Abstract
Age related bone loss is one of the most prevalent diseases in the elder population. The osteoblasts are the effectors cells of bone formation and regeneration. With the aging the osteoblasts become senescent reducing their ability to produce bone. Cellular replicative senescence is triggered by telomers shortening. Telomerase elongate the telomers length and maintain the cell proliferative capacity. Here, we demonstrated that the expression of human telomerase reverse transcriptase mediated by an adenovirus vector increases the levels of osteopontin and osteocalcin mRNA during the in vitro osteogenic differentiation of elderly human mesenchymal stem cells. Bone marrow human mesenchymal stem cells were obtained from old donors (>65 years) and induced to differentiate into osteoblasts for 14 days. The levels of mRNA of human telomerase reverse transcriptase, osteopontin and osteocalcin during the differentiation were assessed by semi-quantitative PCR before and during the differentiation on days 7 and 14. Infected cells showed 1.5 fold increase in telomerase expression. Also telomerized cells exhibit 1.5 fold increase in osteopontin and 0.5 fold increase in osteocalcin expression compared to primary osteoblasts isolated from the same donors. The transformed cells were not able to form tumours in NUDE mice.
Highlights
Introduction whose function is to maintain the balance between deposition and re-absorption of Osteoporosis is one of the most prevalent diseases in the elder population
As it can be observed in the figure 3, the osteoblasts infected by Ad-hTERT were expressing telomerase and, as expected, non-infected osteoblasts were not
In the present study we demonstrate hTERT has a strong influence on the levels of osteopontin and osteocalcin mRNA during the osteogenic differentiation
Summary
Introduction whose function is to maintain the balance between deposition and re-absorption of Osteoporosis is one of the most prevalent diseases in the elder population. Studies on mice have shown that age-related osteoporosis is the result of impaired osteoblast differentiation associated with cell senescence of mesenchymal stem cells[3]. In old donors where the aging process results in an intrinsic increase in bone marrow fat followed by a reduction in the number of marrow cells, the number of mesenchymal stem cells is compromised. This problem can be overcome by the ex vivo expansion of donor’s cells until they reach an amount necessary for clinical applications. We show that the ectopic expression of hTERT promotes increase of osteopontin and osteocalcin levels during the osteogenic differentiation of human mesenchymal stem cells from old donors
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