title: Neoplastic transformation by TERT in FGF-2-expanded human mesenchymal stem cells.
abstract: The low percentage of human mesenchymal stem cells (hMSCs) in bone marrow necessitates their in vitro expansion prior to clinical use in regenerative medicine. We evaluated the effect of long-term culture of hMSCs on telomere length and transformation capacity by TERT transfection. hMSCs were isolated from the bone marrow aspirates of 24 donors and cultured with fibroblast growth factor-2 (FGF-2). Six cell lines with >500 population doubling levels were considered immortalized. TERT was transfected into two of the six lines for a comparison of telomere length, telomerase activity, differential capacity, colony formation capacity in soft agar and tumorigenicity in immunodeficient (NOD-SCID) mice. hMSC lines exhibited elongated telomeres without the activation of telomerase and retained multi-lineage differentiation potential upon chondrogenic or adipogenic differentiation, while non-immortalized hMSCs showed a marked reduction in telomere length in the differentiation process. Immortalized hMSCs showed anchorage-independence and formed tumors in NOD-SCID mice. Histologically, these tumors consisted of differentiated cells such as fat tissue and cartilage. Two TERT-transfected hMSC lines showed high rates of tumor formation in NOD-SCID mice. These tumors were histologically similar to teratocarcinoma without differentiated cells. These cells may provide a model for the origin of cancer stem cells from adult stem cells, and indicate the possibility that telomerase activation has a major role in the malignant transformation of human stem cells. These data suggest that adult hMSCs have a potential for neoplastic transformation and have implications for the use of hMSCs in tissue engineering and regenerative medicine.
authors.affiliation: Natural Science Center for Basic Research and Development, Hiroshima University, Hiroshima, Japan.
authors.forename: Emi
authors.initials: E
authors.lastname: Yamaoka
authors.forename: Eiso
authors.initials: E
authors.lastname: Hiyama
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sotomaru
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Onitake
authors.forename: Ikuko
authors.initials: I
authors.lastname: Fukuba
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sudo
authors.forename: Taijiro
authors.initials: T
authors.lastname: Sueda
authors.forename: Keiko
authors.initials: K
authors.lastname: Hiyama
mesh_terms: D000328:Adult; D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D006801:Humans; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D016513:Mice, SCID; D019098:Telomerase / Q000235:genetics / Q000378:metabolism*; D014183:Transplantation, Heterologous / Q000473:pathology
chemical_list: D016222:Fibroblast Growth Factor 2; D019098:Telomerase