Stem cell therapy is used for a surprisingly narrow set of proven medical treatments, despite the enormous range of conditions it’s being tested and marketed for. The only fully approved use in the United States involves blood-forming stem cells, primarily for cancers and disorders of the blood and immune system. Beyond that established category, clinical trials are exploring stem cells for joint damage, type 1 diabetes, neurological diseases, and more, but most of these applications remain experimental. Understanding the gap between what’s proven and what’s promising is essential before considering any stem cell treatment.
How Stem Cells Work in the Body
Stem cells are unique because they can both copy themselves and transform into specialized cell types. That ability makes them useful for medicine in several ways. They can replace damaged or destroyed cells directly, turning into the specific tissue a patient needs. They also release chemical signals that reduce inflammation, stimulate blood vessel growth, and protect nearby cells from further damage. In immune-related diseases, stem cells can recalibrate the immune system, dialing down the overactive responses that cause conditions like autoimmune disorders.
These mechanisms vary depending on the type of stem cell and how it’s delivered. Blood-forming stem cells from bone marrow or umbilical cord blood rebuild the blood and immune system after intensive cancer treatment. Mesenchymal stem cells, often sourced from bone marrow or fat tissue, are being studied mainly for their anti-inflammatory and tissue-repair signaling rather than for directly becoming new tissue.
Blood Cancers and Immune Disorders: The Proven Uses
Bone marrow and cord blood transplants are the backbone of approved stem cell therapy. The FDA has approved roughly a dozen cord blood products for clinical use, all designed to rebuild a patient’s blood-forming system. These transplants treat a wide range of blood cancers and related conditions:
- Leukemias: acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML), and chronic lymphocytic leukemia (CLL)
- Lymphomas: both Hodgkin and non-Hodgkin lymphoma
- Bone marrow failure: myelodysplastic syndromes, severe aplastic anemia, and other marrow failure diseases
- Inherited blood disorders: sickle cell disease and transfusion-dependent thalassemias
- Immune deficiencies and autoimmune diseases: including inherited immune deficiency disorders, systemic sclerosis, and multiple sclerosis
- Certain solid tumors in children: neuroblastoma, Ewing family tumors, and medulloblastoma
The basic process involves high-dose chemotherapy to destroy the patient’s diseased marrow, followed by an infusion of healthy stem cells through an IV. Those new cells travel to the bone marrow and begin producing healthy blood cells. Recovery is slow. It can take up to a year before patients feel they’re genuinely improving, and the weeks immediately after transplant carry significant risks of infection and complications because the immune system is essentially rebuilt from scratch.
Joint Pain and Osteoarthritis
Stem cell injections into arthritic knees and shoulders are one of the most commonly marketed applications outside of cancer care, but the evidence is mixed. Clinical trials using mesenchymal stem cells injected directly into osteoarthritic joints have shown some cartilage regeneration and pain relief, with generally mild side effects. However, the improvements may not be enough for full repair of cartilage defects. Researchers have noted that getting the right dose of viable cells in the right treatment schedule is critical, and no standardized protocol exists yet.
These injections are not FDA-approved as a standard treatment. Most orthopedic stem cell procedures are offered by private clinics on a cash-pay basis. Knee injections typically cost between $5,000 and $10,000, while back and shoulder treatments range from $5,000 to $15,000. Insurance generally does not cover these procedures.
Type 1 Diabetes: A Rapidly Advancing Frontier
One of the most exciting areas of stem cell research involves growing insulin-producing cells in a lab and transplanting them into people with type 1 diabetes. In a recent study published in The Lancet, three patients with type 1 diabetes and no remaining natural insulin production received stem cell-derived islet tissue. One patient who received cells from a healthy donor saw dramatic results: the percentage of time spent in a healthy blood sugar range jumped from 25% to 94% over a year, dangerous low blood sugar episodes disappeared, and daily insulin needs dropped from about 57 units to 16 units.
The results provide real clinical evidence that stem cell-derived islet transplants can produce stable blood sugar control. But there’s a major catch. Every patient in these trials, including those who received cells grown from their own tissue, needed chronic immunosuppressive drugs to prevent rejection. Those drugs carry risks of serious infection, cancer, and other side effects. For now, this limits the therapy to patients with severe, life-threatening diabetes complications where the benefits clearly outweigh those risks. It’s not yet a practical option for the typical person living with type 1 diabetes, especially children.
Safety Risks Worth Knowing
The risks of stem cell therapy depend heavily on the type of procedure. Bone marrow transplants for cancer are inherently high-risk treatments performed when the disease itself is life-threatening. The most serious complication is graft-versus-host disease, where the transplanted immune cells attack the patient’s own tissues. The immunosuppressive drugs needed to prevent this reaction also increase vulnerability to pneumonia and other infections.
For mesenchymal stem cell treatments, like those marketed for joint pain, the injection itself tends to produce only minor side effects. But lab-cultured stem cells carry their own concerns. Studies have found that mesenchymal stem cells can undergo malignant transformation after weeks in culture, with roughly 46% of cells showing tumor-like changes in one lab study. When those transformed cells were implanted in mice, tumors formed. Separately, patients who received mesenchymal stem cells alongside standard bone marrow transplants had significantly higher cancer relapse rates (60% versus 20%) compared to those who received bone marrow transplants alone.
Cultured stem cells can also harbor viruses. Testing has found that stem cell preparations may contain persistent viruses, with parvovirus B19 and torque teno virus detected in over 60% of samples in one analysis. Bacterial contamination of cultured cells is another recognized threat.
The Unproven Clinic Problem
Hundreds of clinics across the United States market stem cell treatments for conditions like Parkinson’s disease, ALS, Lyme disease, stroke, kidney failure, autism, vision loss, and neuropathy. None of these uses are FDA-approved. The FDA has taken enforcement action against clinics offering unapproved stem cell products, sending regulatory correspondence to 46 manufacturers and healthcare professionals in a single year and pursuing court cases against others.
The agency has been direct in its assessment: there currently isn’t enough evidence to support using stem cells for purposes beyond rebuilding the blood and immune system. Products offered by these clinics would legally need to demonstrate safety and effectiveness before being marketed, just like any other drug or biologic. Yet many operate in a regulatory gray area, and patients pay significant out-of-pocket costs. Treatments for neuropathy range from $2,500 into the tens of thousands, vision loss procedures start around $20,000, and cord blood treatments for autism generally run $20,000 or more. Medicare covers established bone marrow transplants but does not cover unproven stem cell therapies.
What’s Experimental vs. What’s Available
The gap between the science and the marketplace is the most important thing to understand about stem cell therapy right now. On one side, rigorous clinical trials are producing genuinely promising results for diabetes, cartilage repair, and autoimmune conditions. On the other, cash-pay clinics offer treatments with little or no clinical evidence for dozens of conditions. The average cost of a stem cell treatment in 2025 is around $10,000, with many procedures exceeding $20,000.
If you’re considering stem cell therapy for a blood cancer, sickle cell disease, or another condition where transplant is a standard treatment, you’re looking at a well-established medical procedure typically covered by insurance. For anything else, the treatment is experimental regardless of how it’s marketed. Clinical trials listed on databases like ClinicalTrials.gov offer a way to access emerging therapies with proper safety monitoring and at no cost to the patient, which is worth exploring before paying out of pocket for an unproven procedure.