Landyn Holdren is an eight-year-old autistic child who has high support needs and is nonspeaking. His mother, Christy Holdren, says he can be self-harming, slapping his chest, face or head when distressed.
Later this month, she will spend $15,000 on an unapproved stem cell treatment she hopes might help him.
They went for the first round of the treatment last October at a Florida stem cell clinic that charged Holdren $12,500. The procedure is not approved by the Food and Drug Administration (FDA), and scientists say there is little evidence it works for autism, raising concerns that desperate families are being sold false hope.
Yet as stem cell clinics multiply across America, they are finding an influential ally in the US health secretary, Robert F Kennedy Jr.
Holdren knows there is no “cure” for autism, which is a condition, not a disease. But she said she was determined to do her utmost to help her child.
“He actually looks at us and not through us, and that’s huge for us,” she said of the small but significant changes she believes followed Landyn’s first infusion. “We can cut his hair without him freaking out. That may sound little, but when you have to wrangle an alligator to clip his nails, that’s big things.”
Seven months on, Landyn’s aggressive and self-harming behaviour is worsening again. So, despite the cost that has driven Holdren to take out a loan against her retirement savings, she is preparing to return for a second stem cell dose.
A ‘completely bogus’ treatment
The Holdrens are far from alone.
Across the US, children with autism as young as 18 months old are being given unapproved stem cell treatments at clinics in Florida, Texas and elsewhere, part of a growing market operating beyond the bounds of FDA approval.
The procedure often involves the child being sedated before receiving intravenous doses of millions of stem cells commonly derived from human umbilical cords harvested at birth.
In some cases, the doctors selling the treatments have no scientific expertise in autism or child development. Instead, physicians from unrelated specialties, including plastic surgery and orthopaedics, have entered the booming stem cell sector, billing the procedures as “regenerative medicine” for children, some of whom have severe disabilities.
Up to now, Americans seeking therapies that lack federal approval have tended to look abroad. That has fed the flourishing multibillion-dollar industry of “stem cell tourism” in places such as Mexico and Panama – and as far afield as Abu Dhabi.
Now the practice appears to be gaining strength inside the US, and there are fears that under Kennedy’s leadership, the FDA may be loosening its rigorous regulation.
Paul Knoepfler, a stem cell biologist at the UC Davis School of Medicine who acts as an unofficial watchdog of stem cell clinics through his blog, the Niche, has detected a slump in enforcement activity under Kennedy. He is concerned that the pattern will harden into a change of government policy.
“We haven’t seen the FDA taking action in the last 18 months. I think we’re going to see big change coming from the FDA very soon, backing off oversight of birth-related stem cells,” he said.
Arnold Kriegstein, professor of neurology at the University of California San Francisco who led its stem cell research for almost two decades until 2022, said that concern was growing about the spread of expensive and medically unproven interventions on highly vulnerable children.
“I’m appalled that this is being allowed to go on in the US, and that so many desperate people are being taken advantage of with a ‘treatment’ that in my view is completely bogus.”
The FDA has so far only approved stem cells for use in a very narrow range of cases, such as bone marrow transplants or to boost a cancer patient’s immune system after chemotherapy using their own, their siblings’ or unrelated donors’ matching stem cells. But the technique is attracting mounting attention for use in a range of treatments.
Stem cells are the body’s master cells, from which all other cells derive. They can renew themselves, develop into specialised cells and heal after injury.
Their use is showing enormous promise with specific diseases that involve dysfunctions at the cellular level, and there are more than 100 clinical trials currently under way under federal oversight.
Scientists are excited about the prospects for Parkinson’s disease, which causes dopamine-producing neurons in the brain to be depleted, and type 2 diabetes, in which beta cells in the pancreas produce insufficient insulin.
But autism is not like that. It is a very heterogeneous neurodevelopmental condition that varies almost with each person, and cannot be pinpointed to a precise cell-based complication. It is also still relatively poorly understood, which makes the search for new, effective treatments as hard as shooting a target in the dark.
