Radioprotective effects of a protein-free hemodialysate in human epidermis

The accidental or therapeutic exposure of human skin to ionizing radiation is known to cause the radiation syndrome with its various manifestations. The aim of the study was to investigate the potential radioprotective effects of the protein-free hemodialysate Actovegin. After exposure to X-rays (single dose, 6 Gy), 70% of the cells died. In the presence of the hemodialysate, irradiation did not lead to cell death. Instead a slight increase in cell number was observed. A 5-fold increased cell number was found after 6 days when the cells were treated with the hemodialysate alone. To elucidate molecular mechanisms of the observed biological effects the correlation between the expression of the epidermal growth factor receptor (EGFR) and the demonstrated growth activation was investigated. Radiation alone resulted in a clear induction of EGFR, whereas the combination of irradiation and Actovegin treatment led to a strong downregulation after 2 days. Thus, the hemodialysate suppressed one of the radiation-induced effects. Further investigations have to elucidate the role of other proteins which are involved in the signal transduction cascade of tyrosine kinases (e.g. Ras, Raf, MAP kinases) leading to the transcription factor AP-1 in response to radiation under Actovegin treatment.