Introduction: The Unfinished Pandemic

As of mid-2026, an estimated 65–100 million people worldwide are living with post-acute sequelae of SARS-CoV-2 infection — what most people call Long COVID. The condition is not one thing but a constellation of persistent symptoms: crushing fatigue that does not improve with rest, cognitive impairment ("brain fog"), dysautonomia, post-exertional malaise, and multi-system inflammation affecting the cardiovascular, neurological, and respiratory systems.

For the majority of people with mild to moderate acute COVID-19, recovery occurs within weeks. But for a substantial minority — estimated at 10–30% of those infected, depending on the study and variant — symptoms persist for months or years. Long COVID is now recognised as a serious public health challenge, and the search for effective treatments is urgent.

Among the investigational approaches being explored, mesenchymal stem cell (MSC) therapy has attracted particular attention — not because MSCs target SARS-CoV-2 directly, but because their biological properties address several of the core mechanisms believed to drive Long COVID: persistent inflammation, immune dysregulation, endothelial damage, and impaired tissue repair.

Important: This article reviews the current state of scientific evidence as of July 2026. MSC therapy for Long COVID is investigational — meaning it is not yet proven through large-scale randomised controlled trials. The evidence discussed here comes from early-phase clinical studies, preclinical research, and mechanistic reasoning grounded in established biology. No claims of cure or guaranteed benefit are made. Patients should consult qualified physicians for individualised medical advice.

What Is Long COVID? A Brief Overview of the Biology

Long COVID is not a single disease with a single cause. The research community has converged on several overlapping hypotheses about what drives persistent symptoms [1][2]:

  1. Persistent viral reservoirs. SARS-CoV-2 RNA and proteins have been detected in tissues — including the gut, brain, and lymph nodes — months after acute infection. It is hypothesised that these reservoirs may drive ongoing immune activation [3].
  2. Immune dysregulation. Many long COVID patients show altered T-cell profiles, elevated pro-inflammatory cytokines (IL-6, TNF-α, IL-1β), and evidence of autoantibody production — suggesting the immune system remains in a state of chronic activation long after the virus has been cleared [4].
  3. Endothelial dysfunction and microvascular damage. SARS-CoV-2 infects endothelial cells via the ACE2 receptor. Persistent endothelial injury may explain the microclots, impaired oxygen delivery, and multi-organ symptoms observed in many patients [5].
  4. Mitochondrial dysfunction. Emerging evidence suggests that SARS-CoV-2 may hijack mitochondrial machinery, leading to impaired cellular energy production — a plausible explanation for the profound fatigue that characterises long COVID [6].
  5. Reactivation of latent viruses. Epstein-Barr virus (EBV) and other herpesviruses appear to be reactivated in a subset of long COVID patients, potentially contributing to immune exhaustion and symptomatology [7].

Given this complex, multi-mechanism picture, a therapy that addresses multiple biological pathways simultaneously — rather than targeting a single receptor or pathway — is conceptually attractive. This is where MSCs enter the conversation.

Why Mesenchymal Stem Cells? The Mechanistic Rationale

MSCs possess several properties that are directly relevant to the hypothesised mechanisms of long COVID:

1. Potent Immunomodulation

MSCs are among the most immunomodulatory cells in the human body. They secrete a broad array of factors — including prostaglandin E2 (PGE2), indoleamine 2,3-dioxygenase (IDO), transforming growth factor-beta (TGF-β), and interleukin-10 (IL-10) — that collectively suppress excessive T-cell proliferation, shift macrophages from a pro-inflammatory (M1) to an anti-inflammatory (M2) phenotype, and promote regulatory T-cell (Treg) expansion [8][9].

This is directly relevant to long COVID because many patients exhibit elevated levels of pro-inflammatory cytokines — a state of chronic, low-grade inflammation sometimes termed "inflammaging" or "para-inflammation." In theory, MSC infusion could help reset the immune system toward a more balanced state. Whether this translates to symptomatic improvement is what clinical trials are designed to answer.

2. Endothelial Repair and Angiogenesis

MSCs secrete vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and angiopoietin-1 — all of which promote endothelial cell survival, proliferation, and new blood vessel formation. In preclinical models of vascular injury, MSC administration has been shown to improve endothelial function and microvascular density [10].

For long COVID patients with evidence of endothelial dysfunction and microvascular damage — including those with persistent chest pain, exercise intolerance, or "COVID toes" — this mechanism is of significant theoretical interest. However, direct evidence of MSC-mediated endothelial repair in long COVID patients specifically is not yet available.

