Submitted on April 30, 2007
Accepted on September 7, 2007
A role of Wnt/
-catenin signals in hepatic fate specification of human umbilical cord blood-derived mesenchymal stem cells
Yoko Yoshida1, Takashi Shimomura1, Tomohiko Sakabe1, Kyoko Ishii1, Kazue Gonda1, Saori Matsuoka1, Yumi Watanabe1, Kazuko Takubo2, Hiroyuki Tsuchiya1, Yoshiko Hoshikawa1, Akihiko Kurimasa1, Ichiro Hisatome3, Taro Uyama4, Masanori Terai5, Akihiro Umezawa5, and Goshi Shiota1*
1 Deprt of Genetic Medicine and Regenerative Therapeutics, Tottori University, Yonago, Japan
2 Department of Oral and Maxillofacial Biopathological Surgery, Tottori University, Yonago, Japan
3 Regenerative Medicine and Therapeutics, Tottori University Graduate School of Medical Science, Yonago, Japan
4 Department of Reproductive Biology and Pathology, National Reseach Institute for Child Health and Development, Tokyo, Tokyo, Japan
5 Department of Reproductive Biology and Pathology, National Reseach Institute for Child Health and Development, Tokyo, Japan
* To whom correspondence should be addressed. E-mail: gshiota{at}grape.med.tottori-u.ac.jp.
Human umbilical cord blood-derived mesenchymal stem cells (UCBMSCs) are expected to to be an excellent source of cells for transplantation. In addition, the stem cell plasticity of human UCBMSCs, which can transdifferentiate into hepatocytes, has been reported. However, the mechanisms involved remain to be clarified. To identify the genes and/or signals that are important in specifying the hepatic fate of human UCBMSCs, we analyzed gene expression profiles during the hepatic differentiation of UCBTERT-21 cells, UCBMSCs immortalized by infection with a retrovirus carrying telomerase reverse transcriptase (hTERT), but whose differentiation potential remains unchanged. Efficient differentiation was induced by 5-azacytidine/HGF/OSM/FGF2 treatment in terms of function as well as protein expression: 2.5-fold increase in albumin, 4-fold increase in CCAAT enhancer-binding protein 
(C/EBP , 1.5-fold increase in cytochrome p450 1A1/2 (CYP1A1/2), and 8-fold increase in periodic acid-schiff (PAS) staining. Consequently, we found that the expression of Wnt/
-catenin-related genes down-regulated, and the translocation of -catenin was observed along the cell membrane and in the cytoplasm, although some -catenin was still in the nucleus. Down-regulation of Wnt/-catenin signals in the cells by Fz8-siRNA treatment, which was analyzed with a Tcf4 promoter-luciferase assay, resulted in similar hepatic differentiation to that observed with 5-azacytidine/HGF/OSM/FGF2. In addition, the subcellular distribution of -catenin was similar to that of cells treated with 5-azacytidine/HGF/OSM/FGF2. In conclusion, the suppression of Wnt/-catenin signaling induced the hepatic differentiation of UCBMSCs, suggesting that Wnt/-catenin signals play an important role in the hepatic fate specification of human UCBMSCs.
