前列腺素E2促骨髓来源内皮前体细胞分化的机制

目的：探讨前列腺素E2在调节小鼠骨髓来源内皮前体细胞分化、增强血管新生潜能中的作用及其相关分子机制。方法：贴壁法获得C57BL/6J小鼠后肢股骨和胫骨骨髓来源的内皮前体细胞（bone marrow derived progenitor cells, BMPCs）， 免疫荧光染色法鉴定BMPCs。用前列腺素E2（prostaglandin E2, PGE2）处理该群细胞，通过定量PCR、Western blot等分子生物学方法检测BMPCs中内皮前体细胞标志物以及内皮细胞标志物的表达情况，体外成血管实验检验BMPCs血管新生调节能力。利用PGE2及其受体亚型2、4（EP2、EP4）阻断剂处理BMPCs，定量PCR和Western blot方法分析Krüppel样转录因子2（Krüppel like factor 2，KLF2）的表达情况。结果：BMPCs表面表达内皮前体细胞标志物c kit以及内皮细胞（endothelial cells，ECs）标志物血管性血友病因子（von Willebrand factor，vWF）、血管内皮钙黏素（vascular endothelial cadherin, VE-cadherin）。1 μmol/L PGE2显著促进BMPCs中与成熟ECs相关的分子标记物血小板内皮细胞黏附分子（platelet endothelial cell adhesion molecule-1 ，PECAM-1/CD31）和内皮型一氧化氮合酶（endothelial nitric oxide synthase，eNOS）的表达，上调倍数2倍，且BMPCs形成新血管的能力也明显增强。在此过程中转录因子KLF2的表达升高至原有水平的2倍以上，利用PGE2受体阻断剂处理BMPCs，发现EP4受体阻断剂处理BMPCs后，KLF2表达下降。结论：PGE2通过EP4受体作用于BMPCs，上调KLF2表达，促进BMPCs向ECs方向分化，从而增强其血管新生潜能。

Mechanisms of prostaglandin E2-induced bone marrow-derived progenitor cell differentiation

Objective：To identify the functions and mechanisms of prostaglandin E2 (PGE2)-induced bone marrow-derived progenitor cells (BMPCs) maturation and its involved angiogenesis. Methods:BMPCs harvested by flushing through the femoral and tibial bones and cultured. This population of cells was identified by immunofluorescence staining. From which, 1 μmol/L PGE2 was taken, and quantitative-PCR (Q-PCR) and Western blot were used to detect the expressions of endothelial markers and Krüppel like factor 2 (KLF2) in BMPCs. In vitro tube formation assay was performed to demonstrate the capacity of angiogenesis. Furthermore, PGE2 and its receptors EP2 and EP4 agonists were used to elucidate the regulation of PGE2 to KLF2. Results: C-kit, von Willebrand factor (vWF) and vascular endothelial cadherin expressed in BMPCs. Treatment with PGE2 (1 μmol/L) significantly increased the differentiation of BMPCs. The mRNA levels of endothelial markers platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31）and endothelial nitric oxide synthase (eNOS)， were significantly upregulated in about 2 folds by PGE2 detected with Q-PCR assay. Matrigel tube formation assay also demonstrated PGE2 enhanced the ability of angiogenesis in BMPCs. In addition, the expression of KLF2 increased in more than 2 folds with PGE2 treatment compared with the control. Such effect of PGE2 could be blocked by EP4 blocking peptide.Conclusion:Promoting the differentiation of BMPCs, PGE2 reinforced their angiogenesis by binding to the receptor of EP4 in a KLF2-dependent manner.