The experiments involving mice were performed in accordance with the Animal (Scientific Procedures) Act (UK) of 1986 prepared by the Institute of Laboratory Animal Resources and under the auspices of UK Home Office Project and personal licenses. Eight-week-old CD1 male mice underwent surgical induction of unilateral limb ischemia (LI) by performing occlusion of the left femoral artery, as we reported previously.45 Immediately after LI induction, mice received 100 μg of exosomes derived from either PF or plasma into the ischemic adductor muscle, while a control group received PBS (n = 20 mice/group). The superficial blood flow to both ischemic and non-ischemic feet was measured using a high-resolution laser color Doppler imaging system (Moor LDI2, Moor Instruments) at days 0 and 7 after induction of limb ischemia. Blood flow recovery was calculated as a percentage versus day 0 of the control PBS. At day 7, mice under terminal anesthesia were perfusion-fixed successively with 6 mL of 0.05 M EDTA and 10 mL of 10% formalin solution. Limb muscles were harvested and stored in PFA 4% overnight at room temperature then washed with PBS and finally treated with 30% sucrose overnight at 4°C. The tissue samples were then embedded in optical cutting temperature (OCT) compound and stored at −80°C until histological and immunohistochemical analyses. A second set of mice (n = 12 per group) were made ischemic and immediately treated with either PF exosomes or PBS as described above. Doppler analyses were performed at baseline, 7, 14, and 21 days post-ischemia induction. For molecular biology analyses, mice were sacrificed at 3 days after surgery, and the ischemic abductor muscles were dissected and snap-frozen in liquid nitrogen. Total RNA was extracted from snap-frozen muscles as described above.