Abstract
Low back pain is one of the major health concerns in the US. It affects up to 80% of the population at some time during their lives. It not only causes discomfort to patients and affects their physical ability but also has a huge economic impact on society. Although the cause of low back pain is still poorly understood, it is implicated that degeneration of the intervertebral disc is the primary factor. Currently, researchers are trying to use tissue engineering approaches to develop new treatments capable of removing the degenerated disk and replacing it with a biological substitute. However, to create such a biological substitute, we need to first understand the structure-function relationship of the tissue. Only when we understand the function of the tissue, can we begin creating biological substitutes. While culturing a biological substitute, we also need methods to determine how the substitute responds to its environment. At present, there are many different types of bioreactors developed for cartilaginous tissues. However, there is a lack of a system that can detect the chemical, electrical and mechanical response noninvasively with control feedback in real-time. It is hard to provide the optimal culture environment to the substitute without knowing its response in real-time. The objective of this dissertation is to develop new methods to investigate the transport property, oxygen consumption rate and mechano-electrochemical and mechanical properties of the tissue. Because cells are responsible for the tissue health, it is necessary to understand how they can obtain nutrients under different environments, e.g. under different loading condition. In addition, with the use of a bioreactor with the capability of detecting the real-time response combined with a feedback control system, we can provide the most favorable conditions for tissue or biological substitutes to grow. The new measurement methods developed in this dissertation can contribute to further understanding the function of the tissue. The methods outlined in this dissertation can also provide new tools for future tissue engineering applications. Moreover, the findings in this dissertation can provide information for developing a more comprehensive theoretical model to elucidate the etiology of disc degeneration.