Background The increasing prevalence of patients with chronic non-healing wounds complicated by diabetes mellitus in China has become a major public health challenge, owing to persistent disease progression, recurrent infections, and high amputation risks.

Objective To investigate whether plasma-activated liquid (PAL) exhibits therapeutic effects in promoting wound healing in diabetic rats.

Methods In vivo: Forty male Sprague-Dawley (SD) rats were injected intraperitoneally with 50 mg/kg streptozotocin (STZ) to establish diabetic models. Thirty-three successfully modeled rats were randomly divided into blank control group (n=11), topical saline/PAL treatment (wet dressing) group (n=11), and subcutaneous saline/PAL injection group (n=11). Four full-thickness circular wounds (0.8 cm diameter) were created bilaterally along the dorsal midline, with contralateral wounds in treatment groups receiving saline or PAL. Each wound served as an independent experimental unit. Histological staining, collagen quantification, and immunohistochemistry were performed to assess healing progression. In vitro: PAL's antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa was evaluated via agar diffusion assays. Coagulation time was measured using whole blood clotting assays. L929 fibroblast proliferation and migration were analyzed using CCK-8 and scratch assays.

Results In vivo: Both PAL-treated groups exhibited accelerated wound closure and superior granulation tissue maturation. By day 14, collagen content was significantly higher in the topical PAL and subcutaneous PAL groups compared to controls (64.94%±3.09%, 69.93%±2.42% vs 53.69%±0.88%, P < 0.001), with a marked increase in the type Ⅰ/Ⅲ collagen ratio. Immunohistochemistry revealed suppressed IL-6 (P < 0.001) and elevated IL-10 (P < 0.001) expression in PAL groups on day 3. By day 10, PAL-treated wounds demonstrated upregulated α-SMA and VEGF (P < 0.05) and enhanced CD31 immunofluorescence, indicating robust angiogenesis and transition to scar formation. In vitro: PAL exhibited potent bactericidal activity (clear inhibition zones), significantly shortened coagulation time (P < 0.001), and stimulated L929 proliferation (P < 0.05) and migration (P < 0.05).

Conclusion PAL exhibits certain antibacterial, procoagulant, and cell migration- and proliferation-promoting properties, and can facilitate the healing of diabetic wounds.