TGFB1 and Parkinson disease: Based on scRNA-seq, ATAC-seq combined with ISO-seq analysis, and a functional assay, we found that improvement in the neuroinflammatory response, as well as recovery of neural function upon exposure to hOM-MSCs, are at least partially mediated by TGF-β1 in the SN of PD through the activation of the ALK-PI3K-Akt signaling pathway in microglia.