NTP antitumor soft treatment: evidence of a triggering effect?
Résumé
Intensive ongoing research in the field of anticancer treatment points to the atmospheric non-thermal plasma (NTP) as a new potential mean to attack tumors from a distinct innovative approach. The antitumor effect of NTP has been clearly shown in vivo on murine models with various cancer types (glioblastoma, colon, pancreas). Although the mechanism is far from being fully understood, the therapeutic effect is admitted. To date, the literature reports mainly induction of apoptosis, effect which is not restricted to cancer cells and probably mask other aspects of the NTP for cancer therapy.
Our work focuses on “soft” application allowing highlighting interesting effects as recently shown [1] on blood vessel parameters: blood flow and tissue oxygenation. With this aim to avoid the deleterious impact of plasma on cells and tissues, various plasma conditions were established to allow a daily treatment without skin burn or damage. Plasma Gun helium NTP used in this work not only leads to the production of reactive species, but also generates transient electric fields. Immuno-competent balb/c mice were used to study the proliferation of orthotopically implanted 4T1 breast carcinoma (Mice were double grafted. One tumor was used to apply a specific treatment condition whereas the second tumor of the same mouse was used as control tumor (untreated)). Preliminary data show a regulation of tumor proliferation regardless the variations among the treatment conditions applied (connected or not to the ground, treated through H2O impregnated compress or directly, 2 kHz vs 200 Hz). This observation is in favor of a triggering effect, evidenced for the first time, of the plasma fraction which similarly affects the tumor proliferation (treated group figure A) as compared to untreated tumor (contra-laterally grafted on each mice). This comparable reduction of tumor proliferation obtained whatever the plasma soft treatment conditions, with a significant reduction of standard deviations in all cases, clearly indicates a tumor growth regulation. Taking into consideration the recent vessel normalization based-cancer treatment, the NTP effect should be further investigated in view of blood vessels structure and function (blood flow) as well as tumor hypoxia compensation to confirm a possible NTP-based adjuvant approach for cancer treatments. These results suggest a new way to consider the plasma and its therapeutic delivery in NTP-based tumor therapy.
In vivo study of 4T1 breast carcinoma proliferation with distinct treatment conditions (see text)
[1] G. Collet, E. Robert et al, PSST 23 (2014) 012005
Acknowledgments: This work is supported by the APR Region Centre PLASMEDNORM.