Response of rat incisor mesenchymal cells to doxorubicin after bleomycin pretreatment

Abstract

Beomycin is a possible synchronizing agent of dividing cell populations in vivo. Utilizing this property, we studied doxorubicin-induced alterations in incisor mesenchymal cells by light microscopy in rats pretreated with bleomycin. Two experimental groups were given 25 mg/kg and 75 mg/kg bleomycin, respectively, followed by a dose of 5 mg/kg doxorubicin after 32 h. At that time, the synchronized cells were theoretically entering the synthesis phase of the cell cycle, in which they are most vulnerable to doxorubicin. Animals given 75 mg/kg bleomycin had indications of cell synchronization, resulting in increased destruction of the basal pulp 1 day after doxorubicin administration. Two odontoblast/dentinal lesions were seen on the 5th day of observation, each induced by injury to cells that were late preodontoblasts at the time of bleomycin and doxorubicin injection. The histomorphological alteration seen after the lowest bleomycin dose in combination with doxorubicin included necrosis of basal pulp cells after 1 day and dentinal dearrangements after 5 days, corresponding to what has previously been found in animals given doxorubicin only.