PDE1A and pulmonary arterial hypertension: Bone marrow mesenchymal stem cell-derived extracellular vesicles (BMSC-EVs) have reportedly been used in the treatment of PH, and researchers have found that BMSC-EVs containing miR-200b can be internalized by alveolar macrophages and can attenuate PAH by promoting M2 macrophage polarization via the PDE1A/PKA axis [150].