Stem cells from a fetus can travel to the heart and regenerate the muscle, essentially saving a mother’s life.
If there is a silver lining to peripartum cardiomyopathy, it’s that it is perhaps the most survivable form of heart failure. A remarkable 50% of women recover spontaneously. And there’s an even more remarkable explanation for that glowing statistic: The fetus‘ stem cells migrate to the heart and regenerate the beleaguered muscle. In essence, the developing or recently born child saves its mother’s life.
Saving mama
While this process has not been observed directly in humans, it has been witnessed in mice. In a 2015 study, researchers tracked stem cells from fetal mice as they traveled to mothers’ damaged cardiac cells and integrated themselves into hearts.
Evolutionarily, this function makes sense: It is in the fetus’ best interest that its mother remains healthy.
Scientists also have spotted cells from the fetus within the hearts of human mothers, as well as countless other places inside the body, including the skin, spleen, liver, brain, lung, kidney, thyroid, lymph nodes, salivary glands, gallbladder, and intestine. These cells essentially get everywhere. While most are eliminated by the immune system during pregnancy, some can persist for an incredibly long time — up to three decades after childbirth.
This integration of the fetus’ cells into the mother’s body has been given a name: fetal microchimerism. The process appears to start between the fourth and sixth week of gestation in humans. Scientists are actively trying to suss out its purpose. Fetal stem cells, which can differentiate into all sorts of specialized cells, appear to target areas of injury. So their role in healing seems apparent. Evolutionarily, this function makes sense: It is in the fetus’ best interest that its mother remains healthy.
Sending cells into the mother’s body may also prime her immune system to grow more tolerant of the developing fetus. Successful pregnancy requires that the immune system not see the fetus as an interloper and thus dispatch cells to attack it.
Fetal microchimerism
But fetal microchimerism might not be entirely beneficial. Greater concentrations of the cells have been associated with various autoimmune diseases such as lupus, Sjogren’s syndrome, and even multiple sclerosis. After all, they are foreign cells living in the mother’s body, so it’s possible that they might trigger subtle, yet constant inflammation. Fetal cells also have been linked to cancer, although it isn’t clear whether they abet or hinder the disease.
A team of Spanish scientists summarized the apparent give and take of fetal microchimerism in a 2022 review article. “On the one hand, fetal microchimerism could be a source of progenitor cells with a beneficial effect on the mother’s health by intervening in tissue repair, angiogenesis, or neurogenesis. On the other hand, fetal microchimerism might have a detrimental function by activating the immune response and contributing to autoimmune diseases,” they wrote.
Regardless of a fetus’ cells net effect, their existence alone is intriguing. In a paper published earlier this year, University of London biologist Francisco Úbeda and University of Western Ontario mathematical biologist Geoff Wild noted that these cells might very well persist within mothers for life.
“Therefore, throughout their reproductive lives, mothers accumulate fetal cells from each of their past pregnancies including those resulting in miscarriages. Furthermore, mothers inherit, from their own mothers, a pool of cells contributed by all fetuses carried by their mothers, often referred to as grandmaternal microchimerism.”
So every mother may carry within her literal pieces of her ancestors.
Recent immigration restrictions have left many foreign researchers' projects and careers in limbo—and some in jeopardy.
"I spent about $4,000 on lawyer fees and another $1,200 to pay for the motions I filed," she recalls. "I had to borrow money from my parents and my cousin because without my salary I just didn't have the $7,000 at hand." But the already narrow window of opportunity slammed completely shut when the Trump administration suspended issuing new visas for foreign researchers in June. All Mohan's attempts were denied. In August, she had to leave the country. "Given the recent work visa ban by the administration, all my options in the U.S. are closed," she wrote a bitter note on Twitter. "I have to uproot my entire life in NY for the past 6 years and leave." She eventually found a temporary position in Calcutta, where she can continue research.
Mohan is hardly alone in her visa saga. Many foreign scholars on H- and J-type visas and other permits that let them remain employed in America had been struggling to keep their rights to continue research, which in certain cases is crucial to battling the pandemic. Some had to leave the country, some filed every possible extension to buy time, and others are stuck in their home countries, unable to return. The already cumbersome process of applying for visas and extensions became crippled during the lockdowns. But in June, when President Trump extended and expanded immigration restrictions to cut the number of immigrant workers entering the U.S., the new limits left researchers' projects and careers in limbo—and some in jeopardy.
"We have been a beneficiary of this flow of human capacity and resource investment for many generations—and this is now threatened."
Rakesh Ramachandran, whose computational biology work contributed to one of the first coronavirus studies to map out its protein structures—is stranded in India. In early March, he had travelled there to attend a conference and visit the American consulate to stamp his H1 visa for a renewal, already granted. The pandemic shut down both the conference and the consulates, and Ramachandran hasn't been able to come back since. The consulates finally opened in September, but so far the online portal has no available appointment slots. "I'm told to keep trying," Ramachandran says.
