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
Neointimal hyperplasia causes vascular graft failure as a result of hypertrophy of - 
Select and explain. 
A. Enodthelial cells, B. Collagen fibers, C. Smooth muscle cells, D. Elastic fibers
C: Smooth muscle cells
Answer: C: Smooth muscle cells 
Explanation: 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.
Intimal hyperplasia followed by stenosis or restenosis is the principle cause of failure in vascular grafts.
Intimal hyperplasia occurs because of smooth muscle cells. These SMCs


are activated by vascular injury
migrate from media to the intima
multiply as intimal SMCs
synthesize & deposit extracellular matrix.