The experiments involving mice were performed in accordance with the Animal (Scientific Procedures) Act (UK) 1986 prepared by the Institute of Laboratory Animal Resources and covered under the UK Home Office Project license PPL/30/3373. The functional impact of PF- and plasma-derived exosomes on treatment of CD1-ischemic mice was assessed by measuring capillary density in the adductor muscle. Eight-micrometer-thick muscle sections were stained using biotin-conjugated Isolectin B4 (from Griffonia Simplicifolia; Thermo Fisher Scientific) and streptavidin-conjugated Alexa 488 (Thermo Fisher Scientific) antibodies to detect capillaries. Nuclei were stained with DAPI (4′,6-diamidino-2-phenylindole). The slides were mounted using Fluoromount-G (eBioscience). The relative number of positive cells was counted in eight randomly selected high-power fields (magnification 20×) using a Zeiss inverted fluorescence microscope. Analyses were performed using muscles from eight mice per group. Capillary density was expressed as number per square millimeter.