Baptiste Charbonnier: Developing innovative biomaterials to repair our jaws
In Nantes, Baptiste Charbonnier is developing biomaterials capable of treating bone loss in the jaw, thus enabling dental implants to be placed. For this project, the Inserm researcher obtained ATIP-Avenir funding.
Globally, it is estimated that 23% of people over the age of 60 have at least one missing tooth, and 7% have no teeth at all. This leads to difficulty chewing and nutrition disorders that removable dentures attempt to remedy. Unfortunately, these devices are generally uncomfortable and cause problems of inflammation and infection, among other things. While fixed dental implants give better functional results and are better tolerated, they still need to be fitted. An endeavour not helped by the fact that the absence of mechanical demands on the jawbone due to the missing tooth or teeth causes the bone tissue to resorb. Its volume becomes insufficient to successfully implant the prosthesis. With his team based at the Regenerative Medicine and Skeleton (RMeS) research unit in Nantes, Baptiste Charbonnier obtained ATIP-Avenir funding to develop new biomaterials which, when placed on the bone, promote an increase in bone volume and enable dental replacement.
This work is in line with his initial training as a materials chemistry engineer. ‘It was a generalist course and nothing predestined me to work in biomaterials. But I had an appetite for the health field. I was able to work in it during various internships abroad, on the development of approaches to stabilise fractures or on the phenomena of wear and tear of hip replacements. And when I decided to do a PhD, I was lucky to meet David Marchat, member of the Engineering and Health Centre of École des Mines in Saint-Etienne, who welcomed and encouraged me in the field of bone regeneration.’
A flexible implant that hardens once in place
Replacing bone tissue is much more complex than one might think, because bone is a structure that is constantly remodelling and interacting with the surrounding tissue. The ceramics that are currently used to remedy bone loss in the jaw are not satisfactory: they are rigid and therefore difficult to adjust to the area to be filled. They are also fragile and can break during or after the procedure. ‘For this type of application, we need a material that’s easy to place, which constitutes a scaffold that bone cells can gradually colonise. It must remain in place to aid bone and vessel formation, but resorb sufficiently to allow for new bone tissue. And it all must be able to withstand the mechanical stresses of chewing’.
The biomaterial that he has developed meets these expectations. Flexible in the hands of the surgeon, it hardens once in place. It consists of a mixture of a calcium phosphate cement precursor powder that hardens on contact with water once in place, and a hydrogel that gives it flexibility and maintains the three-dimensional structure after placement. It comes in the form of a paste that is extruded with a 3D printer to generate an implant suitable for each patient. The ATIP-Avenir funding enabled the team to build a printing machine capable of giving it a porous three-dimensional structure. ‘The diameter of the pores must be controlled and heterogeneous, because each dimension has its function, explains the researcher: for example, large pores are gradually invaded by neighbouring cells, while the smallest pores host proteins that will facilitate the adhesion and differentiation of the bone cells. We can even include ions in some of them, such as magnesium or silicon, to promote certain biological processes when they are released in situ.’
From puppies to humans
Like the signature dish of a Michelin-starred restaurant, the recipe for the ideal material requires time and extensive expertise. Charbonnier draws his own from several years of post-doctoral studies, where he developed biomaterials and additive manufacturing techniques, automated artificial intelligence image analysis routines, and a taste for working with animals. He recently led a project focused on the care of canine patients. ‘I joined the RMeS laboratory as a senior post-doc on the GI Jaw project: the aim was to develop innovative 3D printable formulations to fill the cleft palate, also known as the harelip.’ With 1 to 4% of puppies born spontaneously with such a maxillofacial defect, the researcher had an interesting clinical model for developing the ideal biomaterial. He worked in collaboration with the veterinary school of Nantes: ‘The veterinarians identified the puppies and cared for them until they were 6 months old. Then we made the custom-designed implant. In this situation, we need a material that serves as scaffold for the cells, but which resorbs completely because the dog continues to grow: if it stays in place as it is, it creates defects when the jaw grows.’ This project has now been successfully completed. The researchers must now obtain regulatory certification for the biomaterial they have developed from bone cement and hyaluronic acid. A necessary step for envisaging clinical development. If all goes well, its use in children could start within 10 years.
‘Each application has its particularities and requirements, and therefore requires a specific material. In this dynamic, the ATIP-Avenir funding has been a great support: it is a huge springboard, making it possible to sustain our activities, develop collaborations and expand our team. It also helps to attract the support of other funding parties.’ Today, the researcher works in constant contact with veterinarians and clinicians on new projects, such as the treatment of maxillary bone loss due to age or periodontitis, and the development of gum substitutes. The prospects are many.
‘Being a researcher requires relentless work, but also offers great encounters. I’m very satisfied with what I’m currently doing. When I was a student, I couldn’t imagine getting as far as this. I thought I’d turn to teaching instead. As a researcher, I can still give classes, and it’s a real pleasure to interact with future researchers. In the same spirit, I try to keep time to help my team, understand the efforts made and the difficulties encountered at the lab bench. Without this, the administrative tasks associated with my role as team leader could swallow up all my research time and my ability to develop the projects I have in mind.’
In Nantes, Baptiste Charbonnier is developing biomaterials capable of treating bone loss in the jaw, thus enabling dental implants to be placed. For this project, the Inserm researcher obtained ATIP-Avenir funding.
