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A suppository kit for metronomic photodynamic therapy: The elimination of rectal cancer in situ
- Shi, X.F., Jin, W.D., Gao, H., Yin, H.J., Li, Y.X., Huang, H., Ma, H., Dong, H.J.
- Journal of photochemistry and photobiology 2018 v.181 pp. 143-149
- apoptosis, carcinoma, colorectal neoplasms, encapsulation, epoxides, fatty acids, histopathology, magnetic resonance imaging, models, neoplasm cells, photochemotherapy, rabbits, staining
- Metronomic photodynamic therapy (mPDT) was developed to improve tumor-specific responses through cell death by apoptosis. We developed an mPDT suppository kit including ALA and LED suppositories and analyzed its killing effect on rectal tumors in rabbits. Methods: The ALA (10 wt%) suppository was prepared using ALA powder, type 36 semi-synthetic fatty acid glyceride, and azone. The LED suppository was constructed by encapsulating LED units and a circuit in transparent epoxy resin. VX2 cells were injected into the rectal submucosa of rabbits to establish a carcinoma model in situ. The ALA suppository was inserted into the rectal cavity for 30 min of uptake and activated for 1 h by the LED suppository at a power density of 20 mW/cm2. The mPDT process was repeated three times once a day. MRI was used to monitor tumor growth, histopathology and TUNEL staining were performed at 14 days after mPDT. Results: The overall response rate was 60% in the mPDT group using the kit in which the tumor size was decreased up to about 50% at 7 days post-mPDT and almost eliminated at 14 days. HE staining showed that only 6.16% of the tumor tissue remained after mPDT treatment. TUNEL detection showed that the apoptosis rate was 18.9%. Conclusion: We verified the killing effect of the mPDT suppository kit on rectal tumors in rabbits based on mPDT that induced tumor cell apoptosis.