Smooth muscle cells (SMC) are primary contributors to the development of arterial disease. The ability of vascular SMC to switch to a proliferative phenotype is one of the main factors in the development and progression of vascular disease. Human Pulmonary Artery Smooth Muscle Cells (PASMC) express VEGF and FGF-2 and depend on mechanical forces during pulsatile blood flow. Chronic lung hypoxia causes vascular remodeling with PASMC hyperplasia, and results in pulmonary hypertension. PASMC play an important role in vascular disease research helping to identify new therapeutic targets to treat pulmonary vascular disease. They are also useful tools to stablish in vitro disease models for High Throughput and High Content Screening.