STIMULATION OF DNA-SYNTHESIS BY ENDOTHELIN-1 IN PRIMARY CULTURES OF HUMAN DENTAL-PULP

Endothelin (ET), besides being a powerful vasoactive agent, acts as a mitogen in some cell types. ET-like immunoreactivity has been recently detected by immunocytochemistry in the vascular endothelium of human tooth germ and dental pulp, thus providing evidence for local ET produ ction in these tissues. The effects of ET-1 on DNA synthesis in primar y cultures of human dental pulp were now investigated. DNA synthesis w as evaluated by flow cytometric assay and by 5-bromo,2'deoxyuridine in corporation as detected by immunocytochemistry. Cultured cells were mo rphologically similar to dental pulp cells and displayed vimentin immu noreactivity. Incubation of cultures with ET-I resulted in a dose-depe ndent increase in the number of S-phase-traversing cells over control (unstimulated) cultures. Control skin fibroblasts were also responsive to ET. This finding raises the possibility that the multifunctional p eptide ET-1 might subserve growth-promoting activity in the human toot h. It is tentatively suggested that such as an activity might be impor tant during tooth development and in pulp inflammation and healing.