Bioengineered probiotics derived bacterial extracellular vesicle as bioactive nanocarrier for the local VEGF expression to accelerate wound healing

The angiogenesis is a pivotal process during wound healing. Its deficiency usually causes diminished oxygen and nutrient conveyance, compromising the cell function and decelerating the wound closure. Since being identified as the potent stimulator of angiogenesis, vascular endothelial growth factor (VEGF) has been explored as the leading therapeutic candidate. To overcome its inherent instability, both recombinant proteins and gene therapies have been proposed. Nonetheless, evidences of their therapeutic benefits for wound healing were limited. Over the past decades, bacterial extracellular vesicles (BEVs) have been recognized as versatile bioactive nanocarriers for the cross-kingdom communication. Herein, BEV derived from the recombinant probiotics Escherichia coli Nissle 1917 (BEV-pVEGF) was bioengineered to deliver the shuttle plasmid encoding VEGF. The BEV-pVEGF was proven could facilitate the intracellular delivery and local expression of the exogenous pVEGF, promoting the proliferation, migration, and angiogenesis of the endothelial HUVEC. Moreover, it was also proven to enable the intracellular delivery of the endogenous miR-21-5p, activating the PI3K-AKT signaling pathway and expediting the proliferation and migration of the epidermal HaCaT. Upon its subcutaneous administration for 7 consecutive days, the vascularized granulation tissue formation and re-epithelialized wound closure were significantly accelerated on mice bearing full-thickness wounds, with no obvious immunogenicity and toxicity being detected. These bioengineered BEV-pVEGF nanocarriers provide a readily-available, mass-producible, and cost-effective approach to developed effective and safe therapeutic modality for the future wound management.