生长因子及细胞外基质对肝前体细胞体外增殖及分化的影响

目的 明确多种生长因子对胚胎肝脏前体细胞体外增殖分化的影响。方法 用胶原酶从胎龄14．5d SD大鼠胚胎肝脏分离单个细胞，采用^3H-TdR掺入法检测生长因子对胎肝细胞体外增殖的促进作用，并观察生长因子及细胞外基质成分对胎肝干细胞集落形成的影响。采用免疫细胞双标记及G-6-P酶活性测定以检测肝前体细胞表面标记的表达及向成熟肝细胞的分化能力。结果 肝前体细胞在体外培养时显示克隆样生长的特性。促肝细胞生长因子(HGF)、表皮生长因子(EGF)能促进肝前体细胞的增殖，使DNA合成加速，并促进干细胞集落的形成及角蛋白19、白蛋白、G-6-P的表达。转化生长因子α对肝前体细胞的促增殖作用较弱。转化生长因子β对肝前体细胞的增殖起到抑制作用。细胞基质成分Ⅰ型胶原、Ⅳ型胶原、层黏连蛋白能促进肝干细胞集落的形成，而纤维连接蛋白的作用较弱。肝干细胞单克隆增殖需要生长因子及细胞外基质的共同参与，加入新鲜分离胎肝细胞培养液上清液时单细胞增殖较快，于第5天即形成细胞集落。结论 HGF、EGF对肝前体细胞的增殖分化起重要作用，细胞外基质成分亦参与了其增殖分化过程。肝干细胞单克隆培养除需生长因子和细胞外基质外，可能亦有某些造血细胞、间质细胞分泌的因子参与其增殖分化的调控。

Effects of growth factors and extracellular matrix on proliferation and differentiation of fetal liver progenitor cell in vitro

OBJECTIVE: Liver development needs a number of growth factors and components of the extracellular matrix. The study is to explore how growth factors and extracellular matrix regulate proliferation and differentiation of fetal liver progenitor cell. METHODS: We demonstrate isolation of hepatic progenitor/stem cells from ED 14.5 SD rat liver, which contains a large number of hepatoblasts. Proliferation assay-3H thymidine incorporation was used to detect the effect of growth factors on proliferation of hepatic progenitor cell. Growth factor and extracellular matrix were added and stem cell clone formation was counted. Mark of bile duct and hepatocyte were detected with double-marker immunocytochemistry. RESULTS: Progenitor liver cells displayed clonogenic capacity, expressed markers of hepatocytes and bile duct cells and G-6-P. HGF, EGF can accelerate DNA synthesis and stem cell clone formation of hepatic progenitor cell. Extracellular matrix collagen I, collagen IV or laminin were essential for formation of stem cell clone. Single cell culture needed HGF, EGF, extracellular matrix and supernatant of mix cell (which contained fetal parenchymal cells, mesenchymal cells and hematopoietic cells) culture. CONCLUSION: Growth factors especially HGF and EGF play crucial role in proliferation and differentiation of liver progenitor cell. Some factors secreted from mesenchymal cell and hematopoietic cells may be involved.