| Objective To evaluate the effectivity and safety of Temozolomide/PLGA microspheres in interstitutial chemotherapy. Furthermore, to explore the mechanism of Temozolomide/PLGA microspheres in C6 rat glioma. Additionally, to investigate the changes in C6 rat glioma after the combined chemotherapy with temozolomide/PLGA microspheres and Vatalanib.Methods Fifty SD male rats were injected with 2×10~6 C6 cells into the left caudate nucleus area using steoreotaxis techniques. The animals were scanned with MRI at the 4th day after implantation to monitor tumor growth. The rats were divided into five groups. The control group (n=10) received sham operation. The temozolomide group were treated with temozolomide 50mg/kg/day p.o.for 5 days from the 6th postoperation day. The Temozolomide/PLGA microspheres (TM-MS) 12mg group (n=10), TM-MS 16mg group (n=10) and TM-MS 20mg group (n=10) were treated with interstitial TM-MS chemotherapy. The biocompatibility of TM-MS was investigated through histology on different days after the operation. Then, forty SD rats were divided into 4 groups . The control group (n=10) received sham operation. The TM-MS 16mg group (n=10) were treated with interstitial TM-MS chemotherypy. The 5-FU group were treated with interstitial 5-FU chemotherapy, and the VM group were treated with VM-26 via intraveins approach. The technical aspects, therapeutic effectivity, and complications of chemotherapy were analyzed. The therapeutic efficacy was evaluated by histology and transmission electron microscopy investigation. In order to investigate the antitumor mechanism of the Temozolomide/PLGA microspheres, C6 cells apoptosis were measured by transmission electron microscopy investigation and TUNEL method. P53 and caspase-3 were measured by Western Blot method. Forty rats were divided into the four groups. The control group (n=10) received sham operation. The TM-MS 16mg group (n=10) were treated with interstitial TM-MS chemotherapy. The Vatalanib group were treated with Vatalanib with 5ml/kg p.o. for 20 days and the combined chemotherapy group were treated with both TM-MS and Vatalanib. All the animals were undertaken autopsy and pathology examinations. All statistical analyses were performed with computer software SPSS 11.0. For all statistical analyses, P <0.05 was considered statistically significant. Results The tumorigenic rate was 90%. Rat's head enhanced MRI shows the glioma in the left caudate putamen area. Pathology shows the GFAP and PCNA were positive in tumor cells. Transmission electron microscopy investigation discovered the C6 tumor cells. All rats tolerated the chemotherapy well. TM-MS group acquired effective outcome (P=0.0000), the TM-MS 16mg group didn't show any statistic difference with TM-MS 20mg group (P>0.05) ,and 16mg is the appropriate dose. TM-MS showed good biocompatitility. The TM-MS 16mg group got better outcome than FU group and VM-26 group. The TUNEL data discovered the apoptosis cells in TM-MS group were more than those in sham operation group (P=0.0000). P53 was up-regulated in the TM-MS group (P=0.0000).Caspase-3 show obvious difference between the TM-MS group and the sham operation group (P=0.0000). All rats well tolerated with the combined chemotherapy. Pathology showed PCNA in combined chemotherapy group was down-regulated (P<0.01), microvessel density (MVD) was reduced in combined chemotherapy group, VEGF was also decreased in combined chemotherapy group(P<0.01). ICAM-1 and MMP-9 were reduced in combined chemotherapy group (P<0.01).Conclusions (1) the models of C6 glioma rat were suitable for the study of interstitial chemotherapy and combined chemotherrpy. (2) Temozolomide/PLGA interstitial chemotherapy was a safe and effective therapeutic option for C6 glioma. (3) Temozolomide/PLGA induced tumor cells apoptosis. P53 and caspase-3 were associated with tumor cell apoptosis. (4) Combined chemotherapy with Temozolomide/PLGA and Vatalanib was safe, and more effective than single drug chemotherapy.
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