Renewal and migration of rat incisor mesenchymal cells after doxorubicin administration

Ten female rats were intravenously injected with doxorubicin (20 mg/kg) and divided into two equal groups receiving a dose of tritiated thymidine either simultaneously with doxorubicin or 1 h before being killed after 5 days. Six control animals were correspondingly injected with 3H-thymidine. The left and right maxillary incisors were prepared for histologic and microautoradiographic investigation, respectively. The distribution of labeled cells in animals injected 1 h before death showed the regions of proliferation, whereas migration from these regions was evaluated by longer observation time. A zone of reduced dentin deposition lined by irregular odontoblasts being young odontoblasts and late preodontoblasts was observed at the time of doxorubicin injection. Pulpally to the dentinal lesion, islands of irregular predentin were deposited by non-progenitive pulp cells and depolarized odontoblasts. The late preodontoblasts were renewed from progenitive pulp cells, leading to a disturbed mantle predentin deposition.