Method Approach for preparing placental materials Experimental data derived
Placental Membrane Preparations Isolation of brush border and basal membranes, generally from term human placenta Transport of solutes across brush border or basal membranes of syncytiotrophoblast. Interaction of solutes on membrane transport mechanisms. No data on solute metabolism or retention by the placenta.
Placental Cell Culture Primary trophoblast cell culture and transformed trophoblast cell culture, across gestational ages. Uptake, metabolism of solutes by trophoblast. Impact of solutes on trophoblast metabolism and function.
Placental explants Isolated villi in perifusion medium, across gestational ages. Uptake, metabolism and retention of solutes by placental villi, Impact of solutes on villous function.
Placental perfusion Identification of intact cotyledon with perfusion of maternal and fetal portions of the placenta, generally from term human placenta. Possible to study placenta from maternal, fetal or placental disease states. Uptake, metabolism and retention of solutes by placenta. Directionality of transport (maternal to fetal or reverse). Impact of solute on placental function, integrity of placental vasculature and vascular responses.
Maternal and fetal bloods sampled from umbilical cord Samples taken generally at term following delivery, however some studies have sampled fetal blood in utero. Placental materials are generally not studied in these analyses. Concentrations of parent solute and metabolites at fixed periods of time after maternal dosing.
See [17] for a more detailed discussion of these various methods for assessing placental disposition and impact of opioids
Table 3: Methodological approaches for studying human placental disposition of opiates and opioids.