Localization of Gli1-expressing cells after pulp revascularization and their involvement in newly formed mineralized tissue in mice.

The aim of this study was to elucidate the localization of Glioma-associated oncogene homolog 1–expressing (Gli1⁺) cells during the healing process of pulp revascularization. In addition, we investigated their contribution to newly formed mineralized tissue using lineage-tracing analysis. Five-week-old Gli1-CreERT2-Tomato mice underwent pulp revascularization in maxillary right first molars and were sacrificed at 1 h and 3, 7, 14, and 21 days postoperatively. At 3 days, co-localization of Gli1⁺ cells with osterix, a cementoblast marker, was observed, whereas nestin-positive odontoblast-lineage cells were not detected in the treated root canal. Because proliferative activity is an important component of early healing, Ki-67–immunoreactive cells were also examined. Ki-67–immunoreactive cells were present in the periapical tissues and within the root canal at 3 days, with partial overlap with Gli1⁺ cells, but no Ki-67–positive cells were found at 14 days. Periostin, a marker of periodontal ligament fibroblasts, was not expressed in the root canal or in regions populated by Gli1⁺ cells. These findings suggest that Gli1⁺ cells migrate from periapical tissues into the root canal and contribute to the formation of cementum-like mineralized tissue during wound healing after pulp revascularization.