Hyperthermia experiments on mouse mesothelioma lines

November 2007

Initially, we wanted to evaluate the effects of hyperthermia on cell growth. It has been well described in literature that hyperthermia inhibits cell growth in cancerous cells to various extents. This has been shown across different cancers with different levels of success. Of the many reviews available, Fiorentini and Szasz recently reviewed modern applications of hyperthermia and its uses in cancer treatment. 1

Two different mouse mesothelioma lines, designated as line 7 and line 40, were used to test the effects of different temperatures on cancer cell survival. Using multiple cell lines enables researchers to reproduce experiments and determine an overall trend.

The cell lines were exposed to temperatures varying from 39°C to 45°C over varying periods of time from 20 minutes to120 minutes. The lines were then examined after 4 hours, 6 hours and 25 hours to determine if the effect (if any) was brief or longer lasting.

Figure 1 shows the effects of the heat shock on mouse mesothelioma line 7 at 42°C. Figure 2 compares the same heat shock on mouse mesothelioma line 40.

Figure 1: Heat treatments of mouse mesothelioma cell line 7

Figure 2: Heat treatments of mouse mesothelioma cell line 40

These experiments suggest there is no significant difference in survival between heat treated mouse cell lines and control (37°C) mouse cancer cells at temperatures ranging from 39°C to 42°C.  However, a significant difference in survival is observed at 45°C. This is shown in Figure 3 below.

Figure 3: A graphic representation of survival of mouse mesothelioma cell line 7 after heat treatment

Figure 3 (above) represents a survival curve (y axis) for mouse cell line 7, exposed to higher temperatures (x axis) and to control temperature (37°C). The highest drop in survival is observed at the highest temperature tested (45°C). Furthermore, cells appear to continue to be affected by the high temperature since, after 25 hours, there are less cells than present after five hours.

Conclusion:
At the highest temperature tested (45°C) cell survival decreases in mouse mesothelioma cell lines compared to control (non-treated). At most, there is a 15-20% drop in survival which continues after 25 hours.