Ties van der Meer doesn’t know how many siblings he has.

The 47-year-old was conceived at a private fertility clinic in the Netherlands using sperm provided by an anonymous donor. After the Netherlands banned anonymous donation in 2004, the doctor who ran the clinic destroyed records that might have identified those donors, he says.

He describes the situation as “problematic.” Children have a right to know their biological parents, he says. While he did ultimately track down one sibling, who helped him identify his father along with other genetic relatives, he may have others he’ll never find.

Other donor-conceived people who have been able to track down siblings have found they have tens or even hundreds of them. One donor-conceived woman who found 25 half-siblings over the course of seven years told the Guardian, “It does make you feel a bit mass-produced.”

We need international limits on the number of children a single donor can contribute to, a European fertility organization argued yesterday. At a conference in London, members laid out plans to start with a Europe-wide limit.

Today many countries, including the UK, have banned anonymous egg and sperm donation. But anonymity can’t be guaranteed even in places where it is technically allowed. Genetic tests offered by companies like Ancestry and 23andMe, along with genetic registries, have made it much easier for donor-conceived people to find parents and siblings who share their genes.

And because sperm can be frozen and stored for years before it is eventually used, the current set-up can result in situations where donor-conceived people discover the identity of a genetic parent only after the person’s death. They might also find that they have siblings of very different ages, all around the world.

Some people are finding hundreds of siblings. Sperm from Jonathan Meijer, a Dutch man who began donating in 2007, was used to conceive between 550 and 600 children. (Stichting Donorkind, a foundation and advocacy group for donor-conceived people that’s chaired by van der Meer, took him to court, and he was ordered to stop donating in 2023.)

Stories like these can be distressing for donor-conceived people. And there are other reasons why limits are considered important. The offspring of a prolific donor might be at risk of unknowingly forming romantic or sexual relationships, for instance. And some people are concerned that a donor with a harmful genetic mutation might pass that down to many children.

This is unlikely, given the level of screening that most donors undergo. But it has happened. A man who donated his sperm to a sperm bank in Denmark was found to have a genetic mutation that significantly increased the risk of multiple cancers. But his sperm had already been used to conceive at least 197 children across Europe. Some of those children developed cancer. Some died.

Many countries already have legal limits for donors. In Malta and Cyprus, for example, both egg and sperm donors are allowed to contribute to the birth of just a single child, according to data presented at the European Society of Human Reproduction and Embryology (ESHRE) meeting in London on July 8.

Other countries set limits based on the number of families a single donor can contribute to, allowing recipients to have children who share a genetic link. In the UK, that limit is set at 10 families per donor.

But these limits are difficult to enforce, partly because donated gametes don’t necessarily stay in their original country. In Denmark, the national limit is set at 12 families. But the country is a major exporter of sperm. In the UK, for example, more than half of sperm donations in 2020 were imported—with most of those coming from either Denmark or the US.

“The only thing that really makes sense is a transnational limit,” Jackson Kirkman-Brown, a professor of reproductive biology at the University of Birmingham, said at the meeting.

Kirkman-Brown and his colleagues have spent months putting together a document that represents ESHRE’s position on these limits. After consulting with fertility specialists, clinics, sperm and egg banks, donors, and donor-conceived people, the team has developed a plan to start with a Europe-wide limit on sperm and egg donations.

ESHRE is calling on sperm and egg banks, as well as fertility clinics, to respect an initial limit of 50 families per donor. That’s still very high, according to a handful of people I spoke to at the meeting. But at least it’s a start.

Europe should move toward setting limits at 15 families per donor, Kirkman-Brown said. “We may find that 15 is also too high,” says Vasanti Jadva, who studies the psychological well-being of people conceived using donated eggs, sperm, and embryos at City St George’s in London. “We still don’t know what the right number is.”

It will be difficult to enforce these limits, too. And if they end up limiting the supply of donor sperm, there’s a chance that some people will turn to unregulated sperm donations from people who do not undergo health screening. Unregulated donations can lead to other problems for prospective parents, including the possibility that donors will seek parental rights over the children conceived using their sperm.

