Cells of primarily extravascular origin in neointima formation following stent implantation: coordinated expression of endothelial progenitor, dendritic and neural crest-derived cells

The Current State of MicroRNAs as Restenosis Biomarkers

In-stent restenosis corresponds to the diameter reduction of coronary vessels following percutaneous coronary intervention (PCI), an invasive procedure in which a stent is deployed into the coronary arteries, producing profuse neointimal hyperplasia. The reasons for this process to occur still lack a clear answer, which is partly why it remains as a clinically significant problem. As a consequence, there is a vigorous need to identify useful non-invasive biomarkers to differentiate and follow-up subjects at risk of developing restenosis, and due to their extraordinary stability in several bodily fluids, microRNA research has received extensive attention to accomplish this task. This review depicts the current understanding, diagnostic potential and clinical challenges of microRNA molecules as possible blood-based restenosis biomarkers.

Endovascular stent-induced alterations in host artery mechanical environments and their roles in stent restenosis and late thrombosis

Cardiovascular stent restenosis remains a major challenge in interventional treatment of cardiovascular occlusive disease. Although the changes in arterial mechanical environment due to stent implantation are the main causes of the initiation of restenosis and thrombosis, the mechanisms that cause this initiation are still not fully understood. In this article, we reviewed the studies on the issue of stent-induced alterations in arterial mechanical environment and discussed their roles in stent restenosis and late thrombosis from three aspects: (i) the interaction of the stent with host blood vessel, involve the response of vascular wall, the mechanism of mechanical signal transmission, the process of re-endothelialization and late thrombosis; (ii) the changes of hemodynamics in the lumen of the vascular segment and (iii) the changes of mechanical microenvironment within the vascular segment wall due to stent implantation. This review has summarized and analyzed current work in order to better solve the two main problems after stent implantation, namely in stent restenosis and late thrombosis, meanwhile propose the deficiencies of current work for future reference.

Long-term effects of ACE inhibitor on vascular remodelling

The long-term pathomorphological changes of the injured vessels under angiotensin-converting-enzyme (ACE) inhibitor are still not known. Therefore, we assessed the alternations of vascular architecture after three-month therapy with ACE inhibitor and identified new target cells for this medication. Carotid arteries of spontaneously hypertensive rats underwent balloon angioplasty. 14 days prior intervention, half of the animals was treated with ACE inhibitor. After three months of vascular trauma, the injured vessels were explored by histomorphology and immunohistochemistry for angiotensin-II receptor (AT1R), dendritic and HSP47+ cells. The neointimal growth decreased significantly only up to 28 days under ACE inhibitor. In contrast, the reductive effect of ACE inhibitor on media area persisted up to three months after intervention. A significant fraction of early neointimal cells was of a dendritic cell type. The relevant portion of these cells showed an expression of AT1R and HSP47. AT1R was present in 70% and HSP47 in 18% of all early neointimal cells in both groups. ACE inhibitor may at least temporarily diminish remodelling processes in injured vessels. The detection of AT1R on dendritic cells identifies these cells as important targets for therapeutic strategies involving modulation of the renin-angiotensin system.

Endothelial progenitor cells: what use for the cardiologist?

Endothelial Progenitor Cells (EPC) were first described in 1997 and have since been the subject of numerous investigative studies exploring the potential of these cells in the process of cardiovascular damage and repair. Whilst their exact definition and mechanism of action remains unclear, they are directly influenced by different cardiovascular risk factors and have a definite role to play in defining cardiovascular risk. Furthermore, EPCs may have important therapeutic implications and further understanding of their pathophysiology has enabled us to explore new possibilities in the management of cardiovascular disease. This review article aims to provide an overview of the vast literature on EPCs in relation to clinical cardiology.