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Stem cell therapies have the potential to treat many conditions, but so far there’s little proof that they do. Even so, clinics around the world offer stem cell-based treatments for a host of medical problems. New research warns that some of these treatments might not be effective and can, in fact, cause harm — sometimes many years down the line.

A report in the journal CMAJ details the case of a 38-year-old man who developed a benign tumor on his spinal cord that his doctors linked to an experimental stem cell treatment he received 12 years earlier. They said his case highlights the hazards of unproven stem cell-based therapies, as well as the length of time it can take for serious problems to arise.

“The worst-case scenario is not necessarily that [stem cell therapy] doesn’t work,” said Dr. Nanette Hache, one of the man’s physicians and a professor of radiology at Memorial University of Newfoundland. “There can be other complications, such as tumor formation.”


When the man was 20 years old, he injured his spine during a trampoline accident. Even after surgery and rehabilitation, he was left with some paralysis in his arms and severe paralysis in his legs and torso. At age 26, he underwent a stem cell procedure in Portugal that involved transplanting cells from inside his nose onto the spot of his spinal cord injury. The goal was to alleviate his pain and perhaps even help him walk again.

For people who have run out of conventional options, the choice to try something that hasn’t been solidly tested could seem low risk and high reward.


“You can imagine if you had this type of injury you’d want to research it and see if there was anything out there that could potentially help you,” Hache said. “Even if wasn’t mainstream medicine.”

Instead of relief, the man experienced additional pain and never gained extra use of his arms or legs. Twelve years later, he was referred to Hache and her colleagues after he noticed decreasing function in his arms and bladder over the previous three or four years.

The team identified a large mass on the upper part of his spine. When they analyzed samples taken from the mass, they matched the cells in the samples to the type of cells that had been transplanted into his spinal cord: cells from the olfactory mucosa — the mucous membrane that lines the nasal cavities.

Hache and her colleagues surgically removed part of the man’s tumor but could not remove it entirely without risking further injury. While the tumor isn’t considered cancerous, the team is using radiation to help slow its regrowth.

Cells from inside the nose may seem like a strange choice for a spinal graft, but the olfactory mucosa is easy to access and contains cells that can differentiate to form various cell types. Scientists are studying their use in stem cell transplants, and there is some evidence to support the idea that this approach could help patients recover from spinal cord injuries.

The procedure has shown some promise in animal models, and the team in Portugal that performed the man’s transplant published a pilot study of the procedure in 20 individuals with spinal cord injuries. They reported improvements in about half of them. Other studies had similar findings.

But as Hache and her colleagues point out in the CMAJ report, these studies examined a small number of patients and were neither randomized nor blinded. Given the lack of controls, it is difficult to know whether any improvements were due to the transplant or to the rehabilitation that patients underwent after surgery.

University of Minnesota bioethicist Leigh Turner said this case demonstrates what can happen when techniques and cells that aren’t fully understood are used to treat disease.

“If you put the wrong kinds of cells in the wrong location in the human body, there can be unwanted effects that just aren’t clear at the time,” he said. “And they aren’t necessarily picked up in preclinical research or with animal models.”

Some stem cell-based therapies, like bone marrow transplants, are known to be relatively safe and effective. For many other stem cell approaches though, Hache and others believe that more research is needed before they are offered to patients.

The patient she treated joins what may be a growing group of people who experience serious complications from stem cell transplants. A 2018 analysis reported 35 cases of complications or deaths following unproven stem cell-based treatments, including loss of vision, infections, cardiovascular complications, and cancer. While the researchers acknowledged that some of these problems could have been caused by the implant procedure, others “are likely the direct result of the yet unproven treatments using stem cells,” they wrote.

Cases like this sometimes bring up concerns about “stem cell tourism,” in which people travel to different countries for operations and treatments that aren’t available or accessible in their home countries.

While this patient did travel to Portugal, Turner, who has long voiced criticism of clinics that offer unproven treatments, said his case is complicated.

“It’s not quite as simple as individuals from Canada, United States, and elsewhere going to some kind of dodgy, obscure clinic in the far ends of the world,” Turner said, pointing out that the doctor who performed the transplant has published in peer-reviewed journals and appears to have observed few adverse effects in the patients he and his team treated and tracked.

Stem cell-based therapies are available in North America, and the United States actually has the largest number of stem cell clinics in the world. But invasive procedures like this tend to happen more often outside the U.S. and Canada, Hache said.

