The use of in vitro models for neural injury with superimposed hypoxia in the development of new head injury tolerance criteria.

This study uses an in vitro model of isolated neural cells in order to determine the hypoxic ischemia effect on the recovery of neural cells from mechanical insult. The model is composed of a neuroblastomax glioma cell hybrid (NG108-15). This is grown in a chamber designed to deliver a known strain and strain rate to the cell, while the chemical environment of the cell is independently controlled. The actual cell deformation is determined in the form of the average strain in the cell membrane using fluorescent microspheres. The normal bathing media is replaced with media containing 2-deoxyglucose (25 mM) and salicylate (3 mM). The aim is to produce hypoxic ischemia. The intracellular concentration of calcium is used as an index of cell injury. It is measured fluorimetrically in real time using a calcium indicator dye. The responses of cells to mechanical stimulus with and without hypoxic ischemia are compared. Experiments were performed in which the cells were exposed to mechanical deformation only, hypoxic ischemia only, and the combination. These data are used to improve injury tolerance criteria by relating the response of single cells to both mechanical insults and to the effects of systemic responses such as hypoxic ischemia.