Keloid animal model establishment

Eighteen healthy male BALB/c nude mice (Charles River, Beijing, China), aged 4–6 weeks, were selected for the experiment. Anesthesia was administered, and an 8-mm incision was made in the scapular area of each nude mouse. Keloid tissues, obtained during surgery, were cut into blocks approximately 4 mm³ in size and implanted in the subcutaneous space of the nude mice. The skin was then sutured to secure the implants. After 21 days, the mice were randomly divided into three groups: control, ³²P isotope injection, and ³²P isotope skin patch. The mice in the group ³²P isotope skin patch were treated using the customized ³²P isotope therapy patch from China Atomic Energy Research Institute, with an effective treatment area of 1.0 cm × 1.0 cm, with a radiation dose of 1.08 cGy/s·cm². 6 layers of tin foil were used to protect the non-irradiated skin, and ³²P isotope therapy was applied to the surface of the skin for 150 s each time. The treatment frequency is once every 2 days, with a total of 10 treatments. The gross morphology and histopathology of keloids were observed after 21 days of continuous injection. The dosage of ³²P isotope was determined based on our pre-experiment and previous report [9].