Tsuchiya Atsunori, Heike Toshio, Baba Shiro, Fujino Hisanori, Umeda Katsutsugu, Matsuda Yasunobu, Nomoto Minoru, Ichida Takafumi, Aoyagi Yutaka, Nakahata Tatsutoshi
Department of Pediatrics, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Stem Cells. 2007 Apr;25(4):895-902. doi: 10.1634/stemcells.2006-0558. Epub 2007 Jan 11.
Few studies on the long-term culture of postnatal mouse hepatic stem/progenitor cells have been reported. We successfully adapted a serum-free culture system that we employed previously to expand fetal mouse hepatic stem/progenitor cells and maintained them in culture over long periods. The expanded postnatal cells contained immature alpha-fetoprotein-positive cells along with hepatocytic and cholangiocytic lineage-committed cells. These cells expressed CD49f but not CD45, CD34, Thy-1, c-kit, CD31, or flk-1, and oncostatin M induced their differentiation. This heterogeneous population contained side population (SP) cells, which express the ATP-binding cassette transporter ABCG2, and sca-1+ cells. As mice aged, the frequency of SP and sca-1+ cells decreased along with the ability of cultured cells to expand. Approximately 20%-40% of the SP cells expressed sca-1, but only a few sca-1+ cells were also SP cells. Analysis of colonies derived from single SP or sca-1+ cells revealed that, although both cells had dual differentiation potential and self-renewal ability, SP cells formed colonies more efficiently and gave rise to SP and sca-1+ cells, whereas sca-1+ cells generated only sca-1+ progeny. Thus, SP cells are more characteristic of stem cells than are sca-1+ cells. In regenerating livers, ABCG2+ cells and sca-1+ cells were detected around or in the portal area (the putative hepatic stem cell niche). The expanded cells share many features of fetal hepatic stem/progenitor cells or oval cells and may be useful in determining the mechanisms whereby hepatic stem cells self-renew and differentiate.
关于出生后小鼠肝干细胞/祖细胞长期培养的研究报道较少。我们成功改良了一种无血清培养系统，该系统曾用于扩增胎鼠肝干细胞/祖细胞，并能使其长期维持在培养状态。扩增后的出生后细胞包含未成熟的甲胎蛋白阳性细胞以及肝细胞和胆管细胞系定向分化的细胞。这些细胞表达CD49f，但不表达CD45、CD34、Thy-1、c-kit、CD31或flk-1，制瘤素M可诱导其分化。这个异质性群体包含表达ATP结合盒转运体ABCG2的侧群（SP）细胞和sca-1+细胞。随着小鼠年龄增长，SP细胞和sca-1+细胞的频率以及培养细胞的扩增能力均下降。约20%-40%的SP细胞表达sca-1，但只有少数sca-1+细胞也是SP细胞。对源自单个SP或sca-1+细胞的集落分析显示，虽然这两种细胞都具有双分化潜能和自我更新能力，但SP细胞形成集落的效率更高，可产生SP细胞和sca-1+细胞，而sca-1+细胞仅产生sca-1+后代。因此，SP细胞比sca-1+细胞更具有干细胞特征。在再生肝脏中，ABCG2+细胞和sca-1+细胞在门静脉区（假定的肝干细胞龛）周围或内部被检测到。扩增后的细胞具有许多胎肝干细胞/祖细胞或卵圆细胞的特征，可能有助于确定肝干细胞自我更新和分化的机制。
