Ex vivo skin model for the evaluation of sunscreen-based skin photoprotection


Laboratoire BIO-EC 
Biological research and cutaneous experimentations center, 1 chemin de Saulxier – 91160 Longjumeau, France

The prolonged excessive sun exposure leads to numerous complications correlated with various pathological consequences of the damage and sunburn of the skin. A photoprotection is therefore required.

-     Due to their different level of energy, radiation enters into the skin in a different way.

  • The epidermis absorbs UVB because the keratin which is inside is rich in polar amino acids, only 10% reach the dermis,
  • UVA (95% of the total UV radiation) and visible light passes thought the epidermis but only 20% to 30% reach the dermis,
  • Infrared (IR) reach into the hypodermis.

This penetration in the skin triggers several modifications and can cause damage in the epidermal and dermal deeper layers that links to skin aging, wrinkle formation, and DNA damages.

The solar radiations can modify the composition of certain body molecules, such as: 


  • DNA: UV-induced free radicals are also attacking the cells and DNA within. It can appear thymine dimer by UVB action.
  • Protein: can be inactivated due to a spatial structural modification (UVA and UVB).
  • ...