George · The Biohack Diaries
Is stem cell therapy safe? The questions I get asked most
“Do stem cells cause cancer?” is usually the first thing people ask me — often before they’ve asked anything else. It’s a fair question. I’ve been having stem cells myself for ten years, so this page is the safety questions I hear most often, answered with what I felt, what I’ve seen, and what I was told when I asked the same things. What’s right for your own body is a conversation for a doctor. This is the part I can speak to.
I wasn’t worried the first time
Ten years ago, someone who loves me asked me to do it. I’d smoked heavily all my adult life, and they wanted to preserve me. I didn’t think about cancer or about risk at all. I thought I was healthy, and I just thought I’d try it.
I was fine. But “I was fine” is not the same sentence as “you’ll be fine,” and not being worried isn’t the same thing as it being safe. Most of what’s on this page I learned afterwards, from being around this every day.
Do stem cells cause cancer?
This is where most of the fear sits, so it’s the question I asked about more than any other.
The explanation I was given is that the fear started with a different kind of stem cell. Early laboratory work found that pluripotent stem cells — embryonic stem cells, and induced pluripotent stem cells (iPSCs), which are adult cells reprogrammed in a lab — could form teratomas when they were injected into animals. A teratoma is a benign tumour made of several kinds of tissue. That research got a lot of media coverage, and most people never heard which cells it was actually about.
The cells I’ve had are a different kind: mesenchymal stem cells (MSCs) from umbilical cord tissue. The explanation I was given is that MSCs are multipotent, not pluripotent. That means they can only become a limited range of cell types, such as cartilage, bone, fat and skin. I was also told they work mostly by signalling: they release molecules that calm inflammation and prompt the body’s own repair, rather than multiplying out of control. That is why, as it was explained to me, they aren’t expected to form teratomas the way pluripotent cells can.
I was also told that MSCs have been studied in people for many years, across a large number of clinical trials, and that tumour formation hasn’t been a finding when the cells were properly prepared. I haven’t read those studies myself, so I won’t quote them at you. What I can tell you is what ten years in my own body has been like.
Then why do people link stem cells with cancer at all? Partly because of bone marrow transplants. People hear “stem cell transplant” in the same sentence as leukaemia and lymphoma. The explanation I was given is that those are hematopoietic stem cells — the blood-forming kind — used in a completely different way, for a completely different reason.
What about people who have cancer now? People with active cancer aren’t treated. The reason I was given isn’t that the cells cause cancer. It’s that their effect on the immune system could get in the way of cancer treatment.
What side effects are normal?
For me, it was feeling tired and sleepy afterwards. That’s the only thing I’ve noticed.
This is the list of mild, short-lived side effects I was given, which some people get after an infusion:
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a low-grade fever
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tiredness for a day or two
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minor soreness where the needle went in
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a mild headache, or chills
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feeling a bit flu-like
I was told these usually settle on their own. One man I met caught a cold in the weeks after his treatment, and he mentioned it as a surprise rather than a problem. Another family told me their mother went through a really painful stretch before things improved. Not everyone’s path is smooth, and I’d rather you heard that here first.
The rare, serious risks — and what I was told is done about each one
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Infection. Sterile technique and single-use equipment, every time.
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Allergic reaction. The cells are grown xeno-free, meaning no animal-derived products, which I was told lowers that risk.
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Immune rejection. The explanation I was given is that umbilical cord MSCs don’t provoke a strong immune reaction, and donors are carefully screened.
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Tumour formation. Only mesenchymal cells are used. Never embryonic cells or iPSCs.
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Poor-quality cells. Every batch is tested before it’s used. More on that below.
Cells only go in through a vein or directly into the area being treated — no risky routes like intrathecal injection, into the fluid around the spinal cord.
Where the risk actually sits
I know of someone who had stem cells somewhere else and had a reaction that put them in intensive care. They never walked again.
I think about that more than anything else on this page. The risk isn’t in the needle or the chair. It’s in everything that happens before that: where the cells came from, how they were grown, how they were tested, who checked the person receiving them, and whether anyone was allowed to say no.
More people travel for this now than when I started. That’s the reason this page exists. Safety is decided a long way before you sit down.
What I check before I trust a lab
The rule I started with — we don’t offer anything we haven’t tried on ourselves first — matters more here than anywhere.
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I try it on myself first. New cells, new lab: my body goes first.
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I go and see the lab myself. Not a brochure, not a video.
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I look at the documents for every batch — a certificate of analysis that shows what was tested and what the results were.
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We’re partners with the lab we chose. We work with it as a partner, not as a customer.
Here is what the lab does, as it was explained to me. The umbilical cord tissue comes from healthy donors who have been screened. The cells are grown in a Lab class 100 cleanroom and are xeno-free. Each batch is tested for sterility, identity and viability, and is prepared for the person who will receive it.
What happens before anyone is treated
Before anyone is approved, a doctor goes through their full medical history, orders blood tests if they’re needed, and decides the dose, the route and how often. Preparation instructions come beforehand, and the consent and the explanation are given in English and Thai.
These are the people I’ve seen turned away, from the list the doctors gave me:
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active cancer
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pregnancy or breastfeeding
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serious blood-clotting disorders
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infections that haven’t cleared up
The people who make these calls are licensed doctors. I’m not the one who decides who is suitable, and I’m glad I’m not.
“How do I know I’m getting real stem cells?”
Paperwork. Every batch comes with documentation of where it came from and what it was tested for. One family I met was given the lab report for the cells their mother received. A GP (general practitioner) who came here told me that what decided it for him wasn’t the room. It was the documentation on where the cells came from, how they were processed and how they were stored.
“The reviews look too good”
One man said exactly that to me before his treatment. He’d read the reviews, thought they looked AI-generated, and was half expecting to be scammed. Another arrived calling himself a sceptic. He’s a scientist, and he had spent three months comparing clinics around the world before he chose. I’d rather people come like that. When someone isn’t sure, I’d rather they go away and take their time than feel rushed by me.
Other questions people ask
Can stem cells cause cancer later in life? The explanation I was given is that nothing links properly prepared MSCs to cancer later on. It was never a worry for me, and ten years on it still isn’t. That’s my experience, not a promise.
Do I need to stay overnight? How soon will I notice anything? Those are about the day itself and what comes after, so they’re on What to expect on the day.
Keep reading
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Stem cell therapy — where my interest sits
If there’s a safety question I haven’t answered here, ask me.
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I’m George. Thirty years in business, then ten years trying this whole field on myself before offering it to anyone else.
This is where I write down what I use, what I stopped using, and what I’d never do again. More about me →