And it will be even harder to establish international limits. When I asked the American Society of Reproductive Medicine for its thoughts on ESHRE’s proposed limits, a representative directed me to a guidance document saying “it has been suggested” that for a population of 800,000, single donors should be limited to “no more than 25 births” in order to avoid the risk that relatives will have children together. (Considering the US has a population of over 340 million, the total figure could be pretty high, but many sperm banks opt to limit the number of families contributed to by a single donor at around 25.)

Van der Meer thinks that even a limit of five families from a single donor would be high. International donation makes it even harder for donor-conceived people to connect with genetic relatives, so the limit for international contributions should be set at two families, he says.

Still, he thinks ESHRE’s suggested limit is a “positive first step.” Van der Meer has managed to track down a sibling, his father, and nephews, aunts, and uncles. He hopes that future policies respect the rights of donor-conceived children to know, and be in contact with, their genetic relatives.

“But,” he says, “you have to start somewhere.”

This article first appeared in The Checkup, MIT Technology Review’s weekly biotech newsletter. To receive it in your inbox every Thursday, and read articles like this first, sign up here.

This week, I covered the story of Casey Harrell—a man with ALS who is “the first power user” of a brain implant, according to the researchers who worked with him. Harrell is paralyzed and unable to speak coherently without the device. He has now spent almost three years using a brain-computer interface (BCI) that enables him to “speak,” surf the web, and perform his job as a climate activist, largely independently.

Since Harrell was implanted with the device, in July 2023, a team at the University of California, Davis, has worked with him to adjust and improve its offerings. They’ve refined its accuracy, for example. And they’ve introduced settings including a privacy mode and a “profanity filter” that lets Harrell talk to his daughter without risking accidental swearing.

Harrell told me that, for him, the device is “nothing short of revolutionary!” It has enabled him to maintain an income, reconnect with friends and family, and read to his daughter. 

The team that developed his BCI is one of several working on ways to use technology to allow people with paralysis to communicate, engage with the online world, and regain some independence. And Harrell is one of a growing number of people volunteering their brains to, as he puts it, “pay it forward and do the scientific research … [and] get some personal benefit.”

Over the past couple of years, the number of BCI trial volunteers has soared. This year, China became the first country to approve a BCI for medical use. Advances in technology are allowing engineers to provide more features than ever. BCI research is properly taking off.

I should first point out that BCIs come in different forms. Harrell’s device includes a set of electrodes embedded in his brain that pick up the electrical activity associated with speech. Those electrodes are connected to two docking ports on top of his head that can be plugged into a computer.

That computer is loaded with software trained to decode his brain signals into phonemes (units of sound in speech) and predict what Harrell wants to say. He can then use an eye gaze tracker to make any corrections before the speech is played out loud.

But some BCIs don’t need to be “plugged in”—they’re fully implanted and wireless. Others are less invasive; they might involve placing wired electrodes on the surface of the brain or simply wearing a cap of electrodes, for example. There are trade-offs—the closer you get to the neurons you want to record from, the better your signal will be. But generally speaking, the more invasive the surgery, the higher the risk of complications.

BCIs can also have different functions. Harrell has ALS, but most BCIs in use today are sitting in the brains of people with spinal cord injuries. Typically, these individuals have some degree of paralysis; for example, they may be unable to move their arms and legs, but their face and ability to speak are unaffected. In those cases, BCIs can be used to control other kinds of devices that might help with mobility.

In 2024, Michelle Patrick-Krueger, then at the University of Houston, and her colleagues published a roundup of all trials of BCIs conducted between 1998, which is when they believe the first device was implanted, and the end of 2023. They identified 21 research groups that, among them, had trialed BCIs in a total of 67 volunteers.

“Since then, that number has increased a lot,” says Mariska Vansteensel, a BCI researcher at University Medical Center Utrecht. In January, Neuralink (the BCI company founded by trillionaire Elon Musk) announced that it has implanted 21 people with its device in the past two years.