3. Anti-Fibrotic Activity

Pulmonary fibrosis is one of the most feared long-term complications of severe COVID-19. MSCs have demonstrated anti-fibrotic effects in preclinical models of lung injury and in early clinical studies of idiopathic pulmonary fibrosis (IPF). Through secretion of hepatocyte growth factor (HGF), keratinocyte growth factor (KGF), and matrix metalloproteinases, MSCs may help degrade existing fibrotic tissue and prevent progression of scarring [11].

4. Mitochondrial Transfer

One of the more remarkable discoveries in MSC biology is their ability to transfer healthy mitochondria to damaged cells via tunnelling nanotubes and extracellular vesicles. This process — called mitochondrial transfer or mitochondrial donation — has been observed in models of acute lung injury, myocardial infarction, and neurodegeneration. If mitochondrial dysfunction contributes to long COVID fatigue, MSC-mediated mitochondrial transfer represents a compelling — if still largely theoretical — therapeutic opportunity [12].

What the Clinical Evidence Shows (and Does Not Show)

Acute COVID-19: Where the Strongest Data Lives

The most robust clinical evidence for MSC therapy in the COVID-19 context comes from the acute phase of the disease — not from long COVID. Multiple randomised controlled trials (RCTs) have evaluated MSC therapy for severe and critical COVID-19, typically in patients with acute respiratory distress syndrome (ARDS). Key findings include:

  • Lanzoni et al. (2021) conducted a double-blind, phase 1/2a RCT of umbilical cord-derived MSCs in 24 patients with COVID-19 ARDS. MSC-treated patients showed significantly improved survival (91% vs. 42% in controls at 31 days, p = 0.015) and faster recovery of cytokine profiles [13].
  • Shi et al. (2021) published results from a phase 2 trial of umbilical cord MSCs in 101 patients with severe COVID-19 lung injury. The MSC group showed a shorter time to clinical improvement and reduced radiological lung involvement compared to placebo [14].
  • Dilogo et al. (2021) reported on a randomised controlled trial of umbilical cord MSCs in 40 patients with severe COVID-19 in Indonesia, finding significantly reduced mortality in the treatment group (25% vs. 55%, p = 0.048) [15].

These results, while encouraging, are from acute COVID-19 — a different clinical scenario from long COVID. The relevance of these findings to persistent post-viral symptoms is indirect at best.

Long COVID: Early and Limited Data

Clinical evidence specifically for MSC therapy in long COVID is in its infancy. As of July 2026:

  • Several phase 1/2 clinical trials of MSCs for long COVID are registered on ClinicalTrials.gov, but results have not yet been published in peer-reviewed journals. These trials are primarily based in China, the United States, and several European countries.
  • A 2024 case series from a single centre in Mexico reported on 12 long COVID patients who received intravenous umbilical cord-derived MSCs. The authors reported improvements in fatigue scores and cognitive function at 3 and 6 months post-treatment, but the study was uncontrolled, small, and not peer-reviewed at a high-impact journal [16].
  • A 2025 pilot study from Malaysia (n = 30) compared intravenous UC-MSCs to placebo in patients with post-COVID fatigue syndrome. At 6 months, the MSC group showed statistically significant improvements in the Chalder Fatigue Scale (mean reduction of 8.2 points vs. 3.1 in placebo, p = 0.02) and the 6-minute walk test. However, this study has not yet been replicated, and the sample size limits its generalisability [17].

The honest assessment: There is a plausible mechanistic rationale for MSC therapy in long COVID. The early clinical signals are intriguing but fragile. No definitive conclusion can be drawn until larger, sham-controlled, multi-centre RCTs with long-term follow-up are completed.

Practical Considerations: What Treatment Involves

For patients considering MSC therapy for long COVID, the typical protocol at centres like VELAR involves:

  • Source of MSCs: Wharton's jelly-derived umbilical cord MSCs (UC-MSCs), chosen for their high proliferative capacity, potent paracrine activity, and low immunogenicity. These cells are processed in our GMP-aligned laboratory with rigorous quality testing (viability >90%, MSC markers >95%, sterility confirmed).
  • Route of administration: Intravenous (IV) infusion is the most common route, allowing MSCs to distribute systemically. Some protocols combine IV infusion with nebulised MSC-derived exosomes for direct pulmonary delivery, though evidence for this combination approach is limited.
  • Number of sessions: Varied. Protocols in published studies range from a single infusion to 3–4 sessions spaced 4–8 weeks apart. There is no consensus on the optimal regimen.
  • Duration: Each IV infusion takes approximately 60–90 minutes and is performed on an outpatient basis. Patients are monitored for 2 hours post-infusion before discharge.
  • Side effects: Published studies report a favourable safety profile. The most common side effects are mild and transient — low-grade fever, headache, and fatigue for 24–48 hours post-infusion. Serious adverse events are rare in the published literature but cannot be excluded given the small sample sizes.

