Subminute thermal damage to cell types present in the skin

Abstract

Introduction

Psoriasis is characterized by an increase in the proliferation of keratinocytes and nerve fiber activity, contributing to the typical skin lesions. Pulsed Dye Laser (PDL) treatment is effective for the treatment of psoriatic lesions but its mechanism remains unclear. One hypothesis is that PDL causes thermal damage by the diffusion of heat to neighboring structures in lesional skin. There is limited information on the thermal sensitivity of these neighboring skin cells when exposed to hyperthermia for durations lasting less than a minute. Our study aimed to investigate the cell-specific responses to heat using sub-minute exposure times and moderate to ablative hyperthermia.

Materials and Methods

Cultured human endothelial cells, smooth muscle cells, neuronal cells, and keratinocytes were exposed to various time (2–20 sec) and temperature (45–70 °C) combinations. Cell viability was assessed by measuring intracellular ATP content 24 h after thermal exposure and this data was used to calculate fit parameters for the Arrhenius model and CEM43 calculations.

Results

Our results show significant differences in cell survival between cell types (p < 0.0001). Especially within the range of 50–60 °C, survival of neuronal cells and keratinocytes was significantly less than that of endothelial and smooth muscle cells. No statistically significant difference was found in the lethal dose (LT50) of thermal energy between neuronal cells and keratinocytes. However, CEM43 calculations showed significant differences between all four cell types.

Conclusion

The results imply that there is a cell-type-dependent sensitivity to thermal damage which suggests that neuronal cells and keratinocytes are particularly susceptible to diffusing heat from laser treatment. Damage to these cells may aid in modulating the neuro-inflammatory pathways in psoriasis. These data provide insight into the potential mechanisms of PDL therapy for psoriasis and advance our understanding of how thermal effects may play a role in its effectiveness.

Keywords:

• Hyperthermia
• laser therapy
• thermal sensitivity
• thermal damage
• cell viability

Acknowledgments

We would like to thank J. de Vos and R. Otto for setting up the culture of human smooth muscle cells. We would also like to thank N.B. van der Beek for fruitful discussions. We would also like to thank C. de Winter-Korver from the lab of fertility (AMC) for generously providing the keratinocytes. Lastly, we would like to thank T. Kaptein from the lab of experimental immunology (AMC) and K.W. Geijtenbeek from Medical Biology (AMC) for the use of their equipment.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are openly available in figshare at 10.6084/m9.figshare.24467440 (data under embargo till publication).

Additional information

Funding

The collaboration project was co-funded by the PPP Allowance made available by Health ∼ Holland, Top Sector Life Sciences & Health, to stimulate public-private partnerships under Grant number 23385.