Prophylactic Application of Human Adipose Tissue–Derived Products to Prevent Radiation Disorders

Background: Radiation therapy is a mainstay treatment for malignancies, but it can induce deterministic adverse effects in surrounding healthy tissues, including atrophy, fibrosis, ischemia, and impaired wound healing. This exploratory study investigated whether prophylactic administration of products containing adipose tissue–derived stem cells immediately after radiotherapy could prevent the development of long-term functional disorders in irradiated tissues. Methods: A total irradiation dose of 40 Gy (10 Gy, four times weekly) was delivered to the dorsal skin of nude mice. Subsequently, a prophylactic treatment with vehicle, fat tissue, stromal vascular fraction, or micronized cellular adipose matrix was injected subcutaneously into the irradiated area. Six months after these prophylactic treatments, a cutaneous punch wound was created to evaluate histologic changes and wound healing. Results: Histologic assessments demonstrated dermal thickening, atrophy, and increased collagen deposits in the subcutaneous fatty layer 6 months after radiotherapy. In addition, wound healing was significantly delayed. The prophylactic treatments with three different types of human adipose tissue–derived products significantly prevented radiation-induced histologic changes and accelerated wound healing compared with the vehicle-treated irradiated group. Conclusions: This is the first study to demonstrate potential for prophylactic treatments after radiotherapy, which could prevent the progression of chronic radiation therapy disorders. The results could have a substantial impact on current anticancer radiotherapies; a next-generation radiation therapy may need to be always combined with a stem cell therapy. Such prophylactic treatments have the potential to improve wound healing of irradiated tissue and clinical outcomes of reconstructive surgery required after cancer radiotherapy. Clinical Relevance Statement: The results of this study suggest that it is clinically possible to prevent the development of radiation disorders using stem cell therapies. This study may provide a new concept of prophylactic treatment, which would be a paradigm shift in radiotherapy.