So far, Kennedy has made no public moves to relax FDA restrictions on stem cell therapies. Instead, he has focused his energies on cutting scientific research into autism by about $31m, attacking existing evidence-based science, firing thousands of federal health officials and attempting to reduce the recommended list of childhood vaccinations.
At the same time as assailing established science, Kennedy has championed the providers of alternative medicine who operate on the margins of scientific controls, and has spoken openly about his desire to weaken federal regulation of the so-called “wellness industry”. He told Gary Brecka, a podcaster, that he would “end the war at FDA against alternative medicine”, including the “war on stem cells”.
He added that the FDA should “not tell physicians what they can and cannot prescribe. If you want to take an experimental drug, you can do that, you ought to be able to do that.”
Early in his tenure, Kennedy invited a leading provider of umbilical stem cells, Dr Chadwick Prodromos, an orthopaedic surgeon who had been operating largely out of the Caribbean island of Antigua, to join him at a roundtable in Washington DC that to reportedly discuss how to dilute federal regulations of stem cell treatments. Kennedy asked the physician to advise him on how to open up the US to such procedures despite the FDA’s ongoing prohibition without allowing a “‘wild, wild west’ environment”.
It later emerged that Prodromos had treated Kennedy personally in Antigua, administering him stem cells for his voice condition, spasmodic dysphonia.
In an email exchange with the Guardian, Prodromos said that he had made recommendations in line with Kennedy’s request that focused on how to lower the cost and timeline of new treatments so that FDA approval could be attained sooner. The process in the US “leading to drug approval is so expensive that the number of trials is very limited and many worthwhile treatments are never undertaken due to lack of funding”, he said.
He added that the challenge was to modify regulations without compromising safety. “The FDA is currently actively involved in attempting to do just this: an effort which I support.” When asked about whether the treatments amounted to experimentation, he replied that informed consent was carried out by the parents, adding: “We have seen no serious adverse events.”
Since Prodromos’s exchange with Kennedy, the Guardian has learned that he is now offering umbilical cord stem cell infusions to autistic children from two of his US clinics – in Naples, Florida, and Dallas, Texas. In its marketing, the clinic says that 85% of its autistic patients have had “meaningful improvement” in their behaviour and calmness, communication and speech, sleep, and seizure activity.
Fiona O’Leary, a campaigner against pseudoscience from Cork, Ireland, contacted the Prodromos Stem Cell Institute as part of her monitoring of regenerative medicine clinics. O’Leary, who has four autistic children, spoke to a Prodromos staff member and was told that families no longer needed to travel to Antigua for the procedure because it is newly available within the US.
“We do it in the US now, you don’t have to go overseas,” the employee said.
O’Leary was told that the shift had happened after Florida passed a law last year that allows clinics to offer stem cell treatments that were still unapproved by the FDA. She asked whether the Florida law covered autism, and the staff member said yes.
In fact, Florida’s law that came into effect last July only allows physicians to perform federally unapproved stem cell therapy for orthopaedics, wound care or pain management.
The areas covered are specifically stipulated, and autism is not one of them. “Florida’s law is super-specific – it only speaks to stem cells, and only speaks to physicians applying them for those three specific purposes,” said Jeff Cohen, an expert in health law who is founder of the Florida Healthcare Law Firm.
O’Leary said that the unraveling of US controls was upsetting. “Kennedy is undoing so much hard work to hold back the misinformation. Autistic kids are being experimented on. Families are spending huge amounts, and losing everything.”
After her conversation with Prodromos, O’Leary was sent a form to fill out as the first step towards receiving care. It asked her what specific condition she was interested in having treated, with options being “hair thickening, skin rejuvenation, improved intimacy, back pain, neck pain, joint pain, other …”
The clinic told her that if she took up the treatment, her son would be administered 150m umbilically derived stem cells provided by a company in New Jersey. He would be mildly sedated to calm him, and then the cells would be transfused into his body through an IV.
The cost of the first transfusion: $20,000.
Prodromos told the Guardian that he had begun offering stem cells to autistic children in the US under the new Florida statute, using the “pain management” category. “The patients we treat for autism all have documented need for pain management – for example chronic headaches which are a well-described component of autism in many such patients,” he said.
