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Putting stem cell-based therapies in context

November 16, 2022

Clinical researchers Karen Wai, Theodore Leng, and Jeffrey Goldberg, Stanford University, weigh the promise of future stem cell therapies against the reality of their current limitations for the NIH Science, Health, and Public Trust website.

Karen Wai, Theodore Leng, and Jeffrey Goldberg

Karen M. Wai, M.D., Theodore Leng, M.D., MS, and Jeffrey Goldberg, M.D., Ph.D., Byers Eye Institute at Stanford, Stanford University School of Medicine, Palo Alto, California. 

In recent years, the potential of stem cell-based therapies to treat a wide range of medical conditions has given hope to patients in search of novel treatments or cures. At the same time, thousands of rogue clinics have sprung up across the U.S and around the world, offering stem cell-based therapies before being tested for safety and efficacy. When communicating to the public about stem cell-based therapies, it is important to put any treatment claims in context.

Stem cell-based therapies include any treatment that uses human stem cells. These cells have the potential to develop into many different types of cells in the body. They offer a theoretically unlimited source of repair cells and/or tissues. (For more about stem cells, see

Over the past three decades, the Food and Drug Administration (FDA) has approved several stem cell-based products. These include bone marrow transplants, which have been transformational for many cancer patients, and therapies for blood and immune system disorders.1 Other approved treatments include dental uses for gum and tissue growth and in skin for burns. Since the early 2000s, stem cell-based therapies have been explored in many eye diseases, including age-related macular degeneration and glaucoma.2 Stem cell-based therapies are also being explored for neurodegenerative diseases such as stroke and Alzheimer’s disease, and for countless other conditions.

Over time, we expect that breakthroughs will continue with stem cell-based therapies for many conditions. However, at this time, rogue clinics, driven by profits, are taking advantage of patients desperate for cures and are claiming dramatic results, often exaggerated in sensational media testimonials. The clinics may mimic legitimate practices. They may extract a patient’s own stem cells, concentrate or modify the cells, and then re-inject them. Some manufacturers offer stem cell-based derived products, such as “biologic eye drops” made with placenta extract or amniotic fluid to treat dry eye. Clinics may provide misleading information and advertise their practice as running clinical trials. However, these clinics almost always work without FDA regulatory approval and outside of legitimate clinical trial approaches.

These unproven, unregulated stem cell treatments carry significant risk. The risks range from administration site reactions to dangerous adverse events. For example, injected cells can multiply into inappropriate cell types or even dangerous tumors. A 2017 report described one Florida clinic that blinded patients with stem cell eye injections.3

The Pew Charitable Trusts gathered 360 reports of adverse events related to unapproved stem cell therapies, including 20 cases that caused death.4 Further, adverse events are likely underreported because these products are not FDA approved or regulated. Many unproven stem cell-based therapies cost thousands of dollars to patients and are not covered by insurance. Further, even if patients avoid adverse events from these therapies, they may suffer consequences from delaying evidence-based treatments.

The FDA has made substantial progress toward regulation of stem cell-based therapies. In 2017, it released guidance under the 21st Century Cures Act that clarifies which stem-cell based therapies fall under FDA regulation. It also better defined how the agency will act against unsafe or unregulated products.5 As of May 2021, the FDA has more strongly enforced compliance for clinics that continue to market unproven treatments.6

Despite this increased regulation, rogue clinics are still relatively commonplace. A 2021 study estimated that there are over 2,500 U.S. clinics selling unproven stem cell treatments.7 Patients at these clinics are often led to believe that treatments are either approved by the FDA, registered with the FDA, or do not require FDA approval. It is important to recognize that there are limits to the FDA’s expanded reach, especially when it is targeting hundreds of clinics at once. Our clinic at Stanford recently cared for a patient who had received stem cell injections behind his eyes, where he developed tumors that ultimately ruined vision in both eyes.

Progress in stem cell science is rapidly translating to the clinic, but it is not yet the miracle answer we envision. With time, stem cell-based therapies will likely expand treatment options. People considering a stem-cell based therapy should find out if a treatment is FDA-approved or being studied under an FDA-approved clinical investigation plan. This is called an Investigational New Drug Application. Importantly, being registered with does not mean that a therapy or clinical study has been authorized or reviewed by the FDA. For more information about stem cell therapies, visit (link is external), a resource from the International Society for Stem Cell Research.

As we look hopefully to the future, we need greater awareness of the current limitations of stem cell therapy and the dangers posed by unregulated stem cell clinics. Strong FDA regulation and oversight are important for ensuring that stem cell-based therapies are safe and effective for patients. Accurate communication to the public, careful advocacy by physicians, and education of patients all continue to be crucial.

1. U.S. Food and Drug Administration, “Approved Cellular and Gene Therapy Products,” Sept. 9, 2022, (link is external).

2. Stern JH, Tian Y, Funderburgh J, Pellegrini G, Zhang K, Goldberg JL, Ali RR, Young M, Xie Y, Temple S. Regenerating Eye Tissues to Preserve and Restore Vision. Cell Stem Cell. 2018 Sep 6;23(3):453. doi: 10.1016/j.stem.2018.08.014. Erratum for: Cell Stem Cell. 2018 Jun 1;22(6):834-849. PMID: 30193132.

3. Kuriyan AE, Albini TA, Townsend JH, Rodriguez M, Pandya HK, Leonard RE 2nd, Parrott MB, Rosenfeld PJ, Flynn HW Jr, Goldberg JL. Vision Loss after Intravitreal Injection of Autologous "Stem Cells" for AMD. N Engl J Med. 2017 Mar 16;376(11):1047-1053. doi: 10.1056/NEJMoa1609583. PMID: 28296617; PMCID: PMC5551890.

4. The Pew Charitable Trusts, “Harms Linked to Unapproved Stem Cell Interventions Highlight Need for Greater FDA Enforcement,” June 1, 2021, (link is external).

5. U.S. Food and Drug Administration, “FDA announces comprehensive regenerative medicine policy framework,” Feb. 2, 2022, (link is external).

6.  U.S. Food and Drug Administration, “FDA Extends Enforcement Discretion Policy for Certain Regenerative Medicine Products,” July 7, 2020, (link is external).

7. Turner L. The American stem cell sell in 2021: U.S. businesses selling unlicensed and unproven stem cell interventions. Cell Stem Cell. 2021 Nov 4;28(11):1891-1895. doi: 10.1016/j.stem.2021.10.008. PMID: 34739831.