REPOUSSES

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.