3.5. Subpopulation Analyses of Suspension Cultures
In suspension cultures, there were no clear subpopulations of cells based on PCA. However, there remained the possibility of hidden subpopulations of cells. We generated histograms of gene expression and found a gene, enolase, that had a multipeak distribution. We divided the individual D4 cells into groups with high enolase expression (giI625221705IrefIXM_003512016.2I; 2000–4200 RPM) and low enolase expression (0–2000 RPM; Figure 5a) and used PCA to analyze these individual D4 cells. The PC1 of the individual D4 cells were plotted against those for PC2. Individual D4 cells with high and low enolase expression formed distinct clusters (Figure 5b), which represents the hidden subpopulations of CHO cells in suspension cultures. This phenomenon is contrary to expectations. Hidden cellular subpopulations such as those found in this study hint at the future discovery of intrinsic factors giving rise to cell-to-cell variability in cell populations.