Effect of amifostine (Ethyol (R)) on the development of extraembryonic blood vessels in chick embryos

Aim: Systemic and local side effects can limit radio- as well as chemothera py in patients suffering from neoplastic diseases. One possibility to reduc e the therapy-dependent side effects is to attenuate radical induced altera tions of normal healthy tissue by application of antioxidants. Preclinical and clinical studies demonstrated the ability of amifostine to protect norm al, but not neoplastic, tissues from cytotoxic effects of chemotherapy or i rradiation. The purpose of the present study was to establish whether amifo stine (Ethyol(R)) can affect microvessel density in vivo. Material and Methods: For this study fertilized crossbred "White-Plymouth-R ocks x Sussex" eggs were used. After 48 hours of incubation 0.05 mi solutio n containing 25.7 mu g (approximately 120 mu M) amifostine were injected ne xt to the germ disc. Taking into account the mean surface area of the area vasculosa and the embryo, this corresponds to a dose of 26 mu g/cm(2). As c ontrols, the area vasculosa of eggs treated with 0.05 mi NaCl 0.9% were use d. Twenty-four and 48 hours after injection of amifostine or NaCl photograp hs and video microscopic pictures from treated areas and controls were take n and evaluated for vascular density. Results of vascular density are given as vascular intersections per mm? (VIS/mm(2)). Results: There was a significant (p < 0.001) difference in vascular density with a mean microvessel count of 30.40 (+/- 12.84 SD) VIS/mm(2) in the NaC l control and 53.69 (+/- 24.56 SD) VIS/mm(2) in the amifostine-treated area vasculosa. Conclusion: The results show that amifostine induced an increase in vascula r density in the rapidly proliferating area vasculosa of the early chick em bryo.