Constructal thermodynamics combined with infrared experiments to evaluate temperature differences in cells

Abstract

The aim of this work was to evaluate differences in energy flows between normal and immortalized cells when these distinct biological systems are exposed to environmental stimulation. These differences were considered using a constructal thermodynamic approach, and were subsequently verified experimentally. The application of constructal law to cell analysis led to the conclusion that temperature differences between cells with distinct behaviour can be amplified by interaction between cells and external fields. Experimental validation of the principle was carried out on two cellular models exposed to electromagnetic fields. By infrared thermography we were able to assess small changes in heat dissipation measured as a variation in cell internal energy. The experimental data thus obtained are in agreement with the theoretical calculation, because they show a different thermal dispersion pattern when normal and immortalized cells are exposed to electromagnetic fields. By using two methods that support and validate each other, we have demonstrated that the cell/environment interaction can be exploited to enhance cell behavior differences, in particular heat dissipation. We propose infrared thermography as a technique effective in discriminating distinct patterns of thermal dispersion and therefore able to distinguish a normal phenotype from a transformed one.

Figure 1. Thermal dispersion of cellular models.

Thermal dispersion was evaluated at room temperature by the infrared thermographic camera. Two different preparations of primary fibroblasts (Fb1 and Fb2) and NIH 3T3 cells were analysed in the same conditions, either exposed for 6 days to electromagnetic field (ELF) or not exposed. The figure is representative of a set of three independent experiments.

Figure 2. Differences in thermal dispersion of cells exposed to electromagnetic field.

Two different preparations of primary fibroblasts (Fb1 and Fb2) and NIH 3T3 cells were analysed after 6 days of exposure to electromagnetic field. Values of ΔT were calculated for each well. Values of NIH3T3 cells were compared with values of primary fibroblasts seeded on the same plate. Temperature difference: T_NIH3T3 − T_Fb.

Figure 3. Differences in thermal dispersion of cells inside and outside the electromagnetic field.

Primary fibroblasts (FB1) and NIH3T3 cells were analysed after 6 days of exposure to electromagnetic field or regular culture condition. Values of ΔT were calculated for each well. Values of NIH3T3 cells were compared with values of primary fibroblasts seeded on the same plate. Temperature difference: T_NIH3T3 − T_Fb.

Figure 4. Thermal dispersion index of cellular models.

Primary fibroblasts (Fb1) and NIH 3T3 cells were analysed after 6 days of exposure to electromagnetic field. Values of ΔT were calculated for each well. Values of NIH3T3 cells were compared with values of primary fibroblasts seeded on the same plate and expressed as percentage. The rate is represented.

Figure 5. A sample of the infrared image.