视黄酸促进限定性内胚层细胞向胰腺前体细胞分化

研究视黄酸（RA）在限定性内胚层细胞向胰腺前体细胞诱导过程中的最佳作用方式。在无饲养层培养体系下联合多因子分阶段诱导经历10天时间获得胰腺前体细胞。获得的细胞不仅表达胰腺前体细胞的标记pdx1，但是也同时表达肝脏前体细胞的标记afp。有研究表明在胰腺特化过程中RA能起到抑制afp的作用，因此在不同的时间点添加RA并持续不同的作用时间来调节内胚层细胞向肝胰分化的命运。收集d7到d10的细胞用免疫组化和RT—PCR检测pdx1和afp的表达情况。结果显示RA从d3开始持续作用到d10可以获得更高的pdx1阳性细胞同时能有效的抑制afp的表达，并且在d9可以获得最高比率的pdxl阳性细胞，提示RA持续作用促进限定性内胚层细胞向胰腺前体细胞分化。

Retinoic Acid Promotes Pancreatic Precursor Cells Differentiation From Definitive Endoderm Cells

To confirm the best effective time window of RA in the progress of inducing definitive endoderm into pancreatic precursor cell. Combined multiple factors and step stage introduction method, pancreatic precursor ceils could be obtained within l0 days under feeder free culture system. The ceils not only express the pancreatic precursor marker pdxl, but also express the liver precursor marker afp. Some studies have shown that RA can suppress afp expression in pancreatic specialization process, so RA was added at different time and last for different days to adjust the liver and pancreas differentiation from endoderm cells. The cells from day 7 to day 10 were collected to test the expression of pdxl and afp by immunofluorescence and RT-PCR. The method treated definitive endoderm with RA from day 3 to day 10 which could make us obtain the higher positive of pdx1 cells and at the same time suppress the expression of afp effectively, and which could make us obtain the highest pdxl ceils on day 9. It suggested that persistent RA promotes pancre-atic precursor cells differentiation from definitive endoderm cells.