STRETCH-INDUCED INJURY OF CULTURED NEURONAL, GLIAL, AND ENDOTHELIAL-CELLS - EFFECT OF POLYETHYLENE GLYCOL-CONJUGATED SUPEROXIDE-DISMUTASE

Background nod Purpose There is abundant evidence that after in vivo t raumatic brain injury, oxygen radicals contribute to changes in cerebr ovascular structure and function; however, the cellular source of thes e oxygen radicals is not clear. The purpose of these experiments was t o use a newly developed in vitro tissue culture model to elucidate the effect of strain, or stretch, on neuronal, glial, and endothelial cel ls and to determine the effect of the free radical scavenger polyethyl ene glycol-conjugated superoxide dismutase (PEG-SOD; pegorgotein, Dism utec) on the response of each cell type to trauma. Methods Rat brain a strocytes, neuronal plus glial cells, and aortic endothelial cells wer e grown in cell culture wells with 2-mm-thick silastic membrane bottom s. A controllable, 50-millisecond pressure pulse was used Co transient ly deform the silastic membrane and thus stretch the cells. injury was assessed by quantifying the number of cells that took up the normally cell-impermeable dye propidium iodide. Some cultures were pretreated with 100 to 300 U/mL PEG-SOD.Results increasing degrees of deformation produced increased cell injury in astrocytes, neuronal plus glial cul tures, and aortic endothelial cells. By 24 hours after injury, all cul tures showed evidence of repair as demonstrated by cells regaining the ir capacity to exclude propidium iodide. Compared with astrocytes or n euronal plus glial cultures, endothelial cells were much more resistan t to stretch-induced injury and more quickly regained their capacity t o exclude propidium iodide. PEG-SOD had no effect on the neuronal or g lial response to injury but reduced immediate posttraumatic endothelia l cell dye uptake by 51%. Conclusions These studies further document t he utility of the model for studying cell injury and repair and furthe r support the vascular endothelial cell as a site of free radical gene ration and radical-mediated injury. On the assumption that like aortic endothelial cells, stretch-injured cerebral endothelial cells also pr oduce oxygen radicals, our results further suggest the endothelial cel l as a site of therapeutic action of fl ee radical scavengers after tr aumatic brain injury.