FIGURE 5.

Human Treg EVs protect against alloimmune mediated human skin allograft damage. BALB/c Rag2^–/–γc^–/– mice were transplanted with human skin and 6 weeks later mice were reconstituted with 5 × 10⁶ allogenic CD4⁺25^– T cells plus polyclonal 1 × 10⁶ Tregs or Treg EVs derived from 50 × 10⁶ Tregs. Control mice received saline only or control EVs (media EVs). Human skin grafts were removed 5 weeks post-injection, and cryopreserved sections were fixed and stained for human CD45/Ki67/DAPI (A), or CD31/involucrin/DAPI (A). Representative images of human skin graft sections with the various treatments are shown. (B) Quantification of the number of human CD45⁺ cells and Ki67⁺ keratinocytes cells per field of view was performed using NIS Elements and FIJI imaging software. Results represent 3–9 mice per group where four to six fields of view were quantified per section and data are representative of 5 individual experiments. Statistical significance was tested using one-way ANOVA and Turkey multiple comparison post hoc test where *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001, and ns, non-significant. DAPI, 4’,6-diamidino-2-phenylindole.