Heterotopically differentiated PDLSCs-laden 3D bioprinting scaffolds for concurrent oral hard and soft tissue regeneration

Following dental extraction, the alveolar bone and gingival tissues could undergo varying degrees of resorption, affecting subsequent implant integration and aesthetic outcomes. Adequate volume of both hard and soft tissues is essential for optimal results. Three-dimensional (3D) bioprinting technology offers the advantages of biomimicry, personalization, and precise spatial distribution, which are pivotal for enhancing the success and esthetics of dental restorations. In this study, we fabricated a construct with a natural transition and varying material concentrations by 3D bioprinting, comprising an upper layer of Collagen/Alginate/periodontal ligament stem cells (PDLSCs) and a lower layer of Collagen/nano-hydroxyapatite (nHA)/Alginate/PDLSCs. Characterization of the physicochemical properties revealed that the incorporation of nHA significantly enhanced the mechanical properties of both the bioink and the construct. Flow cytometry analysis confirmed the stemness of PDLSCs. Scanning electron microscopy (SEM) revealed that the construct possesses satisfactory pore density and a natural transition at the stratification point. The construct displayed good cell viability and proliferation, with the cellular movement observed at the stratification interface after bioprinting. Differentiation staining and quantitative reverse transcription-polymerase chain reaction (RT-qPCR) results demonstrated that PDLSCs within the 3D construct are capable of both osteogenic and fibroblastic differentiations. Ectopic transplantation in mice confirmed the biocompatibility of the construct. A rat tooth extraction model validated the construct's effectiveness in the integrated regeneration of both hard and soft tissues in alveolar ridge preservation (ARP). In conclusion, this personalized, concentration-varied 3D construct exhibits excellent biocompatibility and tissue preservation effects, holding significant potential for clinical application.