The liver is supplied by a dual blood supply, including the portal venous system and the hepatic arterial system; thus, the liver organ is exposed to multiple gut microbial products, metabolic products, and toxins; is sensitive to extraneous pathogens; and can develop liver failure, liver cirrhosis and hepatocellular carcinoma (HCC) after short-term or long-term injury. Although liver transplantation (LT) serves as the only effective treatment for patients with end-stage liver diseases, it is not very popular because of the complications and low survival rates. Although the liver is generally termed an immune and tolerogenic organ with adaptive systems consisting of humoral immunity and cell-mediated immunity, a high rejection rate is still the main complication in patients with LT. Growing evidence has shown that mesenchymal stromal cell (MSC) transplantation could serve as an effective immunomodulatory strategy to induce tolerance in various immune-related disorders. MSCs are reported to inhibit the immune response from innate immune cells, including macrophages, dendritic cells (DCs), natural killer cells (NK cells), and natural killer T (NKT) cells, and that from adaptive immune cells, including T cells, B cells and other liver-specific immune cells, for the generation of a tolerogenic microenvironment. In this review, we summarized the relationship between LT and immunoregulation, and we focused on how to improve the effects of MSC transplantation to improve the prognosis of LT. Only after exhaustive clarification of the potential immunoregulatory mechanisms of MSCs in vitro and in vivo can we implement MSC protocols in routine clinical practice to improve LT outcome.

中文翻译：

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间充质干细胞的免疫调节在改善肝移植的预后中起着至关重要的作用。

肝脏由双重血液供应，包括门静脉系统和肝动脉系统。因此，肝脏器官暴露于多种肠道微生物产物，代谢产物和毒素。对外来病原体敏感；短期或长期伤害后可能发展为肝功能衰竭，肝硬化和肝细胞癌（HCC）。尽管肝移植（LT）是晚期肝病患者唯一有效的治疗方法，但由于并发症和生存率低，它并不十分流行。尽管通常将肝脏称为具有适应性系统（包括体液免疫和细胞介导的免疫）的免疫和致耐受性器官，但高排斥率仍然是LT患者的主要并发症。越来越多的证据表明，间充质基质细胞（MSC）移植可以作为一种有效的免疫调节策略，以诱导对各种免疫相关疾病的耐受性。据报道，MSC可抑制先天免疫细胞（包括巨噬细胞，树突状细胞（DC），自然杀伤细胞（NK细胞）和自然杀伤性T（NKT）细胞）和适应性免疫细胞（包括T细胞）的免疫应答， B细胞和其他肝脏特异性免疫细胞，用于产生耐受性微环境。在这篇综述中，我们总结了LT与免疫调节之间的关系，并集中于如何改善MSC移植的效果以改善LT的预后。