Theres a trendy new cure-all in townyou might have seen ads pop up on social media or read rave reviews in beauty magazines. Exosomes are being touted as a miraculous treatment for hair loss, aging skin, acne, eczema, pain conditions, long covid, and even neurological diseases like Parkinsons and Alzheimers. Thats, of course, if you can afford the price tagwhich can stretch to thousands of dollars.Theyre magic! claims one YouTube review. One US clinic exhorts: Unlock the fountain of youth with exosome therapy. All aspects of skin health improve with exosome therapy, states one UK clinics website, adding that this is as cutting-edge as it gets. Exosome particles could be used to treat any inflammatory disease you could think about, which is almost all of them, the founder of an exosome company says in a video on YouTube.But theres a big problem with these big promises: We dont fully understand how exosomes workor what they even really are.We do know that exosomes are tiny particles that bud off from cells and that their contents can vary hugely, depending on the source of the cell (some popular options include human umbilical cords, salmon testicles, and roses) and how healthy or stressed it is. Even cell biologists cant agree on what, exactly, is inside them, and how beneficialor dangerousthose contents may be.The world of exosome treatments is being likened to a Wild West by some researchers. Rigorous trials have not been conducted, so we dont know how safe it is to spray on or inject these tiny mystery blobs. Exosome products have not been approved by regulatory agencies in the US, UK, or Europe, where the treatments are growing in popularity. Nor have they been approved for medical uses in Japan or South Korea, two other countries where exosome treatments are popular. Still, exosomes have emerged as a sort of panacea for almost everything, says Leigh Turner, a bioethicist and public health researcher at the University of California, Irvine, who tracks direct-to-consumer marketing of unapproved health products. Risks are commonly minimized, and benefits are commonly exaggerated.This hasnt stopped customers from flocking to the growing number of aesthetic centers, stem-cell clinics, and medspas offering exosome treatments, hoping for a miracle fix. The global market for exosome skin-care products was valued at $256 million in 2023 and is forecast to grow to $674 million in the next six years.Mystery blobsTechnically referred to as vesicles, exosomes are made inside cells before being released. Theyve long been mysterious. The term exosome was introduced in the 1980s. Before that, tiny particles that are now thought to have been exosomes were described as platelet dust or matrix vesicles.At first, scientists assumed that exosomes functioned as trash bags, shuttling waste out of the cell. But research in 1996 suggested that exosomes might also work to help cells communicate by delivering signals between them. If a cell is dying, for instance, it could perhaps send a signal to neighboring cells, giving them a chance to produce more protective substances in order to save themselves from the same fate. Cancer cells, on the other hand, could potentially use exosomes to send signals that co-opt other cells to support the growth of a tumor. Still, its not fully understood what signals are actually being sent.Another major mystery is what, exactly, is inside exosomes. It depends who you ask, says James Edgar, who studies exosomes and similar vesicles at the University of Cambridge, UK. Cell biologists agree that exosomes contain proteins, lipids, and other molecules that result from cell metabolism. Some believe they also contain DNA and RNA, but not everyone is convinced. Its just very difficult to prove or disprove, says Edgar.Thats partly because exosomes are so smallonly about 70 nanometers wide, around one-hundredth the size of a red blood cell. While the first images of them were published in the 1970s, we still dont even know for sure what they look like; Raghu Kalluri at MD Anderson Cancer Center in Houston and his colleagues are studying the shape of exosomes to figure out if they are round, oval, or rod-like, for example.Further complicating all of this, cell biologists dont know what triggers the release of an exosome from a cell. Most cells release them at a relatively steady pulse. Some cells release a lot of exosomes; others release a relatively small number. Immune cells, for example, release more exosomes than cancer cells. We dont really understand why thats the case, says Edgar.Fundamentally, we dont know enough, he adds. We dont quite know yet where these things go when they hit cells, and if theyre released into that cellor how any of it happens, basically.Exosome explosionDespite these enduring questions, exosomes have taken off as a beauty and health treatment. Turner has been tracking stem-cell clinics both in the US and globally for years. When he and his colleagues assessed US clinics offering direct-to-consumer treatments in 2016, exosomes just didnt pop up at all, he says. When he did the same analysis in 2021, he identified around 100 clinics in the US offering exosome therapies.Its not clear why exosomes are taking off now. Its not as though theres an overwhelming amount of safety and