Embryonic Cell Extracts Ameliorate Wound Healing in Diabetic Mice

Wound healing (WH) is a physiological function in which a balanced inflammatory response is required for tissue regeneration and successful wound closure. In diabetic patients WH is impaired and negatively impacts diabetic individuals in terms of morbidity, mortality and social disability, while the lack of an effective wound care highlights the need for novel therapeutic strategies. Extracts obtained from embryonic stem cells (EXTs) exhibited immunomodulatory properties and we hypothesize that EXTs may improve WH in diabetes. Here we explored the in vitro and in vivo effect of EXTs on WH using the diabetic db/db mouse model. Our data show that in vivo EXT topical administration ameliorates wound closure, contraction and re­epithelization by significantly reducing local inflammation and enhancing angiogenesis as compared to acellular protein extracts from 3T3 fibroblast cells (3T3xt) or no treatment. EXTs increased the percentage of regulatory T cells in the wound in vivo and inhibited T cell activation and IFNγ production in vitro. Db/db­derived dendritic cells exposed to EXTs showed decreased maturation, with downregulation of the costimulatory molecules CD80, CD86 and CD40. On the other hand, in vivo 3T3xt administration caused poorer wound closure with enhanced leucocyte infiltration of wounds and CD80, CD86 and CD40 upregulation on activated dendritic cells both in vivo and in vitro. Finally, proteomic analysis revealed 82 molecular entities differentially segregating in the EXT and 3T3xt group. Following unbiased selection, 10 proteins were filtered and assayed for their immune activity. Apurinic/Apyrimidinic Endodeoxyribonuclease 1 (APEX1) revealed strong immunomodulatory properties at ELISpot analysis by inhibiting IFNγ secretion of human PBMCs. APEX1 may result as the key factor mediating the beneficial effect of EXT on WH. EXTs or acellular extracts with upregulated APEX1 is a tool of remarkable translational potential for a safe, innovative and cost-effective application in the clinic.