Objective: Aprotinin is used in cardiac surgery for its anti-inflammatory and hemostatic benefits. Recent reports describe the neuroprotective effects of other serine protease inhibitors via reduced excitotoxic cell death, a common pathway causing cytotoxic edema induced in various neuropathologic conditions. The purpose of this study was to investigate whether aprotinin directly protects against glutamatergic excitotoxicity in cell cultures.
Methods: Mixed cortical cultures containing neuronal and glial cells were prepared from fetal mice at 13 to 15 days' gestation and plated on a layer of confluent astrocytes from 1- to 3-day-old postnatal pups. Near-pure neuronal culture containing less than 5% astrocytes was obtained from the same gestational stage and plated in multiwell vessels previously coated with poly-D-lysine and laminin. Both cultures were used at 12 to 14 days in vitro. Slowly triggered excitotoxicity was induced at 37 degrees C by 24-hour exposure to 12.5 microM N-methyl-D-aspartate or 50 microM kainate. Neuronal death was quantified by measuring the release of lactate dehydrogenase from damaged cells into the bathing medium. Data were analyzed by analysis of variance with post hoc Bonferroni comparisons.
Results: Aprotinin at a clinically relevant concentration of 100 KIU/mL significantly reduced N-methyl-D-aspartate-induced neuronal death in both pure and mixed cultures (P < .001). Aprotinin also reduced neuronal death induced by kainate from 36% to 23% in mixed cortical culture (P = .008) and from 40% to 27% in near-pure culture (P = .015), indicating that the neuroprotective effects of aprotinin are mediated directly through neurons.
Conclusion: Aprotinin provides direct neuroprotection against glutamatergic excitotoxicity as demonstrated by reduced neuronal death in near-pure neuronal cell culture. Additional studies are needed to evaluate the potential of aprotinin to reduce neurologic injury in patients at high risk of cerebral injury, including those undergoing circulatory arrest.