for being such a wise and talented scientist, and thanks for your endless guidance, friendship and moral support throughout my study. The same applies to Dr Sotirios Korossis; thanks for your invaluable knowledge, support and friendship, and thanks for giving me the opportunity of continuing my work in the tissue engineering field in your laboratory in Germany. My deepest thanks go also to Dr Daniel Thomas, my lab tutor; thanks for your endless moral support and guidance and thanks for answering my continuous questions. The time you spent helping me with my work with the bioreactor is unforgettable, you never left me alone during that challenging and hard time! Professor Eileen Ingham, Dr Sotirios Korossis and Dr Daniel Thomas have been like a family to me, during my nice time spent at Leeds. My sincere thanks also go to Professor John Fisher, thanks for the precious instructions and advice you gave me during my work with the bioreactor, your support has been crucial for the completion of the final experiments. This thesis would not have been possible without the help, support and patience of these great four scientists mentioned above! I would like to thank Dr Nagitha Wijayathunga and Mr Irvin Homan for their continuous support with the ordering of the tissue needed for my experiments; my deepest thanks also go to Mr Lee Wetherill, Mr Philip Wood and Mr Keith Dyer for their constant technical support, especially with the mechanical design and manufacture of the equipment I needed. Thanks also to Mrs Amisha Desai and Dr Nicholas Roberts for their support when working with the mechanical testing device. My deepest thanks also go to our great technicians at Professor Ingham's lab, Fiona, Natalie and Laura, (now PhD student), thanks for your help and support during the last experiments with the bioreactor, your help has been essential for the completion of the work for my PhD. Thanks to everybody from Professor Ingham's lab, especially thanks to Iraklis, Blessing, Ji and Tay for answering my questions and for their kind assistance during this project. TVPs Transvalvular pressures TBS Tris buffered saline UTS Ultimate tensile strength VECs Valve endothelial cells VICs Valve interstitial cells