The ductus arteriosus is a normal fetal structure that connects the pulmonary artery to the aorta. Before birth, the fetus does not use the lungs for oxygen exchange; oxygen-rich blood arrives through the placenta, and the ductus helps divert blood away from the fluid-filled lungs. After delivery, the lungs expand, oxygen levels rise, and placental circulation stops. These changes usually trigger functional closure of the ductus, followed by permanent anatomical sealing. In some premature infants, however, the vessel remains open. This condition, known as PDA, can allow blood to flow continuously from the higher-pressure aorta into the pulmonary arteries, creating what physicians call a left-to-right shunt.

That shunt can place stress on an immature cardiovascular system. Excess blood may be pushed toward the lungs, increasing pulmonary blood flow and potentially interfering with ventilation. At the same time, the circulation supplying organs such as the kidneys, intestines, and brain may receive less effective blood flow, particularly when the ductus is large and the infant’s ability to compensate is limited. The consequences can include respiratory deterioration, difficulty reducing ventilator support, pulmonary edema, impaired kidney function, and intestinal complications. Yet the presence of an open ductus does not automatically mean that these problems will occur. Many infants have a PDA that is small, transient, or clinically insignificant.

That distinction has made PDA one of the most contested issues in neonatal care. For decades, clinicians often treated an echocardiographically visible ductus with medications designed to promote closure, including indomethacin, ibuprofen, and, in some settings, acetaminophen. Surgical ligation or catheter-based closure may be considered when a PDA is large, persistent, and associated with serious cardiovascular effects. The underlying logic appears straightforward: if the ductus can impose an abnormal workload on the heart and lungs, closing it should improve the infant’s condition. But neonatal physiology is rarely that simple, and clinical trials have not consistently shown that routine closure translates into better long-term outcomes.

The central problem is that PDA is not a single condition with a uniform biological effect. Its impact depends on the diameter and shape of the ductus, the amount of blood crossing it, the pressure in the pulmonary circulation, the infant’s gestational age, lung disease, cardiac function, fluid status, and the ability of other vessels to regulate blood flow. Echocardiography can reveal whether the ductus is open and can provide clues about shunt volume, but measurements such as ductal diameter or flow pattern do not always predict how an individual infant will respond. A vessel that appears substantial on an ultrasound may be tolerated in one patient but destabilizing in another.

This uncertainty has challenged the idea that anatomical closure should be the primary goal. Drug treatment is not harmless: cyclooxygenase inhibitors can reduce blood flow to the kidneys and intestines, affect platelet function, and create complications in infants who are already medically fragile. Acetaminophen may have a different safety profile, but it also requires careful consideration of liver function, dose, timing, and long-term evidence. Invasive procedures carry their own risks, including bleeding, infection, vocal-cord injury after surgical ligation, and complications associated with catheter access. The crucial question, therefore, is not simply whether clinicians can close a PDA, but whether closing it at a particular moment will produce a net benefit greater than the risks of intervention.

Schmölzer’s article arrives as neonatal researchers increasingly distinguish between a “hemodynamically significant” PDA and an incidental finding. The term refers to a ductus that produces measurable cardiovascular consequences, rather than merely remaining anatomically open. Clinicians may look for signs such as left-heart enlargement, excessive pulmonary blood flow, reduced systemic perfusion, changes in diastolic blood flow, worsening respiratory status, or an inability to progress with feeding and other supportive care. Even these indicators must be interpreted in context. A premature infant with severe lung disease may deteriorate for several reasons at once, making it difficult to identify the ductus as the true driver of illness.

The most important shift may be toward individualized, physiology-based management. Instead of automatically treating every open ductus or waiting indefinitely for spontaneous closure, physicians could combine serial echocardiography with bedside signs of organ perfusion and respiratory performance. This approach recognizes that the ductus can change rapidly as pulmonary resistance falls, fluids are adjusted, infection develops, or respiratory support is modified. A watchful strategy may be reasonable for an infant who is stable and showing no evidence of excessive shunting, while targeted treatment could be more compelling when the ductus is large, persistent, and linked to cardiovascular compromise. The challenge is converting this concept into reliable criteria that can be applied across hospitals and populations.

