A 5G source, only exposing a small skin-area, will be placed on each arm of the participants. Only one of the two sources will emit waves (controlled by a computer). One arm will be exposed to 20W/m2 (a dose rate inferior to the recommended maximum for EMW exposure in Switzerland), the other not (sham-exposed). The exposure time is 20 min.

A 5G source, only exposing a small skin-area, will be placed on each arm of the participants. Only one of the two sources will emit waves (controlled by a computer). One arm will be exposed to 20W/m2 (a dose rate inferior to the recommended maximum for EMW exposure in Switzerland), the other not (sham-exposed). The exposure time is 20 min.

A 5G source, only exposing a small skin-area, will be placed on each arm of the participants. Only one of the two sources will emit waves (controlled by a computer). One arm will be exposed to 20W/m2 (a dose rate inferior to the recommended maximum for EMW exposure in Switzerland), the other not (sham-exposed). The exposure time is 20 min.

A 5G source, only exposing a small skin-area, will be placed on each arm of the participants. Only one of the two sources will emit waves (controlled by a computer). One arm will be exposed to 20W/m2 (a dose rate inferior to the recommended maximum for EMW exposure in Switzerland), the other not (sham-exposed). The exposure time is 20 min.

A 5G source, only exposing a small skin-area, will be placed on each arm of the participants. Only one of the two sources will emit waves (controlled by a computer). One arm will be exposed to 20W/m2 (a dose rate inferior to the recommended maximum for EMW exposure in Switzerland), the other not. The exposure time is 20 minutes.

After the exposure, the participants will wait one hour and a 7.5-mm biopsy by punch (two pieces: one 5-mm punch + half a 5-mm punch) will be performed under local anesthesia on each arm. The wound will be closed by a simple suture. A second set of samples will be taken 24h after the exposure, using the same procedure.

For each participant, 1 full biopsy per arm and per time-point will be used for single-cell-RNA-sequencing analysis. The selected method uses generic probed sequencing and does not generate patient-specific genomic information.

Measure: Fold of expression of messenger RNAs, as measured by single cell RNA analysis. This is measure of the overall tissue composition and cellular activity.

Further information:

Inputs: ScRNAseq data from the sample, age, sex, groups, skin thickness, arm of the biopsy, 1h or 24h after exposure, concomitant medication, healing process, adverse effects.

Outputs: based on our own analyses and others (ref). We will use Seurat package to perfom the quality controls of the data on individual samples, then integrate the samples for each patient to analyze their inter-variability. To determine cell types, we will combine unsupervised clustering and differential expression to compare top differentially expressed genes (using Wilcoxon rank sum tests of the FindMarker function of Seurat) with cell type specific expression known from literature. We will also use ProjecTILs package30 to define more precisely the immune subtypes.

Measure: Fold of expression of messenger RNAs, as measured by single cell RNA analysis. This is measure of the overall tissue composition and cellular activity. For further details, see primary outcome.