A method for chronic membrane plasmapheresis in the rat

Therapeutic apheresis as applied to humans may encompass a single treatment or numerous treatments for disorders ranging from acute poisoning to severe chronic autoimmune disease. However, the mechanisms of beneficial effects of apheresis are not well characterized. Utilizing a miniaturized hollow-fiber membrane system, we have developed a reliable technique for long-term vascular access in the rat that permits repetitive plasmapheresis. We established vascular access in 14 animals, with 8 and 6 rats randomized to 3- and 7-wk experimental periods, respectively. Immunoglobulin levels of blood samples obtained immediately before and after each plasmapheresis were measured to examine membrane filtration characteristics. Overall, 100% of the animals survived and 93% successfully completed their assigned experimental periods. Mean decrease of immunoglobulin G and M levels for 28 plasmapheresis treatments in five rats was 66.9 +/- 8.1 and 61.0 +/- 7.3% (SD), respectively, indicating effective membrane filtration. This model of apheresis can be applied to several disorders in the rat, including, but not limited to, spontaneous insulin-dependent diabetes mellitus and experimental inflammatory bowel disease.