Seattle’s Circulate Health Raises $12M to Expand Longevity Blood-Cleaning Service

Seattle-based longevity startup Circulate Health has secured $12 million in seed funding as it looks to expand a specialized blood-cleaning treatment aimed at helping people live longer and healthier lives.

The company is working with 24 clinics across eight U.S. states, offering a therapeutic plasma exchange service designed to remove inflammatory substances and other biological compounds linked to aging. Although the treatment has gained attention in the growing longevity industry, experts stress that it has not been proven to slow aging, and it is not covered by health insurance.

Circulate uses therapeutic plasma exchange (TPE), a medical procedure that removes a patient’s blood, separates the plasma, and returns the blood cells with a replacement protein solution. The company believes this process may help refresh the circulatory system by reducing harmful age-related factors in the bloodstream.

“Our first goal is to make plasma exchange widely available as an outpatient treatment,” said Dr. Brad Younggren, Circulate Health’s co-founder and CEO. He described the company’s long-term vision as leading a new era of targeted blood-cleaning therapies focused on longevity.

Since launching its services in May 2024, Circulate has completed more than 1,000 treatments. A single session typically costs between $8,000 and $10,000, making it an expensive elective procedure for consumers interested in anti-aging therapies.

Study Shows Early Signs, but Questions Remain

The startup recently published findings in the scientific journal Aging Cell, reporting results from a study involving 42 adults with an average age of nearly 67 years.

Participants were divided into three groups: one received a placebo, another underwent six plasma exchange sessions, and a third received six plasma exchanges combined with antibody treatments. According to the study, the group receiving plasma exchange plus antibodies experienced an average reduction of 2.61 years in biological age, based on several cellular aging biomarkers.

Younggren said the results were encouraging and aligned with signs of cellular rejuvenation.

However, the research also came with important limitations. The study involved a relatively small number of participants and only monitored outcomes over two to five months. Researchers did not evaluate whether patients actually felt healthier, experienced cognitive improvements, or achieved longer-term health benefits.

Medical experts have also urged caution. In a New York Times report published in May, several specialists questioned whether the findings demonstrate meaningful longevity benefits.

Dr. Jeffrey Winters, chair of transfusion medicine at the Mayo Clinic, said the available evidence does not show that plasma exchange leads to longer or healthier lives, noting that convincing proof “really isn’t there.”

Critics additionally pointed out that improvements appeared to decline in the final blood samples collected during the study, raising the possibility that any benefits may fade over time. Like many medical procedures, plasma exchange also carries risks, including infections and other potential complications. Each treatment session lasts about two hours.

A Growing Market for Longevity Care

Therapeutic plasma exchange is already an established treatment for several medical conditions, including certain cases of multiple sclerosis, leukemia, Guillain-Barré syndrome, sickle cell disease, and some organ transplant situations.

More recently, however, the procedure has become popular among biohacking enthusiasts seeking cutting-edge methods to improve health and extend lifespan, even when long-term scientific evidence remains limited.

Circulate officially launched in January 2024 after operating quietly for several years. The company was co-founded by Dr. Eric Verdin, CEO of the Buck Institute for Research on Aging, whose research serves as the scientific foundation for Circulate’s approach. The company collaborated with the Buck Institute on the Aging Cell study.

Most of Circulate’s partner clinics specialize in longevity medicine, offering services such as advanced blood testing, genomic sequencing, full-body MRI scans, coronary artery imaging, and other preventive health assessments.

Younggren acknowledged that much more research is needed. The company is continuing to analyze patient data collected through its clinic network to better understand the long-term effects of plasma exchange.

He also highlighted differences between Circulate’s treatment and traditional plasma donation. The startup removes a larger volume of plasma, replaces it with albumin instead of saline, and administers an antibody dose that may support cellular rejuvenation.

Investors Back the Future of Longevity

Before joining Circulate, Younggren spent seven years as chief medical officer at Seattle telehealth company 98point6. He later recruited former 98point6 executive Robbie Schwietzer as Circulate’s chief operating officer.

The new funding round was led by Khosla Ventures, with participation from Seaside Ventures and CSC Ventures. The investment also helped support the Aging Cell research.

Circulate faces competition from U.S. companies including MaxWell Clinic and Next Health, both of which offer plasma exchange services focused on longevity.

According to PitchBook, longevity technology companies attracted $1.8 billion in investment between 2021 and the first quarter of this year. The sector has increasingly shifted its attention from treating age-related diseases to addressing the biological processes behind aging itself.

Major technology figures, including Jeff Bezos and Sam Altman, have also invested in longevity startups. Meanwhile, U.S. Health and Human Services Secretary Robert F. Kennedy Jr. has publicly supported anti-aging practices as part of his “Make America Healthy Again” initiative.

Looking ahead, Younggren said Circulate may seek U.S. government funding to support additional research into plasma exchange and healthy aging.

“We believe the idea of making America healthier aligns closely with the work we’re doing,” he said.

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