TGFB1 and Leigh syndrome: It has been found that HUCMSC-EVs can carry miR-146a-5p to promote spinal cord functional recovery by targeting neurotoxic astrocytes, which is critical for the repair of chronic spinal cord injury in LSS.[100] Cheng et al[101] for the first time, used HUCMSC-EVs as a vehicle to deliver 2 miRNAs, miR-146a-5p and miR-221-3p, to inhibit LFH by suppressing the TGF-β/SMAD4 signaling pathway.