IADR Abstract Archives
Mesenchymal Dental Pulp Cells Attenuate Dentin Resorption Homeostasis.
Objectives: To clarify whether mesenchymal stem/progenitor cells in dental pulp attenuate osteoclastgenesis.
Methods: Mononucleated and adherent cells from donor-matched rat dental pulp (dental pulp cells or DPCs) and alveolar bone (alveolar bone cells or ABCs) were isolated and separately co-cultured with primary rat splenocytes. Total RNA of DPCs and ABCs was extracted and the expressions of RANKL and OPG were detected by quantitative real-time PCR. Meanwhile, rat maxillary incisors were atraumatically extracted, followed by retrograde pulpectomy and immediate replantation into the extraction sockets to allow re-population of surgerical treated root canal with periodontal and alveolar bone derived cells.
Results: Primary splenocytes readily aggregated and form osteoclast-like cells in chemically defined osteoclastgenesis medium with 20 ng/ml MCSF and 50 ng/ml RANKL. Striking DPCs attenuated osteoclastgenesis when co-culture with primary splenocytes,whereas ABCs slightly but signicicantly promoted osteoclastgenesis. DPCs yeilded 20 fold lower RANKL expression, but over 2 fold higher OPG expresssion than donor-matched ABCs, yeilding a RANKL/OPG ratio of 41:1 (ABCs:DPCs).In vivo study showed that multiple dentin/root resorption lacunae were present in root dentin with robust RANKL and OPG expression. There were areas of dentin resorption alternating with osteodentin formation in root dentin surface in the observed eight wks.
Conclusions: These finding suggest that dental pulp cells of the mesenchymal compartment have an innate ability to attenuate osteoclastgenesis, and that this innate ability may be responsible for the absence of dentin resoprtion homesatasis. Mesenchymal attenuation of dentin resorption may have impactions in pulp/dentin regeneration and root resorption in orthodontic tooth movement.
Methods: Mononucleated and adherent cells from donor-matched rat dental pulp (dental pulp cells or DPCs) and alveolar bone (alveolar bone cells or ABCs) were isolated and separately co-cultured with primary rat splenocytes. Total RNA of DPCs and ABCs was extracted and the expressions of RANKL and OPG were detected by quantitative real-time PCR. Meanwhile, rat maxillary incisors were atraumatically extracted, followed by retrograde pulpectomy and immediate replantation into the extraction sockets to allow re-population of surgerical treated root canal with periodontal and alveolar bone derived cells.
Results: Primary splenocytes readily aggregated and form osteoclast-like cells in chemically defined osteoclastgenesis medium with 20 ng/ml MCSF and 50 ng/ml RANKL. Striking DPCs attenuated osteoclastgenesis when co-culture with primary splenocytes,whereas ABCs slightly but signicicantly promoted osteoclastgenesis. DPCs yeilded 20 fold lower RANKL expression, but over 2 fold higher OPG expresssion than donor-matched ABCs, yeilding a RANKL/OPG ratio of 41:1 (ABCs:DPCs).In vivo study showed that multiple dentin/root resorption lacunae were present in root dentin with robust RANKL and OPG expression. There were areas of dentin resorption alternating with osteodentin formation in root dentin surface in the observed eight wks.
Conclusions: These finding suggest that dental pulp cells of the mesenchymal compartment have an innate ability to attenuate osteoclastgenesis, and that this innate ability may be responsible for the absence of dentin resoprtion homesatasis. Mesenchymal attenuation of dentin resorption may have impactions in pulp/dentin regeneration and root resorption in orthodontic tooth movement.