Characterization of dental follicle cells in developing mouse molar

Dental follicle has been implicated as the origin of alveolar bone, cementu m and periodontal ligament, but there is no direct evidence of their cellul ar lineage. The present pilot study was designed to characterize the phenot ype of cultured cells obtained from the dental follicle of neonatal mouse m olars. Developing mandibular molars from 6-day-old CD-1 mice were subjected to 1% trypsin in Hank's balanced sail, solution. After trypsinization, the dental follicle was enucleated from the tooth germ and separated from the associated epithelial root sheath. Pure dental follicle tissue was cultured in alpha-minimal essential medium containing 10% fetal bovine serum and an tibiotics. The nature of the cultured follicle cells was determined in situ by immunocytochemical staining for type I and III collagen, fibronectin, a nd alkaline phosphatase expression. Earlier phenotypic markers for minerali zation such as bone sialoprotein and osteopontin were also examined by in s itu hybridization of matched molar tissues. The extracellular matrix protei ns (such as type I collagen and fibronectin) were moderately expressed cyto chemically. However, type III collagen was strongly stained. Gene expressio n of bone sialoprotein and osteopontin was detected in sections of mouse mo lars of similar age. The ALPase activity showed moderate to strong intensit y in these primary cultured cells and responded to 1,25(OH)(2) vitamin D-3 treatment. Cytokeratin stains were not noted in these cells. In conclusion, the 6-day-old dental follicle cells exhibit partial characteristics of a m ineralized tissue-forming phenotype even though the expression of osteopont in, type I collagen and fibronectin was low at this stage. (C) 1999 Elsevie r Science Ltd. All rights reserved.