He said the cost of treatment was in line with other reputable clinics and reflected the expense of the research they conduct. “We pay for a research study in which patients are followed up more or less in perpetuity that is incredibly expensive, but we do it because it is the right thing to do.”
Prodromos summarised his US offering as “evidence-backed treatment which is very safe. This is not exploiting vulnerable children, but rather providing real benefit.” Prodromos accepted that official warnings about unscrupulous clinics were to some extent valid. “Those disclaimers are unfortunately often true, and deception definitely occurs,” he said. But he described his own US offering as evidence-backed treatment.
The Tijuana experiment
For years, advocates of fringe autism treatments largely operated on the margins of US medicine. Under Kennedy, some are now gaining unprecedented influence with the federal government.
In January, Kennedy appointed Tracy Slepcevic, the mother of an autistic child and a vocal supporter of alternative therapies, to a federal committee that helps steer national autism research policy. She was one of 21 new appointees who were elevated to the panel after Kennedy dismissed all its previous members. Several of the new advisers, Slepcevic included, share the health secretary’s skepticism toward vaccines.
Slepcevic describes in her book, Warrior Mom, how she arranged for her child to undergo several unproven treatments including high-dose vitamin C, hyperbaric oxygen chambers, intravenous ozone and chelation therapy, a technique to remove heavy metals from the body. The FDA has warned that chelation can cause serious and possibly fatal side-effects such as kidney failure.
Slepcevic also took her son to Ukraine for stem cell therapy following a protocol set by Jeff Bradstreet, a controversial anti-vaccine doctor. (Bradstreet died in an apparent suicide in 2015 shortly after his wellness center in Buford, Georgia, was raided by the FBI in an investigation into “frauds and swindles”.)
In April, Slepcevic, who is also a leader of the California chapter of Children’s Health Defense, the anti-vaccination group that Kennedy chaired until 2023, staged an Autism Health Summit in San Diego for the second year running.
The star speaker, beamed in on video, was Kennedy.
The health secretary described Slepcevic and her husband, Steve, as his “good friends”. He promised attenders that he planned to “create opportunities that extend across a lifetime”, and exhorted his audience to “work with us to drive solutions together”.
Slepcevic did not respond to a Guardian request for comment.
It was at the summit that Slepcevic announced a “pioneering” new experiment that she has initiated in partnership with a clinic in Tijuana, Mexico. Given its location, the center operates outside the FDA’s stringent controls, falling under the remit of the Mexican regulator Cofepris.
The Tijuana experiment, which is being billed as a “clinical trial” under Mexican oversight, will begin on 15 July. It will involve umbilical stem cells being given to a target group of 120 boys and girls aged seven to 15 who have an official autism diagnosis ranging from mild to severe.
Researchers will spend 12 months testing whether the treatment appears safe while also looking for signs in the children that it works. If the early results look promising, they hope to cross the border with a much larger trial at a newly opened clinic in Nashville, Tennessee, and other US sites.
The overall cost of the Mexican experiment has been put at between $1.5m and $5m, for which donations were being warmly invited in San Diego.
Slepcevic has partnered for the trial with Ed Clay, the founder and owner of the Tijuana-based Cellular Performance Institute (CPI). Clay, a Nashville native, is a former boxer and MMA fighter who manufactured Brazilian jiujitsu uniforms and owned the jiujitsu magazine Submission Fighter.
After he tore ligaments in a fight, he turned to alternative treatments. He bought a disused hospital in Mexico and converted it into a clinic that offers stem cells for “anti-aging”, chronic pain relief and sports injuries.
The CPI prides itself as being the official stem cell therapy provider of the Ultimate Fighting Championship (UFC). Clay also promotes his close ties to Kennedy’s Make America Healthy Again (Maha) movement, and his work has been enthusiastically backed by Joe Rogan, the podcaster.
The upcoming “clinical trial” in Tijuana is Clay’s first foray into stem cells for autistic children. “The goal definitely is to, if this works, get it approved in the United States,” he told the San Diego summit.
