[Change in characteristics of human mesenchymal stem cells during the in vitro culture -- c-myc gene expression and chromosome aberrations at the c-myc locus].

We investigated mRNA expression of c-myc and chromosome aberrations at the c-myc locus in the same passage number of human mesenchymal stem cells (hMSCs). To understand the sensitivity of mRNA expression and the induction of chromosome aberrations, we first tested them in hMSC and cancer cell lines (HeLa S3, HOS, and OUMS-27). The c-myc mRNA expressions in HeLa S3 and OUMS-27 were significantly higher than those in hMSC, but then those in HOS were not. On the other hand, c-myc aberrant cells detected by fluorescence in situ hybridization in HeLa S3, HOS, and OUMS-27 were significantly higher than that in hMSC. Both analyses were performed in hMSCs derived from five donors for the culture period of 50 days. In hMSCs from one donor, the frequency of c-myc aberrant cells significantly increased at 20 and 50 days respectively, and each mRNA expressions had a tendency to increase, but there is no significant change among 3, 20 and 50 days. In hMSCs from the others, both endpoints did not change for 50 days. For safe use of somatic stem cells in the regenerative medicine, the investigation of characteristic change of them during the in vitro culture is important. In the present study, we showed the mRNA expressions and chromosome aberrations of hMSCs in in vitro culture as the first step for establishing of safety evaluation of tissue engineered medical devices using normal hMSCs.