Characterization of progesterone receptor isoform expression in fetal membranes

Objective To quantify expression of progesterone receptor (PR) messenger RNA (mRNA) isoforms in fetal membranes, and to determine whether these levels change in culture. Study design Placentas from women undergoing term cesarean delivery before labor were collected. Layers of amnion, chorion, and decidua were separated manually, enzymatically digested, and separated further with the use of a density gradient. RNA was extracted immediately and after culture for 48 hours, then analyzed by quantitative reverse transcription polymerase chain reaction for PR-A, PR-B, and β-2 microglobulin mRNA expression. Separation of cell types was confirmed by immunohistochemistry. Results PR isoform expression was identified in fetal membranes, with levels highest in decidua and below the limits of detection in amnion. The ratio of PR-A/PR-B mRNA was not significantly different between cell layers. PR mRNA isoform levels did not differ significantly in fresh versus cultured cells. Conclusion Quantitative reverse transcription polymerase chain reaction was used to quantitate expression of PR mRNA isoforms in cells of fetal membranes and to validate systems for further study of PR with respect to inflammation, infection, and preterm delivery.