| Research Abstract |
The aim of this study is to develop a new technology which enables anti-cancer drugs and gene-vector to be accumulated into tumor cells in vivo, when these agents are given bolus into vessels. We underwent animal experiments of multi-disciplinary treatments using chemotherapy and gene-therapy using in vivo electroporation, to discuss the possibility and limits for clinical trials.
Result 1.
We developed an animal experiment system which enables time-lapse observation of tumor hemodynamics using a fluorescence stereomicroscope. We observed the time-lapse change of fluorescence from tumors in skid and C3H mice using Dextran, Oregon Green which was bolus injected intravenously. We measured and compared each accumulated fluorescence for 20 sec after the start of injection. Relative accumulated fluorescence reached maximum during 20-40 sec after the start of injection. The addition of contrast media into Dextran, Oregon Green did not affect time-lapse accumulation of fluorescence.
Result 2.
The
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C3H mice were used for experiments at age of 8 weeks. We transplanted murine fibrosarcoma, FSa-II cells onto rt.thigh of C3H mice. When tumors reached 65 mm3, tumors were treated with cyclophosphamide(CY) of 250mg/kg, and in vivo electroporation(EP). We divided mice into 5 groups ; control, CY alone, EP alone, EP following by CY bolus injection (EP-CY), CY bolus injection following by EP with interval 20-40 sec (CY-EP). At least 16 mice were used for each group, and total mice used were 114. After treatments the volume of tumors were measured 3 times a week for 120 days. Tumor growth were evaluated with tumor growth (TG) -50 methods. The TG-50 (days) is the time for half number of tumors to reach 800mm3 from 65 mm3. The TG-50s (days) were 13 for control, 15 for EP alone, 24 for CY alone, 26 for EP-CY, and 31 for CY-EP. These indicates that electroporation combined with bolus intravenous injection of CY significantly enhances the effect of CY, when the timing between two treatments was adequate.
Result 3.
The C3H and skid mice were used for experiments at age of 8 weeks. We transplanted murine fibrosarcoma, FSa-II cells onto rt.thigh of mice. When tumors reached 65 mm3, the pEGFP-N1 plasmid, which has expressed enhanced green fluorescent protein (EGFP) in vitro, was bolus injected. After the interval of 20-40 sec., tumors were treated with in vivo electroporation The fluorescence were observed at each 24 hours for 3 days using a fluorescence stereomicroscope. No fluorescence was observed on tumors under the used condition. Less
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