DNA aneuploidy in porcine bone marrow-derived mesenchymal stem cells undergoing osteogenic and adipogenic in vitro differentiation

In this study, we estimated the distribution of DNA diploidy and aneuploidy in porcine mesenchymal stem cells (pMSCs) that were subjected to osteoblast/osteocyte and adipocyte differentiation to determine the impact of long-term in vitro culture and differentiation on the cell cycle distribution and nuclear DNA profile. This determination could be helpful to confirm or exclude the suitability of physico-chemical culture conditions for the purposes of both the maintenance of an undifferentiated state and to promote differentiation in pMSCs. Flow cytometry was applied to analyze the cell cycle and occurrence of aneuploidy/diploidy, and real-time PCR was used to quantify aP2 and osteocalcin, markers of adipocytes and osteocytes, respectively. The chi-squared test was used to compare the total rates of G0/G1-, S-, and G2/M-phase cell fractions with diploid and aneuploid DNA and the DNA index ratios between three experimental groups of pMSCs. Five weeks of in vitro culture under differentiating conditions resulted in a considerable reduction of DNA stability and a remarkable increase in the rate of cells exhibiting an aneuploid DNA stem line; however, a similar dependence was not found in the nondifferentiated MSCs. Furthermore, the cell fraction rates in each phase of the mitotic cycle and the DNA index (DI) were calculated. The results of real-time PCR for aP2 and osteocalcin proved positive MSC differentiation toward adipocytes and osteocytes. In terms of the possible use of differentiated MSC lines in tissue engineering and regenerative medicine, we propose cytokinetic diagnostics using flow cytometry as an objective and useful method for screening the tumor-forming capacity and malignancy potential of both in vitro long-term cultured MSCs and MSCs subjected to ectopic differentiation.