Activin-A Regulates Bone Morphogenetic Protein Signaling in Pulmonary Endothelial Cells Without Affecting Bone Morphogenetic Protein Type-II Receptor Expression

Phenotypic transition of pulmonary artery smooth muscle cells (PASMCs) under hypoxic conditions, which in turn causes increased proliferation and migration capacity, is an important pathological process in Hypoxic pulmonary hypertension (HPH). Although research on the phenotypic transition of PASMCs has been ongoing, little is known about the specific molecular mechanisms underlying this process.

ACE2 has shown effectiveness in treating pulmonary hypertension in multiple animal models and has some promise in early human trials. The key barrier to translation is that enzymatically active ACE2 is difficult to manufacture and exhibits a short half-life in humans, making chronic administration challenging.

Pulmonary arterial endothelial and smooth muscle cell homeostasis is regulated through the bone morphogenetic protein (BMP) and transforming growth factor beta (TGF-β) receptor pathways. Pathway imbalance results in pulmonary hypertension (PH). Each pathway has ligands and modulators influencing this balance. How these pathways differ in pediatric PH patients is unknown.

Pulmonary arterial hypertension (PAH) is characterized by progressive narrowing and obliteration of distal, pre-capillary pulmonary vessels. Yet, noninvasive biomarkers that reflect this disease-defining process are lacking. A systematic review of PAH studies that measured circulating progenitor cells (CPCs) or circulating endothelial cells (CECs) in PAH by flow cytometry was performed to understand how future studies, leveraging state-of-the-art single-cell analyses, can advance the field.