Background: Successful pulp regeneration depends on identification of pulp stem cells capable of differentiation\nunder odontoblastic lineage and producing pulp-dentinal like structure. Recent studies demonstrate that plateletderived\ngrowth factor (PDGF) plays an important role in damage repair and tissue regeneration. The aim of this\nstudy was to identify a subpopulation of dental pulp cells responsive to PDGF and with dentin regeneration potential.\nMethods: Pulp tissues were isolated from 12 freshly extracted human impacted third molars. Pulp cells were\nsorted by their expression of PDGFR�² and stem cell marker genes via flow cytometry. For the selected cells,\nproliferation was analyzed by a colorimetric cell proliferation assay, differentiation was assessed by real time PCR\ndetection the expression of odontoblast marker genes, and mineralization was evaluated by Alizarin Red S\nstaining. GFP marked PDGFR�²+/c-kit+ pulp cells were transplanted into emptied root canals of nude rat lower left\nincisors. Pulp-dentinal regeneration was examined by immunohistochemistry.\nResults: PDGFR�²+/c-kit+ pulp cells proliferated significantly faster than whole pulp cells. In mineralization media,\nPDGFR�²+/c-kit+ pulp cells were able to develop under odontoblastic linage as demonstrated by a progressively\nincreased expression of DMP1, DSPP, and osteocalcin. BMP2 seemed to enhance whereas PDGF-BB seemed to\ninhibit odontoblastic differentiation and mineralization of PDGFR�²+/c-kit+ pulp cells. In vivo root canal transplantation\nstudy revealed globular dentin and pulp-like tissue formation by PDGFR�²+/c-kit+ cells.\nConclusions: PDGFR�²+/c-kit+ pulp cells appear to have pulp stem cell potential capable of producing dentinal like\nstructure in vitro and in vivo.
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