Human Airway Smooth Muscle (ASM) cells are primary cells isolated from the human airway. These cells are fundamental to regulating airway tone and responsiveness, and their dysfunction is a hallmark of various respiratory diseases, including asthma and COPD. ASM cells are involved in bronchoconstriction and airway remodeling, with their proliferation and phenotype plasticity contributing to airway wall thickening and hyperresponsiveness. Researchers utilize these cells to investigate mechanisms of smooth muscle contraction, inflammation, and the effects of therapeutic agents on airway function.