Tetramethylpyrazine Protects Endothelial Progenitor Cells from Senescence by Activating the NRF2 Pathway

Abstract

Background: Tetramethylpyrazine (TMP) is an effective treatment for pulmonary arterial hypertension (PAH), but it is unclear whether its mechanism is related to the regulation of endothelial progenitor cells (EPCs). In this study, we aimed to explore the effect and mechanism of TMP on EPCs. Methods: A rat model of PAH was established by intraperitoneally injecting monocrotaline in Sprague Dawley rats, followed by intraperitoneal injection with 100 mg/kg TMP. The effects of TMP on pulmonary pathological morphology were evaluated using hematoxylin-eosin staining. The hemodynamics and right ventricular hypertrophy index (RVHI) of PAH rats were evaluated. EPCs were isolated from healthy rats and identified by double positive staining with acetylated low-density lipoprotein (acLDL), Ulex europaeus agglutinin-1 (UEA-1), and flow cytometry assay. The expression of Nuclear factor erythroid 2-related factor 2 (NRF2) in lung tissue and EPCs was determined using quantitative reverse transcription polymerase chain reaction (qRT-PCR). After NRF2-specific short hairpin RNA (shNRF2) transfection and/or TMP (50, 100, 200 μM) treatment on EPCs, the viability, proliferation, senescence, and protein expression levels of NRF2, p53 and p21 in EPCs were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 5-ethynyl-2-deoxyuridine (EdU), β-Galactosidase staining and Western blot assays. Results: TMP treatment improved the pathological condition of lung tissue, hemodynamic score and RVHI of PAH rats (p < 0.001). On the contrary, NRF2 silencing had negative effects on EPCs, including inhibition of viability and proliferation, promotion of senescence, and elevation of the protein levels of P53 and P21 in EPCs (p < 0.001). However, TMP treatment reversed the above effects of NRF2 silencing on EPCs (p < 0.01). Conclusions: TMP protects EPCs from senescence by activating the NRF2 pathway.