Exosomes released from adipose tissue mesenchymal stem cells (AT-MSCs) treated obese mice by transmitting and activating signal transducer and activator of transcription 3 (STAT3), Guided M2-type replacement of activated macrophages, improved insulin sensitivity, reduced obesity, and improved hepatic steatosis [52]. The gene discussed is STAT3; the disease is obesity due to melanocortin 4 receptor deficiency.