Multimodal Optical 3D-Imaging System - Hardware and Software

Imaging technologies for three-dimensional (3D) analyses are needed for acceleration of progress in the tissue engineering (TE) research. The imaging methods that are available do not provide adequate information required for the assessment of TE products or they are destructive to the tissue. The optical imaging methods provide a low damage and high resolution solution. By merging different methods, their advantages can be combined and more information about the sample will be obtained. The aim of the thesis was to develop and build a multimodal imaging system to examine the structure and function of TE constructs. To quantify the properties of a tissue-engineered graft, we need to see how the cells are organized in the graft and how the tissue functions. Hydrogels offer a non-opaque 3D culturing platform to be imaged with optical imaging methods. The optical 3D imaging methods considered for TE research included optical projection tomography (OPT) and single/selective plane illumination microscopy (SPIM). These imaging methods are well suited for mesoscopic scale (1mm - 10mm) presented by the TE products while offering information of the cell structure on anatomical and fluorescence level. A custom multimodal imaging system combining OPT and SPIM was developed and built during this thesis. Furthermore, a control program was coded for controlling the system. By taking advantage of the optical properties of hydrogels, live 3D high-resolution imaging of TE samples was attained with an OPT-SPIM setup. The cell distribution in the scaffold was obtained with bright-field OPT, and the fluorescence information was obtained with SPIM. The built system is capable of capturing very fine detail in the sample, the lateral resolution being under 1µm. The major advantage of this setup is the possibility of imaging the sample for extended periods of time through the stages of cellular development within hydrogels. This is enabled by the non-destructive nature of both imaging methods. Moreover, it is possible to gain information for further development of hydrogels as scaffolds for cell research and for graft validation before implantation