Clay gave further details of how the experiment came about to the Guardian. He said he was contacted by Autism Health, Slepcevic’s company, asking whether he could expand his clinic’s work into stem cells for autism.
He replied that as he had no experience in this area, he wouldn’t feel comfortable treating autism patients, especially children. But he did agree to pursue a clinical trial fully licensed under the Mexican health regulator Cofepris.
He said that any comparison between the work of his full-service hospital, staffed by experts and with laboratories in Boston and Nashville, and unscrupulous clinics scamming parents “could not be further from the truth”. “As to my position on the grifting that occurs in this field, I agree it is a problem. The claims that are made regarding stem cells as a cure-all for every condition are ridiculous. And the quality of cells is suspect.”
Merino sheep stem cells injected into children
One of the most arresting presentations at the San Diego summit came from Mike Chan, a Malaysian doctor who told the audience that stem cells could regenerate the body’s organs with the potential to prolong human life. His company, European Wellness, operates, despite its name, mainly out of Asian countries where, Chan says, “laws are more relaxed”. He claims to be able to “reverse” a person’s biological age by eight to 10 years and help them achieve a “more youthful appearance”.
At the summit, Chan introduced himself as an “esteemed scientist and stem cell research pioneer” and emphasised his work with autistic children.
“It is my ambition to God that I must save every child,” he said.
His clinic in Thailand markets five-day “autism treatment packages” priced at 450,000 baht (about $13,800), with parents told that for “best success” they should repeat the experience every six months.
Visual PowerPoint pages displayed in San Diego laid out the advances Chan claims to have made, including “expertise across species: specializing in human, animal, plant and myco stem cells & therapies”.
Chan said he was an innovator in “developing & introducing SPF sheep & rabbits to the world” (SPF stands for “specific-pathogen free”, meaning pure or disease free). A separate visual set out alleged benefits of using precursor stem cells obtained from a “certified closed colony of sheep and rabbits”, which are then introduced to the body through “intramuscular injection”.
The Guardian has learned that Chan’s center in Bangkok is injecting autistic kids with fetal stem cells extracted from slaughtered merino sheep raised in Germany. It markets the technique to parents with the promise that it can restore the children’s intellectual capacity.
The clinic’s staff explain to families how the fetal sheep cells are transmitted. Children are forcefully pinned down, often kicking and screaming, as the cells are injected into their buttocks.
“It’s very painful because the patient is crying,” an administrator told O’Leary when she called up Chan’s clinic in Bangkok. “The kid is trying to get loose and we are trying to pin the kid down to give the injections. We hold the back, we hold the buttocks and the feet so the patient will not kick.”
Knoepfler, the stem cell biologist, said that such techniques were “extremely worrisome. We don’t know how the human body reacts to rabbit or sheep stem cells. It might trigger activity by the immune system in ways that are harmful.”
Contacted by the Guardian in Miami, Chan said that he had been treating many autistic American children with compulsive behaviour. The sheep stem cells he administered were “totally safe”, he said.
He did not know why one of his staff had talked about restraining children. “You do not need to pin down the child. We never force any child to be treated, and all are accompanied by parents.”
He added: “People like what I am doing. I’m very confident in treating autistic children.”
‘It’s unreal that there’s so little assistance’
Parents who are drawn towards stem cell treatment often speak of a sense of abandonment living in the US.
“The lack of government assistance for children with autism is truly mind blowing,” a mother with a three-year-old son told the Guardian.
The mother, who asked not to be named given the sensitivities of her family’s situation, reckons she has already spent $20,000 in out-of-pocket expenses for her child. Now she is preparing to spend several thousand more to visit a clinic in Florida for umbilical stem cells that are not approved by the FDA.
“It’s unreal to me that there’s so little assistance. We were encouraged to put my child in a 40-hour-a-week facility for his autism, yet we couldn’t even get insurance to approve two hours of occupational therapy,” she said.
Her son has been diagnosed with the most severe level of autism spectrum disorder (ASD). He has minimal speech and a need for “very substantial support”.
