The clinical application of this project is focused on bone regeneration afterlong time to repair fractures in elderly population or in the case of complex fractures (bone lengthening, regeneration of large bone volume ). Current therapeutic approaches include bone grafts (self- and allograft transplants) or implants composed of various biomaterials, but none of them are currently acceptable. Generally, an autologous bone graft contains all the elements required for bone repair: an osteoconductive structure, osteoinductive and angiogenic growth factors, and cells with osteogenic potential. The use of bone grafts has major disadvantages. If the success rate is high, complications or consolidation defects are observed, especially in the case of large bone regeneration. In addition, replacement of the site damaged by the host bone is often incomplete, and hardening of the autologous bone often results in morbidity of the donor site. Moreover, alternative biomaterials may be given adequate osteoconductivity/inductivity and increased osteogenic potential through cellularization. However, this approach has not shown its fully efficacy in bone regeneration yet. The main causes of this failure may lie in the fact that the initial state of the different tissues is not taken into account.. This also leads to vascular problems. The osteogenic function of the periosteum has been recognized since the 18th century. It occurs in any situations leading to bone surface detachment , whether of traumatic, infectious, tumorous or surgical origin. This fibro-cellular tissue provides dual functions: interwined mechanical and biological. While its outer fibrous layer plays a mechanical role, its deep cellular layer is able to initiate a massive production of skeletal tissue, as diverse as bone, cartilage, tendons and ligaments and even muscle tissue. This "cambial" layer contains mesenchymal progenitor cells which have preserved a potential for multidirectional differentiation. In addition, the periosteum is responsible for the emission of bioactive molecules (growth factors) that allow these various differentiation pathways to be modulated. This project aims at regenerating the periosteum (flexible elastic membrane) and then regenerate bone (viscoelastic hard tissue) based on previousresearch results of some members of the future network The goal of the creation of this network is to develop a consortium which allows s to understand and evaluate the cellular contribution of periosteal cells to bone regeneration, particularly concerning the speed and the spread of the implant vascularization. The aim of the approach will be to make the most effective use of the periosteal function in order to optimize the bone regeneration process. This network will be able to apply for the H2020 SC1-BHC-07-2019 call on the regenerative medicine, and also on the 2020 Biomaterials call. Based on clinical observations of the beneficial role of periosteal tissue, we propose to study the implantation and integration of the periosteal biomimetic composite biomaterials, to accelerate these processes and optimize the quality of regenerated tissue. The approach will include biological, chemical, physical, and tissue and mechanical engineering sciences.

Dystrophic epidermolysis bullosa (DEB) is a genetic skin blistering disorder caused by collagen VII deficiency. The most severe forms of the disease are also characterized by formation of slow healing wounds and progressive soft tissue fibrosis, which significantly contribute to disease morbidity. Furthermore, cutaneous squamous cell carcinoma driven by the injured and fibrotic dermal microenvironment is the major cause of death in severe DEB. Better treatment of the disease is urgently needed but development of causal therapies is hampered by concerns surrounding delivery, efficacy and safety. An alternative is to target the pathological manifestations occurring subsequent to skin fragility. Development of such manifestations is linked to specifc changes in the transcriptome, proteome and degradome, which can be employed as biomarkers of disease progression and severity. However, for both improved symptom-relief therapy and identification of robust biomarkers, an increased knowledge of the mechanisms involved in the establishment and progression of such manifestations is needed. By retrospective detailed analysis of the fibrotic dermal extracellular matrix (ECM), our approach will be to delineate the processes involved in its buildup with a focus on its major components, the fibrillar collagens and their partners. Establishment of a physiological dermal ECM occurs through regulated and coordinated activity of the epidermis and dermis, leading to collagen fibrillogenesis and ECM organization with biomechanical properties optimized to support skin function. In fibrosis, these processes are disrupted. In this proposal, we plan to comprehensively analyze the fibrotic ECM in order to characterize the most severely affected processes in DEB and to identify (i) novel biomarkers for improved monitoring of DEB disease stages during clinical trials and (ii) conceptually novel evidence-based therapeutic approaches to treat DEB. Our consortium brings together a German partner (Dermatology Department, University of Freiburg) and a French partner (LBTI-CNRS, University of Lyon) with internationally-renowned expertise in the fields of DEB disease and ECM biology. The project will be organized in 4 tasks with the following specific goals: 1) to characterize the dermal collagen matrix in DEB skin; 2) to analyze the influence of altered dermal-epidermal communication in DEB; 3) to evaluate the role of ECM remodeling proteinases in DEB fibrosis; 4) to validate, in patient samples, the clinical relevance of biomarkers identified in previous tasks. Together, these studies will provide essential information to understand the main factors contributing to DEB severity and will allow us to make significant progress towards the validation of both novel biomarkers and therapeutic targets. It is also expected that our proposal will have significant spin-off effects for the understanding and management of other types of inflammation- and fibrosis-driven pathological wounds.

