SMCs

SMCs is an acronym that commonly refers to smooth muscle cells, a type of muscle cell that forms the walls of hollow organs and blood vessels. Smooth muscle cells are spindle-shaped, non-striated, and organized into layers within vessel walls, the gastrointestinal tract, airways, and other visceral structures.

They contain contractile proteins such as actin and myosin, and their contraction is regulated by intracellular calcium signaling via calmodulin and myosin light-chain kinase. In contrast to skeletal and cardiac muscle, SMC contraction occurs without visible sarcomeres and is typically slower and more sustained, contributing to the tone and peristaltic movement of organs.

SMCs can adopt different phenotypes. The contractile phenotype is specialized for force generation, while the synthetic phenotype features increased proliferation, migration, and secretion of extracellular matrix components. This phenotypic modulation is important during development, wound healing, and vessel remodeling, but it can contribute to pathology when dysregulated, such as in neointima formation after vascular injury and in atherosclerosis.

Developmentally, cardiovascular SMCs originate from multiple embryonic lineages, including neural crest and various mesodermal precursors, leading to regional diversity in vessel wall composition and behavior. Research focuses on signaling pathways that govern SMC phenotype, such as PDGF and TGF-β, and their roles in vascular stiffness, aneurysm formation, and restenosis.

Outside biology, SMCs can denote the system management controller, a component in Apple computers and some servers responsible for power, thermal management, and battery functions. This usage reflects a distinct domain and is unrelated to cellular biology.