efficacy data, says Turner. I think it might be more of a buzz kind of phenomenon. This seems to be kind of a moment for exosomes.There are many different types of exosomes available on the market. Some are from human cells, including those from the placenta or umbilical cord. Some companies are selling exosomes from plants and animals. In the US, exosomes are regulated as drugs and biological products when they are intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease and intended to affect the structure of any function of the body of man or other animals, according to the Food and Drug Administration, which regulates medicines in the US.Clinics get around this by using them as cosmetics, defined in law as articles intended to be rubbed, poured, sprinkled, or sprayed on, introduced into, or otherwise applied to the human body for cleansing, beautifying, promoting attractiveness, or altering the appearance. What practitioners are not allowed to do is make claims about the health benefits of exosomes. After all, even anti-dandruff shampoo, which purports to treat a skin condition, is considered a drug by the FDA.Dev Patel offers exosome treatments at his anti-aging and skin rejuvenation clinic, Perfect Skin Solutions, in Portsmouth, UK. Over the last 10 years, he says, he has noticed a trend: Customers are less interested in injectable treatments that merely give an impression of youth, like fillers and Botox, and more interested in the idea of treatments that can rejuvenate their skin. The demand for devices like lasers, which create heat on the skin and trigger repair, has gone through the roof, he says. Now, exosomes are catching on too.Patelwho has a medical degree, served in the Royal Navy, and holds a postgraduate diploma in dermatologyleft his job in the UKs National Health Service to start his clinic around 10 years ago. He didnt start offering exosome treatments until 2020, after he heard about them at a meeting for aesthetic clinicians.The first treatment he offered involved unapproved exosomes derived from human fat cellsmaking them illegal to sell in Europe, he says. Patel says that he didnt realize this until after hed bought the exosomes and started using them, partly because of the misinformation hed been fed by the distributor. He says some of the sellers were telling doctors that they were allowed to use the exosomes topically (on a persons skin) and then inject them as part of an off-label use. Patel wont name the distributor he bought from, but he says the company continued to sell its exosome products to clinics in the UK for at least two years after that point.Patel stresses that as soon as he found out about the regulations surrounding exosomes derived from human cells, he stopped using the product. I had probably had 5,000 [around $6,500] worth of product sitting in my clinic, and it was just thrown away, he says. Instead, he switched to exosomes from plant cells and, more recently, others derived from salmon testes.For hair regrowth, Perfect Skin Solutions offers a course of five exosome treatments, each delivered during a half-hour appointment, at a total cost of 2,000. When it comes to skin treatments, Patel recommends two or three sessionsmore for those who are looking to counter the signs of aging. By harnessing the power of exosomes, you can achieve a more youthful and radiant complexion, while also addressing specific skin concerns and promoting overall skin health, according to the companys website.Patel says he uses the exosomes to treat clients for baldness around four times a week. He and his team members will first perform microneedling on the scalp. This technique uses tiny needles to make miniature holes in the skin80,000 holes a minute, he says. Microneedling is often used to trigger a wound healing process that can improve the look of the skin. But after Patel performs the procedure on a persons head, he uses a jet propulsion device that uses carbon dioxide to spray cooled salmon exosomes into the tiny indentations. You basically create these micro-icicles containing the product, he says. They pierce the skin, but you dont feel it. It feels quite nice, actually. After six to 10 weeks, customers can expect healthier skin and thicker, stronger hair, he says.The results are amazing, says Patel. Ive had it done on my hair, which is probably why its looking out of control now, he adds, pointing to his thick but neatly styled do, combed back and shaved at the sides.Not everyone is as enthusiastic. Sarah, who is being identified by a pseudonym to protect her professional image, tried exosomes last year, though not at Patels clinic. Now in her 30s, she had acne as a teenager, and her dermatologist suggested that rubbing exosomes from human umbilical-cord cells into her face after a microneedling treatment might reduce the scarring. But he didnt fully explain exactly what exosomes are or what they were expected to do, she says.I feel like its a little bit of health marketing bullshit, she says. I dont really understand how they work.Sarah received three treatments, three months apart, as part of a trial her dermatologist was participating in. As a participant, Sarah didnt have to pay for her treatment. In each of the sessions, the doctor numbed Sarahs face with lidocaine