Mesenchymal Stromal Cell Research
What mesenchymal stromal cells (often called MSCs or "mesenchymal stem cells") are, the one approved use, and what trials in knee arthritis, COVID-19 and kidney injury show.
Content last updated . This page has not been medically reviewed.
Naming matters
The cells were long called "mesenchymal stem cells." The International Society for Cell and Gene Therapy (ISCT) committee recommends using "MSCs" for mesenchymal stromal cells unless rigorous evidence of stemness exists from both lab and living-organism data, and suggests naming the tissue source and showing functional tests. [1] Its older minimal criteria say human MSCs must stick to plastic in culture, carry and lack certain surface markers, and form bone, fat and cartilage cells in a dish. [2] Those criteria identify cells in a lab. They do not prove treatment effects.Products also differ by tissue source, donor and manufacturing. A 2026 review found efficacy in early cancer-related MSC trials varied because of heterogeneity of MSC sources, manufacturing challenges and lack of standardized potency assays. [3]
Knee osteoarthritis: promising but limited
A 2026 systematic review and meta-analysis pooled six randomized trials with 551 patients using injections of autologous fat-derived MSCs. Compared with control, pain and function scores were lower at 3 and 6 months (for example WOMAC total score mean difference about minus 8 points at both times), and the risk of any adverse event was not significantly increased. [5] The authors cautioned that differences in comparators, blinding and cell products, and limited long-term evidence, mean the findings do not establish efficacy of a specific standardized product or structural disease modification. [5]FDA states regenerative medicine therapies have not been approved for orthopedic conditions including osteoarthritis. [6] Trial participation is different from commercial offers. See cell-therapy clinical trials vs commercial treatments.
Acute kidney injury: neutral so far
A 2026 review found that early trials of MSCs and extracellular vesicles in sepsis- and surgery-related kidney injury showed safety but limited efficacy signals. [10] Cell-free products are covered at extracellular vesicles and exosomes.Frequently asked questions
Are mesenchymal stem cells the same as embryonic stem cells?
No. MSCs are not embryonic cells. ISCT recommends treating them as stromal cells unless rigorous evidence of stemness is shown. [1]
Is any MSC treatment approved?
Yes, one: Ryoncil for pediatric steroid-refractory acute graft versus host disease in the United States. [4]
Do MSC injections work for knee arthritis?
Trials report symptom improvement on average, but products and designs differ and long-term benefit is not established. [5]
Do MSCs treat COVID-19 or long COVID?
Hospital trials show a pooled mortality signal in severe disease, but FDA says no product is approved for COVID-19. [7] [8]
Where can I learn about related fat-derived and cord products?
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
How to read the evidence labels
Labels used on this page: approved medicine, promising but limited, mixed, marketing claim. See how we label evidence.
Approved medicine: graft versus host disease in children
The evidence was a single-arm study (no comparison group) in 54 children. Overall response at Day 28 was 70% (95% confidence interval 56.4 to 82.0), including 30% complete response. [4] Common adverse reactions included viral and bacterial infections, fever, bleeding, swelling, abdominal pain and high blood pressure. [4] This approval applies to this product and this indication only. See hematopoietic transplantation context.
COVID-19: mixed, and not approved
Risks
References
- Viswanathan S, et al. Mesenchymal stem versus stromal cells: ISCT MSC committee position statement on nomenclature. Cytotherapy. 2019. PMID 31526643. Read 2026-10-22.
- Dominici M, et al. Minimal criteria for defining multipotent mesenchymal stromal cells. The International Society for Cellular Therapy position statement. Cytotherapy. 2006. PMID 16923606. Read 2026-10-22.
- Wu Y. Preclinical and clinical translation of immunomodulatory role of mesenchymal stem cells in cancer therapy era. Tissue Eng Regen Med. 2026. PMID 42601582. Read 2026-10-22.
- U.S. Food and Drug Administration. FDA approves remestemcel-L-rknd for steroid-refractory acute graft versus host disease in pediatric patients. Read 2026-10-22.
- Han JH, et al. Autologous adipose-derived mesenchymal stromal cell injection for knee osteoarthritis: systematic review and meta-analysis of randomized controlled trials. Knee Surg Sports Traumatol Arthrosc. 2026. PMID 42573097. Read 2026-10-22.
- U.S. Food and Drug Administration. Important Patient and Consumer Information About Regenerative Medicine Therapies. Content current as of 04/08/2024. Read 2026-10-22.
- Yuan MQ, et al. Therapeutic potential of mesenchymal stromal cells in COVID-19: a meta-analysis of clinical trials. Stem Cell Res Ther. 2026. PMID 42035205. Read 2026-10-22.
- U.S. Food and Drug Administration. Consumer Alert on Regenerative Medicine Products Including Stem Cells and Exosomes. July 22, 2020; content current as of 04/09/2024. Read 2026-10-22.
- Turner L, et al. Businesses marketing purported stem cell treatments and exosome therapies for COVID-19: an analysis of direct-to-consumer online advertising claims. Stem Cell Reports. 2023. PMID 37890484. Read 2026-10-22.
- Salybekov AA, et al. Cell and extracellular vesicle therapies for AKI in critical care. Front Med. 2026. PMID 42494444. Read 2026-10-22.