TH and Parkinson disease: Further analysis of the functions of these key genes revealed that iPSC mainly consisted of immune-related key genes, while ESCs had many key genes involved in neural growth and development, such as TH and GAP43. Thus, these results indicated a close association between iPSC and ESCs in improving PD, with ESCs having additional key genes related to neural development compared to iPSC, suggesting that iPSC mainly exerts its effects in improving PD through immune mechanisms.