Scientists have recreated a human placenta in the lab to study Zika virus
5 March 2016, Nirapad News: A new scientific model could help explain how the Zika virus infects an unborn baby by crossing the placenta from mother to fetus.
After the Zika was reported in South America in 2014, there has been mounting fear – in Brazil in particular – that the virus is linked to a surge in cases of microcephaly, a rare birth defect.
The condition causes babies to be born with a smaller than usual head, and often brain damage as a result of their underdeveloped brain.
Last month, such was the weight of the concern surrounding the as yet unproven link, the World Health Organization declared the outbreak an international public health emergency.
Amid the growing concerns scientists have been focusing their efforts on proving the link.
Earlier today, a study by experts at Johns Hopkins, Florida State and Emory universities suggested how the virus could cause microcephaly.
They believe Zika virus specifically infects the cells that form the fetus’s cortex – the brain’s outer layer.
The virus causes those cells to die rather than divide to create healthy brain cells, the researchers found.
While not proof of a link between Zika and microcephaly, the findings have been hailed a ‘critical step’.
But the question remains – how does the virus pass from mother to baby?
To address that part of the puzzle a team at the University of Pittsburgh and Magee-Womens Research Institute have devised a cell-based model of the human placenta.
They hope it will help explain how pathogens that cause birth defects, including the Zika virus, cross from the mother to her unborn baby.
The placenta is a complex and poorly understood organ that anchors the developing fetus to the uterus, nourishes the baby and provides a barrier to the spread of microorganisms from an infected mother to the fetus, explained Dr Carolyn Coyne, associate professor of microbiology and molecular genetics at Pitt School of Medicine and a member of the MWRI.
‘The human placenta is unique and unlike that of many other placental mammals,’ she said.
‘With our new model in the research toolkit, we and other specialists hope to advance our knowledge of the placenta, examine its function, and learn how it can prevent most, but not all, maternal infections from causing problems for the baby.’
Dr Coyne and her team cultured a group of human placental cells in a microgravity bioreactor system developed by NASA.
Those cells along with blood vessel cells were added to small beads, which then spun around a container filled with cell culture fluid.
The result was to create shear stress and rotational forces to better mimic the environment at the maternal-fetal interface.
The scientists managed to cause the cells to fuse to form syncytiotrophoblasts – resembling the cells lining the outermost layer of human placental tissue.
Next, the researchers tested the functional properties of their model by exposing it to a virus and to Toxoplasma gondi – a parasite found in cat feces that can lead to fetal infection, causing miscarriage, congenital disease and, or disability in later life.
Dr Jon Boyle, associate professor of biological sciences at Pitt, and co-investigator, said: ‘We found that the syncytiotrophoblasts formed in our system recapitulated the barrier properties of the naturally occurring cells and they resisted infection by a model virus and three genetically different strains of Toxoplasma.
‘With this model, we can experiment with different biological factors to see what might allow an infectious agent to get through the placental barrier to the fetus.’
Understand the placenta might one day lead to ways to prevent fetal damage from the so-called TORCH infections: toxoplasmosis, rubella, cytomegalovirus, herpes and HIV, he added.
The researchers are beginning to use their model to test whether Zika virus, and other pathogens associated with congenital disease, can infect placental cells and/or cross the placental barrier.
The findings are published in Science Advances.