Detection and characterization of rat hepatic stellate cells in a 3-dimensional, perfused, liver bioreactor
Author(s)Wack, Kathryn E. (Kathryn Eilleen), 1978-
Massachusetts Institute of Technology. Biological Engineering Division.
Linda G. Griffith.
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One of the major challenges in liver research today lay in the understanding of the complex relationship between liver structure and function. The highly orchestrated events that take place in the liver to maintain homeostasis require the presence of all liver cell types. In vivo experiments offer only a snapshot of the liver, and usually involve perturbation of normal function through injury or experimental disease. The role of cell-cell interactions in maintaining normal liver function is far less understood than in pathological conditions. This may be because of the lack of methods in monitoring normal function in vivo. Culturing systems may capture pieces of the puzzle, but often capture only two cell types, and involve mediators presented to the cells in concentrations much higher than physiological values. In addition, the liver lobule contains a 3-dimensional metabolic zonation, and liver cell types comprise a heterogeneous population from the portal triad where the blood flows into the sinusoids to the central vein area where the blood flows out of the sinusoids. Liver cell types are dynamic responders to environmental cues from soluble factors to heterotypic cell interactions, to extracellular matrix proteins. Therefore, a system that serves to promote the health of all liver cell types through a 3-dimensional, perfused scaffold, and allows for self-organization of the liver cells in response to the engineered environment, would serve as a useful tool in understanding some of these complex, orchestrated events. In the research presented here, methods were developed to detect and characterize the heterogeneous population that makes up the hepatic stellate cell population inside the liver bioreactor (Griffith et. al).(cont.) This cell type, comprising a small percentage of total liver cells (approximately 5-10%), rapidly change their phenotype in response to liver injury, and, similarly, upon being taken out of the liver and cultured in 2-D on tissue culture plastic. This cell type plays a major role in relaying signals to and from both parenchymal and other nonparenchymal cells; stellate cells are also in charge of maintaining the components of the Space of Disse and are the key players in the pathology of liver fibrosis. They are found to be tightly complexed with sinusoidal endothelial cells and at the same time found to be tightly interacting with hepatocytes, sometimes even penetrating the hepatic plate. Stellate cell function, is therefore, highly dependent upon its interaction with other liver cells in maintaining the tightly knit structure-function relationship. For this reason, the liver bioreactor serves as a highly useful tool, in order to better understand the hepatic stellate cell's role in these complex situations. In this dissertation, detection and characterization methods are developed with the goal of capturing the heterogeneous stellate cell population as a whole with a toolbox of characterization markers, as well as to learn more about their functionality and location within tissue structures. These tools can be used to detect and characterize the population at various timepoints during tissue formation inside the bioreactor, as well as after exposure to physiologically-relevant concentrations of toxins, viruses, pharmaceuticals, etc. ...
Thesis (S.M.)--Massachusetts Institute of Technology, Biological Engineering Division, 2004.Includes bibliographical references (leaves 59-61).
DepartmentMassachusetts Institute of Technology. Biological Engineering Division.
Massachusetts Institute of Technology
Biological Engineering Division.