Investigations of Olfactory Stem Cells in Schizophrenia Author Abrahamsen, Greger Published 2009 Thesis Type Thesis (PhD Doctorate) School School of Biomolecular and Physical and Physical Sciences DOI https://doi.org/10.25904/1912/3043 Copyright Statement The author owns the copyright in this thesis, unless stated otherwise. Downloaded from http://hdl.handle.net/10072/366642 Griffith Research Online https://research-repository.griffith.edu.au Investigations of olfactory stem cells in schizophrenia by Greger Abrahamsen, B.Sc., M.Sc. (Hons) School of Biomolecular and Physical Sciences Faculty of Science, Environment, Engineering and Technology Griffith University A thesis submitted in fulfillment of the requirements for the degree of Doctor of Philosophy September 2008 Acknowledgements I would like to thank Professor Alan Mackay-Sim for his patience, support and guidance, especially during the writing of this thesis. It has been an enormous privilege to have access to someone of your experience. Also, special thanks must go to Dr Wayne Murrell. Your advice, technical expertise and friendship throughout these years has been invaluable. Your support and willingness to sacrifice your time was greatly appreciated. Many thanks to Dr. Carolyn Sue, Rachel Shepherd and Farrah-Yasmin Tate for sharing their technical expertise. I would also like to thank Dr. Tom Byrne for his advice on statistical analysis. Thanks also to Professor John McGrath, Professor Denis Crane and Associate Professor Dianne Watters for their help and guidance. I would also like to thank the other members of the lab: Ben Baldwin, Stacey Andersen, Dr Bernadette Bellette, Colm Cahill, Dr. Carla Toland, Dr. Andrew Wetzig, Dr Ian Hayward and Nick Matigian for their technical assistance and most importantly their friendship. You created a fun environment that made my work enjoyable. I also wish to express my sincere appreciation for my family. Finally I would like to thank my wife Kathy, your love and support made this possible. Also to our son Jacob, for always making me smile. II Abstract Schizophrenia is a severely debilitating psychiatric disorder with a complex aetiology where aberrant expression of multiple genes, concurrent with neurodevelopmental events, is believed to lead to the disorder. The ability to biopsy and culture olfactory neuroepithelium from patients with schizophrenia may provide a window into the processes underlying the altered brain development and function in the disorder. It has been established that neurogenesis, the formation of new neurons, occurs throughout life. There are several lines of evidence suggesting adult neurogenesis may be affected in schizophrenia. The functional relevance of neurogenesis in the adult mammalian brain remains unknown, however a disruption of neurogenesis during early development is consistent with the neurodevelopmental hypothesis of schizophrenia. The presence of a neural stem cell has been established in the olfactory neuroepithelium, which can give rise to various neural populations, providing a valuable source for studying various aspects of neurogenesis. The aim of this study was to investigate the utility of olfactory stem cell lines in studying the processes underlying altered brain development and brain functioning in schizophrenia. We also investigated the skin fibroblast cell model, to assess the utility of non-neural cells in studying schizophrenia. A mitochondrial dysfunction and increased oxidative stress have been linked to patients with schizophrenia, and have been proposed to be involved in the pathophysiology of the disorder. We compared gene expression, neural differentiation, mitochondrial function and focal adhesion in cells from patients with schizophrenia and healthy controls. Our results showed significant disruptions of signaling pathways important in adhesion, cell communication and signaling in the olfactory stem cell lines from the patients group, and no significant pathway disrupted in the skin fibroblasts. Though both cell models indicated a focal adhesion dysfunction in schizophrenia, we found that olfactory stem cell lines show signs of a more severe dysregulation when compared to skin fibroblasts, which may reflect the differing structural roles of fibroblasts compared to neural cells. There was also an impaired oxidative stress response in both cell models, and also a mitochondrial dysfunction in the olfactory stem cell lines, phenomena which support the hypothesis that mitochondrial dysfunction and oxidative stress are involved in schizophrenia pathophysiology. Significantly, differences in differentiation between patient and control groups were revealed. Altered neurogenesis in cells from patients with schizophrenia, support our other hypothesis that adult III neurosgenesis is involved in schizophrenia pathophysiology. Though the details of adult neurogenesis, focal adhesion, mitochondrial function and oxidative stress remain to be elucidated in schizophrenia, these findings together with their proposed roles in brain function make them relevant to schizophrenia research. While we found that fibroblasts are not informative as a cell model for schizophrenia, we conclude that olfactory stem cell lines are a promising tool for studying neurobiological aspects of schizophrenia. IV Content Acknowledgements .............................................................................................................. II Abstract ............................................................................................................................... III Content ................................................................................................................................. V List of Figures ..................................................................................................................... IX List of Tables ........................................................................................................................ X List of abbreviations ........................................................................................................... XI Statement of Originality .................................................................................................. XIII Declaration of Work Performed .................................................................................... XIV Chapter 1: General introduction......................................................................................... 1 1.1 Introduction .......................................................................................................... 2 1.2 The schizophrenic brain........................................................................................ 3 1.2.1 Brain pathology .............................................................................................. 4 1.2.2 Development of schizophrenia ....................................................................... 5 1.3 Adult neurogenesis ............................................................................................... 6 1.3.1 Animal studies ................................................................................................ 7 1.3.2 Human studies ................................................................................................ 8 1.4 Adult neurogenesis in schizophrenia .................................................................... 8 1.4.1 Animal studies ................................................................................................ 9 1.4.2 Human studies .............................................................................................. 11 1.4.3 Post-mortem studies ..................................................................................... 13 1.4.4 Gene association ........................................................................................... 15 1.5 Oxidative stress, mitochondria and schizophrenia ............................................. 17 1.5.1 Mitochondrial dysfunction ........................................................................... 18 1.5.2 Glutathione system ....................................................................................... 19 1.5.3 Calcium signaling ......................................................................................... 20 1.5.4 Nitric oxide synthase (NOS)......................................................................... 21 1.5.5 Role of mitochondria in the pathophysiology of schizophrenia ................... 22 1.6 Summary ............................................................................................................. 22 1.7 Cell models ......................................................................................................... 23 1.7.1 Olfactory epithelium ..................................................................................... 23 1.7.1.1 Olfactory stem cells ...................................................................................... 25 1.7.2 Skin fibroblasts ............................................................................................. 26 1.8 Hypothesis and aims ........................................................................................... 27 Chapter 2: General methods ............................................................................................. 28 2.1 Tissue biopsy ...................................................................................................... 29 2.1.1 Tissue culture initiation .....................................................................................