Previous studies have shown that hepatocyte-like cells can be generated from fibroblasts using either lineage-specific transcription factors or chemical induction methods. However, these methods have their own deficiencies that restrict the therapeutic applications of such induced hepatocytes. In this study, we present a transgene-free, highly efficient chemical-induced direct reprogramming approach to generate hepatocyte-like cells from mouse embryonic fibroblasts (MEFs). Using a small molecule cocktail (SMC) as an inducer, MEFs can be directly reprogrammed into hepatocyte-like cells, bypassing pluripotent and immature hepatoblast intermediate stages. These chemical-induced hepatocyte-like cells (ciHeps) closely resemble mature primary hepatocytes in terms of morphology, biological behavior, gene expression patterns, marker expression levels, and hepatic functions. Furthermore, transplanted ciHeps can integrate into the liver, promote liver regeneration, and improve survival rates in mice with acute liver damage. ciHeps can also ameliorate liver fibrosis caused by chronic injuries and enhance liver function. Notably, ciHeps exhibit no tumorigenic potential either in vitro or in vivo. Mechanistically, SMC-induced mesenchymal-to-epithelial transition and suppression of SNAI1 contribute to the fate conversion of fibroblasts into ciHeps. These results indicate that this transgene-free, chemical-induced direct reprogramming technique has the potential to serve as a valuable means of producing alternative hepatocytes for both research and therapeutic purposes. Additionally, this method also sheds light on the direct reprogramming of other cell types under chemical induction.

中文翻译：

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化学诱导下小鼠成纤维细胞高效转化为功能性肝细胞

先前的研究表明，可以使用谱系特异性转录因子或化学诱导方法从成纤维细胞中产生肝细胞样细胞。然而，这些方法都有其自身的缺陷，限制了此类诱导肝细胞的治疗应用。在这项研究中，我们提出了一种无转基因、高效的化学诱导直接重编程方法，从小鼠胚胎成纤维细胞（MEF）中产生肝细胞样细胞。使用小分子混合物 (SMC) 作为诱导剂，MEF 可以直接重编程为肝细胞样细胞，绕过多能和未成熟肝母细胞的中间阶段。这些化学诱导的肝细胞样细胞（ciHeps）在形态、生物学行为、基因表达模式、标志物表达水平和肝功能方面与成熟的原代肝细胞非常相似。此外，移植的ciHeps可以整合到肝脏中，促进肝脏再生，提高急性肝损伤小鼠的存活率。ciHeps还可以改善慢性损伤引起的肝纤维化，增强肝功能。值得注意的是，ciHeps 在体外或体内均没有表现出致瘤潜力。从机制上讲，SMC 诱导的间充质到上皮的转变和 SNAI1 的抑制有助于成纤维细胞向 ciHeps 的命运转变。这些结果表明，这种无转基因、化学诱导的直接重编程技术有潜力成为生产替代肝细胞的有价值的手段，用于研究和治疗目的。此外，该方法还揭示了化学诱导下其他细胞类型的直接重编程。