Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology, and Nutrition, Stanford University, Palo Alto, CA, USA.
Liver Int. 2010 Jul;30(6):913-22. doi: 10.1111/j.1478-3231.2010.02231.x. Epub 2010 Mar 26.
Several studies have demonstrated techniques in differentiating human adipose-derived stem cells (hADSCs) into hepatocytes. Unfortunately, transdifferentiation is inefficient, and the function of these induced hepatocyte-like cells (which we termed 'iHeps') is low compared with that of real hepatocytes.
We aimed to identify transcriptional deficiencies in iHeps that are critical to hepatocyte development, which may provide insights into improving the efficiency of transdifferentiation.
hADSCs were differentiated into iHeps, and iHeps were assayed for hepatocyte-like activity. iHeps were then screened for expression of several growth factors, receptors and transcription factors (TFs) critical to liver development using reverse transcription-polymerase chain reaction (RT-PCR). Deficient TFs were transduced into hADSCs and hepatocyte function was reassessed after hepatic differentiation.
Differentiation of hADSCs into iHeps resulted in the upregulation of hepatic proteins. However, the levels of expression of hepatocyte-specific proteins in these iHeps were well below those of Huh 7.5 hepatoma cells, used in comparison. Five developmental TFs were notably absent on the RT-PCR screen. Lentiviral transduction of these TFs into hADSCs followed by culture in hepatocyte induction medium resulted in increased albumin expression compared with untransduced hADSCs treated in a parallel fashion.
These five missing TFs are known to regulate hepatocyte differentiation and some are required to establish the competence of the foregut endoderm. Presumably due to their mesenchymal lineage, hADSCs do not express these endodermal TFs and are not fully competent to respond to critical developmental signals. Supplementation of these TFs may induce competency and enhance the differentiation of hADSCs into hepatocytes.
多项研究已经证明了将人脂肪来源的干细胞（hADSCs）分化为肝细胞的技术。不幸的是，转分化效率不高，并且这些诱导的肝细胞样细胞（我们称之为“iHeps”）的功能与真正的肝细胞相比较低。
我们旨在确定 iHeps 中对肝细胞发育至关重要的转录缺陷，这可能为提高转分化效率提供思路。
将 hADSCs 分化为 iHeps，并检测 iHeps 的肝细胞样活性。然后使用逆转录-聚合酶链反应（RT-PCR）筛选 iHeps 中几种对肝脏发育至关重要的生长因子、受体和转录因子（TFs）的表达。将缺陷型 TF 转导至 hADSCs 中，并在肝分化后重新评估其肝细胞功能。
hADSCs 分化为 iHeps 导致肝蛋白的上调。然而，这些 iHeps 中肝细胞特异性蛋白的表达水平远低于用作比较的 Huh 7.5 肝癌细胞。RT-PCR 筛选中明显缺失了 5 种发育 TF。将这些 TF 经慢病毒转导至 hADSCs 后，在肝细胞诱导培养基中培养，与平行处理的未转导的 hADSCs 相比，白蛋白表达增加。
这 5 种缺失的 TF 已知可调节肝细胞分化，其中一些是建立前肠内胚层能力所必需的。推测由于其间充质谱系，hADSCs 不表达这些内胚层 TF，并且不完全有能力对关键发育信号作出反应。补充这些 TF 可能诱导其能力，并增强 hADSCs 向肝细胞的分化。
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