BREAKTHROUGHS BLOG

July 31, 2016

Research Roundup: Placenta-on-a-chip, nasal bacteria against MRSA, and an experimental yellow fever vaccine

Senior Program Assistant
GHTC

Researchers at the University of Pennsylvania have designed a placenta-on-a-chip: a small device that mimics the placental barrier, enabling scientists to study the transport of molecules from mother to fetus. The silicone device contains a permeable membrane surrounded by endothelial and trophoblast cells, which are found in fetal blood vessels and where the placenta meets the maternal blood supply, respectively. The model imitates the development of the placenta throughout pregnancy, as trophoblast cells merge and as the barrier becomes thinner. Previously, donated placental tissue has been used in research, however samples are scarce and only viable for a few hours after delivery. The team completed an initial, successful test of the device by comparing the transfer of glucose across the placental barrier in both donated tissue and the placenta-on-a-chip. As testing continues, plans are underway to use the device in studies on preterm birth.

Methicillin-resistant Staphylococcus aureus bacteria (yellow, round items) killing and escaping from a human white cell. (Photo: National Institute of Allergy and Infectious Diseases, National Institutes of Health)
Methicillin-resistant Staphylococcus aureus bacteria (yellow, round items) killing and escaping from a human white cell. (Photo: National Institute of Allergy and Infectious Diseases, National Institutes of Health)

The secret to fighting methicillin-resistant Staphylococcus aureus (MRSA) could be an antibiotic produced by the microbes inhabiting the human nose. MRSA is a dangerous bacterium, resistant to several leading antibiotics, that causes staph infections, sepsis, and pneumonia, resulting in 20,000 deaths annually. Researchers at the University of Tübingen in Germany cultured the bacteria in snot samples from 37 healthy individuals, hoping to understand why vulnerability to staph infections varies from person to person. Next, they placed S. aureus alongside the different bacteria, and identified another species of staph— Staphylococcus lugdunensis—that successfully combatted S. aureus. The team then collected snot samples from 187 hospital patients, and with just one exception, found either S. aureus or S. lugdunensis in every sample, suggesting that the two cannot flourish in unison. The key compound—lugdunin—successfully treated staph infections in mice and, after leaving the two bacteria in petri dishes for a month, S. aureus was unable to develop resistance to S. lugdunensis.

An ongoing outbreak of yellow fever in Angola and the Democratic Republic of the Congo has resulted in more than 5,000 cases and nearly 450 deaths. The existing vaccine against the virus is extremely effective, but is not recommended for pregnant women and those over 60 years of age. The vaccine takes a year to produce and the limited global stockpile has already been depleted twice this year. Last week, the US National Institutes of Health initiated a phase 1 clinical trial to test the safety and tolerability of an experimental yellow fever vaccine. The vaccine candidate, developed by Danish company Bavarian Nordic, uses a weakened version of the Modified Vaccinia Ankara virus as a vector to transport genes from the yellow fever virus. This delivery platform has been used in vaccinating more than 7,600 individuals, 1,000 of them immunocompromised. The trial will enroll 90 healthy volunteers, 15 of whom will receive the existing, approved yellow fever vaccine, and 75 of whom will receive one or two doses of the experimental vaccine or a placebo, with or without a booster.

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