Figure 4.

Lactate-Induced Medium Acidification Induces DNA Damage

(A–D) Alkaline COMET assay shows that the DNA damage increases in hESC growing in medium with increasing lactic acid concentration (A, B) and decreasing pH (C, D) (n = 3, p < 0.05; ANOVA). The results are presented relative to condition L1 and pH1, respectively. L1–L4 and pHA–pHD contain lactic acid concentrations or are acidified to the equivalents of densities A–D, on a cell density equivalent to B. (B) and (D) present the distribution of COMET assay results shown in (A) and (C), respectively, in four groups based on tail DNA per cell.

(E) Summary of the relative increase of DNA fragmentation as measured with alkaline COMET assay in the culture density series (Figure 1B), lactic acid series (A), and pH series (C). The different increases in DNA damage (comparing D, L4, and pH4) are not statistically significantly different (p = 0.86; ANOVA).

All results are presented as mean ± SEM, and presented relative to condition A. Asterisk marks differences with p ≤ 0.05.