Fausto Nelson, Campbell Jean S
Department of Pathology, University of Washington, Seattle, WA, USA.
Mech Dev. 2003 Jan;120(1):117-30. doi: 10.1016/s0925-4773(02)00338-6.
The liver has the unique capacity to regulate its growth and mass. In rodents and humans, it grows rapidly after resection of more than 50% of its mass. This growth process, as well as that following acute chemical injury is known as liver regeneration, although growth takes place by compensatory hyperplasia rather than true regeneration. In addition to hepatocytes and non-parenchymal cells, the liver contains intra-hepatic "stem" cells which can generate a transit compartment of precursors named oval cells. Liver regeneration after partial hepatectomy does not involve intra or extra-hepatic (hemopoietic) stem cells but depends on the proliferation of hepatocytes. Transplantation and repopulation experiments have demonstrated that hepatocytes, which are highly differentiated and long-lived cells, have a remarkable capacity for multiple rounds of replication. In this article, we review some aspects of the regulation of hepatocyte proliferation as well as the interrelationships between hepatocytes and oval cells in different liver growth processes. We conclude that in the liver, normally quiescent differentiated cells replicate rapidly after tissue resection, while intra-hepatic precursor cells (oval cells) proliferate and generate lineage only in situations in which hepatocyte proliferation is blocked or delayed. Although bone marrow stem cells can generate oval cells and hepatocytes, transdifferentiation is very rare and inefficient.
肝脏具有调节自身生长和质量的独特能力。在啮齿动物和人类中，肝脏在被切除超过50%的质量后会迅速生长。这个生长过程，以及急性化学损伤后的生长过程，被称为肝脏再生，尽管生长是通过代偿性增生而非真正的再生发生的。除了肝细胞和非实质细胞外，肝脏还含有肝内“干细胞”，这些干细胞可以产生名为卵圆细胞的前体细胞过渡区。部分肝切除术后的肝脏再生不涉及肝内或肝外（造血）干细胞，而是依赖于肝细胞的增殖。移植和再填充实验表明，肝细胞作为高度分化且寿命较长的细胞，具有进行多轮复制的显著能力。在本文中，我们回顾了肝细胞增殖调控的一些方面，以及不同肝脏生长过程中肝细胞与卵圆细胞之间的相互关系。我们得出结论，在肝脏中，正常情况下静止的分化细胞在组织切除后会迅速复制，而肝内前体细胞（卵圆细胞）仅在肝细胞增殖受阻或延迟的情况下才会增殖并产生谱系。尽管骨髓干细胞可以产生卵圆细胞和肝细胞，但转分化非常罕见且效率低下。
