Aims: We have previously reported that nano-selenium quantum dots (SeQDs) prevented endothelial dysfunction in atherosclerosis. This study is to investigate whether amorphous SeQDs (A-SeQDs) increase endogenous tetrahydrobiopterin biosynthesis to alleviate pulmonary arterial hypertension.

Results: Both A-SeQDs and C-SeQDs were stable under physiological conditions, while the size of A-SeQDs was smaller than C-SeQDs by high resolution-transmission electron microscopy scanning. In monocrotaline-injected mice, oral administration of A-SeQDs was more effective to decrease pulmonary arterial pressure, compared to C-SeQDs and organic selenium. Further, A-SeQDs increased both nitric oxide productions and intracellular BH4 levels, upregulated dihydrofolate reductase activity in lungs, and improved pulmonary arterial remodeling. Gene deletion of dihydrofolate reductase abolished these effects produced by A-SeQDs in mice. Finally, the blood levels of tetrahydrobiopterin and selenium were decreased in patients with pulmonary arterial hypertension.

Conclusion: A-SeQDs increase intracellular tetrahydrobiopterin to prevent pulmonary arterial hypertension through recoupling endothelial nitric oxide synthase.

Methods: Two polymorphs of SeQDs and A-SeQDs, and a crystalline form of SeQDs (C-SeQDs) were prepared through self-redox decomposition of selenosulfate precursor. Mice were injected with monocrotaline to induce pulmonary arterial hypertension in vivo. Pulmonary arterial pressure was measured.