By Vivonyx · Last reviewed: October 2026
Achilles tendon pain can make running, stairs, and even the first steps of the morning hard work. If you've read about stem cell injections for it, the big question is: can stem cells help Achilles tendinopathy?
This article walks through what the human Achilles studies actually tested and found. It's education, not medical advice, and it isn't a recommendation for or against anything.
Achilles tendinopathy in one minute
The Achilles tendon connects the calf muscles to the heel and lets you push your foot down when you walk, run, or jump [1]. When it becomes irritated, often from overuse, people may notice pain along the tendon, stiffness in the morning, and trouble rising onto their toes [1].
The main approaches don't involve surgery. They include changes in activity and footwear, plus stretching or "eccentric loading" exercises shown by a provider or physical therapist [1]. A 2024 physical therapy guideline reviews the evidence for midportion Achilles tendinopathy, where pain sits in the middle of the tendon rather than at the heel [2].
Stem cell research asks whether cells could add something when symptoms persist.
What "stem cells" means in Achilles studies
Three quite different things have been tested in people:
Lab-grown (culture-expanded) MSCs. Mesenchymal stromal cells are taken from a person's bone marrow, grown in a lab for several weeks, then injected into the tendon [3].
Bone marrow aspirate concentrate. Marrow is drawn from the pelvic bone and concentrated for injection [4].
Stromal vascular fraction (SVF). A mix of cells processed from fat tissue and injected into the tendon [5].
These products contain different cells in different amounts, so a result for one doesn't carry over to another. Our science page explains what MSCs are, and our hip arthritis article looks at similar products studied in a joint.
Three kinds of cell products studied for Achilles tendinopathy. Educational summary of the sources cited in this article.
What the Achilles studies found
The short version: human studies of cells for Achilles tendinopathy are few and small. A 2022 review of cell therapy for tendon disorders found just one randomized controlled trial for the Achilles [6].
Fat-tissue cells vs. PRP (randomized). In a trial in Italy, 44 people with long-lasting Achilles tendinopathy in the middle of the tendon were assigned to an SVF or a PRP (platelet-rich plasma) injection [5]. Both groups improved from where they started. The SVF group scored better at 15 and 30 days, but at 2, 4, and 6 months the groups weren't significantly different, and imaging findings didn't track with symptoms [5].
Lab-grown MSCs (first in humans). A UK study injected 10 people's own lab-grown bone marrow MSCs into the tendon; all had tried other treatments first [7]. No serious adverse reactions were seen at 24 weeks, and pain and function scores improved. With no comparison group, the authors described it as a proof-of-concept step toward a larger randomized trial [7].
Bone marrow concentrate (chart review). A U.S. review of 15 people's records found average pain scores fell from about 6.3 to 2.6 out of 10 over 48 weeks, with no complications recorded [4].
Why does a comparison group matter? Tendon pain can rise and fall on its own, and rest, exercise, and expectations all shape how people feel. Without a control group, a study can't separate those effects from the cells.
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What reviews of tendon research say
Because Achilles studies are so few, reviews usually pool tendons from across the body:
A 2017 review found only the lowest level of evidence, with every trial at high risk of bias, and concluded that stem cell therapy for tendon disorders was "currently not advised" in clinical practice [8].
A 2021 meta-analysis of 4 prospective trials reported better pain and function, but stressed the need for large randomized trials to confirm it [9].
A 2025 review found 8 randomized trials of MSCs for any tendon, only one of them in the Achilles. They carried a high risk of bias and barely described rehab afterward [10].
A 2024 review of biologic injections for Achilles injuries found only case series and reports for bone marrow and stem cells; "high-level evidence studies are lacking" [11].
More broadly, trials of cell-based therapies are far fewer than those of blood-based ones like PRP, and mostly focus on knee arthritis [12].
How PRP compares
PRP has been studied more than cells for the Achilles. A 2025 meta-analysis of 6 randomized trials (422 people) found PRP did not improve pain or function compared with placebo, and found no difference between PRP and SVF [13]. That matters when reading the SVF trial above, since PRP was its only comparison.
FDA status and new trials
The FDA says regenerative medicine products, including stem cell and fat-derived products such as SVF, have not been approved for any orthopedic condition, naming tendonitis as an example [14][15]. The only FDA-approved stem cell products are blood-forming stem cells from umbilical cord blood, approved for certain blood disorders [14]. The FDA has also received reports of blindness, tumor formation, and infections linked to unapproved products [15]. Our guide Is Stem Cell Therapy FDA Approved? explains what approval means.
A ClinicalTrials.gov search for Achilles tendinopathy and stem cells returns 2 listings [16]: the UK study above, with its status listed as unknown [17], and a single-group U.S. study of a same-day fat-tissue injection for several kinds of long-lasting tendon pain, including the Achilles [18]. The FDA warns that a ClinicalTrials.gov listing doesn't, by itself, mean a product is legally marketed [15].
What we still don't know
Whether cells beat a placebo or exercise-based care. The only randomized trial compared cells with PRP [10][5].
Which product or dose matters most. Studies used very different preparations [11][9].
Whether any benefit lasts. Follow-up in the Achilles studies ran 6 to 12 months [5][4].
Long-term safety. Early reports found few problems, but the groups were small [7][6].
Frequently asked questions
Can stem cells help Achilles tendinopathy? Small studies have reported less pain afterward, but there is only one randomized trial, and at 6 months it found no difference between fat-tissue cells and PRP [6][5].
Are there randomized trials of stem cells for Achilles tendinopathy? Very few. Reviews have found one, which compared a fat-tissue cell preparation with PRP rather than with a placebo [6][10].
What kinds of cells have been studied? Lab-grown bone marrow MSCs, bone marrow aspirate concentrate, and stromal vascular fraction from fat tissue. These are different products [7][4][5].
