Repopulation of a 3D-simulated periapical lesion cavity with triggered osteoblastic-differentiated dental pulp stem cell spheroids

Abstract

We established a proof of concept model system for the biological repair of periapical lesions using stem cell spheroids. A mesenchymal stem cell line isolated from the dental pulp of deciduous teeth (shed cells) was cultured in a 2D monolayer and then in 3D multicellular spheroids. An image of a periapical lesion of an upper lateral incisor tooth was obtained by computed micro tomography, which was used as a model for photopolymer resin 3D printing to generate a negative frame of the lesion. The negative model served to prepare a positive model of the periapical lesion cavity in an agarose gel. Shed cells cultured in monolayers or as spheroids were seeded in the positive lesion mold before or after osteoblastic differentiation. The results showed that compared to cells cultured in monolayers, the spheroids featured uniform cellularity and had a greater viability within the lesion cavity, accompanied by a temporal reduction in the expression of mRNAs typically expressed by stem cells (Cd13, Cd29, Cd44, Cd73, and Cd90). Concomitantly, there was an increase in the expression of protein markers that characterize osteoblastic differentiation (RUNX2, ALP, and BGLAP). These results provide a new perspective for regenerative endodontics with the use of spheroids prepared with shed cells to repair periapical lesions.