Ultrastructural changes produced in dorsal root ganglia in vitro by exposure to ethylene oxide from hemodialyzers

Ethylene oxide (EO) gas, used to sterilize hemodialysis equipment, is a known neurotoxin and residual gas remains in dialyzers after airing. If tissue culture medium is incubated in dialyzers and then rat dorsal root ganglion (DRG) cultures are exposed to this medium, characteristic changes occur. These include axonal swellings and the death of neurons after five days. Electron microscope findings were compared between DRG grown in control medium containing 10% calf serum, DRG incubated in the same medium exposed to the blood compartment of capillary flow or plate dialyzers and DRG grown in medium supplemented with 10% dialysis patient serum. Electron microscope findings included frequent axonal swellings with the accumulations of membrane bound vesicles and the apparent disruption of micro-tubules. There were also conspicuous accumulations of membrane bound vesicles, dense bodies, myeloid figures, and areas of vesicular degeneration in Schwann cells. These changes were seen with dialyzer exposed medium or with medium containing patient serum but not with controls or with medium incubated in plate dialyzers. The changes were similar to those reported in nerve biopsy specimens from patients with known EO neuropathy.