As the deadly Bundibugyo strain of Ebola continues to ravage parts of Central Africa, physicians once again find themselves scrambling for ways to keep the sickest patients alive.
Existing antibody treatments are strain-specific and don’t target the virus responsible for the current outbreak, leaving few therapies capable of clearing virus from the bloodstream. This forces doctors to rely largely on supportive care for people in advanced stages of disease.
That treatment gap is reviving interest in experimental blood-filtering devices that can physically remove viral particles from the bloodstream.
These systems have been studied primarily as treatments for cancer, where they help remove tumor-derived particles, and in more common infectious diseases such as COVID-19 and hepatitis C. However, one such device was successfully deployed during the last major outbreak of Ebola, helping to drive down exceedingly high viral levels in one critically ill patient.
If the current outbreak expands further, as some infectious-disease experts warn it could, the same technology may once again be called into action—not just as a desperate last-resort intervention for a single patient, but as a potential tool for keeping more Ebola patients alive.
“It could really help,” says Stefan Büttner, a nephrologist and intensive-care specialist at the Klinikum Aschaffenburg-Alzenau in Germany.
Filter Removes Millions of Viral Particles
This year’s Ebola outbreak, though serious, is nowhere near the scale of the catastrophic epidemic that started in late 2013 and persisted for nearly 2.5 years.
Back then, there were more than 28,000 confirmed cases and 11,000 deaths—mostly in the West African nations of Sierra Leone, Liberia, and Guinea, though the virus spread in nearby countries as well. Today, the toll is far smaller: roughly 1,000 suspected cases and fewer than 300 related deaths, all concentrated in the eastern Democratic Republic of Congo, with limited spillover into Uganda.
Still, the emergence of the Bundibugyo strain, coupled with the lack of approved therapies designed to target it, has raised fears that doctors could once again find themselves without effective tools if the virus spreads further.
The situation was similar in 2014, before the development of monoclonal antibody therapies that dramatically improved survival against the more common Zaire strain of Ebola. So, when a Ugandan doctor—infected with Ebola while treating patients in Sierra Leone—was medevaced to Germany in critical condition, the ICU team at Frankfurt University Hospital, which included Büttner at the time, tried nearly everything they could.
Nothing seemed to halt the disease’s progression. The man’s condition only got worse. His organs began to shut down.
Then, with emergency approval from German regulators, Büttner and his colleagues connected the patient to the Hemopurifier, a baton-sized cartridge filled with sticky proteins from the common snowdrop plant. These proteins, like a kind of molecular Velcro, latch onto sugar molecules that coat viruses like Ebola and trap them as blood passes through the system.
The Hemopurifier itself is not electrical. Instead, it connects inline to an intensive care-grade dialysis machine, the artificial kidney-like device that pumps the patient’s blood through its own filter to strip out toxins and surplus fluid before returning it. The Hemopurifier rides on that same circuit, and on that same machine’s electronics. The dialysis unit’s pumps push the blood through the cartridge, while its sensors balance fluid, watch circuit pressures for safety, and automatically meter the anticoagulant that keeps the blood from clotting along the way.
Though he had been on emergency dialysis for days, the Ugandan doctor had the Hemopurifier added into the circuitry for just 6.5 hours. His blood sloshed through the device’s tiny channels and pressed against its protein snares. By the end of the brief treatment, the device had captured a whopping 253 million copies of the Ebola virus, and the man’s situation quickly turned around.
His viral load dropped from around 380,000 particles per milliliter of blood before the procedure to roughly 6,000 the next day. His immune system, no longer overwhelmed by runaway viral replication, then regained the upper hand and finished the virus off on its own.
Less than a week after the treatment, as Büttner’s team reported in 2015 in the journal Blood Purification, the patient was Ebola-free.
The Technology is Ready to Deploy
Though it is impossible to know how much of his recovery could be attributed to blood filtration, Büttner believes the treatment played an important role. And he is confident the approach could prove even more beneficial for patients with much higher viral loads, who might not otherwise survive, while also helping to limit the organ damage and other complications that often arise during prolonged stays in intensive care.
“Earlier is better,” Büttner says.
Should the need to test that idea emerge during the current outbreak, Aethlon Medical, the company behind the Hemopurifier system, says it is prepared to move quickly.
Back in 2014, the company secured FDA authorization for a compassionate-use protocol allowing the Hemopurifier to be used in up to 20 patients with Ebola across 10 clinical sites in the United States. More than a decade later, authorization remains active and available for use, according to the company. “That avenue is still open,” says chief medical officer Steven LaRosa.
And although the device has never been evaluated against the Bundibugyo strain, LaRosa says its mode of action suggests it should work regardless of Ebola subtype. Given Büttner’s experience treating the man infected with the Zaire strain, together with laboratory studies demonstrating capture of the related Marburg virus, he expects the Hemopurifier would be able to filter Bundibugyo virus as well.
“I have confidence that it would likely be removed,” LaRosa says.
For proponents of blood filtration, the major obstacle is therefore not technological. The devices already exist, can be integrated into standard dialysis and critical-care equipment, and appear capable of capturing a broad range of pathogens, Ebola included.
The harder challenge, they say, is convincing physicians, regulators, and health systems to embrace a treatment paradigm built around physically extracting disease-causing agents rather than targeting them with pharmaceuticals. And even if that skepticism were to fade, major logistical challenges remain.
The Hemopurifier and other systems like it are designed to operate with dialysis-style blood-circulation systems that require specialized equipment, reliable power, trained personnel, and large-bore vascular catheters. Such resources are readily available for patients who can be evacuated to major European medical centers in places like Frankfurt. They are typically non-existent in the austere settings where Ebola outbreaks most often occur.
What the field still needs is therefore a “ruggedized” version of the technology that can hold up outside the controlled environment of a hospital ICU, says Michael Super, an infectious-disease researcher at the Wyss Institute for Biologically Inspired Engineering at Harvard who has spent years developing his own blood-cleansing devices.
“That, from a practical point of view, could be something that’s very useful,” he says.
Designing for the Outbreak Zone
Lower-tech versions of blood-filtration systems are in development, and some medical device makers have begun sketching out designs that could, in principle, operate without any hospital infrastructure—some even without electricity.
For example, patent filings from Stavro Medical, a company recently acquired by ExThera, describe a manual system in which a healthcare worker uses syringes to push blood through a filter cartridge in batches—or, alternatively, simply raises one reservoir above another so that blood flows downhill through the filter on its own.
Aethlon, for its part, is pursuing a more modest goal. According to LaRosa, the company is developing a stripped-down version of its Hemopurifier system that could run through a standard IV line rather than the thick catheter that dialysis often requires. “That’s not ready for prime time yet,” he says. “But we’re working on it.”
In the end, however, what may push blood filtration into the Ebola treatment toolkit is not an engineering advance but a body count. A spreading outbreak could hasten the climb from experimental footnote to front-line tool.
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