Stem Cell Therapy for Bronchopulmonary Dysplasia (BPD) in Premature Infants

What This Article Covers

Bronchopulmonary dysplasia (BPD) is a chronic lung disease that develops in some of the most fragile patients in medicine: infants born extremely preterm, whose lungs are injured by the mechanical ventilation and supplemental oxygen needed to keep them alive. Researchers in South Korea, the United States, and China have spent over a decade testing whether mesenchymal stem cells (MSCs), most often derived from donated umbilical cord blood or cord tissue, can calm the inflammation that drives BPD and support healthier lung development. This article summarizes what early-phase human trials have actually found, where the science stands with the FDA and other regulators, and why — despite some genuinely encouraging early signals — no stem cell product is approved anywhere for BPD today.

How It's Thought to Work

BPD arises when a preterm infant's underdeveloped lungs are exposed to ventilator pressure, high oxygen concentrations, and infection-driven inflammation during the newborn period, interrupting the normal growth of air sacs (alveoli) and blood vessels. Current care — gentler ventilation strategies, corticosteroids, diuretics, and supportive respiratory therapy — helps infants survive but doesn't reverse the underlying arrested lung development. MSCs are being studied because, rather than becoming new lung tissue themselves, they appear to act like a biological signaling system: secreting anti-inflammatory and growth-supporting factors that, in animal models, reduce fibroblast activity, limit oxygen-related injury, and promote more normal alveolar and vascular growth. That paracrine, "cell as messenger" mechanism is the basis for moving the approach into human trials.

What the Evidence Shows

The most-cited human data come from a series of trials using cord blood-derived MSCs (the investigational product Pneumostem, developed by Medipost). Chang and colleagues (2014, The Journal of Pediatrics) ran the first-in-human Phase I dose-escalation study, giving a single intratracheal dose to extremely preterm infants at high risk of BPD; the treatment was tolerated, with no serious adverse events attributed to the cells. Building on that, Ahn and colleagues (2021, Stem Cells Translational Medicine) conducted a randomized, placebo-controlled Phase II trial in 66 infants born at 23–28 weeks. The trial's overall primary outcome — death or moderate/severe BPD — didn't differ significantly between groups (52% with MSCs versus 55% with placebo). But a planned subgroup analysis produced a genuinely striking result worth sitting with: among the most extremely immature infants, born at 23–24 weeks, severe BPD fell from 53% to 19% with MSC treatment. The trial was underpowered to confirm this as a definitive effect, and the authors were careful to say so — which is exactly why a larger, focused follow-up trial in that youngest subgroup is now underway. Separately, Xia and colleagues (2023, Genes & Diseases) tested intravenous cord-derived MSCs in 13 infants who already had established severe BPD, in China; no infusion-related adverse events occurred, though two deaths in the study were adjudicated by investigators as unrelated to treatment — a reminder of how sick this population is at baseline. A broader clinical review in Pediatric Research (2017) confirms short-term safety and tolerability across early trials while flagging real unknowns: cell source, processing, and dose all appear to affect outcomes, and researchers have identified some MSC populations with less favorable inflammatory profiles, underscoring that this is not a settled, one-size-fits-all therapy.

Who Might Be a Candidate

Right now, this therapy is not an option outside of registered clinical research. Infants who have participated in or been considered for trials generally include:

• Extremely preterm infants (roughly 23–28 weeks gestation) at high risk of developing moderate-to-severe BPD
• Infants already diagnosed with established, severe BPD in treatment-focused (rather than prevention-focused) trial protocols
• Cases enrolled through academic neonatal intensive care units running IRB-approved, registered studies
• Families who have discussed trial eligibility, risks, and realistic expectations directly with a neonatology research team
• Infants without contraindications specified by a given trial's safety protocol (this varies by study)

Bottom Line

The BPD stem cell field is a good example of cautious optimism done right: a real, biologically plausible mechanism; consistent short-term safety signals across small trials; and at least one subgroup finding — the drop in severe BPD among the most extremely premature infants in the Ahn 2021 trial — that is genuinely exciting and worth the larger trial now testing it. But it would be a mistake to overstate where things stand. No MSC product has met its primary efficacy endpoint in a full Phase II trial, and none has received approval — conditional or otherwise — from the FDA, Korea's Ministry of Food and Drug Safety, or any other regulator for BPD. Medipost's Pneumostem holds FDA Fast Track and Orphan Drug designations (and EMA Orphan Drug status), which speed up the regulatory process but are not approvals; it remains in Phase 2 testing. For families facing a BPD diagnosis today, the honest picture is: promising, actively-studied, safety data so far reassuring in small numbers — and still strictly investigational, available only inside clinical trials.