Pathophysiological Rationale and Cell Sources

Bronchopulmonary dysplasia is a chronic lung disease of prematurity characterized by arrested alveolar development, inflammation, fibrosis, and dysmorphic pulmonary vascular assembly resulting from hyperoxia and volutrauma.
Stem cell therapy represents a regenerative approach aiming to restore physiological alveolarization, decrease chronic inflammation, and repair damaged lung architecture.
Mesenchymal stem cells are the primary and most widely studied cell source.
Cells are predominantly harvested from allogeneic neonatal tissues, specifically umbilical cord blood and Wharton’s jelly.
These sources are preferred due to their low immunogenicity, high proliferative capacity, and ethical feasibility.

Mechanisms of Action

Mesenchymal stem cells do not rely on long-term engraftment; instead, they exert profound effects via the secretome, which includes soluble paracrine factors and extracellular vesicles or exosomes.
Anti-inflammatory properties involve the suppression of neutrophils and pro-inflammatory cytokines like IL-6 and TNF-alpha.
Therapy upregulates anti-inflammatory mediators like IL-10 and drives a phenotypic switch in pulmonary macrophages from the pro-inflammatory M1 state to the pro-resolving M2 state.
Pro-angiogenic and alveolar growth promotion is achieved through the release of growth factors, including VEGF, HGF, and KGF, which stimulate secondary septation.
Anti-fibrotic actions occur by reducing TGF-beta signaling, thereby decreasing myofibroblast differentiation and aberrant collagen deposition.

Intratracheal instillation is the preferred clinical route, as it bypasses systemic circulation, avoids hepatic or splenic entrapment, and delivers cells directly to the alveolar spaces.
Intratracheal delivery is frequently co-administered with exogenous surfactant acting as a vehicle.
Intravenous infusion carries a theoretical risk of systemic microvascular embolization.

Therapy optimally targets a window of opportunity between 7 to 14 days of life.
Intervening during this early proliferative phase interrupts the inflammatory cascade before chronic, established fibrotic bronchopulmonary dysplasia sets in.

Recent meta-analyses demonstrate that mesenchymal stem cell therapy significantly reduces the overall incidence and severity of bronchopulmonary dysplasia.
Clinical trials report faster weaning from oxygen, reduced pulmonary hypertension, and significant neurodevelopmental gains at 18 to 24 months corrected age.
Indian feasibility studies demonstrate safety in preterm infants under 32 weeks, highlighting reduced inflammatory markers with no infusion reactions.
Phase trials confirm excellent short-term safety with no acute anaphylaxis or respiratory decompensation.
Long-term follow-up shows no increased malignancy or tumorigenesis, despite theoretical concerns.
Exosome-derived cell-free therapies are entering early phase trials to entirely circumvent cell-related risks.

Mesenchymal stem cell therapy remains strictly investigational per ESPNIC, AAP, IAP, and ICMR guidelines.
Routine clinical use is not currently endorsed outside registered clinical trials or Centers of Excellence.
Guidelines continue to emphasize evidence-based prevention, including antenatal steroids, caffeine, and lung-protective ventilation, alongside trial enrollment for high-risk preterm infants.