Exosomes Are Being Hyped as a ‘Silver Bullet’ Therapy. Scientists Say No.

By Dr. Shelly Xuelai Fan

December 26, 2024

When human stem cells were discovered at the turn of the century, it sparked a frenzy. Scientists immediately dreamed of repairing damaged tissues due to aging or disease. A few decades later, their dreams are on the brink of coming true. The US Food and Drug Administration (FDA) has approved blood stem cell transplantation for cancer and other disorders that affect the blood and immune system. Moreover, more clinical trials are underway, investigating the use of stem cells from the umbilical cord to treat knee osteoarthritis—where the cartilage slowly wears down—and nerve problems from diabetes.

The Dark Side of Stem Cells

However, the promise of stem cells came with a dark side. Illegal stem cell clinics popped up soon after the cells’ discovery, touting their ability to rejuvenate aged skin, joints, or even treat severe brain disorders such as Parkinson’s disease. Despite FDA regulation, as of 2021, there were an alarming number of clinics across the country, each advertising stem cell therapies with little scientific evidence. “What started as a trickle became a torrent as businesses poured into this space,” stated an expert team in the journal Cell Stem Cell in 2021.

A New Hope: Exosomes

History appears to be repeating itself with an up-and-coming “cure-all”: exosomes. Exosomes are tiny bubbles made by cells to carry proteins and genetic material to other cells. While research into these mysterious bubbles is still in its infancy, there are indications that they may contribute to aging or be responsible for the spread of cancers across the body. Clinical trials are currently underway, ranging from exosome therapies to slow hair loss to treatments for heart attacks, strokes, and bone and cartilage loss.

Despite their potential, a growing number of clinics are also advertising exosomes as their next best seller, with one forecast predicting a significant growth in the exosome market by 2030.

The Uncertain Nature of Exosomes

The problem? We don’t really know what exosomes are, what they do to the body, or their side effects. In a manner, these molecular packages are like Christmas “mystery boxes,” each containing a different mix of biological surprises that could alter cellular functions, like turning genes on or off in unexpected ways.

There have been reports of serious complications associated with exosome treatments. “There is an urgent need to develop regulations to protect patients from serious risks associated with interventions based on little or no scientific evidence,” cautioned a team in Stem Cell Reports.

Cellular Space Shuttles

In 1996, molecular scientist Graça Raposo made an intriguing observation: immune cells she was studying seemed to send messages to each other via tiny bubbles. Upon experimentation, she found that when treated with a toxin, these immune cells absorbed the toxins, encapsulated them in bubbles, and released them into their surroundings.

Upon harvesting these exosomes and applying them to other immune cells, the cells exhibited a similar immune response. Initially thought to be mere garbage collectors of the cell, the role of exosomes quickly evolved into recognized carriers of significant biological information. Their interest surged once scientists discovered exosomes harvested from tumor-fighting cells in mice.

Despite the excitement surrounding exosomes, understanding their full biological function remains elusive. Exosomes can potentially carry messages from dying cells to nearby cells or even aid tumor cells in manipulating neighboring cells to support cancer growth and spread.

Challenges in Research

Studying exosomes is challenging due to their small size—about one-hundredth the size of a red blood cell—and the unpredictability of their release from different cell types. Until recently, scientists struggled to come to an agreement on how to define them. However, a collective effort among researchers has begun to establish standardized naming conventions and methods for exosome preparation.

The Wild West of Exosome Therapies

While scientists work towards solidifying exosome-based treatments, unregulated clinics have proliferated around the world. Their initial pitch to the public was to combat COVID-19, with 60 clinics in the US advertising exosome-based therapy as a preventive or therapeutic measure—without scientific backing. More recently, exosome applications in skincare and hair growth have become widespread, notably in the US, UK, and Japan.

Exosomes are considered biological medicinal products governed by the FDA in the US and the European Medicines Agency (EMA) in the EU, necessitating agency approval before marketing. Sadly, some clinics have marketed unapproved exosomal therapies, leading to dire consequences; patients in Nebraska developed sepsis—an infection throughout the body—resulting from unauthorized treatments.

Regulatory frameworks for exosome treatments in Japan are even more relaxed, leading to the establishment of nearly 670 clinics offering unproven therapies, primarily for cosmetic purposes.

Risks and Safety Concerns

While exosomes themselves may not be harmful, their methods of extraction and handling play a crucial role in safety. In unregulated settings, there is a heightened risk of contamination with endotoxins or bacteria, leading to severe inflammatory responses.

“From a very basic point of view, we don’t really know what they’re doing, good or bad… I wouldn’t take them; let’s put it that way,” stated James Edgar, an exosome researcher from the University of Cambridge.

Scientific Progress in Exosome Research

Unregulated clinics not only pose a risk to patient safety but also threaten to hinder scientific advancements. While scientific progress is often slow, it is necessary to ensure safety and efficacy despite the allure of novel treatments. Researchers continue to undeniably forge ahead in utilizing exosomes for various health problems while recognizing the complexity that surrounds these therapeutic agents.

References

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