Effect of micro-nano-hybrid structured hydroxyapatite bioceramics on osteogenic and cementogenic differentiation of human periodontal ligament stem cell via Wnt signaling pathway

Lixia Mao,1,* Jiaqiang Liu,1,* Jinglei Zhao,1 Jiang Chang,2 Lunguo Xia,1 Lingyong Jiang,1 Xiuhui Wang,2 Kaili Lin,2,3 Bing Fang11Center of Craniofacial Orthodontics, Department of Oral and Cranio-maxillofacial Science, Top Priority Clinical Medical Center of Shanghai Municipal Commission of Health and Family Planning, Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Shanghai Jiao Tong University, 2State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 3Shanghai Engineering Research Center of Tooth Restoration and Regeneration, School of Stomatology, Tongji University, Shanghai, People’s Republic of China*These authors contributed equally to this workAbstract: The surface structure of bioceramic scaffolds is crucial for its bioactivity and osteoinductive ability, and in recent years, human periodontal ligament stem cells have been certified to possess high osteogenic and cementogenic differential ability. In the present study, hydroxyapatite (HA) bioceramics with micro-nano-hybrid surface (mnHA [the hybrid of nanorods and microrods]) were fabricated via hydrothermal reaction of the α-tricalcium phosphate granules as precursors in aqueous solution, and the effects of mnHA on the attachment, proliferation, osteogenic and cementogenic differentiations of human periodontal ligament stem cells as well as the related mechanisms were systematically investigated. The results showed that mnHA bioceramics could promote cell adhesion, proliferation, alkaline phosphatase (ALP) activity, and expression of osteogenic/cementogenic-related markers including runt-related transcription factor 2 (Runx2), ALP, osteocalcin (OCN), cementum attachment protein (CAP), and cementum protein (CEMP) as compared to the HA bioceramics with flat and dense surface. Moreover, mnHA bioceramics stimulated gene expression of low-density lipoprotein receptor-related protein 5 (LRP5) and β-catenin, which are the key genes of canonical Wnt signaling. Moreover, the stimulatory effect on ALP activity and osteogenic and cementogenic gene expression, including that of ALP, OCN, CAP, CEMP, and Runx2 of mnHA bioceramics could be repressed by canonical Wnt signaling inhibitor dickkopf1 (Dkk1). The results suggested that the HA bioceramics with mnHA could act as promising grafts for periodontal tissue regeneration.Keywords: surface topography, periodontal ligament stem cells, Wnt signaling pathway, bioceramics, periodontal reconstruction