May 15, 2020

Pursuing the perfect Petri dish placenta

Photo: William Au

Learning how this magical, mysterious organ develops could have an enormous impact on human health

Meghan Riddell’s research path was determined during a third-year university class when the aspiring immunologist “got tricked into the placenta.”

Captivated might be a better description.

“The placenta is, quite simply, the most important organ you no longer have,” she wrote in her 2013 doctoral thesis. A mysterious building block of life, its unique cells appear days after the egg is fertilized, making it possible for the pregnancy to begin. For nine months, it cares for the growing fetus, providing oxygen and nourishment, removing waste, maintaining water balance and somehow preventing the mother’s body from rejecting the fetus, defying basic laws of immunologic biology.

“It’s so interesting and so little is known,” Riddell says. “It’s this magical thing that sustains and allows for life, but compared to the heart or the brain or the kidney, we just don’t understand properly what goes wrong.”

Abnormal placenta development is the mystery that Riddell, WCHRI’s newest recruit for perinatal health research, is determined to solve.

Malfunctioning placentas are linked to complications like preeclampsia, threatening the health of the mother and baby, and intrauterine growth restriction, causing babies to be born much too small. By identifying the factors that cause abnormal development, doors could open for new diagnostic tools and medical interventions.

But first, Riddell needs access to a placenta as it develops from a few cells to a complete organ. “That’s where our placenta-in-a-dish model comes in.”

Breakthroughs in recent years have made it possible for a three-dimensional placenta to be grown outside of a mother’s body. However, it grows inside-out, meaning the placenta’s most powerful attribute—the single trophoblast cell that forms its entire surface—is stuck in the middle, says Riddell.

With funding from the Stollery Children’s Hospital Foundation and the Alberta Women’s Health Foundation, Riddell’s work aims to grow a placenta that is properly oriented and represents the real thing.

The research, she says, is “innovative, cutting edge and important.”

In future medical treatments, where targeted therapies are delivered directly to the placenta, that outside cell—which measures about 10-square-metres at term—will be one of the most important factors.

Nothing else in the human body is even comparable, she says. “The way that it functions has to be different because fundamentally, its structure is very, very different. … It’s one gigantic cell instead of millions working in co-operation.”

It’s an incredibly focused research project that Riddell says could potentially have an enormous impact.

“There’s a huge amount of evidence that says if you come from a compromised pregnancy, you have increased risk of lifelong health problems,” she says. “So if we can treat the placenta, we have the chance to improve the health of the entire population.”

Riddell is one of the newest perinatal researchers recruited to the University of Alberta by WCHRI, with funding from the Stollery Children’s Hospital Foundation and the Alberta Women’s Health Foundation.