There are several known cases in which individuals developed similar spinal tumors after undergoing stem cell transplants using olfactory mucosal cells. At least one of them received a stem cell transplant from the same medical team in Portugal as the man Hache is now treating. In its pilot study, the Portuguese team followed patients after their surgery for an average of about 28 months. For Hache’s patient, that would not have been long enough to detect the mass that eventually grew on his spine.

“It’s such a slow process for these tumors to grow,” Hache said. “The latency period can be years and in his case was greater than seven years.”

Given the longer time frame needed for such side effects to show, similar cases could arise down the line. There could also be patients who are experiencing long-term effects that haven’t led to case reports.

“Are there other individuals walking around who have these complications and they just didn’t make it into the academic literature?” Turner said. “I think it’s a possibility. It may be that from a long-term perspective, the safety profile is different. We need to be aware of the possibility of long-term complications.”

Stem cell clinics in North America and around the world have been criticized for advertising unproven therapies to patients.

“Because people are vulnerable and because they’ve got this illness and they’re desperate for a cure of some sort, they’re willing to take risks,” Hache said. “And they pay a good sum of money to have these treatments done.”

The case report notes that olfactory mucosal transplants cost about $50,000, which does not take into account expenses for travel, accommodation, and recovery. Patients may be aware of the costs and some of the risks, said Hache, but cases like this show how many unknowns remain regarding the long-term effects of unproven stem cell therapies.

“The patient probably figured, at the end of the day I guess I lost that money and I am not any better,” Hache said. “Not realizing that there was a worse outcome.”

  • To Christina McAlister I’m so glad to hear this procedure worked for you and I’d like to know more, like where do you get these injections? I had an acdf (c5/c6) 01/30/2018 as the result of a motor vehicle accident, I have lost so much from this, it’s difficult to even fold laundry as my arms & shoulders just ache. Can these injections still possibly help even after surgery? Please if you can send me any information I will greatly appreciate it. I’ve also had surgery for a ruptured disc in 2009 and suffer much from fbss (failed back surgery syndrome) resulting in spinal stenosis & lower limb neuropathy, wondering if stem cell injections may also help with these conditions. I’m only 57 and my 80yr old mother gets around better than me. I’m currently on disability as I was unable to return to my job after the MVA and recovery from acdf was not 100%.
    Thank you

    • Wanda, I recieved 4 injections. Two on the sides of my neck, two in my shoulders. I am a former xray tech. So I refused surgery and just prayed for relief. MVA was in 2007. Dr. Barlow with chiropractic neurology center set everything up. It was $10,000. Average is 2-5000 per injection. The relief I feel, I would have paid more. The money i have spent on medications, creams, massages, physical therapy, braces …its incompairable. Feel free to email me. [email protected]

  • Brittany, that’s not accurate, they were OEGs. Even if it were accurate, why put “stem cells” in the title other than for click bait? Using “stem cells” in the title is irresponsible and dangerous, and doesn’t serve any purpose other than for getting clicks. I have a spinal cord injury (quadriplegic) from a fall 20 years ago, you’re not helping doctors, researchers, or the patient population calling it “stem cells”.

  • I really get angry when people confuse the science. I have a C4 spinal cord injury, considered going to Portugal for the therapy in this article. The story is wrong, they did NOT transplant stem cells, they transplanted Olfactory Osheathing Glial cells(OEG). I have no idea if stem cells work, but using the term “stem cells” so broadly and making blanket statements is dangerous and uninformed, it does nothing to help the science.

    • There Williams using Adult Stem cell help people with spine cord lesion, but is not a simple procedure, is more complex and need fist evaluation of what tipo is the lesion a follow up, the “stem cell clinics” procedure is not choice one for treat this condition.
      There several trial actually working with stem cell (adult stem cell with minimal manupulation) with good results (look Sr. Vaquero in Puerta de hierro Hospital in Madrid) our group treat only three patient with good results, but is not sufficient, we need more evidence.
      But Adult Stem Cell DO NOT SHOW PRODUCE ANY KIND OF TUMOR, only develop tumors embrionary cells, iPSC, or any no adult stem cell

    • I had stem cell injections on April 18. I was suffering from C5/6 herniated disk. Bilateral rotar cuff tendonitis, rt bicep tendinitis, and subscapular bursa. I work as a dog groomer. It was all I could do to groom 4 dogs a day. I dreaded washing my hair. I don’t believe I mopped for 3 months. Within a month I felt 80% better. I mopped my entire house and was able to clean the pool the following day. They told me it would change my life and it did. I am grateful for this treatment. I am 41. A new business owner. Very active and I get to stay that way. No more facing spinal surgery. A true blessing. I did not receive my own stem cells. Emblcal cord cells donated by healthy mothers and baby.

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