title: Reconstituting telomerase activity using the telomerase catalytic subunit prevents the telomere shorting and replicative senescence in human osteoblasts.
abstract: The rate of bone formation is largely determined by the number of osteoblasts, which in turn is determined by the rate of replication of progenitors and the life span of mature cells, reflecting the timing of death by apoptosis. However, the exact age-dependent changes of the cellular activity, replicative potential, and life span of osteoblasts have not been investigated to date. Here, we present evidence that the cellular activity, telomere lengths, and replicative life span of osteoblastic cells obtained from juxta-articular bone marrow gradually decrease with the advance of donor age. Recently, telomerase reverse transcriptase (hTERT) has been identified as a human telomerase catalytic subunit. We transfected the gene encoding hTERT into telomerase-negative human osteoblastic cells from donors and osteoblastic cell strain NHOst 54881 cells and showed that expression of hTERT induces telomerase activity in these osteoblastic cells. In contrast to telomerase-negative control cells, which exhibited telomere shortening and senescence after 10-15 population doublings, telomerase-expressing osteoblastic cells had elongated telomere lengths and showed continued alkaline phosphatase activity and procollagen I C-terminal propeptide (PICP) secretion for more than 30 population doublings. These results indicate that osteoblasts with forced expression of hTERT may be used in cell-based therapies such as ex vivo gene therapy, tissue engineering, and transplantation of osteoblasts to correct bone loss or osteopenia in age-related osteoporotic diseases.
authors.affiliation: Department of Orthopedic Surgery, Toyama Medical and Pharmaceutical University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yudoh
authors.forename: H
authors.initials: H
authors.lastname: Matsuno
authors.forename: F
authors.initials: F
authors.lastname: Nakazawa
authors.forename: R
authors.initials: R
authors.lastname: Katayama
authors.forename: T
authors.initials: T
authors.lastname: Kimura
mesh_terms: D000368:Aged; D000375:Aging / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D000469:Alkaline Phosphatase / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics; D020134:Catalytic Domain; D002455:Cell Division; D002478:Cells, Cultured; D004268:DNA-Binding Proteins; D005260:Female; D015870:Gene Expression; D006801:Humans; D008297:Male; D008875:Middle Aged; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D015675:Osteocalcin / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D011347:Procollagen / Q000378:metabolism; D016601:RNA-Binding Proteins; D019098:Telomerase / Q000235:genetics / Q000378:metabolism*; D016615:Telomere / Q000502:physiology*; D014019:Tissue Donors; D014162:Transfection
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D010446:Peptide Fragments; D011347:Procollagen; D016601:RNA-Binding Proteins; C104342:TEP1 protein, human; C042813:procollagen type I carboxy terminal peptide; D015675:Osteocalcin; D019098:Telomerase; D000469:Alkaline Phosphatase