In vitro metabolism of 25-hydroxycholecalciferol by isolated cells from human decidua.

An increase in maternal serum levels of 1 alpha, 25-dihydroxycalciferol during pregnancy has been linked to enhancement of intestinal calcium absorption. Several sites of its synthesis have been proposed in different species, human decidua being one of them. Collagenase-dispersed decidual cells isolated from term placenta were fractionated on a Percoll gradient. The isolated cells were set in culture in the presence of 6 nM [3H]cholecalciferol. Two cell populations of similar morphology hydroxylated the substrate, yielding a compound that had a mass spectrum identical to and that comigrated with authentic 1 alpha, 25-dihydroxycholecalciferol in four chromatographic systems and bound to a specific rachitic chick receptor. These preparations, thus, provide a potential system by which the kinetics and regulation of the synthesis of the hormonal form of vitamin D by human placenta can be studied in vitro.