Bone Regeneration by Dedifferentiated Fat Cells Using Composite Sponge of Alfa-Tricalcium Phosphate and Gelatin in a Rat Calvarial Defect Model

Mechanical and resorbable scaffolds are in high demand for stem cell-based regenerative medicine, to treat refractory bone defects in craniofacial abnormalities and injuries. Multipotent progenitor cells, such as dedifferentiated fat (DFAT) cells, are prospective sources for regenerative therapies. Herein, we aimed to demonstrate that a composite gelatin sponge (α-TCP/GS) of alfa-tricalcium phosphate (α-TCP) mixed with gelatin scaffolds (GS), with/without DFATs, induced bone regeneration in a rat calvarial defect model in vivo. α-TCP/GS was prepared by mixing α-TCP and 2% GS using vacuum-heated methods. α-TCP/GS samples with/without DFATs were transplanted into the model. After 4 weeks of implantation, the samples were subjected to micro-computed tomography (μ-CT) and histological analysis. α-TCP/GS possessed adequate mechanical strength; α-TCP did not convert to hydroxyapatite upon contact with water, as determined by X-ray diffraction. Moreover, stable α-TCP/GS was formed by electrostatic interactions, and verified based on the infrared peak shifts. μ-CT analyses showed that bone formation was higher in the α-TCP/GS+ DFAT group than in the α-TCP/GS group. Therefore, the implantation of α-TCP/GS comprising DFAT cells enhanced bone regeneration and vascularization, demonstrating the potential for healing critical-sized bone defects.