The visa restrictions affected researchers worldwide, regardless of disciplines or countries. A Ph.D. student in neuroscience, Morgane Leroux had to do her experiments with mice at Gladstone Institutes in America and analyze the data back home at Sorbonne University in France. She had finished her first round of experiments when the lockdowns forced her to return to Paris, and she hasn't been able to come back to resume her work since. "I can't continue the experiments, which is really frustrating," she says, especially because she doesn't know what it means for her Ph.D. "I may have to entirely change my subject," she says, which she doesn't want to do—it would be a waste of time and money.
But besides wreaking havoc in scholars' personal lives and careers, the visa restrictions had—and will continue to have—tremendous deleterious effects on America's research and its global scientific competitiveness. "It's incredibly short-sighted and self-destructing to restrict the immigration of scientists into the U.S.," says Benjamin G. Neel, who directs the Laura and Isaac Perlmutter Cancer Center at New York University. "If they can't come here, they will go elsewhere," he says, causing a brain drain.
Neel in his lab with postdocs
(Courtesy of Neel)
Neel felt the outcomes of the shortsighted policies firsthand. In the past few months, his lab lost two postdoctoral researchers who had made major strides in understanding the biology of several particularly stubborn, treatment-resistant malignancies. One postdoc studied the underlying mechanisms responsible for 90 percent of pancreatic cancers and half of the colon ones. The other one devised a new system of modeling ovarian cancer in mice to test new therapeutic drug combinations for the deadliest tumor types—but had to return home to China.
"By working around the clock, she was able to get her paper accepted, but she hasn't been able to train us to use this new system, which can set us back six months," Neel says.
Her discoveries also helped the lab secure about $900,000 in grants for new research. Losing people like this is "literally killing the goose that lays the golden eggs," Neel adds. "If you want to make America poor again, this is the way to do it."
Cassidy R. Sugimoto at Indiana University Bloomington, who studies how scientific knowledge is produced and disseminated, says that scientists are the most productive when they are free to move, exchange ideas, and work at labs with the best equipment. Restricting that freedom reduces their achievement.
"Several empirical studied demonstrated the benefits to the U.S. by attracting and retaining foreign scientists. The disproportional number of our Nobel Prize winners were not only foreign-born but also foreign-educated," she says. Scientific advancement bolsters the country's economic prowess, too, so turning scholars away is bad for the economy long-term. "We have been a beneficiary of this flow of human capacity and resource investment for many generations—and this is now threatened," Sugimoto adds—because scientists will look elsewhere. "We are seeing them shifting to other countries that are more hospitable, both ideologically and in terms of health security. Many visiting scholars, postdocs, and graduate students who would otherwise come to the United States are now moving to Canada."
It's not only the Ph.D. students and postdocs who are affected. In some cases, even well-established professors who have already made their marks in the field and direct their own labs at prestigious research institutions may have to pack up and leave the country in the next few months. One scientist who directs a prominent neuroscience lab is betting on his visa renewal and a green card application, but if that's denied, the entire lab may be in jeopardy, as many grants hinge on his ability to stay employed in America.
"It's devastating to even think that it can happen," he says—after years of efforts invested. "I can't even comprehend how it would feel. It would be terrifying and really sad." (He asked to withhold his name for fear that it may adversely affect his applications.) Another scientist who originally shared her story for this article, later changed her mind and withdrew, worrying that speaking out may hurt the entire project, a high-profile COVID-19 effort. It's not how things should work in a democratic country, scientists admit, but that's the reality.
Still, some foreign scholars are speaking up. Mehmet Doğan, a physicist at University of California Berkeley who has been fighting a visa extension battle all year, says it's important to push back in an organized fashion with petitions and engage legislators. "This administration was very creative in finding subtle and not so subtle ways to make our lives more difficult," Doğan says. He adds that the newest rules, proposed by the Department of Homeland Security on September 24, could further limit the time scholars can stay, forcing them into continuous extension battles. That's why the upcoming election might be a turning point for foreign academics. "This election will decide if many of us will see the U.S. as the place to stay and work or whether we look at other countries," Doğan says, echoing the worries of Neel, Sugimoto, and others in academia.
Dogan on Zoom talking to his fellow union members of the Academic Researchers United, a union of almost 5,000 Academic Researchers.
(Credit: Ceyda Durmaz Dogan)
If this year has shown us anything, it is that viruses and pandemics know no borders as they sweep across the globe. Likewise, science can't be restrained by borders either. "Science is an international endeavor," says Neel—and right now humankind now needs unified scientific research more than ever, unhindered by immigration hurdles and visa wars. Humanity's wellbeing in America and beyond depends on it.
[Editor's Note: To read other articles in this special magazine issue, visit the beautifully designed e-reader version.]