Is stem cell therapy FDA-approved for Achilles tendon problems? No. The FDA says these products haven't been approved for any orthopedic condition, and it lists tendonitis as an example [14].
Still have questions?
If you'd like help reading a study or a trial listing, email hello@vivonyx.com or use our Ask page. We'll give you a straight answer, including "the research doesn't know yet" when that's the truth.
Related reading
Educational disclaimer: This article is for general educational purposes only and is not medical advice, diagnosis, or treatment. It does not describe or suggest the treatment, cure, or prevention of any disease or condition. Regulatory status can change; check the cited FDA pages for current information. Talk with a qualified, licensed healthcare professional before making any medical decision.
References
MedlinePlus (U.S. National Library of Medicine). Achilles tendinitis. https://medlineplus.gov/ency/article/001072.htm
Chimenti RL, Neville C, Houck J, et al. Achilles pain, stiffness, and muscle power deficits: midportion Achilles tendinopathy revision - 2024. J Orthop Sports Phys Ther. 2024;54(12):CPG1-CPG32. PMID: 39611662. https://pubmed.ncbi.nlm.nih.gov/39611662/
Goldberg AJ, Zaidi R, Brooking D, et al. Autologous Stem Cells in Achilles Tendinopathy (ASCAT): protocol for a phase IIA, single-centre, proof-of-concept study. BMJ Open. 2018;8(5):e021600. PMID: 29764889. https://pubmed.ncbi.nlm.nih.gov/29764889/
Thueakthong W, de Cesar Netto C, Garnjanagoonchorn A, et al. Outcomes of iliac crest bone marrow aspirate injection for the treatment of recalcitrant Achilles tendinopathy. Int Orthop. 2021;45(9):2423-2428. PMID: 34254148. https://pubmed.ncbi.nlm.nih.gov/34254148/
Usuelli FG, Grassi M, Maccario C, et al. Intratendinous adipose-derived stromal vascular fraction (SVF) injection provides a safe, efficacious treatment for Achilles tendinopathy: results of a randomized controlled clinical trial at a 6-month follow-up. Knee Surg Sports Traumatol Arthrosc. 2018;26(7):2000-2010. PMID: 28251260. https://pubmed.ncbi.nlm.nih.gov/28251260/
Mirghaderi SP, Valizadeh Z, Shadman K, et al. Cell therapy efficacy and safety in treating tendon disorders: a systemic review of clinical studies. J Exp Orthop. 2022;9(1):85. PMID: 36042110. https://pubmed.ncbi.nlm.nih.gov/36042110/
Goldberg AJ, Masci L, O'Donnell P, et al. Autologous bone marrow derived mesenchymal stem cells are safe for the treatment of Achilles tendinopathy. Sci Rep. 2024;14(1):11421. PMID: 38763976. https://pubmed.ncbi.nlm.nih.gov/38763976/
Pas HIMFL, Moen MH, Haisma HJ, et al. No evidence for the use of stem cell therapy for tendon disorders: a systematic review. Br J Sports Med. 2017;51(13):996-1002. PMID: 28077355. https://pubmed.ncbi.nlm.nih.gov/28077355/
Cho WS, Chung SG, Kim W, et al. Mesenchymal stem cells use in the treatment of tendon disorders: a systematic review and meta-analysis of prospective clinical studies. Ann Rehabil Med. 2021;45(4):274-283. PMID: 34496470. https://pubmed.ncbi.nlm.nih.gov/34496470/
Dyck B, Clifford C, Hendry GJ, et al. Poor consideration of tissue loading in randomised trials of MSC interventions for tendon pathology: a systematic review using the TIDieR framework. J Exp Orthop. 2025;12(3):e70388. PMID: 40718551. https://pubmed.ncbi.nlm.nih.gov/40718551/
Gopinatth V, Boghosian T, Perugini JM, et al. Current concepts in orthobiologics for Achilles tendon injuries: a critical analysis review. JBJS Rev. 2024;12(11). PMID: 39499787. https://pubmed.ncbi.nlm.nih.gov/39499787/
Winkler T, Oehme S, Hildebrandt A, et al. Evidence-based guidelines on orthobiologics. EFORT Open Rev. 2025;10(6):345-351. PMID: 40459170. https://pubmed.ncbi.nlm.nih.gov/40459170/
Barreto ESR, Antunes Júnior CR, Silva IC, et al. Is platelet-rich plasma effective in treating Achilles tendinopathy? A meta-analysis of randomized clinical trials. Clin Orthop Relat Res. 2025;483(5):779-790. PMID: 39745256. https://pubmed.ncbi.nlm.nih.gov/39745256/
U.S. Food and Drug Administration. Consumer Alert on Regenerative Medicine Products Including Stem Cells and Exosomes. https://www.fda.gov/vaccines-blood-biologics/consumers-biologics/consumer-alert-regenerative-medicine-products-including-stem-cells-and-exosomes
U.S. Food and Drug Administration. Important Patient and Consumer Information About Regenerative Medicine Therapies. https://www.fda.gov/vaccines-blood-biologics/consumers-biologics/important-patient-and-consumer-information-about-regenerative-medicine-therapies
ClinicalTrials.gov (U.S. National Library of Medicine). Search: Achilles tendinopathy, stem cell. https://clinicaltrials.gov/search?cond=Achilles%20Tendinopathy&intr=stem%20cell
ClinicalTrials.gov. NCT02064062: Autologous Stem Cells in Achilles Tendinopathy (ASCAT). https://clinicaltrials.gov/study/NCT02064062
ClinicalTrials.gov. NCT07748793: Autologous Fat Grafting for the Treatment of Chronic Tendinopathy (ASSET). https://clinicaltrials.gov/study/NCT07748793