Regeneration of the skin of oncology patients after radiation therapy using upcycled fish collagen

Radiotherapy is one of the most popular cancer treatment methods, using ionizing X-rays with high ionization energy. Ionization energy causes electrons to be ejected. As energy increases, the ability of the rays to penetrate the skin improves, which helps reduce the dose. Cells undergoing division are most susceptible to radiation. Cancer cells have a higher division frequency than healthy cells, making them more susceptible to damage caused by radiotherapy [1].
Therapies using ionizing radiation are characterized by local effects and are limited to places where cancer lesions occur. The aim of the treatment is to induce specific but desirable therapeutic effects [2]. They lead to biological effects such as damage to cell membranes and DNA, impairing their ability to divide and carry out metabolic processes or causing immediate cell apoptosis. Radiotherapy can be used as a standalone form of treatment or as a supportive therapy to chemotherapy [3].
Unfortunately, the use of radiotherapy also causes side effects, in the epidermis, dermis and subcutaneous tissue. Skin reactions after radiotherapy can be divided into early and late reactions. Early reactions usually appear within a few weeks of starting treatment and are characterized by excessive skin dryness, pigmentation disorders, erythema and hair loss. As a result of exposure, sebaceous and sweat glands, hair follicles and pigment cells are damaged. The body produces more pro-inflammatory cytokines, including interleukins 1 and 6, transforming growth factor b (TGF-b) and tumor necrosis factor a (TNF-a) [4]. Erythema is a photochemical skin reaction, which results from damage to the spinous layer of the epidermis, denaturation of proteins in this layer, and the release of histamine, which dilates blood vessels and results in skin hyperaemia. The duration of erythema depends on the dose and frequency of radiation exposure. The consequence of erythema is exfoliation and thickening of the epidermis.
In the early stage of post-radiation reactions, we observe exfoliation of the epidermis, which occurs as a result of damage to keratinocytes in the basal layer, accompanied by itching. Dry exfoliation turns into wet exfoliation, accompanied by the exudation of serous fluid. Another early reaction is the permanent dilation of blood vessels, i.e., the development of telangiectasia.
Late reactions occur several months after the end of therapy and are caused by the reaction of fibroblasts to radiation. Fibroblasts are cells characterized by low proliferation potential. With the degradation of collagen fibres, atrophic changes appear in the skin. Increased synthesis of collagen with an irregular arrangement of fibres contributes to the appearance of thickening and fibrosis of the skin tissue, and the skin loses its elasticity [5].
Ionizing radiation, which is used in cancer radiotherapy, is responsible for the formation of free oxygen radicals (reactive oxygen species – ROS), which interact with biomolecules. They contribute to the development of the above-mentioned radiation reactions in the skin and subcutaneous tissue [6, 7].