Figure 2. Apoptosis of culture-activated HSCs by superoxide.

Rat HSCs were cultured and used in passage 3. After the cells had achieved semiconfluence, they were subjected to superoxide challenge (1 mM hypoxanthine + 2 mU/ml xanthine oxidase). Control cells were incubated in the presence of hypoxanthine alone. After 24 hours, photomicrograph was taken. Note that superoxide-challenged cells have shrunk, and several have already undergone apoptosis. Magnification ×100.