Long-term expansion enhances the expression of tumor suppressor genes in human bone marrow-derived mesenchymal stem cells

Abstract

Introduction: Mesenchymal stem cells (MSCs) are possibly the most potent type of stem cells for the treatment of many diseases since they possess many advantageous properties, such as abundant source, ease of isolation, and potential to differentiate and trans-differentiate into different types of cells. Although the therapeutic potential of expanded MSCs has been well proven, their biosafety features have not been fully understood. This study aimed to investigate some changes in phenotype and gene expression of bone marrow derived MSCs after long term expansion. Methods: In this study, expanded mesenchymal stem cells derived from human bone marrow (hBMSCs) were identified for their characteristics (which included morphology, immunophenotype, and differentiation potential) at passages 5, 10 and 15. Moreover, they were evaluated for the expression of various tumor suppressor genes (PTEN, p16, and p53) by real-time RT-PCR. Results: The results showed that the hBMSCs at passage 15 displayed a change in morphology and a slight reduction of the expression of CD44 and CD90, whereas their potential for adipogenic and osteogenic differentiation was maintained. Moreover, the expression of tumor suppressor genes in the hBMSCs increased after long-term culture. Conclusion: It could be assumed that prolonged cultures of more than 15 passages drove the hBMSCs into senescence phase. Cultured hBMSCs below passage 10 seemed to be more effective in application because their properties were still preserved.