Anh Tuan Dang

Abstract Introduction: Recently, many researchers have done a lot of work using long bones in the field of dental research. It is well demonstrated that CAR cells, which express high levels of Cxcl12 chemokine, played a central role in the formation and maintenance of the bone and bone marrow in long bones. On the other hand, there are limited studies in terms of stem cells in jawbones, therefore, this research aims to clarify the mesenchymal stem cells that are involved in bone homeostasis and regeneration in the mandible compared to the femur in mice at the single-cell resolution. Aim/Method: Here, we performed single-cell RNA sequencing (scRNA-seq) together with the genetic lineage tracing assay to clarify the differences in mesenchymal stem cells involved in bone homeostasis and regeneration between the jawbones and the long-bones in normal conditions and during the wound healing process. Results: 1. CAR cell tracing assay using LepR-Cre/Tomato mice showed a significantly lower of CAR-derived osteoblast percentage in the 1st molar dental tooth socket in comparison with in defective site of the femur at day 7, which strongly implied that CAR cells are not the main contributor to the bone formation in the mandible. 2. ScRNA-seq revealed that: periodontal ligament-derived mesenchymal stem cells (PDLCs) are the main mesenchymal cell population presented in the mandible, in contrast with the contribution of CAR cells in long bone. On day 3 of the wound healing process: in the femur, the CAR cell proportion was decreased, in contrast with the increase of Osteoblasts percentage. In the mandible, the PDLCs decreased and osteoblasts increased. Pseudo-time analysis revealed a unique trajectory: PDLSCs could differentiate into osteoblasts, leading to bone regeneration. Conclusion: Overall, PDLSCs are the key subtype of dental mesenchymal stem cells critically involved in the regeneration of mouse tooth extraction sockets.

Anh Tuan DANG (D.D.S, Ph.D. student) • 2009 – 2015: D.D.S student, Dental School, Haiphong University of Medicine and Pharmacy, Vietnam. • 2015 – present: D.D.S, Lecturer, Department of Prosthodontics, Dental School, Haiphong University of Medicine and Pharmacy, Vietnam. • 2020 – present: Ph.D. student1,2, major in stem cells and bone research. 1Department of Oral Rehabilitation and Regenerative Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences. 2Department of Molecular Biology and Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences.