Stem Cell Therapy for Pulmonary Fibrosis

What This Article Covers

Idiopathic pulmonary fibrosis (IPF) is a progressive scarring disease of the lungs with no cure and few effective treatments, which has made it a focus of experimental mesenchymal stem cell (MSC) research for over a decade. This article summarizes what small early-phase trials have actually found — including real, if modest, safety and functional signals — and explains why, despite that promise, no stem cell therapy is FDA-approved for pulmonary fibrosis today.

Overview

IPF causes lung tissue to stiffen and scar over time, gradually reducing the ability to breathe. The two FDA-approved drugs for it, pirfenidone and nintedanib, can slow disease progression but don't reverse scarring or restore lost lung function. That gap is why researchers have spent the past ten-plus years testing whether MSCs — cells with anti-inflammatory and tissue-repair properties — might do something current drugs can't: calm the inflammatory and fibrotic processes driving the disease.

How It's Thought to Work

MSCs are typically sourced from bone marrow, umbilical cord tissue, or adipose (fat) tissue, then delivered intravenously, by bronchoscope, or by inhaled nebulizer. They aren't thought to become new lung cells themselves. Instead, the working theory is that they act indirectly — releasing signaling molecules and extracellular vesicles that dial down inflammation, discourage excess collagen deposition (the scarring itself), and support the lung's own limited capacity for repair. This is still a hypothesis being tested in humans, not an established mechanism.

What the Evidence Shows

The best-known human study is the AETHER trial, a Phase I safety trial in which researchers gave a single IV infusion of allogeneic bone marrow-derived MSCs to adults with IPF across three escalating dose levels (Glassberg et al., Chest, 2017). The genuinely good news: the infusions were well tolerated over 60 weeks of follow-up, with no serious treatment-related adverse events, and — notably — measured declines in lung function (FVC and DLCO) stayed below the thresholds typically associated with disease progression, hinting the cells may have helped stabilize things in this small, uncontrolled group. A separate Phase I trial at Prince Charles Hospital in Australia, using placenta-derived MSCs in eight IPF patients, reported a similar pattern: minor, short-term side effects only, and no clinical worsening at six months.

More recently, a 2025 randomized, placebo-controlled Phase I trial published in Signal Transduction and Targeted Therapy tested something different — nebulized (inhaled) extracellular vesicles derived from umbilical cord MSCs, rather than infused cells — in 24 pulmonary fibrosis patients. The results are among the more encouraging seen in this field so far: no serious adverse events over 12 months, meaningful improvements in forced vital capacity and quality-of-life scores versus placebo, and two patients showing visible regression of fibrotic changes on CT imaging.

That said, every one of these studies is small — think dozens of patients, not hundreds — and most weren't designed or powered to prove the therapy works, only that it's reasonably safe. As the Pulmonary Fibrosis Foundation's 2025 position statement puts it, this research "support[s] conducting additional rigorous investigations," not clinical deployment. Larger, controlled Phase II/III trials are the necessary next step, and several (including umbilical cord MSC studies in China) are underway or recruiting.

Who Might Be a Candidate

• Adults with a confirmed IPF or interstitial lung disease diagnosis who want to explore experimental options alongside standard care
• Patients specifically seeking enrollment in an actively recruiting, IRB-approved clinical trial (searchable at ClinicalTrials.gov)
• Those who understand this is investigational and not a replacement for pirfenidone, nintedanib, pulmonary rehabilitation, or lung transplant evaluation
• People willing to undergo the monitoring (lung function tests, imaging, bloodwork) that legitimate trials require
• Not a good fit: anyone considering a for-profit clinic offering unregulated IV stem cell infusions outside a trial — the PFF has documented cases of serious harm, including death, from such unapproved treatments
• Patients with advanced disease or significant comorbidities, who are often excluded from current trial eligibility criteria
• Anyone should discuss candidacy with their pulmonologist before pursuing any stem cell-related option

Bottom Line

The early data on MSCs for pulmonary fibrosis is more encouraging than dismissive coverage sometimes suggests — safety signals have consistently been good, and a few small trials, including a 2025 inhaled extracellular vesicle study, have shown real functional improvement and even imaging regression in some patients. But "promising in small trials" is not the same as "proven," and no stem cell or cell-based therapy is FDA-approved for pulmonary fibrosis. For now, the responsible path is participation in a registered clinical trial, not a paid infusion at an unregulated clinic — and a frank conversation with a pulmonologist about where the evidence actually stands.