He is unable to engage in conversation, though he can sing an entire song flawlessly. He also has challenges with motor skills – he has yet to be toilet trained, cannot eat with cutlery and needs help getting dressed.
The mother said her goal in going through stem cell treatment was partly to help other families like hers. “I hope one day maybe things will be different, and that there will be some peace and understanding for those of us who experience autism.”
She learned about the Florida clinic through a fellow parent on TikTok, which in itself tells a story. TikTok, Instagram, Facebook and other social media platforms are awash with families with young autistic children desperately seeking help.
“I found stem cells on TikTok,” said Katelyn Cook, 27, from Erie, Pennsylvania. “The algorithm served them to me. I know that sounds crazy, but it changed my life.”
To be precise, the algorithm served her videos titled Lynlee’s Journey, in which another mother describes taking her child to a clinic, North Florida Stem Cells, in Orange Park, Florida. The doctor who founded the clinic, Eric Weiss, says in one of the TikTok videos that “umbilical cord blood is like the chicken soup for healing”.
Having reviewed Lynlee’s journey, and having scoured through many other online parental accounts through Facebook groups, Cook decided to follow suit and take her son to Weiss’s clinic.
Colston, now five, initially hit all his developmental milestones: sitting, crawling, walking. But his parents started to worry that his speech was limited, as he spoke in single-word phrases. He was also unresponsive when people called his name, and engaged little with those around him. “He was not very present,” Cook said.
From about three, Colston began to elope, running off when the family was out in public. Most seriously, he developed issues with aggression, including biting.
On 26 June 2025, Colston was sedated and then injected with stem cells drawn from human umbilical cords. That first day, Cook said she noticed an instant change – he ran around and played with his younger sister for the first time.
He was hyperactive for a period after the infusion. But there were other positives in Cook’s view, including a reduction in aggressive behaviour. “He seemed a lot more present in life. He used more words together, though he’s still not conversational. He started holding my hand, and I don’t worry about him running off any more.”
After about six months, Colston started wrestling with emotions again, she said, and aggression returned. She puts it down to the stem cells having left his body, so she’s going back for more.
The first dose cost her $8,000, and she’ll pay the same again for an upcoming second visit. “I mean, it’s not fun. But I paid $10,000 for my car, and my kid, I value him over every single thing in my life. I would spend anything to give him a better chance at life.”
‘We still don’t understand exactly what goes wrong in autism’
Holdren, Landyn’s mom, has no illusions about the promise of stem cells. She worries, she said, about other families online who seem convinced the treatment is miraculous – and fears they could fall prey to unscrupulous providers.
At times, she has worried about being lured in herself.
“I would watch some of the clinics and feel internally uneasy,” she said.
But she has found comfort in the knowledge that Weiss is himself the parent of an autistic child. She was deeply impressed, she said, that he had changed his medical practice to help others. “He was willing to give up his plastic surgery practice to help these kiddos.”
Weiss is indeed certified as a plastic surgeon. In the wake of his son’s autism diagnosis, he has devoted his time to stem cell therapies.
His clinic offers umbilical stem cells obtained from a lab in Las Vegas as treatment for a range of conditions, including arthritis, Alzheimer’s disease and strokes, and as a means to “delay or mitigate signs of aging”. But the bulk of its patients are autistic kids.
The clinic says it treats on average eight children a day, with ketamine used to sedate them before the transfusion begins. Some of its patients are as young as 18 months old.
In his marketing to parents, Weiss makes bold claims. He says that 65-70% of autistic children “respond positively to treatment”, with documented improvements in “intellectual engagement”, “motor function” and “nonverbal communication”.
In one of the Lynlee’s Journey videos on TikTok, he tells families that stem cells are the “only thing that has been given to kids with autism and objectively shown that there’s new growth in the brain, that socialisation increases and there are quantum leaps up”.
In making these claims, Weiss leans heavily on a small, early-stage study carried out by Duke University from 2017. It found that among the 25 autistic children given umbilical cord stem cells, more than two-thirds appeared to show improvements in speech, socialisation and eye contact.