The debate also reflects a broader lesson in medicine: correcting an abnormal test result is not the same as improving a patient’s future. Neonatal outcomes such as survival without bronchopulmonary dysplasia, severe brain injury, intestinal disease, or long-term neurodevelopmental impairment matter more than ductal closure alone. Future research will need to determine which combinations of echocardiographic measurements, clinical findings, biomarkers, and timing can identify infants most likely to benefit from intervention. It will also need to clarify whether early treatment, delayed treatment, or conservative care produces the best balance of benefit and harm for distinct groups of premature newborns.

The question raised by this 2026 Pediatric Research article is therefore larger than the fate of one fetal blood vessel. It asks whether neonatal medicine is ready to move beyond a binary definition of PDA—open or closed—and toward a more precise understanding of circulation, organ vulnerability, and treatment response. For parents and clinicians confronting a fragile newborn’s diagnosis, that distinction is critical. An open ductus may be a dangerous source of cardiovascular strain, a temporary feature of prematurity, or something in between. The next generation of PDA care will depend on identifying which infant is in which category, and on proving that the chosen intervention changes the outcomes that matter long after the ultrasound image has disappeared.

Subject of Research: Patent ductus arteriosus in newborns, particularly its diagnosis, clinical significance, and treatment in premature infants.

Article Title: Patent ductus arteriosus: Are we finally asking the right question?

Article References: Schmölzer, G.M. “Patent ductus arteriosus: Are we finally asking the right question?” Pediatric Research (2026). https://doi.org/10.1038/s41390-026-05415-4

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41390-026-05415-4

Keywords: Patent ductus arteriosus, PDA, premature infants, neonatal medicine, preterm birth, echocardiography, cardiovascular physiology, neonatal treatment, pulmonary blood flow, intensive care.

Bronchopulmonary dysplasia, a chronic lung disease primarily affecting premature infants who require prolonged oxygen therapy and mechanical ventilation, remains a significant clinical challenge due to its complex etiology and limited therapeutic options. When complicated by pulmonary hypertension, a condition characterized by increased blood pressure in the pulmonary arteries, the morbidity and mortality rates escalate sharply. Understanding the intricacies of the molecular crosstalk involved in this disease intersection has been a pressing unmet need in neonatal medicine.

The study by Shirazi and colleagues meticulously explores the role of semaphorin signaling—a family of proteins traditionally known for their functions in axon guidance during neural development—in vascular and pulmonary development. Remarkably, the researchers demonstrate that loss of semaphorin signaling is intricately linked to impaired lung vascularization and remodeling, hallmarks of bronchopulmonary dysplasia complicated by pulmonary hypertension. This pioneering investigation links semaphorin pathways to vascular pathology in the neonatal lung for the first time.

Central to their findings is the functionally decreased expression of FOXF1, a transcription factor indispensable for mesenchymal-epithelial interactions during lung development. FOXF1’s downregulation appears to be not merely a marker but a driving force in the disease process. The authors present compelling evidence that diminished FOXF1 activity exacerbates vascular dysfunction, leading to the characteristic vascular rarefaction and heightened pulmonary pressures observed in BPD with PH. This concept establishes FOXF1 as a pivotal molecular node orchestrating lung structural integrity and vascular homeostasis.

The mechanistic dissection in this study reveals that semaphorin signaling loss leads to transcriptional repression of FOXF1, disrupting the genetic programs necessary for endothelial cell survival and proliferation. Endothelial cells, lining the interior surface of pulmonary vessels, are critical for maintaining vascular integrity and facilitating proper oxygen exchange. Their dysfunction results in hypoxia-induced vascular remodeling, a central pathophysiological event in neonatal pulmonary hypertension. The interdependence of semaphorin pathways and FOXF1 expression thus defines a novel pathogenic cascade in lung injury.

