This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'Neointimal hyperplasia causes vascular graft failure as a result of hypertrophy of - \nSelect and explain. \nA. Enodthelial cells, B. Collagen fibers, C. Smooth muscle cells, D. Elastic fibers', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Neointimal hyperplasia (or also known as intimal hyperplasia) is a response to vascular injury and is seen as a complication of all forms of arterial reconstruction.\nIntimal hyperplasia followed by stenosis or restenosis is the principle cause of failure in vascular grafts.\nIntimal hyperplasia occurs because of smooth muscle cells. These SMCs\n\n\nare activated by vascular injury\nmigrate from media to the intima\nmultiply as intimal SMCs\nsynthesize & deposit extracellular matrix.', 'role': 'assistant'}]