IL4R and systemic sclerosis: It has further been documented that miR-151-5p secreted within exosomes by donor MSCs can be transferred to endogenous MSCs in systemic sclerosis mice to inhibit interleukin 4 receptor α (IL4Rα) expression and block mammalian target of rapamycin (mTOR) pathway activation, which rescues endogenous MSC functional defects in treating osteoporosis81.