Fabrication of Hard Tissue Constructs from Induced Pluripotent Stem Cells for Exploring Mechanisms of Hereditary Tooth/Skeletal Dysplasia.

Tooth/skeletal dysplasia, such as hypophosphatasia (HPP), has been extensively studied. However, there are few definitive treatments for these diseases owing to the lack of an in vitro disease model. Cells differentiated from patient-derived induced pluripotent stem cells (iPSCs) demonstrate a pathological phenotype. This study aimed to establish a method for fabricating hard tissue-forming cells derived from human iPSCs (hiPSCs) for the pathological analysis of tooth/skeletal dysplasia. Healthy (HLTH) adult-derived hiPSCs were cultured in a hard tissue induction medium (HM) with or without retinoic acid (RA) under 3D culture conditions, and mineralization and expression of dentinogenesis- and osteogenesis-related markers in 3D hiPSC constructs were evaluated. hiPSCs derived from patients with hypophosphatasia were also cultured in HM with RA. HLTH-derived hiPSCs formed mineralized 3D constructs and showed increased expression of dentinogenesis- and osteogenesis-related markers; addition of RA promoted the expression of these markers in hiPSC constructs. HPP-derived hiPSC constructs showed lower mineralization and expression of dentinogenesis- and osteogenesis-related markers than HLTH-derived hiPSCs, indicating an impaired ability to differentiate into odontoblasts and osteoblasts. This method for fabricating 3D hiPSC constructs allows for simultaneous assessment of dentinogenesis and osteogenesis, with HPP-derived hiPSC constructs recapitulating pathological phenotypes.