Miniature lab-grown models of human organs have major advantages over standard animal testing.
But he wasn't the only one to follow this train of thought. In the year since the pandemic began, many researchers have been using organoids to study how the coronavirus infects human cells, and find potential treatments. Beumer's pivot represents a remarkable and fast-emerging paradigm shift in how drugs and diseases will be studied in the coming decades. With future pandemics likely to be more frequent and deadlier, such a shift is necessary to reduce the average clinical development time of 5.9 years for antiviral agents.
Part of that shift means developing models that replicate human biology in the lab. Animal models, which are the current standard in biomedical research, fail to do so—96% of drugs that pass animal testing, for example, fail to make it to market. Injecting potentially toxic drugs into living creatures, before eventually slaughtering them, also raises ethical concerns for some. Organoids, on the other hand, respond to infectious diseases, or potential treatments, in a way that is relevant to humans, in addition to being slaughter-free.
Human intestinal organoids infected with SARS-CoV-2 (white).
Credit: Joep Beumer/Clevers group/Hubrecht Institute
Urgency Sparked Momentum
Though brain organoids were previously used to study the Zika virus during the 2015-16 epidemic, it wasn't until COVID-19 that the field really started to change. "The organoid field has advanced a lot in the last year. The speed at which it happened is crazy," says Shuibing Chen, an associate professor at Weill Cornell Medicine in New York. She adds that many federal and private funding agencies have now seen the benefits of organoids, and are starting to appreciate their potential in the biomedical field.
Last summer, the Organo-Strat (OS) network—a German network that uses human organoid models to study COVID-19's effects—received 3.2 million euros in funding from the German government. "When the pandemic started, we became aware that we didn't have the right models to immediately investigate the effects of the virus," says Andreas Hocke, professor of infectious diseases at the Charité Universitätsmedizin in Berlin, Germany, and coordinator of the OS network. Hocke explained that while the World Health Organization's animal models showed an "overlap of symptoms'' with humans, there was "no clear reflection" of the same disease.
"The network functions as a way of connecting organoid experts with infectious disease experts across Germany," Hocke continues. "Having organoid models on demand means we can understand how a virus infects human cells from the first moment it's isolated." Overall, OS aims to create infrastructure that could be applied to future pandemics. There are 28 sub-projects involved in the network, covering a wide assortment of individual organoids.
Cost, however, remains an obstacle to scaling up, says Chen. She says there is also a limit to what we can learn from organoids, given that they only represent a single organ. "We can add drugs to organoids to see how the cells respond, but these tests don't tell us anything about drug metabolism, for example," she explains.
A Related "Leaps" in Progress
One way to solve this issue is to use an organ-on-a-chip system. These are miniature chips containing a variety of human cells, as well as small channels along which functions like blood or air flow can be recreated. This allows scientists to perform more complex experiments, like studying drug metabolism, while producing results that are relevant to humans.
An organ-on-a-chip system.
Credit: Fraunhofer IGB
Such systems are also able to elicit an immune response. The FDA has even entered into an agreement with Wyss Institute spinoff Emulate to use their lung-on-a-chip system to test COVID-19 vaccines. Representing multiple organs in one system is also possible. Berlin-based TissUse are aiming to make a so-called 'human on a chip' system commercially available. But TissUse senior scientist Ilka Maschmeyer warns that there is a limit to how far the technology can go. "The system will not think or feel, so it wouldn't be possible to test for illnesses affecting these abilities," she says.
Some challenges also remain in the usability of organs-on-a-chip. "Specialized training is required to use them as they are so complex," says Peter Loskill, assistant professor and head of the organ-on-a-chip group at the University of Tübingen, Germany. Hocke agrees with this. "Cell culture scientists would easily understand how to use organoids in a lab, but when using a chip, you need additional biotechnology knowledge," he says.
One major advantage of both technologies is the possibility of personalized medicine: Cells can be taken from a patient and put onto a chip, for example, to test their individual response to a treatment. Loskill also says there are other uses outside of the biomedical field, such as cosmetic and chemical testing.
"Although these technologies offer a lot of possibilities, they need time to develop," Loskill continues. He stresses, however, that it's not just the technology that needs to change. "There's a lot of conservative thinking in biomedical research that says this is how we've always done things. To really study human biology means approaching research questions in a completely new way."
