INTRODUCTION Recently, the possibility that tumors originate from cancer stem cells (CSCs) has been proposed. Stem cells and CSCs share certain features such as self-renewal and differentiation potential. The aim of this study was to evaluate whether bone marrow stromal cells (BMSC) after long-term culture are transformed into malignant cells. MATERIAL AND METHODS BMSC from 6 pigs were isolated and propagated continuously. Cell morphology was observed. Transformation properties were evaluated by means of serum dependence assay, Ki- 67 immunostaining, soft agar colony assay, karyotyping, telomerase activity detection assay and analysis of the expression of p53, Fas and c- Myc genes. Multipotency was investigated by biochemical and histological assays and analysis of gene expression. RESULTS BMSC showed a change in appearance, from the initial spindle shape to a more flatted morphology then to small contact shape. After additional passages, BMSC gradually acquired recovery of proliferating capacity and transformation properties such as anchorage-independent growth, chromosomal abnormality, and abnormal gene expression. The expression of P53 and Fas was decreased, while the expression of c-Myc gene was increased and TGF‚ signaling pathway was upregulated. However, telomerase activity maintained negative during culture. CONCLUSION Porcine BMSC can undergo spontaneous transformation, which provides a useful model to study the mechanisms associated with the tumorigenic potential of adult stem cells.
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European Federation of National Associations of Orthopaedics and Traumatology, 2008