Replicative Aging and Gene Expression in Long-Term Cultures of Human Bone Marrow Stromal Cells

Abstract

Bone marrow stromal cells (BMSCs) can be easily isolated from adult marrow and contain a population of pluripotent progenitors that can give rise to different mesenchymal lineages both in vitro and in vivo. These properties make BMSCs an attractive target for cell-based therapeutic strategies for a variety of disorders. However, because of their low frequency in vivo, to obtain a sufficient number of cells for tissue engineering a step of extensive in vitro expansion is required, which could significantly alter BMSC properties. Therefore, effective therapeutic use of BMSCs requires the design of appropriate approaches for in vitro cell expansion. In this study we have investigated the biological effects of in vitro expansion on BMSC proliferative ability and on their spontaneous differentiation. Telomerase activity and telomere shortening kinetics were evaluated together with variations in osteogenic, chondrogenic, and adipogenic gene expression throughout the BMSC life span. In culture BMSCs never displayed telomerase activity and during in vitro expansion telomere length decreased. Furthermore, gene expression patterns spontaneously varied during expansion, indicating a progressive commitment of the population toward the osteogenic lineage. In conclusion, BMSCs in culture undergo progressive replicative aging and osteogenic differentiation. These observations are relevant to their successful use in clinics and should be considered when designing novel therapeutic strategies.

Improved lentiviral transduction of human mesenchymal stem cells for therapeutic intervention in pancreatic cancer

“…The lower proliferation rate was associated with the onset of senescence, characterized by telomere shortening as described in previous studies using MSC. 40 This senescence might have led to reduced proliferation in culture, which was previously shown to diminish transgene (eGFP) expression in other cell populations containing adult stem cells, such as neural stem cells. 41 These results suggest that the transgene, in our case the eGFP marker gene, rather than the LV vector itself, induced earlier senescence of MSC.…”

Bone tissue engineering: A review in bone biomimetics and drug delivery strategies

“…The first and most significant barrier is that a number of studies have shown that MSCs which have been extensively cultured ex vivo lose their phenotypic behavior (such as osteodifferentiation and bone forming capacity) once implanted in vivo. 33,44,45 Secondary challenges confronted in this approach are related to the relative low concentration of MSCs in bone marrow and their characteristic low proliferative capacity making it difficult to obtain sufficient cell density in a large scaffold. 46,47 In addition to the increased risk due to a second surgery, there is a need to establish rigorous sterilization techniques for the cell-seeded scaffold which has been in culture ex vivo for up to several weeks.…”

Local signals in stem cell-based bone marrow regeneration

“…There appears to be significant heterogeneity in normal individuals in the ability of MSC to expand in culture and to maintain multipotentiality [18][19][20]. The number of putative MSCs decreases markedly in aging [21,22]. Therefore, MSCs undergo two parallel and probably interdependent processes during prolonged cultivation.…”