Molecular Phenotyping of Telomerized Human Bone Marrow Skeletal Stem Cells Reveals a Genetic Program of Enhanced Proliferation and Maintenance of Differentiation Responses

Abstract

Long‐term in vitro expansion of bone marrow stromal (skeletal) stem cells (also known as human mesenchymal stem cells [hMSC]) is associated with replicative senescence and impaired functions. We have previously reported that telomerization of hMSC through hTERT overexpression led to bypassing a replicative senescence phenotype and improved in vitro and in vivo functions. However, the molecular consequence of telomerization is poorly characterized. Thus, we compared the molecular phenotype of a well‐studied telomerized hMSC (hMSC‐TERT) cell line with primary hMSC. At a cellular level, both cell populations exhibited strong concordance for the known hMSC CD markers, similar responses to osteoblast (OB) differentiation induction, and formed heterotopic bone in vivo. Overall gene expression was highly correlated between both cell types with an average Pearson's correlation coefficient (R2) between the gene expression of all primary hMSC and all hMSC‐TERT samples of 0.95 (range 0.93–0.96). Quantitative analysis of gene expression of CD markers, OB cell markers, and transcription factors (TF) showed a high degree of similarity between the two cell populations (72%, 77%, and 81%, respectively). The hMSC‐TERT population was enriched mainly for genes associated with cell cycle and cell cycle signaling when compared with primary hMSC. Other enrichment was observed for genes involved in cell adhesion and skeletal system development and immune response pathways. Interestingly, hMSC‐TERT shared a telomerization signature with upregulation of cancer/testis antigens, MAGE, and PAGE genes. Our data demonstrate that the enhanced biological characteristics of hMSC after telomerization are mainly due to enhanced expression of cell proliferation genes, whereas gene expression responses to differentiation are maintained. © 2018 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research

Metabolic Glycoengineering in hMSC-TERT as a Model for Skeletal Precursors by Using Modified Azide/Alkyne Monosaccharides

“…A possibility to overcome these problems is to use an appropriate cell line, for example telomerase-immortalized human mesenchymal stromal cells (hMSC-TERT). The overexpression of telomerase overrides replicative senescence and the cells display a high proliferation rate while maintaining their mesenchymal differentiation capacity [ 4 ]. Therefore, hMSC-TERT are a suitable in vitro model for primary hMSC and can be used to establish standardized methods.…”

Molecular Mechanisms Contributing to Mesenchymal Stromal Cell Aging

“…In accordance to progressive telomere shortening, telomerization of human MSCs through hTERT (human telomerase reverse transcriptase) overexpression allows to bypass the replicative senescence phenotype and to improve in vitro and in vivo functions, while maintaining the cellular phenotype [172]. This was also observed by Trachana et al [173] by exposing MSCs overexpressing hTERT to acute oxidative stress.…”

Notch Signaling Inhibition by LY411575 Attenuates Osteoblast Differentiation and Decreased Ectopic Bone Formation Capacity of Human Skeletal (Mesenchymal) Stem Cells

“…hBMSC-TERT was created through an overexpression of the human telomerase reverse transcriptase (hTERT) gene. hBMSC-TERT expresses typical characteristics of primary hBMSC including stemness markers, multipotency, and molecular signature of global gene expression [13–16].…”