Description du sujet de thèse

In France, approximately 2% of the population is affected by chronic wounds, which often cause discomfort and reduce quality of life. These wounds can also lead to significant disabilities and, in some cases, infectious complications that can be life-threatening for patients. Among the therapeutic options for treating chronic wounds, the use of cold plasmas appears to be a promising solution. This project aims to develop a new source of atmospheric pressure plasma and to characterise the healing mechanisms and bactericidal activity of the plasma source on in vitro infected wound models. Initially, the PhD student recruited will be responsible for developing wound models from reconstituted human epidermis (RHE). Immunohistological staining will be performed on these models to analyse wound closure using fluorescence microscopy. At the same time, the PhD student will evaluate the antibacterial efficacy of plasma on model bacteria in vegetative form (Staphylococcus epidermidis,
hylococcus aureus and Pseudomonas aeruginosa) deposited on acellular skin substrates, such as collagen matrices. These simplified acellular models make it possible to initially avoid complex interactions with living cells. This approach will facilitate the characterisation of optimal plasma parameters (exposure time, power, gas composition) before their application to more complex cellular models. In a second stage, the PhD student will develop models of chronic infected wounds. To do this, they will use skin substitutes and RHEs, with or without wounds, infected with Staphylococcus epidermidis biofilms. In addition to immunofluorescence staining, complementary analyses using scanning electron microscopy (SEM) may be considered to assess the infection and its impact on the healing of the wounds generated. Finally, the PhD student will characterise the effects of plasma on skin cells and bacterial biofilms. This includes evaluating the impacts of plasma on the viability, cell migration and oxidative stress of keratinocytes and fibroblasts cultured in 2D. They will also analyse the effects of plasma on RHE models, particularly with regard to barrier function and cell permeability. Finally, models of skin infected with biofilms will be used to evaluate the impact of plasma on these biofilms.
This position requires strong skills in cell biology and a good command of the development of 3D in vitro skin models. Skills in immunohistochemistry, immunofluorescence, confocal microscopy (two-photon) and image analysis will be necessary to carry out this project. Finally, skills in bacteriology and the development of bacterial biofilms would be an advantage.

Contexte de travail

The thesis will be conducted as part of a collaborative TIRIS project that brings together complementary expertise in plasma physics, biology and sociology from three laboratories (DPHE, IPBS and LISST) at the University of Toulouse. The work will be carried out by the cellular biophysics team at the Institute of Pharmacology and Structural Biology (IPBS) in Toulouse and the non-equilibrium plasma diagnostics team (DPHE) at the Champollion National University Institute in Albi. The thesis work will be supervised by M. Golzio (IPBS) and C. Muja (DPHE). Experimental campaigns will be carried out in both laboratories, with the IPBS as the main site. The doctoral student will participate in the organisation of focus groups analysing the appropriation of plasma technology by users.

Contraintes et risques

Type 2 biological hazards