Synchron, another BCI company, is currently testing its devices in trials in North America and Australia. Shanghai-based Neuracle has been trialing a BCI since November 2024, and it recently obtained approval for the device to be used outside of clinical trials. Precision Neuroscience, cofounded by a former co-creator of rival Neuralink, is also trialing its BCI, which sits on the surface of the brain.

At the same time, academic research has continued. The UC Davis team that worked with Harrell is part of BrainGate—a BCI research effort that has been running for the past two decades. Other academic teams are exploring a variety of devices, from the fully implanted to the minimally invasive.

Since 2024, when Patrick-Krueger’s paper was published, the number of people who have been implanted with a brain electrode has more than doubled, according to Vansteensel. “My current estimation would be around 150 people,” she says.

The technology is improving too. Take the BrainGate trial, for example. The first 17 years of that trial focused on the use of what researchers call “point-and-click” communication—allowing users to control a cursor and “click” with their brain activity. But in recent years the team has pivoted toward decoding speech, says David Brandman, the lead investigator on the team (and the person who implanted Harrell’s electrodes). Today, Harrell’s device uses a voice clone—the speech it produces is based on previous recordings of Harrell’s voice.

But BCIs are still experimental. And plenty of questions remain about who might benefit from them—and how long the devices will last. So far, most BCIs have been implanted in people with spinal cord injuries. We know even less about how they might benefit other people who have ALS, for example. In some cases where the devices initially helped people with ALS—even someone who was completely locked in—the BCIs eventually stopped working. And scientists don’t really know why.

The only way they’ll find out is through more research—and the participation of volunteers like Harrell. So it’s exciting to see trials truly take off. And I promise I’ll update you on where they stand two years from now.

This article first appeared in The Checkup, MIT Technology Review’s weekly biotech newsletter. To receive it in your inbox every Thursday, and read articles like this first, sign up here.

Earlier this week, Life Biosciences, a biotech company focused on reversing age-related diseases, announced that it had dosed its first volunteer. A person with glaucoma has had an experimental treatment injected straight into their eyeball.

The idea is to try to treat the disease—which can cause vision loss—by regenerating healthy nerves in the eye. But David Sinclair, the chairman and cofounder of the company behind the trial, hopes to go further. If the treatment can reverse glaucoma, perhaps similar treatments can reverse other diseases of aging. Maybe, just maybe, they can reverse aging altogether.

The approach is designed to work by “reprogramming” cells to a younger state. It’s one of many strategies being explored by biotech companies looking to slow and reverse the process of aging. But of all of them, it seems to be the one that is truly taking off.

Aging is complicated. As we get older, we experience so many changes across pretty much all our biological systems. Scientists have tried to categorize these effects. In 2013, one team published a seminal paper describing nine “hallmarks of aging.” That list features many of the processes scientists have attempted to target. But some of those targets have fallen in and out of fashion over the years.

Take telomere attrition, for example. Telomeres are DNA sequences at the ends of our chromosomes, often likened to the plastic caps that stop the ends of our shoelaces from fraying. When cells divide, telomeres shorten until, eventually, the DNA is vulnerable to damage.

When I started reporting on aging, telomere shortening was all the rage. Shrinking telomeres had been linked to age-related diseases of the heart and brain. Shortened telomeres were considered a sign of premature aging. In 2015 Liz Parrish, CEO of the biotech company BioViva, injected herself with an experimental gene therapy that she hoped might lengthen her telomeres.

Then it suddenly seemed to go out of style. Research continued, but all the excitement within the aging and longevity community seemed to move on to another hallmark. (Parrish also continued with self-experimentation; she calls herself “the most genetically modified person on Earth.”)

That hallmark was cellular senescence. This happens when cells stop dividing but don’t die, instead entering a “zombie” state in which they churn out chemicals that can cause harmful inflammation.

