**16. Conclusion**

Exploring the microRNAome that controls VSMC phenotype and analysis of their targets have greater possibilities for unraveling unforeseen regulatory pathways and disease mechanisms, development of novel therapeutic approaches. miRNAs in cardiovascular research are a newly emerging powerful biomolecules, which demonstrate several unique opportunities for microRNAs-based therapeutics. Although some of the studies appear to indicate targeting certain miRNAs presents a potential therapy for atherosclerosis, knowledge of full scope of miRNAs in vascular pathogenesis is limited. With 1,000 or more microRNAs encoded by the human genome, only a few of which have been analyzed appear to be linked to vascular proliferative diseases. Considering the complexity of the multifactorial vascular proliferative diseases including atherosclerosis and restenosis, there may be several miRNAs and even several clusters of miRNAs, similar to miRNA-17-92 cluster, which impact the development of vascular pathogenesis. Therefore, several issues have to be addressed prior to use of miRNAbased technology can be translated to clinical therapy such as: profile of miRNAs responsible for vascular proliferative diseases needs to be determined; detailed effects of these miRNAs in the prevention and treatment of vascular proliferative diseases requires investigation; procedures for in vivo miRNA silencing needs to be improved to minimize off-target effects; technology for miRNA upregulation in arterial vessel wall requires development; and potential toxicity of miRNA-based therapy should be determined. Developing miRNAs into therapeutics reveals other significant challenges, such as methods of delivery and duration of action. Methods for local delivery to the arteries via catheters or coated stents may avert these challenges and should minimize off-target effects on other tissues. Besides their therapeutic potential, identification of circulating miRNAs released from injured tissues or highly expressed in patients with cardiovascular diseases suggest miRNAs can also be useful as potential biomarkers for clinical diagnosis of cardiovascular disease patients.
