Effects of human amniotic fluid stem cells on cytokines secretion and on endothelial cells proliferation and apoptosis / 中国组织工程研究

ABSTRACT

BACKGROUND:The benefit of cell therapy may be partly due to the secretion of angiogenic and antiapoptotic growth factors.Whether amniotic fluid stem cells (AFS) could secrete some growth factors requires further studies.OBJECTIVE:To isolate and culture AFS cells,and explore the angiogenic or antiapoptotic effect of cytokines secreted by AFS on endothelial cells.DESIGN,TIME AND SETTING:A in vitro cytological experiment was performed at the Institute of Hypertensive Disease,First Affiliated Hospital,Nanchang University from December 2008 to June 2009.MATERIALSTerm amniotic fluid of ten samples,50 mL/case,was obtained following caesarean delivery.The umbilical vein was used to isolate endothelial cells.Written informed content was obtained from all women.METHODS:AFS isolated from human amniotic fluid was cultured and digested by trypsin at confluence of 80%.The third passage of cells at a density of 5×10~8/L were divided into two groupshypoxia groupthe cells were cultured in 2% O_2 + 5% CO_2 +93% N_2;normal groupthe cells were cultured in 5% CO_2 + 95% air.Two groups were cultured at 37 ℃ for 24 hours.The supematant of two groups was collected.The second passage of human umbilical vein endothelial cells cultured in vitro was collected and seeded onto 12-well culture plate at a density of 2×10~4 cells/well,and divided into 3 groupscontrol group was cultured in 2 mL EBM-2 containing 5% fetal bovine serum (FBS);normal group was cultured in 1 mL EBM-2 containing 5% FBS and 1 mL AFS cell culture solution;hypoxia group was cultured in 1 mL EBM-2 containing 5% FBS and 1 mL hypoxia AFS cell culture solution for 3 days,followed by incubation with 10 μg/L tumor necrosis factor (TNF)-α.MAIN OUTCOME MEASURES:AFS surface phenotype was examined by flow cytometry;the secretion level and mRNA expression of vascular endothelial cell growth factor (VEGF) and hepatocyte growth factor (HGF) were examined by ELISA or RT-PCR.The proliferation and apoptotic rates of endothelial cells were examined.RESULTS:AFS cells were long fusiform-shaped and arranged radially after 7 days of culture.The third passage of AFS cells expressed CD29 and CD105 while did not express CD34.AFS cells of normal culture secreted VEGF and HGF;AFS cells of hypoxia condition significantly increased secrete of VEGF (P＜0.01),and VEGF mRNA expression was significantly upregulated (P＜0.05),while HGF and mRNA expression remained unchanged (P＞0.05).Compared with control group,the number of endothelial cells was significantly increased in normal and hypoxia AFS cell groups after 3 days of culture (P＜0.05).After cocultured with TNF-α for 24 hours,the apoptosis rates of endothelial cells in AFS-conditioned medium was significantly decreased (P ＜ 0.05),and the change degree of hypoxia AFS cell group was greater than normal AFS cell group (P ＜ 0.05).CONCLUSION:AFS can secrete cytokines such as VEGF and HGF.Moreover,it significantly promotes endothelial cells proliferation and inhibits apoptosis.Under hypoxia condition,the secretion of VEGF from AFS cells is increased,and the effects on endothelial cells proliferation and apeptosis are enhanced.