Even so, he thinks that the pandemic marked a shift in people's thinking—no one cared how the results were found, as long as it was done quickly. But Loskill adds that it's important to balance promise, potential, and expectations when it comes to these new models. "Maybe in 15 years' time we will have a limited number of animal models in comparison to now, but the timescale depends on many factors," he says.
Beumer, now a post-doc, was eventually allowed to return to the lab to develop his coronavirus model, and found working on it to be an eye-opening experience. He saw first-hand how his research could have an impact on something that was affecting the entire human race, as well as the pressure that comes with studying potential treatments. Though he doesn't see a future for himself in infectious diseases, he hopes to stick with organoids. "I've now gotten really excited about the prospect of using organoids for drug discovery," he says.
The coronavirus pandemic has slowed society down in many respects, but it has flung biomedical research into the future—from mRNA vaccines to healthcare models based on human biology. It may be difficult to fully eradicate animal models, but over the coming years, organoids and organs-on-a-chip may become the standard for the sake of efficacy -- and ethics.
Amber Freed and Maxwell near their home in Denver, Colorado.
Getting the diagnosis took months of painful, invasive procedures, as well as fighting with the health insurance to get the genetic testing approved. Finally, in June 2018, doctors at the Children's Hospital Colorado gave the Freeds their son's diagnosis—a genetic mutation so rare it didn't even have a name, just a bunch of letters jammed together into a word SLC6A1—same as the name of the mutated gene. The mutation, with only 40 cases known worldwide at the time, caused developmental disabilities, movement and speech disorders, and a debilitating form of epilepsy.
The doctors didn't know much about the disorder, but they said that Maxwell would also regress in his development when he turned three or four. They couldn't tell how long he would live. "Hopefully you would become an expert and educate us about it," they said, as they gave Freed a five-page paper on the SLC6A1 and told her to start calling scientists if she wanted to help her son in any way. When she Googled the name, nothing came up. She felt horrified. "Our disease was too rare to care."
Freed's husband, a 6'2'' college football player broke down in sobs and she realized that if anything could be done to help Maxwell, she'd have be the one to do it. "I understood that I had to fight like a mother," she says. "And a determined mother can do a lot of things."
The Freed family.
Courtesy Amber Freed
She quit her job as an equity analyst the day of the diagnosis and became a full-time SLC6A1 citizen scientist looking for researchers studying mutations of this gene. In the wee hours of the morning, she called scientists in Europe. As the day progressed, she called researchers on the East Coast, followed by the West in the afternoon. In the evening, she switched to Asia and Australia. She asked them the same question. "Can you help explain my gene and how do we fix it?"
Scientists need money to do research, so Freed launched Milestones for Maxwell fundraising campaign, and a SLC6A1 Connect patient advocacy nonprofit, dedicated to improving the lives of children and families battling this rare condition. And then it became clear that the mutation wasn't as rare as it seemed. As other parents began to discover her nonprofit, the number of known cases rose from 40 to 100, and later to 400, Freed says. "The disease is only rare until it messes with the wrong mother."
It took one mother to find another to start looking into what's happening inside Maxwell's brain. Freed came across Jeanne Paz, a Gladstone Institutes researcher who studies epilepsy with particular interest in absence or silent seizures—those that don't manifest by convulsions, but rather make patients absently stare into space—and that's one type of seizures Maxwell has. "It's like a brief period of silence in the brain during which the person doesn't pay attention to what's happening, and as soon as they come out of the seizure they are back to life," Paz explains. "It's like a pause button on consciousness." She was working to understand the underlying biology.
To understand how seizures begin, spread and stop, Paz uses optogenetics in mice. From words "genetic" and "optikós," which means visible in Greek, the optogenetics technique involves two steps. First, scientists introduce a light-sensitive gene into a specific brain cell type—for example into excitatory neurons that release glutamate, a neurotransmitter, which activates other cells in the brain. Then they implant a very thin optical fiber into the brain area where they forged these light-sensitive neurons. As they shine the light through the optical fiber, researchers can make excitatory neurons to release glutamate—or instead tell them to stop being active and "shut up". The ability to control what these neurons of interest do, quite literally sheds light onto where seizures start, how they propagate and what cells are involved in stopping them.
