Golding M, Sarraf C E, Lalani E N, Anilkumar T V, Edwards R J, Nagy P, Thorgeirsson S S, Alison M R
Department of Histopathology, Royal Postgraduate Medical School, London, England.
Hepatology. 1995 Oct;22(4 Pt 1):1243-53. doi: 10.1016/0270-9139(95)90635-5.
When hepatocyte regeneration after a two-thirds partial hepatectomy (PH) in rats is blocked by oral gavage of acetylaminofluorene, a proliferation of ductular cells ensues that results in a profusion of neoductules radiating from each portal tract. To examine the possibility that this population of newly emerging cells harbors cells capable of differentiating into hepatocytes, we have looked in these cells for expression of functional markers of hepatocyte commitment at both the RNA and protein levels. Expression of albumin and alpha-fetoprotein (alpha-FP) messenger RNA (mRNA) transcripts were sought in situ using antisense riboprobes, and the expression of a number of cytochrome P450 enzymes was examined immunohistochemically. Before any signs of differentiation the ductular cells strongly expressed cytokeratins 7, 8, 18, and 19 in the same manner as authentic bile ducts, but unlike the latter also expressed vimentin. In situ hybridization studies showed that small bile ducts close to the limiting plate, as well as the newly formed ducts, expressed albumin and alpha-fetoprotein messenger RNAs, and immunocytochemistry showed that the distribution of the respective proteins was similar. Beginning at 1 week after partial hepatectomy, areas of differentiation could be found in the new ducts, with cells resembling either columnar intestinal-type epithelia or hepatocytes. Intestinal-like cells expressed neither albumin, alpha-FP, nor cytochrome P450 enzymes, whereas ductular cells appearing like hepatocytes with the typical membranous distribution of cytokeratin 8 strongly expressed a variety of cytochrome P450 enzymes normally associated with functional hepatocytes. These observations further support the belief that reactive ductules, sprouted from small ducts, can represent an adaptive response of the liver to replenish lost hepatocytes, although some of the newborn cells appear to differentiate along intestinal lines.
当通过口服乙酰氨基芴灌胃法阻断大鼠三分之二肝部分切除术后的肝细胞再生时，会出现小胆管细胞增殖，导致从每个门管区放射状长出大量新生小胆管。为了研究这群新出现的细胞中是否含有能够分化为肝细胞的细胞，我们在这些细胞中寻找肝细胞定向分化功能标志物在RNA和蛋白质水平的表达。使用反义核糖探针原位检测白蛋白和甲胎蛋白（α-FP）信使RNA（mRNA）转录本的表达，并通过免疫组织化学检测多种细胞色素P450酶的表达。在出现任何分化迹象之前，小胆管细胞以与真性胆管相同的方式强烈表达细胞角蛋白7、8、18和19，但与后者不同的是，它们也表达波形蛋白。原位杂交研究表明，靠近界板的小胆管以及新形成的胆管表达白蛋白和甲胎蛋白信使RNA，免疫细胞化学显示相应蛋白质的分布相似。在肝部分切除术后1周开始，在新形成的胆管中可以发现分化区域，细胞类似于柱状肠型上皮细胞或肝细胞。肠样细胞既不表达白蛋白、α-FP，也不表达细胞色素P450酶，而呈现肝细胞样且细胞角蛋白8具有典型膜性分布的小胆管细胞强烈表达多种通常与功能性肝细胞相关的细胞色素P450酶。这些观察结果进一步支持了这样一种观点，即从小胆管萌发的反应性小胆管可代表肝脏对补充丢失肝细胞的一种适应性反应，尽管一些新生细胞似乎沿着肠系分化。