cream before microneedling it. Then they kind of dribbled the exosomes on with a syringe, she recalls. She was advised to sleep on a clean pillow and avoid washing her face that evening. There was some redness but my skin was mostly back to normal the following day, she says.Her last treatment was a year ago. And she hasnt seen a reduction in her scarring. I dont think Id recommend it, she says. The results were very underwhelming.Safety in salmon?In theory, exosomes should be safer than stem-cell therapies. Cells can be thought of as living drugs, while exosomes are non-living collections of biological molecules, says Ke Cheng at Columbia University in New York, who is doing more conventional research into potential applications of exosomes. Cheng is exploring the use of engineered exosomes for heart diseases. Exosomes are less likely than cells to trigger an immune response, and because they cant replicate, the risk of tumor formation is also lower.But that, of course, does not make them risk-free. There are no established standards or regulations for the manufacture of exosomes to be used in people. This leaves plenty of room for companies to manufacture exosomes in different waysand for disagreements over which method is the best and safest.The product Sarah tried that was derived from human umbilical-cord cells is called Age Zero. Erin Crowley and her father, Michael Crowley, who manufacture and sell the product, have a team that grows the cells and then harvests the exosome-containing liquid surrounding them at a clean lab in Rochester, New York.We have in stock right now about $3.5 billion worth of exosomes, says Michael Crowley. Thats enough for millions of treatments, he says, although the figure will depend on what they are used for: The pair have different companies that sell exosomes for experimental medical use (25 billion to 100 billion exosomes per treatment) and cosmetic use (5 to 10 billion). Cosmetic clinics can buy vials that the company says contain 5, 10, 50, or 100 billion exosomes. Those with 10 billion exosomes are sold in packs of nine for $1,999, according to the companys website.Right now, were in about a little less than a thousand medspas, aesthetician offices, dermatologists, plastic surgeons with our cosmetic product, Erin Crowley says. We can sell direct to consumer, but the product really works great after microneedling or after laser or dermaplaning. They have been selling in the US for the last year and half; she says the product is also available in the UAE, Pakistan, Lebanon, Canada, and Turkey.The Crowleys argue that because their exosomes come from human umbilical-cord cells, they are more effective than those from other sources, although again, rigorous side-by-side comparison studies have not been done. Exosomes from plant or fish cells just dont have the right language to speak to human cells, says Erin Crowley, who has a background in mechanical engineering and quality control. She says that she analyzed the exosome market a couple of years ago and was appalled at what was on offer.The industry now is very, very confused, and the marketing is very confused, she says. Across the board, production quality standards are low, she says, adding that she and her dad hold their product to higher standards by testing for potential sources of infections (which can arise from contamination) and using devices to count exosomes.On the other hand, Primacure, the company that sells the product derived from salmon testicles, argues that fish exosomes are safer than those taken from human cells or from other animals. These exosomes are collected from cells grown in a medium that contains a mix of growth factors and peptides, and the team uses ultrasound to release the exosomes from the cells, according to a video presentation by Mike Lee, CEO of Primacure. We want to refrain from using products that are human-derived, or maybe even animal-derived, that can transmit diseases to humans, Lee says in the video.There are no known cases of exosomes causing such diseases in people. But some practitioners buy that argument: Fish present a very low-risk option in terms of disease transmission, says Patel. Turner, though, isnt convinced: I dont see any reason why they would be [safer], he says, adding that usually, biological materials from other animals are seen as posing a greater risk to patients. The use of animal cells or tissues in humans carries risks of infection, for example.We cant be sure either way, because rigorous research comparing these exosomes and their safety simply has not been done. If they are from different sources, their outcomes and effects will be different, says Cheng. You need to have science; you need to know why they work.Exosomes derived from human cells will still have molecules that are foreign to a persons body and could trigger an immune response, says Edgar. He is also concerned that because exosomes may hold the original cells waste, they could be introducing things that a recipients cells would rather be rid of. They might, for example, shuttle excess receptors for growth factors out of a cell. If another cell takes these up, it might end up with too many growth factor receptors, which could help drive cancer, he says. We do need to understand the basics