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Developmental Biology - Human Placenta
3D Model of Nutrient Exchange in Human Placenta
New three-dimensional imaging of our human placenta helps explain reasons behind fetal growth restriction - a condition affecting thousands...
Across all species of mammals, vital life-giving nutrients are transported around the body by complex networks of blood vessels. Despite their importance, relatively little is known about what determines how solutes such as oxygen, get to tissues and organs. However, new findings published in Science Advances give us more details.
Scientists from The University of Manchester and St Mary's Hospital created 3D mathematical images modeling the life-sustaining placental process.
The placenta's life-support system is built around numerous terminal villi — small structures that contain disordered networks of fetal capillaries — each surrounded by maternal blood.
"In our new study we show how the irregular three-dimensional structure of a terminal villus determines its capacity to exchange solutes between mother and fetus.
Dr Igor Chernyavsky, MRC & Presidential Research Fellow and lead author.
Dr. Chernyavsky: "Combining image analysis and computational fluid dynamics, mathematically quantified the exchange capacity of individual terminal vill. We now anticipate this advance will aid in development of larger-scale computational models of placental function. We hope this new understanding of placental geometry will help clinicians address diseases where placental structure is compromised."
Abstract
Across mammalian species, solute exchange takes place in complex microvascular networks. In the human placenta, the primary exchange units are terminal villi that contain disordered networks of fetal capillaries and are surrounded externally by maternal blood. We show how the irregular internal structure of a terminal villus determines its exchange capacity for diverse solutes. Distilling geometric features into three parameters, obtained from image analysis and computational fluid dynamics, we capture archetypal features of the structure-function relationship of terminal villi using a simple algebraic approximation, revealing transitions between flow- and diffusion-limited transport at vessel and network levels. Our theory accommodates countercurrent effects, incorporates nonlinear blood rheology, and offers an efficient method for testing network robustness. Our results show how physical estimates of solute transport, based on carefully defined geometrical statistics, provide a viable method for linking placental structure and function and offer a framework for assessing transport in other microvascular systems.
Authors
Alexander Erlich1, Philip Pearce, Romina Plitman Mayo, Oliver E. Jensen and Igor L. Chernyavsky.
Acknowledgements
The authors thank J. Aplin, P. Brownbill, E. D. Johnstone, and R. M. Lewis for the helpful discussions. Funding: This work was supported by the MRC (MR/N011538/1) and EPSRC (EP/K037145/1) research grants and the Centre for Trophoblast Research, University of Cambridge. Author contributions: A.E., P.P., O.E.J., and I.L.C. designed the study. A.E., P.P., R.P.M., O.E.J., and I.L.C. performed the research. A.E., P.P., O.E.J., and I.L.C. wrote the manuscript. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. The associated structural datasets and computational codes can be accessed via the Figshare repository (doi.org/10.6084/m9.figshare.7016303). Additional data related to this paper may be requested from the authors.
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May 2 2019 Fetal Timeline Maternal Timeline News
 In the human placenta, primary exchange of solutes are via terminal villi containing networks of fetal capillaries. Villi irregular structure determines exchange capacity. Image analysis and computational fluid dynamics, determined geometric features of terminal villi using a simple algebraic approximation. This revealed transitions between flow and diffusion at vessel and network levels. Results show how physical estimates of solute transport, based on carefully defined geometrical statistics, provide a viable method for linking placental structure and function; a framework for assessing transport in other microvascular systems. CREDIT: University of Manchester, UK.
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