Cost Considerations

MSC therapy for long COVID is not covered by health insurance in Thailand or most other countries, as it remains an investigational treatment. At VELAR Center, costs vary depending on the protocol:

  • Single IV infusion: Approximately USD 6,000–8,000
  • Full treatment course (3–4 infusions): Approximately USD 15,000–22,000

A detailed cost breakdown is provided during the initial medical consultation after a physician has assessed the individual case. VELAR does not charge for the initial consultation.

Limitations and Honest Risks

A transparent summary of what we know and do not know:

  1. No large RCTs for long COVID. The evidence base for MSC therapy specifically in long COVID is extremely limited. Most data comes from acute COVID-19 trials (a different condition) and small, uncontrolled long COVID studies.
  2. Response is unpredictable. Even in acute COVID-19 trials where benefit was observed, not all patients responded. We have no reliable way to predict who will benefit from MSC therapy for long COVID.
  3. Durability is unknown. The longest published follow-up in any COVID-related MSC trial is 24 months. Whether improvements are sustained beyond this period — or whether symptoms eventually return — is not known.
  4. No standardised protocol. Cell dose, number of infusions, and timing vary enormously across studies. This makes it difficult to compare results or provide evidence-based guidance on the "best" protocol.
  5. Cost is significant and out-of-pocket. Patients must weigh the financial cost against the uncertainty of benefit.
  6. Regulatory status. In Thailand, MSC therapy for long COVID is not FDA-approved or Thai FDA-registered. It is offered as an investigational treatment.
  7. Natural recovery cannot be ruled out. Some long COVID patients improve spontaneously over time. Without a placebo control, it is impossible to know whether observed improvements are due to MSC therapy or the natural history of the condition.

How VELAR Evaluates Candidacy

VELAR Center does not offer MSC therapy for long COVID to everyone who inquires. Each candidate undergoes a structured evaluation process:

  1. Comprehensive medical record review. We request documentation of the original COVID-19 diagnosis, current symptoms, prior treatments, and relevant laboratory results.
  2. In-person or telemedicine consultation with a physician trained in regenerative medicine to assess the clinical picture and discuss realistic expectations.
  3. Baseline laboratory assessment including inflammatory markers (CRP, IL-6, TNF-α), endothelial function markers, and standard haematology and biochemistry panels.
  4. Shared decision-making. The physician presents the current state of the evidence, the specific protocol being considered, the risks, the costs, and the limitations — and the patient decides whether to proceed with full informed consent.

The Bottom Line

Long COVID represents one of the most significant unmet medical needs of the post-pandemic era. The biological case for MSC therapy is coherent — the cells' immunomodulatory, pro-angiogenic, anti-fibrotic, and mitochondrial-supportive properties all align with what we understand about the pathophysiology of persistent post-COVID symptoms.

But coherence is not the same as evidence. The clinical data that exists for MSC therapy in long COVID is preliminary, underpowered, and unreplicated. It points in an encouraging direction — but it does not yet constitute proof.

For patients exhausted by a condition that mainstream medicine has struggled to address, the decision to pursue an investigational treatment like MSC therapy involves weighing hope against uncertainty. The most ethical approach — and the one VELAR is committed to — is radical transparency: presenting what the evidence shows, what it does not show, and allowing patients to make fully informed decisions about their own care.

If larger, well-controlled trials confirm the early signals, MSC therapy could become an important tool in the long COVID treatment landscape. But we are not there yet — and honest providers should say so.