"Let's say a seizure started and we shine the light that reduces the activity of specific neurons," Paz explains. "If that stops the seizure, we know that activating those cells was necessary to maintain the seizure." Likewise, shutting down their activity will make the seizure stop.
Freed reached out to Paz in 2019 and the two women had an instant connection. They were both passionate about brain and seizures research, even if for different reasons. Freed asked Paz if she would study her son's seizures and Paz agreed.
To do that, Paz needed mice that carried the SLC6A1 mutation, so Freed found a company in China that created them to specs. The company replaced a mouse SLC6A1 gene with a human mutated one and shipped them over to Paz's lab. "We call them Maxwell mice," Paz says, "and we are now implanting electrodes into them to see which brain regions generate seizures." That would help them understand what goes wrong and what brain cells are malfunctioning in the SLC6A1 mice—and help scientists better understand what might cause seizures in children.
Bred to carry SLC6A1 mutation, these "Maxwell mice" will help better understand this debilitating genetic disease. (These mice are from Vanderbilt University, where researchers are also studying SLC6A1.)
Courtesy Amber Freed
This information—along with other research Amber is funding in other institutions—will inform the development of a novel genetic treatment, in which scientists would deploy a harmless virus to deliver a healthy, working copy of the SLC6A1 gene into the mice brains. They would likely deliver the therapeutic via a spinal tap infusion, and if it works and doesn't produce side effects in mice, the human trials will follow.
In the meantime, Freed is raising money to fund other research of various stop-gap measures. On April 22, 2021, she updated her Milestone for Maxwell page with a post that her nonprofit is funding yet another effort. It is a trial at Weill Cornell Medicine in New York City, in which doctors will use an already FDA-approved drug, which was recently repurposed for the SLC6A1 condition to treat epilepsy in these children. "It will buy us time," Freed says—while the gene therapy effort progresses.
Freed is determined to beat SLC6A1 before it beats down her family. She hopes to put an end to this disease—and similar genetic diseases—once and for all. Her goal is not only to have scientists create a remedy, but also to add the mutation to a newborn screening panel. That way, children born with this condition in the future would receive gene therapy before they even leave the hospital.
"I don't want there to be another Maxwell Freed," she says, "and that's why I am fighting like a mother." The gene therapy trial still might be a few years away, but the Weill Cornell one aims to launch very soon—possibly around Mother's Day. This is yet another milestone for Maxwell, another baby step forward—and the best gift a mother can get.
On May 13th, scientific and medical experts will discuss and answer questions about the vaccine for those under 16.
This virtual event will convene leading scientific and medical experts to discuss the most pressing questions around the COVID-19 vaccines for children and teens. A public Q&A will follow the expert discussion.
DATE:
Thursday, May 13th, 2021
12:30 p.m. - 1:45 p.m. EDT
LOCATION:
Virtual on Zoom
REGISTER NOW
You can submit a question for the speakers upon registering.
Dr. H. Dele Davies, M.D., MHCM
Senior Vice Chancellor for Academic Affairs and Dean for Graduate Studies at the University of Nebraska Medical (UNMC). He is an internationally recognized expert in pediatric infectious diseases and a leader in community health.
Dr. Emily Oster, Ph.D.
Professor of Economics at Brown University. She is a best-selling author and parenting guru who has pioneered a method of assessing school safety.
Dr. Tina Q. Tan, M.D.
Professor of Pediatrics at the Feinberg School of Medicine, Northwestern University. She has been involved in several vaccine survey studies that examine the awareness, acceptance, barriers and utilization of recommended preventative vaccines.
Dr. Inci Yildirim, M.D., Ph.D., M.Sc.
Associate Professor of Pediatrics (Infectious Disease); Medical Director, Transplant Infectious Diseases at Yale School of Medicine; Associate Professor of Global Health, Yale Institute for Global Health. She is an investigator for the multi-institutional COVID-19 Prevention Network's (CoVPN) Moderna mRNA-1273 clinical trial for children 6 months to 12 years of age.
About the Event Series
This event is the second of a four-part series co-hosted by Leaps.org, the Aspen Institute Science & Society Program, and the Sabin–Aspen Vaccine Science & Policy Group, with generous support from the Gordon and Betty Moore Foundation and the Howard Hughes Medical Institute.
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