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.