BMP9 is a ligand of the TGF-β family and is considered as a vascular quiescence factor. Different actors within BMP9 signaling pathway such as receptors ALK1 and BMPR2 are found to be mutated in two rare vascular diseases, Rendu-Osler disease also called Hereditary Hemorrhagic Telangiectasia and Pulmonary Arterial Hypertension, which are due to endothelial dysfunction. Current treatments aim to improve symptoms in patients, whitout providing a real cure. Thus, it is essential today to find new etiological treatments restoring this signaling pathway. To do this, I used high-throughput screening to reposition potential drug candidates from the Prestwick and TargetMol libraries, a total of 2133 molecules approved by FDA and EMA. These screens were realized on endothelial cells models reporting the BMP9 pathway using a BMP sensitive promoter (BRE, BMP Response Element). I developed and miniaturized a first endothelial model HMEC-1 secreting a BRE-controlled Metridia Luciferase, then a second one using double transfection of Firefly luciferase under BRE control and Renilla Luciferase as a transfection control. The first model revealed only false positives hits. However, the second one allowed us to identify several molecules activating the cAMP pathway but which action hasn’t been confirmed at molecular levels. A last screen was performed on non-endothelial cells (Myoblasts C2C12BRA), allowing us to identify two other molecules which are currently undergoing characterisations.