Clostridioides difficile, an anaerobic Gram-positive spore-forming bacterium, is responsible for a wide spectrum of infections ranging from diarrhea to life-threatening pseudomembranous colitis. The use of antibiotic therapy raises concerns about the selection of antibiotic-resistant bacteria at hospitals. New therapeutic targets should be investigated as alternatives to antibiotic treatments. Polysaccharides (PS) biosynthesis enzymes are encoded in a PS locus where most genes are essential for bacterial viability. We propose therefore the enzymes involved in PS biosynthesis as new therapeutic targets. Moreover, vaccines currently under development target the toxins and may not prevent C. difficile colonization and dissemination. We also propose in this project to evaluate PSII and/or LTA as vaccine component(s) of a vaccine that may prevent C. difficile colonization and dissemination. To that aim, the project will (i) define if either one or both PSII and LTA are essential for bacterial viability, ii) identify specific enzymes involved in PSII or LTA biosynthesis, (iii) target them with inhibitors and (iv) test PSII and LTA as vaccine candidates using an innovative approach. We recently developed a new genetic conditional lethal mutant system and have already obtained antibodies directed against PSII. Using these tools, we showed that the PSII seems to be essential for bacterial viability. The project will be divided into three tasks. The first will determine whether PSII, its anchoring and/or LTA are essential and define at least two enzymes as new therapeutic targets, one of each involved in each PS biosynthesis. The second task will look for inhibitors able to target these specific enzymes, using in silico models and a chemistry approach. The last task will test PSII and LTA as vaccine candidates. This project aims to combat C. difficile infections and prevent them using vaccination.

Therapeutic options in response to the SARS-Cov-2 outbreak are urgently needed and existing one are still limited. Facing pandemic development, actual strategy has been to repurpose some existing antiviral drugs used against respiratory diseases (SARS-Cov-1, MERS, Influenza) or chronic diseases (HIV-1, HCV, HBV, etc…). However, side effects are common and required short treatment mainly through intravenous injection, with a non optimal dose, and rarely through pulmonary route. A better formulation of such drug, adapted to this pulmonary disease, will allow an optimal efficacy of current drug or new candidates, such as protease inhibitors. Nanomedicine tools, such as used in HIV-1 treatment, could provide some solution by proposing innovative formulation, leading to the same efficacy with low dose of drugs and nasal/pulmonary delivery. Furthermore, nanoparticulate form favors drug stability, when present in aerosol via sprays or nebulizers. Thus, the CoviNanoMed project aims to formulate and test potential antiviral drugs or Host Targeted Agents using an existing robust nanoparticle platform in order to increase their potential efficacy, while diminishing their side effects. To this aim, we have identified six promising candidates, (non-exhaustive list which could be modulated according to ongoing clinical trials) and have gather four complementary research groups to: i) select the most promising for nanoformulation through in silico modeling and prepare reproducible and stable batch of nanodrugs ii) Assess their antiviral activities and toxicities using state of the art technique, adapted to their nanoparticulate form. It will allow us to classify them and to integrate in an iterative manner new ones according to collaborators iii) Compare nasal and pulmonary delivery in mice through devices used in clinical setting. We will use fluorescent particles and whole body imagine in mice and Non Human Primates to analyze the fate of particles in lung cells and tissue, and iv) Analyse drug release in bronchoalveolar fluids in mice and the most promising formulations in Non Human Primate. As this project concerns existing drugs, the analytical protocols and methods are already determined and will be quickly available. By this project, we expect to identify at least one promising candidate that could be quickly moved to clinical trial, as the biodegradable platform we propose will be considered as a new formulating excipient. Our system is solely based on poly–lactic acid (PLA), a biodegradable polymer approved by the FDA for medical devices such as sutures. It is therefore free of any controversial surfactant that frequently prevent the development of nanosystems to late phases. Additionally, the methodology we have set up could be adapted to new compounds that will emerge through ongoing clinical trials such as the multiple protease inhibitors that are undergoing studies.

Mucosal vaccination, especially nasal administration, constitutes a strategic approach because i) induced immune responses can be both mucosal and systemic, ii) active ingredients are not exposed to extreme gastrointestinal pH or digestive enzymes, iii) numerous microvilli in the nasal epithelium provide a significant absorption surface, iv) no needles or syringes are required. However, despite the growing interest in these strategies, vaccine imaging remains a major challenge. Yet, it would significantly enhance their effectiveness by improving the understanding of the relationship between their localization and the immune response. Indeed, by using nanoparticles as vaccine carriers and optimizing their synthesis, it becomes possible to direct their localization. The goal of this project is to address this issue by using several nanoformulations based on polylactic acid (PLA) nanoparticles with different physicochemical properties through lipid or polymeric coronas. The encapsulation of contrast agents within these nanoparticles will provide access to various imaging modalities. It will then be possible to track these nanoformulations both within the organism and at the tissue and cellular levels to identify their interactions with various components of the immune system. To demonstrate this concept in the context of nasal administration, the choice of the vaccine formulation is focused on the influenza model, and the nanoparticles will be functionalized with the HA and NA antigens. By correlating their location in lymphoid organs after nasal administration with the quality of immune responses, this project will contribute to elucidating the essential parameters required for the design of nanovaccines.