Association between circulating osteoblast progenitor cells and aortic calcifications in women with postmenopausal osteoporosis

Abstract Background and aims Ectopic artery calcification has been documented in women with postmenopausal osteoporosis, in whom an imbalance in the number of circulating osteoprogenitor cells (OPCs) has been identified. Circulating OPCs form calcified nodules in vitro; however, it remains unknown whether an association exists between the number of circulating OPCs and aortic calcifications. We investigated the relationship between OPCs and aortic calcifications in women with postmenopausal osteoporosis. Methods and results The number of circulating OPCs was quantified by FACS analysis in 50 osteoporotic postmenopausal women. OPCs were defined as CD15-/alkaline-phosphatase(AP)+ cells coexpressing or not CD34. Participants underwent measurement of markers of bone metabolism, bone mineral density and abdominal aortic calcium (AAC) by 64-slice computed tomography. Patients with AAC were older, had lower 25(OH)vitamin D levels and higher circulating CD15-/AP+/CD34- cells than those without AAC. Significant correlates of AAC included age (rho = 0.38 p  = 0.006), calcium (rho = 0.35 p  = 0.01), 25(OH)vitamin D (rho = −0.31, p  = 0.03) and the number of CD15-/AP+/CD34- cells (rho = 0.55 p p  = 0.04) and severity ( β  = 0.43, p p  = 0.003). Conclusion In women with postmenopausal osteoporosis, the number of circulating CD15-/AP+/CD34- cells is significantly associated with increased aortic calcifications, that appear to be correlated also with reduced 25(OH)vitamin D levels.