Journal of Dental Research, Vol 72, 1460-1472, Copyright © 1993 by International & American Associations for Dental Research Online Journals
A chondroitin sulfate epitope in mammalian dental pulp and its developmental expression in mouse dental papilla
P. Nieminen, S. Vainio, J. Jernvall, P. L. Lukinmaa, E. Lehtonen and I. Thesleff
Department of Pedodontics and Orthodontics, University of Helsinki, Finland.
The molecular specificity of the dental papilla of a bell-stage tooth was
studied by production of dental-papilla-reactive monoclonal antibodies
(Mabs). One of the Mabs, designated 7C5, recognized an epitope present in
glycosaminoglycan. Several lines of evidence suggested that the 7C5-epitope
consists of chondroitin 6-sulfate. The Mab did not react with mouse dental
epithelium, but reacted uniformly with mesenchymal tissue in the mandibular
process and accumulated in the dental sac and in the papilla of bell-stage
tooth germs. The 7C5-staining was lost from the differentiating
odontoblasts, while the staining in the molar tooth papilla was accumulated
in the subodontoblastic layer. In the developing mouse incisor, the
7C5-epitope was restricted to the lingual-posterior area. The 7C5-epitope
was also present in pulpal tissue and predentin of different types of teeth
of various mammalian species, including man, sheep, swine, and rat.
Collagenase pre-treatment of tissue sections abolished the bulk of the
7C5-reactivity in peridental mesenchyme during embryonic stages while
leaving the staining of the dental papilla intact. In newborn and adult
teeth, collagenase also impaired the reactivity in the pulp except for the
subodontoblastic layer. This suggests the existence of different
subpopulations of the 7C5-epitope containing proteoglycans in dental
papilla and pulp. A high-molecular-weight proteoglycan, sensitive to
chondroitinase ABC but not to heparinase or heparitinase, was
immunoprecipitated by 7C5 from extracts of bell-stage mouse tooth germs. We
suggest that the evolutionary conservation of chondroitin 6-sulfate in the
dental pulp reflects its properties as non-terminally differentiated tissue
and perhaps the retention of a potential to differentiate to odontoblasts.
