In both tumor models injection of 50 mM and 168 mM calcium solution without electroporation has no visible effect on the tumor growth. In contrast, injection of 250 mM calcium solution prolonged tumor doubling times by at least factor of 2 in both tumor models compared to control untreated tumors.
When combined with electric pulses, the tumor doubling time was further prolonged in both tumor models. Antitumor effectiveness was dose dependent in both tumor models, however in B16F10 the tumor doubling time was at the highest dose tested (250 mM calcium solution) only 6.2 days, demonstrating moderate effectiveness. On the other hand, 4T1 tumor model responded better to calcium electroporation as B16F10. Injection of 250 mM calcium solution alone to 4T1 tumors resulted in complete regression of 6/17 tumors (35% CR).
The number of complete responses of tumors after 250 mM calcium electroporation was similar - 6/20 (30%) with no statistical difference between the two experimental groups. These mice were monitored for 100 days for the presence of possible tumor regrowth Synthetic Gloves.
After 100 days they were re-challenged with the same 4T1 cells injected into the opposite (left) flank and they all developed tumors, indicating that long term immune memory was not formed. Morphologically, in both tumor models, the tumors that were treated either with electroporation, calcium alone or combination, developed swelling in the treated area which resolved in 2–3 days. Simultaneously, a visible tumor necrosis and formation of a crust developed (Fig. 3).
Nevertheless, most tumors continued to grow from the tumor rim or beneath the crust. In 4T1 tumors that responded with complete regression, a good cosmetic effects were obtained, leaving only a small scar at the site of the tumor (Fig. 3B). In conclusion, our results demonstrated that calcium electroporation has dose dependent antitumor effectiveness PE Gloves.
Furtheremore, it has tumor histotype specific efficiency. This needs to be further elucidated with regard to selection of therapeutic modality for a specific tumor type. Nevertheless, our results indicate that calcium electroporation is a safe method for treatment of the tumors from different histologies YICHANG.
Acknowledgement. The authors acknowledge the financial support from the Slovenian Research Agency (research core funding no. P3-0003, fellowship granted to Barbara Staresinic). Conflict of Interest. The authors declare that they have no conflict of interest.