Platelets in In-stent Restenosis: From Fundamental Role to Possible Prognostic Application

Background: Introduction of new generations of stents has decreased the percentage of patients experiencing in-stent restenosis (ISR) following the implantation of stent. However, a large number of patients are still afflicted with this phenomenon, which necessitates further study of ISR pathophysiology. Methods: Relevant English literature was searched up to 2018 and retrieved form the PubMed database and Google Scholar search engine. The following keywords were used: "In-stent restenosis", "Platelet", "Chemokine", "Inflammation", "Vascular smooth muscle cell" and "Neointima". Results: Previous studies have shown that ISR is a pathophysiologic response to damage of the artery wall after its elongation and separation of the atherosclerotic plaque. Development of neointimal hyperplasia (NIH) following this pathophysiologic response is a function of inflammation caused by platelets, monocytes, macrophages, and lymphocytes, as well as rapid migration and proliferation of generally quiescent cells in the median layer of the artery wall. Conclusion: After damage to the artery wall, platelets play an essential role in the incidence of NIH by contributing to inflammation and migration of vascular smooth muscle cells and extracellular matrix remodeling, especially via secretion of different chemokines; therefore, developing therapeutic strategies for platelet inhibition in a controlled manner could be the basis of preventive treatments in the near future. In this study, for the first time, we hypothesize that evaluation of platelet activity profile in patients before and after stent implantation may determine the prognosis and likelihood of ISR.