of whats going on here before we jump into the clinic, he adds.At any rate, there are no rigorous human studies to support the safety or effectiveness of using exosomes for skin health, hair growth, or anything else. Look at any clinic website, and it will probably have some impressive-looking before-and-after photos of a customer or two. But these individuals are often having several treatments at the same time. Microneedling alone has been used for decades as an aesthetic treatment. And Patel says he delivers each vial of exosomes alongside a second vial containing a concoction of many other ingredients that are thought to be beneficial to skin health.So how can a clinician be sure that the apparent effects are due to the exosomes? I put this question to Patel. I cant answer that, he told me. Ive never just used the mix on its own to see [what it does]. Youd have to do countless patients with either [vial] to know.Beyond beautyWhile many of the clinics offering exosome treatments are focused on their purported cosmetic benefits, a significant number claim that they can treat diseases. In the three months between November 2021 and January 2022, Turner and his colleagues identified 16 businesses that were marketing exosome-based therapies to treat or prevent covid-19 or long covid, for example. Others claim exosomes can treat sports injuries and even disorders like Alzheimers disease. Again, there is no rigorous research to support these claims.There have been some promising early studies in animals, and a handful of small, weak phase I trials exploring the use of exosomes in medical treatments. But these fall way below the approval standards of the FDA.There are currently no FDA-approved exosome products for any use, Paul Richards, an FDA representative, wrote in an email to MIT Technology Review. Because of this, no exosome product should be marketed for any medical use.There is an abundance of misleading information in the public domain regarding regenerative medicine products, including exosome products, wrote Richards. The FDA continues to remind consumers to be cautious of any clinics, including regenerative medicine clinics, health-care providers, physicians, chiropractors, or nurses, that advertise or offer anything purported to be an exosome product. These products are not without risk and are often marketed by clinics as being safe and effective for the treatment of a wide range of diseases or conditions, even though they havent been adequately studied in clinical trials.No exosome-based products have been approved by the UKs Medicines & Healthcare products Regulatory Agency (MHRA) or by the European Medicine Agency (EMA), either.Theyre unproven technologies, at least from the perspective of the FDA, says Dave Carter, head of research at the biotech company Evox, which is exploring the use of exosomes for drug delivery. We dont really understand [how they work] I personally would be somewhat wary of these types of things outside of the context of proper clinical trials.The FDA has issued letters to some of the clinics providing these treatments. In 2020, for example, the organization wrote to Douglas Spiel, president of Regenerative Solutions of New Jersey, about its claimsbeing published on Facebook at the timethat exosomes could mitigate, prevent, treat, or cure covid. The company was also marketing exosome products for a range of other disorders, including spinal cord injury, Parkinsons, Alzheimers, lupus, and multiple sclerosis.The FDA letter listed the problematic posts and requested a response within 30 days. Spiels current clinic doesnt make any claims about exosomes.Turner is concerned that letters like these have little impact. Its not terribly consequential, he says. No one has to surrender their medical license, and there are no automatic financial penalties.Beyond potential harm to individual patients, both scientists and regulatory agencies are concerned that unapproved, untested, and unregulated exosome treatments could set back an exciting field of research. Potential uses of exosomes to diagnose and treat diseases are being explored through lab-based research and early-stage clinical trials. Companies making unsubstantiated claims to sell products could undermine that progress.These marketing claims are often a mishmash of marketing froth, marketing hype, and some credible claims cut and paste[d] from [scientific] papers and websites, says Turner. It makes it more challenging for us to have any kind of meaningful public understanding or discussion.In the meantime, Turner is one of many scientists cautioning people against the use of exosomes. I would say that its a bit of a Wild West out there with respect to how these are being used, says Kalluri of MD Anderson Cancer Center. Ultimately, some science needs to be done to show that this actually works.From a very basic point of view, we dont really know what theyre doing, good or bad, says Edgar, from the University of Cambridge. I wouldnt take them, lets put it that way.Even Sarah, who received three exosome treatments last year, agrees. I think there needs to be more research around it I would just hold on and see, she says. Maybe [I would feel] different if I looked a million years younger after using it. But that wasnt the case.