Senescent cells gradually accumulate in pretty much every organ studied, where they are thought to contribute to age-related damage. Why not just periodically clear them out? When a team of scientists took that approach in mice in 2011, they found they could delay the onset of age-related conditions like cataracts and hunchback. The treated mice even looked younger.

But when scientists at Unity Biotechnology trialed a similar approach in people with osteoarthritis and an age-related eye condition in the late 2010s and early 2020s, the results were disappointing. The company laid off every employee in May last year and has since shuttered entirely.

Again, that doesn’t mean senolytic drugs that target “zombie cells” won’t work. But it feels as if many in the field have moved on. These days, the buzz is all about reprogramming.

The idea here is to essentially return cells to a young state. It’s based on the Nobel Prize–winning discovery that four genetic factors can turn an adult cell into a stem cell, which can be encouraged to develop into pretty much any other cell type.

Some promising studies in mice suggest that this approach might help wind back the clock. It seems to improve tissue healing, restore vision, and even improve learning and memory.

Running parallel to all this research are repeated injections of hundreds of millions of dollars in funding. In 2021, my colleague Antonio Regalado reported on the founding of the biotech company Altos Labs to pursue reprogramming for rejuvenation.

Altos was funded by the billionaire Yuri Milner—reportedly along with Jeff Bezos, among others—to the tune of $3 billion, a previously unheard-of figure for a biotech startup. Other well-funded companies have since sprung up in this space.

There’s Retro Biosciences, for instance, which is pursuing reprogramming (among other approaches) in an effort to add 10 years of healthy life to human lifespans. Retro’s launch was supported by $180 million from OpenAI’s Sam Altman. Last month, the company announced a valuation of $1.8 billion.

NewLimit, another billionaire-backed biotech exploring reprogramming, says it has promising results from research in mice. It plans to trial a drug designed to rejuvenate the liver in people next year. Last week, the company announced it had raised $435 million toward reaching that goal, among others.

Life Biosciences, which was founded by the Harvard biologist David Sinclair, most recently secured $80 million to support its research. The eye trial is now officially underway, but Sinclair also has plans for whole-body rejuvenation. Earlier this week, he told my colleague Antonio that he plans to test a “highly, highly confidential” oral reprogramming drug as part of a $101 million competition organized by the XPrize Foundation. 

Reprogramming has certainly caught the attention of scientists, biotech companies, and investors. Studies in mice are hugely promising. Human trials are launching. And research in the field has billions of dollars’ worth of support.A lot of people in the field are really excited about reprogramming. But it comes with risks. And we still don’t know if it will work. The question now is: Do we finally have a rejuvenation drug within reach? And if not, what will the next research trend look like?

This article first appeared in The Checkup, MIT Technology Review’s weekly biotech newsletter. To receive it in your inbox every Thursday, and read articles like this first, sign up here.

Correction: This article has been updated to reflect that Liz Parrish claimed to have undergone her first experimental gene therapy in 2015, not 2017.

The alert was raised on May 5. Four health-care workers in the Ituri Province of the Democratic Republic of the Congo had died from an unknown illness within four days.

Rapid response teams were sent to investigate, and tests at a research center in Kinshasa revealed the culprit: the Bundibugyo virus, one of the viruses that cause Ebola. Suspected cases of the disease have snowballed in the last few weeks. By May 24, the WHO had estimated that 223 people had died from the disease. There were over 900 suspected cases. Today’s figures are likely to be higher.

A couple of weeks ago, I covered the hantavirus outbreak aboard a cruise ship. Three people sadly died, but the outbreak itself was kept under control. There have been no further deaths, and passengers have been safely repatriated. The picture for Ebola is far bleaker. And there are several reasons why.

The most obvious is the disease itself. Ebola is a severe disease with an average 50% fatality rate. Previous outbreaks have resulted in thousands of deaths. (Hantavirus also has a high fatality rate, but it doesn’t usually spread as easily between humans.) 

Between 2014 and 2016, an Ebola outbreak in West Africa caused more than 11,000 deaths. A more recent outbreak, which took place between 2018 and 2020, caused 2,299 deaths before being brought under control with a vaccination campaign.

