血小板源生长因子对大鼠肝星状细胞增殖和胶原及血小板源生长因子基因表达的影响

Effects of platelet derived growth factor on the proliferation of hepatic stellate cells and their expressions of genes of collagens and platelet derived growth factor

目的 证实血小板源生长因子 (PDGF)对体外培养大鼠肝星状细胞增殖和胶原基因表达及PDGF自分泌的作用。方法 (1)采用完全无血清培养 ,用3H TdR掺入检测了PDGF、转化生长因子 β1 (TGF β1 )和表皮生长因子 (EGF)对肝星状细胞的DNA合成作用 ;(2 )应用Northern分子杂交检测了PDGF对肝星状细胞的Ⅰ、Ⅲ型前胶原及PDGF B等mRNA表达水平的影响。结果 PDGF、EGF均可剂量依赖性地刺激肝星状细胞增殖 ,其作用在 0 .5～ 10ng ml之间呈剂量依赖性增强 ,剂量大于 10ng ml时 ,促DNA合成作用达到饱和。但PDGF的作用更强。而TGF β1 在本实验条件下对肝星状细胞的增殖没有影响。PDGF可提高肝星状细胞的Ⅰ、Ⅲ型前胶原和PDGF B的mRNA水平 ,且前胶原mRNA的改变呈时相性变化。给予PDGF刺激 12h ,见Ⅰ型前胶原mRNA表达已有增强 ,随后下降 ,至48hⅠ型前胶原mRNA表达显著增强 ;Ⅲ型前胶原mRNA水平在添加PDGF 12h即见表达增强 ,随后下降 ,48h再度低水平增强。体外培养大鼠肝星状细胞可表达PDGF BmRNA ,给予PDGF BB刺激 6h后 ,可见PDGF BmRNA表达增强 2～ 3倍 ,至 2 4h恢复到刺激前水平。结论 PDGF可以促进肝星状细胞的增生和表达胶原 ,后者的时相改变可能与PDGF自分泌有关。

Objective To investigate the effects of PDGF on the proliferation of rat HSC, its gene expression of collagens and the autocrine excretion of PDGF in vitro. Methods 3H TdR incorporation was used to estimate the DNA synthesis elicited by PDGF, TGF β1 and EGF in HSC cultured in an absolutely serum free medium. Northern blot was employed to detect the levels of mRNA expressions of type Ⅰ and Ⅲ procollagens and PDGF induced by PDGF added in the same medium for HSC. Results Both PDGF and EGF enabled to stimulate the proliferation of HSC in a dose dependent manner, and the effect of the former was stronger. The proliferation was dose dependently increased in PDGF and EGF with a dosage between 0.5 and 10 ng/ml, and the synthesis of DNA became saturated when the dosage was over 10 ng/ml. TGF β1 gave no effects on the proliferation of HSC under current experimental condition. Furthermore, PDGF was able to enhance the mRNA expression for type Ⅰ and Ⅲ procollagens and PDGF itself. The promoting effect for the expressions of type Ⅰ and Ⅲ procollagen mRNAs by PDGF was bi phasic between 6 to 48 hours of the cultivation. For type Ⅰ procollagen, mRNA expression began to increase 12 hours after PDGF stimulation, and the increase became prominent at 48 hours. For type Ⅲ procollagen, an increase of mRNA expression was seen before the stimulation of PDGF, and the expression level was comparatively increased 48 hours later. The mRNA expression of PDGF was increased by 2 3 times 6 hours after PDGF stimulation, and back to the original level 24 hours later. Conclusions PDGF enabled to promote the proliferation of HSC and expression of collagens in HSC. The bi phasic effect on the expression of collagens may be interrelated with the autocrine excretion of PDGF.