Tatsumi Kohei, Ohashi Kazuo, Mukobata Shigeki, Kubo Atsushi, Koyama Fumikazu, Nakajima Yoshiyuki, Shima Midori, Okano Teruo
Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University , Shinjuku, Tokyo , Japan.
† First Department Medicine, Nara Medical University , Kashihara, Nara , Japan.
Cell Med. 2012 May 14;3(1-3):25-31. doi: 10.3727/215517912X639496. eCollection 2012 Jan.
Coagulation factor IX (FIX) is synthesized by hepatocytes, and the lack of this protein causes hemophilia B. Liver nonparenchymal cells, including liver sinusoidal endothelial cells (LSECs) and extrahepatic cells in the body, are scarcely shown to have an ability to synthesize and secrete FIX. The present study investigated the existence of cells responsible for synthesizing FIX other than hepatocytes in mice using gene expression analyses and FIX-specific clotting assays. Among the several organs investigated, including liver, lung, spleen, kidney, brain, intestine, and tongue, FIX mRNA expressions were observed only in the liver. From the liver, hepatocytes and LSECs were isolated. FIX mRNA expression and FIX protein secretion were observed exclusively in the hepatocytes. Furthermore, the clotting activity of FIX secreted from the cultured hepatocytes was found to be dependent on the concentration of vitamin K. These findings indicated that the hepatocyte is the only cell type that biochemically produces functional FIX in vivo. This highlights the importance of hepatocytes or cells that are fully differentiated toward the hepatic lineage for possible application for regenerative medicine and for targeting gene delivery to establish new cell-based treatments for hemophilia B.
凝血因子IX（FIX）由肝细胞合成，缺乏这种蛋白质会导致B型血友病。包括肝窦内皮细胞（LSEC）和体内肝外细胞在内的肝脏非实质细胞几乎没有合成和分泌FIX的能力。本研究利用基因表达分析和FIX特异性凝血试验，研究了小鼠体内除肝细胞外负责合成FIX的细胞的存在情况。在所研究的几个器官中，包括肝脏、肺、脾脏、肾脏、大脑、肠道和舌头，仅在肝脏中观察到FIX mRNA表达。从肝脏中分离出肝细胞和LSEC。仅在肝细胞中观察到FIX mRNA表达和FIX蛋白分泌。此外，发现培养的肝细胞分泌的FIX的凝血活性取决于维生素K的浓度。这些发现表明，肝细胞是体内唯一能生化产生功能性FIX的细胞类型。这突出了肝细胞或向肝谱系完全分化的细胞对于再生医学的可能应用以及靶向基因递送以建立B型血友病新的基于细胞的治疗方法的重要性。