Utilizing advanced genetic models and high-resolution imaging techniques, the researchers delineated how attenuated semaphorin signals impair angiogenic cues, leading to defective capillary network formation. This vascular insufficiency not only compromises oxygen delivery but also contributes to persistent inflammation and fibrosis, hallmark features of bronchopulmonary dysplasia. The spatial and temporal expression patterns of FOXF1 were shown to precisely match regions of active vascular morphogenesis, highlighting its essential role in developmental lung biology.

Moreover, the investigators employed transcriptomic analyses to identify downstream targets and interacting partners of FOXF1 within the pulmonary vasculature. Their results suggest that FOXF1 modulates a broad array of genes involved in cell adhesion, migration, and extracellular matrix remodeling. This extensive regulatory network underscores the multifaceted influence of FOXF1 on lung tissue architecture, implicating its disruption in the widespread vascular and alveolar abnormalities seen in affected infants.

Importantly, this study transcends correlative observations by demonstrating causative links through gain- and loss-of-function experiments. Restoration of semaphorin signaling or FOXF1 expression in experimental models partially reversed vascular defects and improved pulmonary pressures, establishing a proof-of-concept for therapeutic intervention. These findings propose that modulating these molecular pathways could mitigate the progression of BPD with PH and improve long-term respiratory outcomes in survivors of preterm birth.

The translational relevance of these discoveries cannot be overstated. Current clinical management of BPD and associated pulmonary hypertension largely relies on supportive care and symptom management, with no approved pharmacological agents directly targeting the underlying molecular defects. This study’s identification of semaphorin-FOXF1 axis as a key determinant of vascular health introduces a potential biomolecular target for drug development, aiming to prevent or ameliorate lung injury early in its course.

From a broader scientific perspective, this work integrates developmental biology, vascular physiology, and molecular genetics to unravel complexities of neonatal lung disease. It exemplifies the power of multidisciplinary approaches—including genomics, cellular biology, and in vivo modeling—to address pressing pediatric health challenges. The insights gained here may also have implications for other pulmonary vascular diseases beyond infancy, such as adult pulmonary arterial hypertension and chronic obstructive pulmonary disease.

Clinically, the prospect of biomarker identification arises from these findings. Levels of FOXF1 expression or semaphorin activity could serve as indicators of disease severity or progression, guiding timely and individualized therapeutic strategies. Early detection of perturbations in these pathways may allow for interventions before irreversible lung damage occurs, changing the paradigm of neonatal intensive care.

The study also sparks questions regarding the interplay of genetic predisposition and environmental factors, such as oxygen toxicity and mechanical ventilation, in modulating semaphorin-FOXF1 signaling. Understanding how these external insults exacerbate molecular dysfunction will be crucial for designing comprehensive prevention measures, encompassing both molecular and clinical strategies.

Future research is undoubtedly needed to elucidate the precise molecular interactions and to translate these findings into clinically feasible treatments. The development of pharmacologic modulators or gene therapy vectors targeting the semaphorin-FOXF1 axis will require rigorous validation in preclinical models and eventually clinical trials, underscoring a promising but challenging translational pathway.

In conclusion, the insightful and methodically robust study by Shirazi et al. advances our molecular understanding of bronchopulmonary dysplasia complicated by pulmonary hypertension. By linking semaphorin signaling loss with FOXF1 downregulation, it underlines a novel pathogenic mechanism with far-reaching implications for diagnosis and therapy. This research not only adds a crucial piece to the puzzle of neonatal lung disease but also exemplifies the potential of targeted molecular medicine in transforming outcomes for vulnerable patient populations.

Subject of Research: Molecular mechanisms underlying bronchopulmonary dysplasia with pulmonary hypertension, focusing on semaphorin signaling and FOXF1 expression.

Article Title: Bronchopulmonary dysplasia with pulmonary hypertension associates with semaphorin signaling loss and functionally decreased FOXF1 expression.

Article References:
Shirazi, S.P., Negretti, N.M., Jetter, C.S. et al. Bronchopulmonary dysplasia with pulmonary hypertension associates with semaphorin signaling loss and functionally decreased FOXF1 expression. Nat Commun 16, 5004 (2025). https://doi.org/10.1038/s41467-025-60371-7

Image Credits: AI Generated