Hemorheological parameters and their correlations in OXYS rats: a new model of hyperviscosity syndrome.

Rheohaemapheresis aims to normalize major rheological parameters and is used to treat patients with dry age-related macular degeneration (AMD). While effective, this approach is invasive and requires specially trained personnel. Therefore, the search for novel effective compounds with hemorheological properties that can be taken orally to treat AMD is justified. The use of a robust rodent model of AMD with high blood viscosity is crucial to test the efficacy of potential hemorheological drugs to treat this disease. The objective of this study was to investigate whether OXYS rats, generally used as an animal model of AMD, have hyperviscosity syndrome. The results of this study show that blood viscosity in OXYS rats at low (3-10 s -1) and high (45-300 s -1) shear rates were 14-20% and 7-10% higher than in Wistar rats, while hematocrit and plasma viscosity were not different. Red blood cells (RBCs) in OXYS rats were more prone to aggregation as shown by 39% shorter half-time than in Wistar rats. RBCs were also more rigid in OXYS than in Wistar rats as shown by 21-33% lower index of elongation at the shear stress of 1-7 Pa. These data indicate that OXYS rats have hyperviscosity syndrome as the result of abnormal RBC deformability and aggregation. We propose to use OXYS rats as an animal model for preclinical studies to test compounds with hemorheological properties aimed to treat AMD.