Objective      To determine the expression profiles and roles of transcription factors Mitf and Pax6 in the differentiation of mouse embryonic stem cells (mESCs) to retinal pigment epithelium (RPE).       Methods      The cell marker of mESCs

SSEA1

was stained with immolunofluorescence and analyzed by fluorescence activated cell sorter (FACS) during the differentiation of ESCs to RPE. The serum-free embryoid body-like (SFEB) culture was performed to induce the differentiation of mESCs into RPE. Flow cytometry was used to analyze RPE precursor markers

Mitf and Pax6

before differentiation (Day 0)

during differentiation (Days 10 and 40).       Results      During the passaging

the morphology of ESCs kept consistent and there was no statistically significant change in the level of embryonic marker SSEA1 (P0.05). RPE-like cells were induced from mESCs by serum-free embryoid body-like method. In 40 d after differentiation

(61.6±2.4)% of cells were Bestrophin positive

(31.0±3.9)% of cells CRALBP positive

and (57.8±2.0)% of cells RPE65 positive. Before differentiation

(1.7±1.5)% of mESCs expressed Mitf and (6.5±0.2)% expressed Pax6. In 10 d after differentiation

(28.5±7.2)% of cells were Mitf positive and (60.2±15.6)% of cells were Pax6 positive. In 40 d after differentiation

(5.7±2.1)% of cells were Mitf positive and (4.6±0.6)% of cells were Pax6 positive.       Conclusion      Both the ratios of Mitf and Pax6 positive cells were raised and then dropped down during differentiation of mESCs to RPE cells， suggesting that Mitf and Pax6 are involved in the differentiation of mESC to RPE.