Verification of Alexa-fluor 633 Binding to Elastic Fibers

INTRODUCTION Abnormalities of elastic fibers and their components have been shown to cause a number of heritable diseases, including Marfan syndrome, Williams-Beuren syndrome, cutis laxa, and many others. Though these diseases exhibit a variety of characteristics and phenotypes, cardiovascular disease involving aortic aneurysms, dissections, stenosis or vascular tortuosity is common to most of them [1]. In addition, research is being conducted on diseases and health issues for which elastic fibers are key players. Research on emphysema treatment requires an understanding of elastic fibers, as it is a disease in which the elastic fibers in the lungs are degraded over time, leading to decreased ability to breathe [2]. Vascular grafts are used to help correct and slow down the progression of vascular disease, the leading cause of death in the United States, and require the same mechanical properties that elastic fibers give to arteries [3]. Artificial skin grafts are being developed to help treat burn patients; these utilize elastic fibers [4]. The ability to label elastic fibers in living tissue could help to quicken and improve the development of these technologies. Elastic fibers are critical components of the extracellular matrix of many tissues, including larger arteries, skin, lungs, and ligaments. Their main function is to allow these tissues to stretch and recoil without lasting damage. Elastic fibers are composed of an inner elastin core surrounded with fibrillin microfibrils, including MAGP-1, and are produced primarily during development [1, 5]. Standardized methods exist to detect these proteins in excised tissue, using immunohistochemical techniques, but currently no widespread and commonly accepted method exists to detect elastic fibers non-destructively in vivo or in vitro [6]. A study conducted in 2007 by Ricard et al. demonstrated that a dye, sulforhodamine B, can be used to non-destructively image elastic fibers in vivo and in situ, but as of yet this technique has not gained widespread acceptance and use [6]. An in vivo method to detect elastic fibers and any abnormalities they might exhibit would be very beneficial to the further study and possible treatment of elastic fiber diseases because it would allow doctors to closely monitor the progression of a disease, and would also greatly help researchers to develop and enhance such technologies as vascular grafts and artificial skin grafts. In their research on neurovascular coupling, Shen et al. demonstrated that the Alexa-Fluor 633 dye can be safely used in vivo in cats, mice, and rats to bind to artery walls, and proposed that it is the elastic lamellae, composed of elastic fibers, that Alexa-Fluor 633 binds to [7]. A second dye that is proven to identify elastic fibers in vivo could help this method, first developed by Ricard et al., to become more well-known and commonly used.