Effects of reduced oxygen and glucose levels on ocular cells in vitro: implications for tissue models

An important goal of tissue engineering is the development of better in vitro tissue models for the study and treatment of diseases, especially those that are difficult to model in animals, such as glaucoma. In order to properly interpret experimental results designed to mimic in vivo conditions, it is necessary to characterize the metabolic state of the in vitro culture. The goal of this study was to determine how porcine lamina cribrosa cells (PLC), porcine scleral fibroblasts (PSC) and rat astrocytes (RAS) respond metabolically to reduced glucose and oxygen levels compared to normal in vitro culture conditions. Throughout the culture period, cell number and the levels of glucose, lactate, pyruvate and glutamate were characterized. Cell number in the PLC and PSC was more sensitive to glucose level than oxygen, while the RAS exhibited sensitivities to both variables. While the pyruvate and glutamate levels did not vary substantially between groups, glucose consumption and lactate production were dependent on culture condition. In addition, the DeltaL/DeltaG ratio was dependent on glucose and oxygen levels, but not cell type at early time points. By day 7, however, the RAS exhibited ratios consistently lower than the other cell types. The results of this study serve as a basis for future studies into the degenerative matrix remodeling in the glaucomatous optic nerve head, and may prove insightful for other tissue engineering applications.