Bacterial extracellular vesicles as bioactive nanocarriers for wound treatment

Bacterial extracellular vesicles (BEVs) secreted by bacteria are considered as messengers for the crosstalk between gut microbiota and wounded skin via the "gut-skin axis". The BEVs with the lipid bilayer nanostructures can deliver various bioactive molecules from their parent bacteria to the host cells, modulating the signal pathways related to wound repair and regeneration. Besides, the cutting-edge gene editing strategies and mature bacterial culture methods further endowed their more customizable and scalable manufacture compared to the most commonly used extracellular vesicles from mammalian cells. Therefore, more and more BEVs have been exploited directly as bioactive nanocarriers or engineered as delivery vehicles for wound treatment. Herein, the present review began with an overview of the gut-skin axis to better comprehend the bioactivates of BEVs towards wound healing. Their biogenesis, isolation, and uptake were then introduced. A summary of recent advancements in exploring BEVs for accelerated wound healing was followed, with a focus on their roles as nanocarriers for delivery. Diverse engineering approaches to functionalize BEVs were especially discussed for optimal wound management. Constructive insights regarding the new upsurge of BEVs for wound treatment were provided in the end to boost these innovative therapeutic modalities from bench to bedside.