Description of the thesis topic

Summary of PhD Project: The project aims to develop functionalized lipid nanoparticles (LNPs) to deliver mRNA encoding the BMP2 protein, in order to induce bone repair. This strategy combines LNPs optimized to target hydroxyapatite ceramics, used in bone tissue engineering, and autologous blood cells as tissue engineering products. The LNP formulations developed will be physico-chemically characterized, tested on human or rat macrophages and mesenchymal stem cells (MSCs) in the presence of ceramics, and then evaluated in vivo in mouse models. This interdisciplinary project brings together two complementary teams: CBM for LNP formulation and B3OA for biological validation. Expected results include proof of concept for bone regeneration and the creation of innovative nanotechnological solutions for orthopedic and maxillofacial surgeons.
State of the Art: Gene therapy based on DNA and mRNA encoding BMPs has shown promising results, enabling in situ expression of the protein of interest at much lower doses. The vectors used, often lipid-based, facilitate cell internalization. Among these, Lipid Nanoparticles (LNPs) offer good stability and an excellent transfection rate.
Objectives: The use of LNPs in regenerative medicine presents challenges, including non-specific biodistribution and variable transfection efficiency depending on the target cells. To improve targeting, different LNP formulations will be produced with specific ligands to target hydroxyapatite ceramics used in bone repair.
Methodology : (1) Design and characterisation of functionalised LNPs: Three types of hydrophobic ligand-anchor conjugates will be tested. The LNPs will be microfluidically formulated and characterised for size, surface charge, mRNA encapsulation efficiency and transfection efficiency on cell lines and primary cells. (2) In vitro transfection efficiency: Selected LNPs will be tested on macrophages and mesenchymal stem cells (MSCs) in the presence of ceramics using mRNA encoding a reporter gene (EGFP or FLuc) followed by BMP2. (3) In vivo evaluation: LNP-ligand-blood clot mixtures will be evaluated in a mouse model to determine their expression kinetics and ability to induce bone formation.
Expected results: We will have formulated and characterised at least three types of functionalised LNPs, assessed their transfection efficiency in vitro and in vivo, and validated their ability to induce bone formation. This project will provide proof of concept for the use of LNPs loaded with mRNA encoding BMP2 in bone repair.

Work Context

This is a collaborative project between UMR 7052 - Biology, Bioengineering and Osteoarticular Bioimaging (B3OA), located on the Villemin site of the Faculty of Health of the Université de Paris Cité ( nearby the Gare de l'Est in Paris) and the Centre de Biophysique Moléculaire (CBM), UPR UPR4301 located on the CNRS campus in Orléans.
The person recruited will work at the B3OA in Paris and will be required to work occasionnaly at the CBM (1 hour by train from Paris to Orléans).
B3OA develops regenerative medicine therapies to repair osteoarticular tissues, using stem cells, recombinant proteins and/or biomaterials. The laboratory also evaluates their success and seeks to understand the underlying mechanisms in in vitro or in vivo models. The laboratory has state-of-the-art equipment for molecular and cell biology, histology, bone imaging and animal surgery. Working at B3OA means working in a collaborative and stimulating research environment that is conducive to learning advanced technologies.

Constraints and risks

Occasional work in Orléans