Physical plasma-activated irrigation therapy clears biofilm infection and promotes wound healing

Biofilm infection is common in diabetic foot ulcers and other human disorders and affects some 17 million people in the US alone. Sharp debridement is the standard of care, but biofilm reappear in about 10 h and becomes life-threatening after 24 h.

Therefore, development of approaches that disrupt biofilm, inactivate microbial pathogens, and promote wound healing is desirable. In this context, we note that endogenous reactive oxygen and nitrogen species (ROS, RNS) are involved in how biofilm infection is mitigated by mammalian cells.

For example, low-level nitric oxide (NO) initiates the dispersal of in vivo biofilm, macrophages synergies NO, superoxide and other ROS to kill microbial pathogens in phagosome, and NO and hydrogen peroxide (H2O2) promotes wound healing and skin regeneration. Collectively, these suggest an immense opportunity for engineering multi-agent cooperation among diverse ROS and RNS to simultaneously target biofilm dispersal, microbial inactivation and wound healing. In vitro, biofilm activity is improved when H2O2 is combined with superoxide or peroxinitrite using nanoparticles of physical plasma-activated solution (PAS).

However, it is known whether such two-agent cooperation is effective against in vivo biofilm. Here, we report a PAS_based irrigation and dressing therapy with multi-agent cooperation for biofilm infection clearance and accelerated wound healing, With special formulation, this cooperative PAS (c-PAS) substantially disrupts mature MRSA biofilm on glass substrate, achieves 7-log10 reduction of pan drug-resistant P. aeruginosa, and promotes angiogenesis in vitro as shown in tube formation of human umbilical vein endothelial cells.

Using a clinically relevant mouse model of full-thickness dermal wounds with 24-h MRSA biofilm, we show that c-PAS substantially disrupts wound biofilm (SEM and FISH data), attains 3.63-log10 CFU reduction of wound bacteria, and promotes neovascularization and wound healing. For translation, a recent Phase-II clinical study has tested and confirmed the efficacy and safety for treatment of human patients with autoimmune skin disorders, suggesting a clear pathway to regulatory approval. Collectively, our data suggest that c-PAS is viable alternative to current management options for chronically infected wounds.