Preservation of human placenta facilitates multicenter studies on the local immune response in normal and aberrant pregnancies

Our standard procedure for phenotypic and functional analysis of immune cells present in the placenta is to isolate leukocytes from the decidua within five hours of the delivery. However, this results in logistical problems with deliveries at night, weekends or in other medical centers. Collecting placentas after complicated pregnancies is even more difficult owing to the low prevalence and the often unscheduled delivery. The aim was to investigate the possibility of preserving the human placenta before phenotypic and functional analysis of decidual lymphocytes. Placentas were obtained after uncomplicated pregnancy. The tissue was divided into two equal parts: decidual lymphocytes from one part were isolated within five hours according to our standard procedure, whereas the other part was preserved in either Celsior®, a storage solution for solid organ preservation, or phosphate-buffered saline (PBS) for 24 h at 4 °C before isolation. Overall, the phenotype and functional capacity of decidual lymphocytes isolated within five hours was comparable to decidual lymphocytes isolated after 24-h preservation in Celsior® or PBS. Minor differences were found between decidual lymphocytes isolated within five hours and decidual lymphocytes isolated after 24-h preservation in Celsior®. The results indicate that PBS is sufficient to preserve the placenta for 24 h for phenotypical and functional studies. The ability to preserve the placenta will simplify the procedure for the isolation of decidual lymphocytes and makes it easier to analyze tissue from women who deliver during the night, at weekends or in other hospitals, and possibly even women with complicated pregnancies.