Decreased endothelial micro-RNA-30b-5p impairs angiogenesis in fetal lambs with persistent pulmonary hypertension

Impaired angiogenesis contributes to increased pulmonary vascular resistance in persistent pulmonary hypertension of the newborn (PPHN). Notch signaling, critical to lung angiogenesis, is modulated by micro-RNAs (miR). RNA sequencing of pulmonary arterial endothelial cells (PAEC) from a PPHN lamb model revealed downregulated miR-30b-5p.

We investigated whether decreased levels of miR-30b-5p in PPHN affect angiogenesis by facilitating excess Dll4, a predicted target for miR-30b-5p. We obtained PAEC from a fetal lamb model of PPHN and transfected them with miR-30b-5p mimic and inhibitor. We assessed protein levels by immunoblotting and in vitro angiogenesis by tube formation in Matrigel. We performed In-situ RNA hybridization for in vivo miR-30b-5p levels in the lamb lungs.

PPHN lamb lungs showed decreased miR-30b-5p levels in vivo. PPHN PAEC transfected with miR-30b-5p mimic showed improved capillary tube formation. Control PAEC showed inhibition of tube formation after transfection with miR-30b-5p inhibitor. Transfection with miR-30b-5p led to the downregulation of Dll4, in PPHN PAEC.

We conclude that decreased miR-30b-5p in PPHN facilitates overexpression of Dll4, which contributes to impaired angiogenesis in PPHN. MiR-30b-5p improves angiogenesis in PPHN by improving Dll4/Jag1 balance (Jag1, a proangiogenic notch ligand), suggesting an epigenetic role in PPHN.

The present study describes a novel mechanism of epigenetic control of impaired angiogenesis in PPHN via miR-30b-5p. The present study also provides new direction for future in vivo studies in animals and patients with PPHN to investigate the role of miR-30b-5p as a biomarker of angiogenesis in PPHN.