Stem Cell vs. Exosome

Despite the growing interest at the turn of the century in pursuing stem cell research to treat physical degeneration, damage and disease, nearly two decades later, the general safety and efficacy of stem cell therapy for regenerative medicine remains largely unproven.

According to the U.S. FDA, the only approved stem cell applications are from bone marrow or blood in transplant procedures to treat patients with cancer and disorders of the blood and immune system.¹

The FDA warns of the potential dangers of unproven stem cell therapies, including administration site reactions, the failure of cells to work as expected and the possibility that cells may move from placement sites and change into inappropriate cell types or multiply.

For example, The New England Journal of Medicine reported a case of macular degeneration that led to blindness in a patient after a stem cell injection into the eye.²

Another patient grew a spinal tumor after receiving an injection of stem cells to the spinal cord, according to the FDA.¹

Foreign stem cells can also be rejected by the immune system.^3,4

Exosomes, on the other hand, are released from stem cells and are cell-free. Researchers from Oxford and Scripps now conclude that it’s the exosomes specifically that have the regenerative benefits.⁵ The tiny sacs, 30 nm to 150 nm across, transfer DNA, RNA or proteins from cell to cell, affecting the function of recipient cells.

Researchers have examined exosomes harvested from human skin cells for skin repair.

In a paper on the subject, researchers at North Carolina University saw the anti-aging potential of exosomes after testing 3D spheroid-grown exosomes compared with a retinoid, 2D spheroid-grown exosomes and bone marrow-derived mesenchymal stem cell (MSC) exosomes (which the authors note are currently used as a stem cell anti-aging treatment) to evaluate skin thickness and collagen production in mice.^6,7

They found that the 3D exosome-treated skin was 20% thicker than untreated skin, 5% thicker than MSC-treated skin, and had 20% more collagen than MSC-treated skin.

Unlike stem cells, exosomes can’t replicate or transform into malignant or harmful cells because they themselves aren’t cells. They also can’t be infected with viruses and are less likely to trigger an immunogenic response.⁵

Their small size gives exosomes the advantage of being able to circulate more easily through the body and be administered without the use of needles. They’re able to penetrate the skin using pressure or jet injection methods.⁷

For all these reasons, exosomes may turn out to be the holy grail initially envisioned with stem cell therapies. Stay tuned for more.

References:

1. FDA Warns About Stem Cell Therapies. U.S. Food and Drug Administration. Sept. 3, 2019. https://www.fda.gov/consumers/consumer-updates/fda-warns-about-stem-cell-therapies
2. Kuriyan AE, Albini TA, Townsend JH, et al. Vision Loss after Intravitreal Injection of Autologous "Stem Cells" for AMD. N Engl J Med. 2017;376(11):1047-1053.
3. Stem cells: What they are and what they do. Mayo Clinic. June 8, 2019. https://www.mayoclinic.org/tests-procedures/bone-marrow-transplant/in-depth/stem-cells/art-20048117
4. Nine Things To Know About Stem Cell Treatments. A Closer Look At Stem Cells. Available at: https://www.closerlookatstemcells.org/stem-cells-medicine/nine-things-to-know-about-stem-cell-treatments/. Accessed June 30, 2020.
5. Ian Dixon, M.D. Exosomes vs Stem Cells: Exosomes as the Next Big Thing after Stem Cell Therapy. Exopharm. July 17, 2019. https://exopharm.com/the-next-big-thing-exosomes-versus-stem-cells/
6. Hu S, Li Z, Cores J, et al. Needle-Free Injection of Exosomes Derived from Human Dermal Fibroblast Spheroids Ameliorates Skin Photoaging. ACS Nano. 2019;13(10):11273-11282.
7. Tracey Peake. Suntanner, Heal Thyself: Exosome Therapy May Enable Better Repair of Sun, Age-Damaged Skin. NC State University News. Oct. 18, 2019. https://news.ncsu.edu/2019/09/exosome-therapy-skin-repair/