Computational study of culture conditions and nutrient supply in cartilage tissue engineering

Different culture conditions for cartilage tissue engineering were evaluated with respect to the supply of oxygen and glucose and the accumulation of lactate. A computational approach was adopted in which the bioreactor was modeled as a batch process and transport was considered within constructs seeded at high cell concentrations and of clinically relevant dimensions. To assess the extent to which mass transfer can be influenced theoretically, extreme cases were distinguished in which the culture medium in the bioreactor environment was assumed either completely static, or well mixed and fully oxygenated.It can be concluded that severe oxygen depletion and lactate accumulation can occur within cartilage tissue engineering bioreactors. However, the results also indicate that transport restrictions are not insurmountable, providing that the medium is well homogenized and oxygenated and the construct's surfaces are sufficiently exposed to the medium. The large variation in uptake rates of chondrocytes requires that for any specific application, the quantification of cellular utilization rates, depending on the cell source and culture conditions, is an essential starting point for optimizing culture protocols.