Heat shock protein 70 expression patterns in dermal explants in response to ablative fractional...

Fractionated ablative laser intervention is effective for treating aged skin by inducing epidermal and/or dermal remodeling. The microneedle device is also used to initiate wound healing. In a previous study, the authors showed a clear time-dependent HSP70 expression profile subsequent to ablative fractional phothothermolysis (AFP) in a human skin explant model. The role of HSP70 after surgical interventions or microneedling is not fully understood. For this reason, the differences in spatio-temporal expressions of HSP70 by immunohistochemis-try in response to AFP, microneedling, and scalpel incisions were analyzed using a human skin explant model.

AFP was performed using a scanned 250 µm CO2-laser. The depth and density of the scalpel incisions were adapted to the defects reached by the laser or microneedle treatments. Skin explants were used as controls, for analysis of immediate responses, or they were subjected to cell culture medium for 1, 3, or 7 days.

HSP70 showed a clear time-dependent epidermal induction by AFP, peaking between 1 and 24 hours post-treatment with a significant decline within the following 7 days. HSP70 expression after scalpel incisions showed a similar time curve with less maximal HSP70 induction than in the laser-treated samples. Microneedling did not lead to histologically visible wounds.

The human skin explant model was able to show a significant up-regulation of HSP70 after ablative thermal laser intervention, as well as surgical treatment, whereas microneedling did not reveal a significant up-regulation. This fact seems to be dependent on the amount of tissue wounding or stress. .