In vivo differentiated human embryonic stem cells can acquire chromosomal aberrations more frequently than in vitro during the same period.

Human embryonic stem cells (hESCs) are regarded as a promising approach to generate transplantable cells for the treatment of several diseases. These cells offer an immense potential as a source of cells for regenerative medicine, but the possible ability of these cells to produce tumors in vivo presents a major impediment for the achievement of this potential in clinical reality. hESCs can obtain growth advantages in vitro by acquired mutations, a phenomenon called culture adaptation. The most common chromosome modifications involve chromosomes 12, 17, and X. The mechanisms that may influence chromosome modification in hESCs are not well known. We have performed a comparative in vitro and in vivo study on 3 hESC lines produced in our laboratory to see if there are changes also during in vivo growth. In vivo differentiated cells and in vitro cultured hESCs were analyzed by using a high-resolution Affymetrix SNP 6.0 array revealing DNA copy number variations. We were able, for the first time, to identify c...