The histological changes in radial artery in uremia and their effects on arterial stiffness

Abstract

To examine the changes of histological parameters of radial artery in uremia, and to explore their effects on arterial stiffness. Sixty uremic patients underwent arteriovenous fistula surgery for hemodialysis and 20 healthy subjects received healthy examination were collected as uremia group and control group, respectively. Segments of radial arteries were obtained from all of uremic subjects and were evaluated by HE, Masson, van Kossa staining and electron microscopy. The expressions of osteopontin (OPN), α-SMA and elastin in arterial wall were detected by immunostaining, and apoptotic cells were determined by TUNEL assay. All of the subjects in the two groups received brachial ankle pulse wave velocity (baPWV) examination and the results were compared. The associations among histological parameters and baPWV were analyzed. More than one half (34/60) of artery samples presented uniformly thickening intima, in which most of cells expressed α-SMA and a few cells underwent apoptosis. The subendothelial matrix was abundant in collagen fibers, and no calcium deposition was found. The media thickened obviously, with increased collagen fibers, reduced elastin, unchanged α-SMA expression, and a few apoptotic smooth muscle cells. Two thirds uremic arteries expressed OPN, of which only one half had significant calcium deposition. The adventitia thickened and no calcium deposition was found. The baPWV level in uremic subjects was (18.5±3.2) m/s, far greater than that in control subjects (P<0.001). Statistical analysis showed that baPWV value was correlated with media thickness, calcification degree, and collagen content positively, and with elastin expression negatively. For diabetic uremic subjects, the OR values of vascular calcium deposition and remarkably-elevated baPWV value were 3.1, 2.3, respectively. Radial arterial intima often presents hyperplasia which is not related with baPWV increment in uremia. Arterial media calcification and collagen content incremental are the most two protuberant characteristics in uremia, especially in ones accompanied with diabetes. Medical calcification, collagen accumulation, and elastin reduction may contribute to the increased arterial stiffness in uremia.