title: Clonal heterogeneity in differentiation potential of immortalized human mesenchymal stem cells.
abstract: Mesenchymal stem cells (MSCs) are bone marrow stroma-derived cells, which can differentiate into several types of mesenchymal tissues. Although regarded as tissue-specific stem cells, human MSCs (hMSCs) have a low proliferative ability with a finite life span, which is a hurdle to further analysis of their biology. Here we attempted to establish immortalized hMSCs by retrovirus-mediated gene transfer. The gain in telomerase activity obtained on expression of human telomerase reverse transcriptase (hTERT) was found not to be enough to make the cell line immortal. A combination of hTERT with human papillomavirus E6 and E7 successfully immortalized hMSCs without affecting the potential for adipogenic, osteogenic, and chondrogenic differentiation. From the parental immortalized hMSC, 100 single-cell derived clones were established, of which the differentiation properties varied considerably, including tri-, bi-, and uni-directional clones, suggesting that hMSCs are constituted by a group of cells with different differentiation potential. These cell lines, being the first established immortalized clonal cell lines of hMSCs, could provide insights into the mechanisms regulating the early steps of differentiation from undifferentiated MSCs into a specific lineage.
authors.affiliation: Department of Tissue Regeneration, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8057, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Okamoto
authors.forename: Tomoki
authors.initials: T
authors.lastname: Aoyama
authors.forename: Tomitaka
authors.initials: T
authors.lastname: Nakayama
authors.forename: Takeharu
authors.initials: T
authors.lastname: Nakamata
authors.forename: Taisuke
authors.initials: T
authors.lastname: Hosaka
authors.forename: Koichi
authors.initials: K
authors.lastname: Nishijo
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakamura
authors.forename: Tohru
authors.initials: T
authors.lastname: Kiyono
authors.forename: Junya
authors.initials: J
authors.lastname: Toguchida
mesh_terms: D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002454:Cell Differentiation; D002461:Cell Line, Transformed; D017931:DNA Primers; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009368:Neoplasm Transplantation; D012190:Retroviridae / Q000235:genetics; D013234:Stem Cells / Q000166:cytology*; D014162:Transfection
chemical_list: D017931:DNA Primers