Thesis
French
ID: <
http://hdl.handle.net/20.500.11794/25838>
Abstract
Research in the field of bioengineered skin substitutes is motivated by the need to find new dressings for people affected by skin injuries (burns, diabetic ulcers), and to develop adequate skin models to test new drug formulations developed in vitro. It is possible to produce human skin substitutes (HSS) consisting in a dermis and a stratified epidermis (living epidermis, LE, and stratum corneum, SC), using the self-assembly method developed by the Laboratoire d’Organogénèse Expérimentale (LOEX). In the present work, vibrational microspectroscopy analyses (infrared, IR, and Raman) were performed to obtain in-depth morpho-spectral characterization of the three characteristic layers of HSS as compared with normal human skin (NHS). Concerning the lipid distribution and organization, IR microspectroscopy results suggest that lipids in the SC are more ordered than those in the LE. Raman microspectroscopy results confirm that the SC is a layer rich in lipids which are well-ordered in both NHS and HSS. The amount of lipids decreases and more disorder appears in the LE for both NHS and HSS. However, the results also show that there are fewer lipids in the HSS and that the lipids are more organized in the NHS. Concerning the secondary structure of proteins and protein content, the data show that they are similar in the HSS and in NHS (keratin in the epidermis and collagen in the dermis). Finally, the lipid organization as well as the protein composition in the different layers are similar for HSS and NHS, confirming that the HSS reproduce essential features of real skin. This study also investigates psoriatic human skin (PHS) and provides a deep understanding of its molecular organization and composition. IR and Raman microspectroscopies reveal a similar distribution of lipids and collagen for NHS and PHS. However, PHS exhibits various characteristics showing a global decrease of the structural organization that is compatible with a reduction in its barrier properties. It is the first characterization of the molecular structure of these HSS, which are already considered as a promising biological wound dressing for clinical applications. The characterization of PHS could be the starting point of the characterization of the pathological substitutes.