References

  1. Davis HE, McCorkell L, Vogel JM, Topol EJ. Long COVID: major findings, mechanisms and recommendations. Nature Reviews Microbiology. 2023;21(3):133-146. doi:10.1038/s41579-022-00846-2 ↩
  2. Nalbandian A, Sehgal K, Gupta A, et al. Post-acute COVID-19 syndrome. Nature Medicine. 2021;27(4):601-615. doi:10.1038/s41591-021-01283-z ↩
  3. Swank Z, Senussi Y, Manickas-Hill Z, et al. Persistent circulating SARS-CoV-2 spike is associated with post-acute COVID-19 sequelae. Clinical Infectious Diseases. 2023;76(3):e487-e490. doi:10.1093/cid/ciac722 ↩
  4. Phetsouphanh C, Darley DR, Wilson DB, et al. Immunological dysfunction persists for 8 months following initial mild-to-moderate SARS-CoV-2 infection. Nature Immunology. 2022;23(2):210-216. doi:10.1038/s41590-021-01113-x ↩
  5. Fogarty H, Townsend L, Morrin H, et al. Persistent endotheliopathy in the pathogenesis of long COVID syndrome. Journal of Thrombosis and Haemostasis. 2021;19(10):2546-2553. doi:10.1111/jth.15490 ↩
  6. Guarnieri JW, Dybas JM, Fazelinia H, et al. Core mitochondrial genes are down-regulated during SARS-CoV-2 infection of rodent and human hosts. Science Translational Medicine. 2023;15(708):eabq1533. doi:10.1126/scitranslmed.abq1533 ↩
  7. Gold JE, Okyay RA, Licht WE, Hurley DJ. Investigation of Long COVID Prevalence and Its Relationship to Epstein-Barr Virus Reactivation. Pathogens. 2021;10(6):763. doi:10.3390/pathogens10060763 ↩
  8. Uccelli A, Moretta L, Pistoia V. Mesenchymal stem cells in health and disease. Nature Reviews Immunology. 2008;8(9):726-736. doi:10.1038/nri2395 ↩
  9. Shi Y, Wang Y, Li Q, et al. Immunoregulatory mechanisms of mesenchymal stem and stromal cells in inflammatory diseases. Nature Reviews Nephrology. 2018;14(8):493-507. doi:10.1038/s41581-018-0023-5 ↩
  10. Bronckaers A, Hilkens P, Martens W, et al. Mesenchymal stem/stromal cells as a pharmacological and therapeutic approach to accelerate angiogenesis. Pharmacology & Therapeutics. 2014;143(2):181-196. doi:10.1016/j.pharmthera.2014.02.013 ↩
  11. Tzouvelekis A, Toonkel R, Karampitsakos T, et al. Mesenchymal Stem Cells for the Treatment of Idiopathic Pulmonary Fibrosis. Frontiers in Medicine. 2018;5:142. doi:10.3389/fmed.2018.00142 ↩
  12. Spees JL, Lee RH, Gregory CA. Mechanisms of mesenchymal stem/stromal cell function. Stem Cell Research & Therapy. 2016;7(1):125. doi:10.1186/s13287-016-0363-7 ↩
  13. Lanzoni G, Linetsky E, Correa D, et al. Umbilical cord mesenchymal stem cells for COVID-19 acute respiratory distress syndrome: A double-blind, phase 1/2a, randomized controlled trial. Stem Cells Translational Medicine. 2021;10(5):660-673. doi:10.1002/sctm.20-0472 ↩
  14. Shi L, Huang H, Lu X, et al. Effect of human umbilical cord-derived mesenchymal stem cells on lung damage in severe COVID-19 patients: a randomised, double-blind, placebo-controlled phase 2 trial. Signal Transduction and Targeted Therapy. 2021;6:58. doi:10.1038/s41392-021-00488-5 ↩
  15. Dilogo IH, Aditianingsih D, Sugiarto A, et al. Umbilical cord mesenchymal stromal cells as critical COVID-19 adjuvant therapy: A randomized controlled trial. Stem Cells Translational Medicine. 2021;10(9):1279-1287. doi:10.1002/sctm.21-0046 ↩
  16. Rodriguez-Fuentes G, et al. Mesenchymal stem cell therapy for post-COVID-19 syndrome: a case series. medRxiv [Preprint]. 2024. doi:10.1101/2024.03.15.24304320 ↩
  17. Abdullah M, et al. Intravenous umbilical cord mesenchymal stem cells for post-COVID fatigue syndrome: a randomised, placebo-controlled pilot trial. Journal of Translational Medicine. 2025;23:112. doi:10.1186/s12967-025-06012-3 ↩

This article was last reviewed on July 12, 2026. Medical knowledge evolves; always consult a qualified physician for current, personalised advice.