Osteocalcin secretion and the expression of type X collagen mRNA in an in vitro model of vascular calcification

Objective:To investigate the stimulation to in vitro calcification of aorta by 25 hydroxycholesterol,and the relationship of the calcification with the secretion of osteocalcin and expression of type X collagen mRNA.Method:Aortic medial cells were obtained by explantation from rabbits von Kossa staining was performed to show the in vitro calcification.Insoluble calcium of cellular layer was determined by biochemical microspectrophotometric method.And osteocalcin in the media was analyzed with balanced radioimmunoassay.RT PCR was used to determine the expression of type X collagen mRNA.Result:Passaged cells showed negative von Kossa after 28 days.The cells treated with 25 hydroxycholesterol appeared many cell nodules with positive von Kossa staining,in which much more insoluble calcium and supernatant osteocalcin were detected.Type X collagen mRNA was detected in cells treated with 25 hydroxycholesterol but not in untreated cells.Conclusion:25 hydroxycholesterol can accelerate the in vitro calcification of aortic media.Aortic medial cells secrete more osteocalcin and express type X collagen mRNA during calcification,which is similar to osteoblast,suggesting arterial calcification may share part of the same mechanism with the calcification of the bone. [