Epigenetic drug 5-azacytidine impairs the potential for odontogenesis but improves tooth morphogenesis in the transplanted embryonic mandible

Influence of a DNA demethylating agent on transplanted embryonic mandible

Abstract

Background and purpose: Epigenetic mechanisms are crucial in regulating development. The aim of the study was to investigate whether a DNA-demethylation drug 5-azacytidine (5azaC) affects odontogenesis in embryonic mandibles ectopically transplanted in vivo.

Materials and methods: Mandibles from 13.5- and 14.5-day-old Fischer rat embryos containing early tooth-primordia (dental laminas) were transplanted under the kidney capsule of adult males. Host animals were treated with 5azaC (5mg/kg, i.p.) for the first three days and sham-controls with PBS. After two weeks, differentiation was analysed by histology and cell proliferation by immunohistochemistry.

Results: In some transplants, the bell stage of incisors and molars developed. Teeth in 13.5-day-old transplants produced only dentine, and the incidence of mandibles with teeth in 5azaC-treated hosts was lower. PCNA was expressed only in odontoblasts. Several 14.5-day-old transplants developed teeth with both dentine and enamel. In 5azaC-treated hosts, Hertwig's epithelial root sheath developed, but the number of mandibles with teeth was lower than in controls (p˂0.05). Somewhat fewer molars than incisors developed under 5azaC-treatment. Differentiation of the bone, cartilage, salivary glands, epidermis, hair, sebaceous glands, and adipose cells proceeded in all transplants, except for myotubes that were absent from older transplanted mandibles.

Conclusions: Embryonic mandibles retained the potential for the development of teeth at the ectopic site, but odontogenesis was more advanced in a-day-older mandibles. In older mandibles, the 5-azaC impaired potential for odontogenesis, but teeth that developed reached a higher stage of organogenesis. These results are contributing to the epigenetic explanation of the development of teeth anomalies.