3D imaging of human epidermis micromorphology by combining fluorescent dye, optical clearing and confocal microscopy

The human epidermis presents a complex organization due to its dynamic and plein-stratified epithelium. Still nowadays, one of the best method to study this layer of the skin remains the histology sections. This approach remains tedious and gives only 2D information.

Rhodamine B is a dye known to have a high affinity for the epidermal layer and to possess fluorescent properties. Associated with a clarification method such as 3DiSCO, this dye maintains a high fluorescence emission. The skin which became transparent can then be investigated with a Laser Scanning Confocal Microscope.

We showed that this technique can collect longitudinal or transversal optical sections of the epidermis as whole. Serial sections allowed to move easily into the epidermis. A 3D imaging can also be generated to study the microrelief of the stratum corneum or the complex organization of the dermal-epidermal junction.

In this work, we describe a simple and fast staining and clearing method for skin samples. In association with a fluorescence microscope such as the confocal, we show a new way to characterize the whole epidermis. This work appears as a valuable and complementary method to understand several topics around skin investigation.