Systemically Transplanted Bone Marrow–derived Cells Contribute to Dental Pulp Regeneration in a Chimeric Mouse Model

• A chimeric mouse model was created through the injection of bone marrow cells from GFP transgenic C57BL/6 mice into the tail veins of recipient wild-type C57BL/6 mice.
• This chimeric mouse model was subjected to pulpectomy and pulp revascularization to study the process in which bone marrow derived cells were involved in revascularization of pulp tissue.
• Dynamic fluorescence imaging in vivo and immunofluorescence were used to explore mechanisms of bone marrow derived cells involved in the process of pulp revascularization.

IntroductionMigratory cells via blood circulation or cells adjacent to the root apex may potentially participate in dental pulp tissue regeneration or renewal. This study investigated whether systemically transplanted bone marrow cells can contribute to pulp regeneration in a chimeric mouse model.MethodsA chimeric mouse model was created through the injection of bone marrow cells from green fluorescent protein (GFP) transgenic C57BL/6 mice into the tail veins of recipient wild-type C57BL/6 mice that had been irradiated with a lethal dose of 8.5 Gy from a high-frequency linear accelerator. These mice were subjected to pulpectomy and pulp revascularization. At 1, 4, and 8 weeks after surgery, in vivo animal imaging and histologic analyses were conducted.ResultsIn vivo animal imaging showed that the green biofluorescence signal from the transplanted GFP+ cells increased significantly and was maintained at a high level during the first 4 weeks after surgery. Immunofluorescence analyses of tooth specimens collected at 8 weeks postsurgery showed the presence of nestin+/GFP+, α smooth muscle actin (α-SMA)/GFP+, and NeuN/GFP+ cells within the regenerated pulplike tissue.ConclusionsThese data confirm that transplanted bone marrow–derived cells can contribute to dental pulp regeneration.