3D Innovative tooth organoids and bioprinting for personalised medicine in rare oro-dental diseases – 3DBioDENT

In rare diseases affecting the head and neck area, dental developmental anomalies are often key diagnostic features orienting clinical diagnosis. These anomalies (tooth number: hypo/oligodontia (HO) and supernumerary teeth, tooth shape, size, structure of hard tissues (dentine, enamel, cement, alveolar bone), eruption, and resorption) are hallmarks of disrupted biological processes fixed in time by mineralization. Dental development is underpinned by epithelial-mesenchymal interactions between epithelial cells of the oral ectoderm and ectomesenchyme derived from the cephalic neural crests. It involves major developmental signaling pathways and results in the establishment of highly specialized mineralized tissues (as enamel and dentin) according to predefined patterns. Very few genes are exclusively specific to odontogenesis and are often involved in larger developmental processes. A targeted study on rare oro-dental diseases, using targeted NGS and Whole Exome Sequencing, currently explore 567 genes, and has allowed the identification of numerous pathogenic genetic variants, but also of variants of unknown significance (VUS, around 20% of cases). These VUS represent a major conundrum and complicate the establishment of a confirmed genetic diagnosis and genetic counselling.
We seek to study the pathophysiology of these VUS involved in dental rare diseases. Several research models have been described over the years, from 2D and 3D cell cultures to genetically modified mouse models. 2D cell cultures do not reproduce all the mechanical and biochemical signals present in vivo and there is not today a fully functional in vitro cell model available to study the molecular mechanisms and cell-to-cell interactions during tooth formation. We propose to develop two main 3D cell culture complementary approaches. First, 3D human and mice cell culture models on bioprinted microscaffolds will be stablish to study abnormalities associated with later stages (Amelogenesis imperfecta and Dentinogenesis imperfecta). The organoids cells lines used for these in vitro 3D models will be transformed by CRISPR/Cas9 for the target and identified genes or VUS and studied in 3D environment. Secondly, we will establish murine embryonic tooth explant cultures, which will allow us to study anomalies linked to early dental developmental stages (Hypo/oligodontia and shape abnormalities).
Both approaches, 3D murine explants model and 3D in vitro bioprinted cellular models will allow us to analyse the effects of VUS identified by the GenoDENT panel in the genes participating in the formation of enamel and dentin and involved in Amelogenesis Imperfecta (AI) and Dentinogenesis imperfect (DI), and in Hypo/Oligodontia (HO), three rare diseases that affect the quality of life of patients, in particular because of financial constraints about their treatment and which also constitute a major public health issue.