The impaired healing of irradiated skin wounds is a noteworthy clinical issue that poses a challenge to the widespread use of radiation therapy. Despite numerous attempts to treat this condition, it is still deemed an intractable wound. Innovative treatment approaches are therefore necessary to tackle the wound complications in irradiated areas.
<br>To promote rapid regeneration of skin wounds, activation of re-epithelialization by keratinocytes migration as leading cells is crucial in the early stages of injury. Plasma medicine has been known to have beneficial effect in wound healing. We conducted in vitro and in vivo experiments to elucidate the action and underlying molecular mechanism of novel microwave plasma-activated water (PAW) on promoting skin cell migration. The study also demonstrated that increased intracellular reactive oxygen species (ROS) level played a role as driving force in activating cell migration, which was controlled by oxidases and mitochondria. To explore the additional advantageous effect of PAW on wound healing, the study assessed the antibacterial properties of PAW against major pathogens. PAW showed high competence in sterilizing bacteria and posed no harm to healthy skin cells. The mediators of sterilization in PAW were investigated by loss of function test.
<br>Finally, the study utilized PAW to treat a composite gel made of silk fibroin and fibrin (S-F) to examine whether the controlled release of PAW from the S-F hydrogel could trigger beneficial cellular responses in a radiotherapy-related skin wound while also modifying the microstructure of the S-F hydrogel, thereby functioning as biomaterials establishing regenerative microenvironment. The scanning electron microscopy and Fourier-transform infrared spectroscopy analyses demonstrated that the application of PAW modified both the microstructure and chemical bonds of the S-F gel, which indicated that PAW enhanced the mechanochemical properties of the S-F gel. Wound healing assays and immunofluorescence staining revealed that treatment of the PAW treated S-F hydrogel led to favorable improvements in cell viability, morphology, and extracellular matrix depositions, which are crucial for the regenerative process of the wound. Using six-week-old C57/BL6 mice, we developed an irradiated skin-flap murine model with S-F hydrogel placing underneath the raised skin flap. In postoperative analysis of the flap tissue suggested that compared to the groups treated with S-F hydrogel only or control, the PAW-treated S-F hydrogel significantly enhanced wound regeneration and reduced the inflammatory response.
<br>Taken together, our study demonstrated that PAW-treated S-F hydrogel as a novel material that can considerably improve irradiated wound restoration by effectively promoting re-epithelialization without damaging epithelial cells by selective cytotoxicity. The additional antimicrobial effect and improvement of the regenerated tissue quality are expected to alleviate chronic radiated tissue distortion and subsequent clinical complications.