Enhanced Bone Regeneration by Scaffold-Free Three-Dimensional Constructs of Human Dental Pulp Stem Cells in a Rat Mandibular Defect Model

Bone defects in the maxillofacial region severely impair patient function and esthetics. Free autologous bone grafting remains the gold-standard treatment; however, surgical intervention at donor sites limits clinical applicability. Treatment using artificial materials also presents challenges, including insufficient bone regeneration and poor biocompatibility. Bio three-dimensional (3D) printing, which enables the fabrication of scaffold-free 3D constructs from cellular spheroids has emerged as a promising regenerative approach. This study investigated the osteogenic potential of scaffold-free constructs composed of human dental pulp stem cell (DPSC) spheroids in a rat mandibular defect model. DPSCs isolated from extracted human teeth were used to generate spheroids, which were assembled into 3D constructs using a Bio 3D printer. The spheroids exhibited higher mRNA expression of stem cells and early osteogenic markers than monolayer cultures. The constructs were transplanted into mandibular defects of immunodeficient rats, and bone regeneration was assessed eight weeks post-transplantation. Radiographic and micro-Computed Tomography analyses revealed significantly greater bone volume and mineral density in the 3D construct group. Histological and immunohistochemical examinations confirmed newly formed bone containing osteogenic cells derived from the transplanted DPSCs. These findings indicate that Bio 3D-printed, scaffold-free DPSC constructs promote mandibular bone regeneration and may provide a novel strategy for maxillofacial reconstruction.