Romina Plitman Mayo1,2 Steve Charnock-Jones,2 Michelle Oyen,2 and Graham Burton2
1Department of Mechanical Engineering, Tel Aviv University, Israel
2Centre for Trophoblast Research, University of Cambridge, UK
The placenta is a unique hemodynamic system that comprises two separate blood systems, the maternal and fetal circulatory systems, which exchange nutrients and waste. Three factors considerably complicate research into placental physiology: in vivo research is restricted by ethical constraints, ex vivo research depends on the availability and accessibility of the organ, and -due to species differences- the validity of animal models is limited. The aim of this project is to create reliable models of the human placenta to investigate these exchange mechanisms.
Materials and Methods
A fresh healthy placenta was obtained for perfusion fixation. Small terminal villi were stained and scanned using a confocal microscope (CLSM). The CLSM data were converted into 3D finite element models. The models included the diffusion of oxygen across the trophoblastic membrane, through the fetal plasma, and its binding to fetal hemoglobin.
Interestingly, the oxygen flux was found to be almost constant for all models. However, the average blood oxygen saturation is 72±17%. As expected, this shows a dependency on the flow rate, with lower rates allowing a higher level of saturation. The models also show that narrow segments transport the blood up to twice as fast as the dilated ones and that capillary bends can decelerate the flow by up to 80%.
Research on the human placenta is challenging and has forced researchers to look for creative approaches in order to elucidate on the structure-function relationship of the human placenta. Computational modeling, therefore, represents an innovative alternative to address questions on the exchange processes of the placenta.