But those outbreaks were caused by the Zaire virus, which has a different genetic sequence. There is no vaccine for the Bundibugyo virus. We don’t know if the two vaccines approved for Zaire might also work for Bundibugyo. There’s a concern they might even make things worse by interfering with a person’s immune response to the virus.  

Scientists are working on potential Bundibugyo vaccines. But the most advanced efforts are still months away from clinical trials. There are no specific antiviral treatments for the virus, either.

So to control the outbreak, health-care workers are trying to stop the spread of the disease. Ebolaviruses can be transmitted to humans by animals including fruit bats, chimpanzees, and gorillas. They can then spread between people via contact with bodily fluids such as blood or vomit.

That’s why the virus is often spread among family members, to health-care workers, and during some burial services. The WHO advises isolating people who have the virus in treatment centers. It also recommends safe burial measures that limit physical contact with the deceased, for example. Communities need to be informed about the virus and how it spreads, and health professionals should be on hand to diagnose cases and track them.

That’s all easier said than done in an era of misinformation. Some members of the community even doubt whether the disease is real. There have been three attacks on health-care facilities in the region in recent weeks.

Last week, two treatment centers were burned down. The first incident occurred after relatives of a deceased man were prohibited from retrieving his (infectious) body. As a result of the second incident, 18 suspected cases reentered the community.

A couple of days later, a group of men unleashed gunfire at Mongbwalu General Hospital, which was also treating people with Ebola. They were demanding the bodies of their deceased relatives.

There are more causes for concern when it comes to the spread of the virus. The Ebola outbreak is thought to have originated in Mongbwalu, a high-traffic mining hub. People who caught the virus in Mongbwalu are thought to have sought care in neighboring districts. And the wider province borders both South Sudan and Uganda. So far, Uganda has reported seven confirmed cases and one death. South Sudan’s health ministry has said it will strengthen surveillance, but no cases have been reported in the country so far. 

Violence in the region is making it much harder to contain the spread of the virus, too. Conflict involving multiple armed groups, including deadly attacks on civilians, has hampered humanitarian and health-care efforts. Poor infrastructure and damaged roads make matters even worse. Food insecurity is ravaging the region as well—this year, nearly 10 million people in the region face acute hunger.

Together, these factors are making it “nearly impossible” to isolate people with Ebola and trace others who have been in contact with them, WHO director general Tedros Adhanom Ghebreyesus said in a statement earlier this week.

The dismantling of US aid programs hasn’t helped either. US government funding for international health projects has steeply declined since the start of President Donald Trump’s second term. These cuts have harmed disease surveillance systems, according to the International Rescue Committee, a humanitarian nonprofit.

“Funding cuts have left the region dangerously exposed,” Heather Reoch Kerr, the organization’s country director for the Democratic Republic of the Congo, said in a statement. “Years of underinvestment and recent funding cuts have left many health facilities without adequate protective equipment, surveillance capacity, or frontline support needed to respond quickly and safely.”

The US has mobilized emergency funding for the outbreak, and a spokesperson for the State Department has argued that none of the administration’s actions have hampered the Ebola response. But health experts counter that the damage has already been done.

On May 17, the WHO declared the Ebola outbreak a public health emergency of international concern. In a statement on Wednesday, Tedros described the situation as “a catastrophic collision of disease and conflict with the Ebola outbreak in Ituri province outpacing the response.”In an online appeal to residents on Wednesday, ahead of an in-person visit, Tedros pleaded for a ceasefire and commended the spirit of community members. He also acknowledged the steep challenges they face. “You are already carrying so much: malaria, hunger, insecurity, and the daily struggle to keep your families safe,” he wrote in French. “And now Ebola. It’s not fair, and I won’t pretend otherwise.”

This article first appeared in The Checkup, MIT Technology Review’s weekly biotech newsletter. To receive it in your inbox every Thursday, and read articles like this first, sign up here.