 - 250 gram Wistar rats. Five days later, a Ho-166 chitosan complex was injected into the same site of the glioma injection. Four injection doses were administered: the control group received PBS 10 μl, group 1 received an injection of 100 μ Ci (10 μl), group 2 received an injection of 50 μ Ci (5 μl), and group 3 received an injection of 10 μ Ci (1 μl). The average tumor volume for each group was 1.385 mm³ for the control group, 0.036 mm³ for group 1, 0.104 mm³ for group 2, and 0.111 mm³ for group 3. Compared with the control group, the size of the tumors in groups 1, 2 and 3 was reduced by an average of 97.4%, 92.5% and 91.9%, respectively. The Kaplan-Meier survival curve of group 2 was the longest, followed by groups 3, group 1 and the control. The mean survival was 22.8, 59, 60, and 44.6 days for the control group and groups 3, 2 and 1, respectively. H-E staining revealed that group 2 yielded the best results in the destruction of the malignant glioma. TUNEL staining and immunohistochemical studies indicated apoptotic features. The Ho-166 chitosan complex proved to be effective in destroying the malignant glioma.