Radial artery calcification in end-stage renal disease patients is associated with deposition of osteopontin and diminished expression of α-smooth muscle actin

Aim: Vascular access is the lifeline of haemodialysis patients and radial-cephalic fistula is the preferred type of access. We investigated vascular calcification in uraemia radial arteries and compared it with clinical parameters. Methods: Artery specimens from 30 end-stage renal disease patients were collected, examined calcification by von Kossa and Alizarin red staining. Expression of alpha-smooth muscle actin (alpha-SMA) and the main component of bone matrix, osteopontin (OP) were detected by immunohistochemistry. Results: In uraemia vessels, calcification was mainly located in the medial layer. Nineteen (63.33%) patients had no evidence of calcification, six (20%) had mild/moderate calcification and five (16.66%) had severe calcification. Upregulation of OP and diminished expression of alpha-SMA occurred in the medial layer, especially in the area of severe calcification. The calcification score, decreased expression of alpha-SMA and upregulation of OP were positively correlated with older age, serum calcium, serum phosphorus and calcium x phosphorus product (P < 0.01). Conclusion: Vascular calcification in uraemia radial arteries is mainly located in the media layer. The risk factors appear to be older age, an elevated serum level of phosphorus, calcium and calcium x phosphorus product.