Inducible immortality in hTERT-human mesenchymal stem cells

• Published in: Journal of orthopaedic research Vol. 30; no. 12; pp. 1879 - 1885
• Main Authors: Piper, Samantha L., Wang, Miqi, Yamamoto, Akira, Malek, Farbod, Luu, Andrew, Kuo, Alfred C., Kim, Hubert T.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.12.2012
• Subjects: Adipogenesis; Adult; Bone Marrow Cells - cytology; Cell Culture Techniques - methods; Cell Differentiation; Cell Proliferation; Cellular Senescence; Chondrogenesis; Doxycycline - pharmacology; Gene Expression Regulation; Humans; immortalized; Male; mesenchymal stem cell; Mesenchymal Stromal Cells - metabolism; multipotential; Osteogenesis; Plasmids - metabolism; Stem Cells - cytology; telomerase; Telomerase - genetics; Telomerase - metabolism; Telomere - ultrastructure; Tissue Engineering - methods
• ISSN: 0736-0266; 1554-527X
• DOI: 10.1002/jor.22162

Human mesenchymal stem cells (hMSCs) are attractive candidates for tissue engineering and cell‐based therapy because of their multipotentiality and availability in adult donors. However, in vitro expansion and differentiation of these cells is limited by replicative senescence. The proliferative capacity of hMSCs can be enhanced by ectopic expression of telomerase, allowing for long‐term culture. However, hMSCs with constitutive telomerase expression demonstrate unregulated growth and even tumor formation. To address this problem, we used an inducible Tet‐On gene expression system to create hMSCs in which ectopic telomerase expression can be induced selectively by the addition of doxycycline (i‐hTERT hMSCs). i‐hTERT hMSCs have inducible hTERT expression and telomerase activity, and are able to proliferate significantly longer than wild type hMSCs when hTERT expression is induced. They stop proliferating when hTERT expression is turned off and can be rescued when expression is re‐induced. They retain multipotentiality in vitro even at an advanced age. We also used a selective inhibitor of telomere elongation to show that the mechanism driving immortalization of hMSCs by hTERT is dependent upon maintenance of telomere length. Thanks to their extended lifespan, preserved multipotentiality and controlled growth, i‐hTERT hMSCs may prove to be a useful tool for the development and testing of novel stem cell therapies. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1879–1885, 2012