Cell characteristics and functions of two enriched fractions of human luteal cells during prolonged culture

Abstract

Two subpopulations of steroidogenic cells exist in the corpus luteum of most species. The aims of the present study were to characterize these cells and to study their function during long-term culture. Human corpora lutea from early and late luteal phases were treated by mechanical and enzymatic digestion, followed by density sedimentation. Five distinct cell bands were obtained, two of which produced large amounts of progesterone. These were characterized according to density, size, steroidogenic enzymes, and numbers. More than 75% of cells expressed immunoreactive 3β-hydroxydehydrogenase (3β-HSD). Cells of higher density/smaller size were obtained in increasing numbers during the luteal phase and were more numerous compared with large cells. Under basal, human chorionic gonadotrophin (HCG)-, and prostaglandin E2-stimulated culture conditions, progesterone synthesis was greater in large cells of the early, but not late, luteal phase. Both cell fractions obtained from late, in contrast to early, luteal phase increased their basal progesterone production during the culture period of 9 days. We conclude that this technique for luteal cell isolation in the human yields two distinct subpopulations of steroidogenic cells, which respond differently to luteotrophic stimuli. We also conclude that cells of late luteal phase readily increase their progesterone synthesis over a period of 9 days, indicating a transition to longevity.