Figure 1

(A-C) Morphology of undifferentiated colonies of hESC lines I3, I6, and BG01V. Phase contrast photographs of hESC colonies cultured on mouse embryonic fibroblast feeders for 4 days. The boxes in the center of the colonies indicate areas shown in A1-C1. (A1-C1) High magnification of the center regions of the colonies from each cell line showing distinct morphologies. The colonies of BG01V and I6 lines exhibit highly compact cells with rather vague borders (A1 and C1), while I3 colonies have a mosaic appearance with loosely packed cells (B1). Bars in A and A1 = 100 μm. (D) Three human embryonic stem cell lines display distinct growth characteristics under the same culture conditions. The growth curves show significant differences in percent increase in the number of cells at day 6 in culture between the three cell lines. I3 cells grow slower than the other two cell lines and have a tendency to differentiate. Therefore, it is more difficult to maintain the I3 cell line in an undifferentiated state. In contrast, the I6 and BG01V cell lines grow faster and are passaged 2–3 days earlier than the I3 cells. Statistical differences for percent increases in cell numbers at 6 days between the BG01V or I6 and I3 are significant ** p < 0.01.