Effects of Compression Loading, Injury, and Age on Intervertebral Disc
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University of Vermont ScholarWorks @ UVM Graduate College Dissertations and Theses Dissertations and Theses 2008 Effects of Compression Loading, Injury, and Age on Intervertebral Disc Mechanics, Biology and Metabolism Using Large Animal Organ and Cell Culture Systems Casey Korecki University of Vermont Follow this and additional works at: https://scholarworks.uvm.edu/graddis Recommended Citation Korecki, Casey, "Effects of Compression Loading, Injury, and Age on Intervertebral Disc Mechanics, Biology and Metabolism Using Large Animal Organ and Cell Culture Systems" (2008). Graduate College Dissertations and Theses. 126. https://scholarworks.uvm.edu/graddis/126 This Dissertation is brought to you for free and open access by the Dissertations and Theses at ScholarWorks @ UVM. It has been accepted for inclusion in Graduate College Dissertations and Theses by an authorized administrator of ScholarWorks @ UVM. For more information, please contact [email protected]. EFFECTS OF COMPRESSION LOADING, INJURY, AND AGE ON INTERVERTEBRAL DISC MECHANICS, BIOLOGY AND METABOLISM USING LARGE ANIMAL ORGAN AND CELL CULTURE SYSTEMS A Dissertation Presented by Casey L. Korecki to The Faculty of the Graduate College of The University of Vermont In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Specializing in Mechanical Engineering May, 2008 Accepted by the Faculty of the Graduate College, The University of Vermont, in partial fulfillment of the requirements for the degree of Doctor of Philosophy specializing in Mechanical Engineering. Advisor Ian A. Stokes, ~h.6. Chairperson ice President for Research nd Dean of Graduate Studies Date: March 26fh,2008 ABSTRACT The intervertebral disc (IVD) is a complex orthopaedic tissue that is located between the vertebrae in the spine. Degeneration of the IVD is thought to be a contributor to low back pain (LBP), which affects up to 80% of the population at enormous economic cost. The role of the intervertebral disc in supporting and resisting applied loading to the spine, along with the observation of disorders associated with abnormal spinal loading, provide support to the theory that applied mechanical loading is crucial in maintaining the health of the intervertebral disc. The encompassing goal of this work was to examine the biological response of the intervertebral disc to changes in the surrounding mechanical environment in a large animal model. Aim 1 utilized an organ culture model to explore the relationship between disc mechanics and biology in needle puncture injury, a commonly used model of experimentally induced disc degeneration, thus providing a possible mechanism for in vivo injury induced disc degeneration models. Aim 2 was to explore the interaction between the amplitude of applied mechanical loading and intervertebral disc cell signaling, also performed in an organ culture model to include cell-matrix signal transduction. Aim 3 addressed frequency and age effects on the IVD response to mechanical stimulation, performed in vitro to control for the effects of varying matrix compositions between old and young animals. Finally, Aim 4 utilized k- means and fuzzy c-means clustering techniques to reveal patterns in experimental phenotype (determined by gene expression data) and gene response to experimental conditions. The application of biclustering, where the gene responses within experimental phenotypes are clustered to elucidate possible mechanisms for different gene level-responses to experimental conditions, was also accomplished. Finally, the ability for the model to predict the behavior of other genes critical to IVD mechanobiology, or in determining the membership of an unexamined experimental phenotype was explored. Overall, applied dynamic compression was not found to significantly alter disc mechanics, while a disruption in the annulus through needle puncture rapidly decreased the compressive modulus. Changes in disc mechanics may precede biological remodeling, with little evidence of remodeling present without mechanical alteration. Aging, however, crucially impacts disc cell biology, particularly in the nucleus pulposus, and will interact with applied loading to further impact the ability for the intervertebral disc cells to maintain a healthy extracellular matrix. Citations Material from this thesis has been published in the following form: Korecki CL, MacLean JJ, Iatridis JC, Dynamic compression effects on intervertebral disc mechanics and biology. Spine : In Press, accepted January 29, 2008 Material from this thesis has been published in the following form: Korecki CL, Costi JJ, Iatridis JC, Needle puncture injury affects intervertebral disc mechanics and biology in an organ culture model. Spine , 33: 235-41, 2008 Material from this thesis has been submitted to the Journal of Orthopaedic Research on March 10 th , 2008 in the following form: Korecki CL, Kuo CK, Tuan RS, Iaridis JC, Intervertbral disc cell response to dynamic compression is age and frequency dependent: J Orthop Res: Submitted March, 2008 ii Acknowledgements This research was possible due to the direct and indirect support of many people. Although space constrains me to thank only a number of them, the help, thoughtful discussions and encouragement of many more individuals is reflected in this work. I would like to thank my advisor, Dr. James Iatridis, for hiring me into the Mechanical Engineering program, and giving me a spot in the Spine Bioengineering Lab. I have been incredibly lucky to have an advisor as dedicated and hard-working as you, and I really appreciate all the time and effort you have put into helping me succeed. I’d also like to thank all the members of the Spine Bioengineering Lab I have had the privilege to work with over the years, and am happy to look back on many of you as friends in addition to co-workers. I wish also to thank people I have considered mentors over the years. Mr Gates and Mr. Davenport at Springstead high school, whose lessons about science remain firmly in my mind although high school seems like a long time ago. Dr. Glen Niebur and Dr. Ryan Roeder, who allowed me my first opportunity to do bioengineering research at the University of Notre Dame thus firmly cementing my plans to go to graduate school. Most importantly, I’d like to thank my friends and family. To my friends, particularly Maureen Cherwin and Amy Johnson, graduate school has consumed iii much of my time leaving me as a very difficult person to stay in contact with (and often forgetfull of birthdays and other special occasions), and I can’t thank you both enough for putting up with it and still calling back repeatedly. My parents, Nicholas and Sheree, have been a source of constant support and inspiration throughout my life and I am grateful for the opportunity to thank them for all their sacrifices along the way to help me succeed. I’m very grateful for my brother John, who often helped put things in perspective, as well as providing technical help with the final chapter. My grandparents, Doris and John Comiskey, who provided such love and support throughout my life and especially during college (in addition to a much needed meal during Easter and Thanksgiving), and who are also a model of hard work and perserverence. You are both very missed. To Tom, my fiancée, for enduring a five-year separation that has been filled with many late night conversations about cells, mechanics, and frustration over experiments gone awry. I know a lesser man would not have handled it with as much compassion and humor as you, and I look forward to spending the rest of our lives together. iv Table of Contents Citations ........................................................................................................................... ii Acknowledgements.........................................................................................................iii CHAPTER 1 Introduction................................................................................................ 1 CHAPTER 2 Background................................................................................................ 9 2.1 Intervertebral disc structure and biology ................................................................ 9 2.2 Intervertebral disc development ........................................................................... 10 2.3 The healthy intervertebral disc ............................................................................. 11 2.4 Pathological changes associated with IVD degeneration ..................................... 17 2.5 Intervertebral disc research................................................................................... 18 2.5.1 In vivo models ................................................................................................. 22 2.5.1.1 Relevant research....................................................................................... 22 2.5.2 Organ culture ................................................................................................... 25 2.5.2.1 Relevant research....................................................................................... 27 2.5.3 Tissue culture................................................................................................... 29 2.5.3.1 Relevant research....................................................................................... 29 v 2.5.4 Cell culture....................................................................................................... 30 2.5.4.1 Relevant