MINERALIZED NODULE FORMATION BY HUMAN DENTAL PAPILLA CELLS IN CULTURE

Human dental papilla cells were enzymatically separated from deciduous tooth germs of an 8-month-old embryo legally aborted. The second pass age cells were cultured up to 35 days in 3 groups. The beta-GP group w as cultured in the Dulbecco MEM containing ascorbic acid and beta-glyc erophosphate supplemented with 15% fetal bovine serum. The Dex group w as in the same medium, in addition containing dexamethasone. The contr ol group contained none of the 3 chemicals. Mineralized nodules were f ormed after 15 days in the beta-GP and Dex groups. Only in the presenc e of ascorbic acid and organic phosphate did they mineralize. The addi tion of dexamethasone caused a significant increase in the number of n odules. By electron microscopy, the nodules contained needle-shaped cr ystals associated with a network of collagen fibrils. Calcium and phos phorus were detected by energy-dispersive X-ray microanalysis in the n odules. Furthermore, the crystalline material exhibited a pattern cons istent with hydroxyapatite and dentin when examined by X-ray diffracto metry. Cells showed high levels of alkaline phosphatase activity, whic h was increased 2 similar to 3 times in the presence of the 3 chemical s. These results indicated that human dental papilla cells have the ab ility to form dentin in culture. The formation of mineralized nodules by human dental papilla in vitro provides a useful model for studying the morphogenesis and differentiation of dental papilla ectomesenchyme .