Effects of Dynamic Loading on Cell Viability in Intervertebral Disc

Sufficient nutrient supply has long been regarded as a crucial factor for maintaining intervertebral disc (IVD) cell viability and preventing IVD degeneration^1,2. Due to avascular nature of the tissue, nutrients for IVD cells are transported, mainly by diffusion, through the dense extracellular matrix of the tissue from the peripheral and endplate vasculatures. Experimental studies on the effects of nutrient deprivation on IVD cell viability showed that glucose is the most critical nutrient affecting the cell density in IVD^3–5. Because of the difficulties in studying mechano-biology of human IVD in vivo, numerical simulations are necessary to investigate how the disturbances of biological, physical, and chemical signals can affect the cellular metabolism and viability in IVD. However, to date, there is no adequate theoretical model that is able to describe the change of cell density in IVD under dynamic conditions. Therefore, the objective of this study was to develop a new constitutive model for cell growth/death in human IVD and to analyze the cell metabolism and cell viability in IVD under dynamic, mechanical loading conditions using numerical methods based on the mechano-electrochemical mixture theory^6,7.