A new rabbit model of impaired wound healing in an X-ray-irradiated field.

Radiation is an important therapy for cancer with many benefits; however, its side effects, such as impaired wound healing, are a major problem. While many attempts have been made to overcome this particular disadvantage, there are few effective treatments for impaired wound healing in an X-ray-irradiated field. One reason for this deficiency is the lack of experimental models, especially animal models. We have previously reported a mouse model of impaired wound healing in which the irradiation area was restricted to the hindlimbs. In this mouse model, due to the size of the animal, a diameter of five millimeters was considered the largest wound size suitable for the model. In addition, the transplanted cells had to be harvested from other inbred animals. To investigate larger wounds and the impact of autologous specimen delivery, a rabbit model was developed. Rabbits were kept in a special apparatus to shield the body and hindlimbs while the irradiation field was exposed to radiation. Six weeks after irradiation, a 2 x 2 cm, full-thickness skin defect was made inside the irradiation field. Then, the wound area was observed over time. The wound area after irradiation was larger than that without irradiation at all time points. Both angiogenesis and collagen formation were reduced. For further study, as an example of using this model, the effect of autologous platelet-rich plasma (PRP) was observed. Autologous PRP from peripheral blood (pb-PRP) and bone marrow aspirate (bm-PRP) was processed and injected into the wounds in the irradiated field. Two weeks later, the wounds treated with bm-PRP were significantly smaller than those treated with phosphate buffer vehicle controls. In contrast, the wounds treated with pb-PRP were not significantly different from the controls. This rabbit model is useful for investigating the mechanism of impaired wound healing in an X-ray-irradiated field.