Weiss places much less emphasis in his marketing on a second clinical trial staged by Duke that was much larger, involving 180 children, and more rigorously controlled. It had a placebo group that was double blind, meaning that neither the participants nor the researchers knew which kids received active cells and which the placebo.
Duke released the findings of its second trial in 2020. It evaluated the kids six months after they received the stem cell infusions and found almost the exact opposite results to the first study: the treatment “was not associated with improved socialization skills or reduced autism symptoms”.
Though the Duke researchers found some improvement in communication skills among a subset of the children with no intellectual disabilities, they concluded that the results did not support the use of umbilical cord stem cells for treatment for autism outside formal clinical trials.
A similar placebo-controlled study with a small sample size of 29 children by Sutter Health reached the same conclusion. It found minimal evidence of any clinical effectiveness, with children given the stem cells responding identically to those given the placebo.
The Guardian asked Weiss detailed questions. He said: “I am a simple doctor who takes good care of his patients. I am trying to change the way the medical establishment looks and treats autism.”
His office is accredited to practise sedation on children and adults, which he has been doing for 40 years, he said. He asserted that umbilical cord blood had been used for various treatments in the US for 60 years.
The treatment, he said, “has been shown to be beneficial for autism. Dramatic benefits have been described, and I have witnessed them in my own son and patients.”
Stem cells changed his son’s life, he said. “He went from 30-40 words and much self-care to fully conversational, living on his own, driving a car and having a job.”
Yet the disappointing findings of Duke’s second trial did not come as a surprise to many stem cell scientists, for whom autism treatment was always going to be a long shot.
“We still don’t understand exactly what goes wrong in autism, and until we have an understanding it will be impossible to design a rational approach,” Kriegstein said.
The one redeeming feature so far has been that stringently conducted clinical trials, including both those by Duke and Sutter Health, have shown little safety risk in infusing stem cells into autistic children. That has brought comfort to parents such as Holdren, who took Landyn to Florida thinking that even if the stem cells didn’t work, at least they were unlikely to harm him.
“If we had heard of any harmful side-effects, that would have been different,” she said.
Yet scientists remain concerned about the potential dangers of this under-regulated world, especially on its more extreme fringes where bacterial and other infections can thrive. A survey by the Pew Charitable Trust of hundreds of unapproved stem cell clinics in the US recorded 360 cases of side-effects including life-threatening blood infections, heart attacks and organ damage.
There are worries too that families who are already financially and emotionally strapped are being ensnared by false and pricey hopes. Though many parents report positive changes in behaviour after stem cell transfusions, it is possible that those perceived improvements could be wishful thinking, or the result of other therapies the children may be receiving.
The cost can be harmful in itself, said Alycia Halladay, chief science officer of the Autism Science Foundation. “We’ve seen families drop out of evidence-based interventions like speech therapy or applied behavioural analysis therapy, or even stop medication, because they’ve gone for stem cells and think they no longer need it.”
Undoing the safeguards
Under Joe Biden, the FDA set out a rash of warning letters to several clinics, ordering them to comply with regulations.
The letters made clear that the FDA classes stem cell products as unapproved drugs that can only be distributed within a controlled clinical trial or with an approved licence.
The FDA laid out its thinking on umbilical cord stem cell therapies in 2021. In a statement, it cautioned that it had received “reports of blindness, tumor formation, infections and more due to the use of these unapproved products”. It reiterated that regenerative medicine therapies “have not been approved to treat autism”.
Addressing parents directly, the FDA said: “Please know that if you are being charged for these products or offered these products outside of a clinical trial, you are likely being deceived and offered a product illegally.”
It is this clearly framed regulatory regime that Kennedy now appears intent on dismantling.
In his interview with the podcaster Brecka, the health secretary said that he didn’t want to see a stem cell “wild west”. But in almost the next breath he contradicted himself, saying: “Of course, you’re going to get a lot of charlatans and people who have bad results, but ultimately you can’t prevent that.”
As Knoepfler pointed out, it is the job of the FDA to prevent precisely that.
“I would have hoped the health secretary would say he is going to do everything in his power to go after the charlatans and protect the kids,” the biologist said.
