Abstract:Atherosclerosis and its associated complications are the primary cause of death in humans.Aging is the main risk factor for atherosclerosis,compared with any other risk factor.After the age of 60 years,age dominates all other risk factors in the risk prediction.But the specific mechanism that contributes to the aging risk remains unknown.For the past few years,the studies on correlations of stem or progenitor cells with disease made great progress.The correla tions of vascular progenitor cells with vascular disease are also paid more and more attention.In 1997,Asahara reported,for the first time,the isolation of putative endothelial progenitor cells(EPC) in the circulating blood.These cells were able to differentiate into mature endothelial cells in vitro and to incorporate into sites of active angiogenesis.This discovery led to a new era of vascular biology and a novel understanding of atherosclerosis and thromboembolic complications.A novel concept for atherosclerosis risk implicates a lack of endothelial progenitor cell(EPC)-dependent arterial repair in the development of atherosclerosis that is secondary to exhaustion of repair-competent EPC.And smooth muscle progenitor cell is one of the sources of smooth muscle cell derived foam cell.This article focuses on the effects of progenitor cells on atherosclerosis,especially on the correlations of endothelial progenitor cell,smooth muscle progenitor cell with atherosclerosis,and the differentiation of vascular progenitor cells.

Abstract:Aim To investigate the effects of sirolimus on proliferation and differentiation of rat smooth muscle progenitor cells(SPC). Methods Total mononuclear cells(MNC) were isolated from marrow of rats by Ficoll density gradient centrifugation method,and then plated on fibronectin-coated culture dishes. Fresh isolated MNC were treated with sirolimus(0.01～100 μg/L) or vehicle control for 12 days.SPC were characterized as adherent cells positive for α-SMA by indirect immunofluorescent staining.After 8 days cultured,attached cells were treated with sirolimus(to make a series of final concentrations: 0.1～200 μg/L) or vehicle control for 24 h.The proliferation and migration of SPC were assayed with MTT and modified Boyden chamber assay respectively.SPC adhesion assay was performed by replating those on fibronectin-coated dishes and counting the adherent cells. Results Sirolimus potently inhibited SPC outgrowth.The number of SPC at 12th day was dramatically decreased by sirolimus.At a concentration as low as 0.1 μg/L,sirolimus significantly reduced(70.9±4.5)% of SPC compared with control(p<0.01).In addition,sirolimus also inhibited SPC proliferative,migratory and adhesive capacity in a concentration-dependent manner. Conclusion Sirolimus could inhibit the proliferation and differentiation of rat smooth muscle progenitor cells.