As shown in Fig 3, we found that IDO cell therapy significantly increased the frequency of splenic Tregs from 4.68% ± 1.01% at the onset of diabetes to 9.65% ± 1.04% (p< 0.001) following IDO cell therapy while frequency of Tregs in the control group showed no significant change (3.94% ± 1.00%, P> 0.05) compared to the diabetes onset. The gene discussed is IDO1; the disease is diabetes mellitus.