Imaging of three-dimensional epithelial architecture and function in cultured CaCo2a monolayers with two-photon excitation microscopy

High-throughput imaging: Focusing in on drug discovery in 3D

3D organotypic culture models such as organoids and multicellular tumor spheroids (MCTS) are becoming more widely used for drug discovery and toxicology screening. As a result, 3D culture technologies adapted for high-throughput screening formats are prevalent. While a multitude of assays have been reported and validated for high-throughput imaging (HTI) and high-content screening (HCS) for novel drug discovery and toxicology, limited HTI/HCS with large compound libraries have been reported. Nonetheless, 3D HTI instrumentation technology is advancing and this technology is now on the verge of allowing for 3D HCS of thousands of samples. This review focuses on the state-of-the-art high-throughput imaging systems, including hardware and software, and recent literature examples of 3D organotypic culture models employing this technology for drug discovery and toxicology screening.

Imaging the Cell and Molecular Dynamics of Craniofacial Development: Challenges and New Opportunities in Imaging Developmental Tissue Patterning

The development of the vertebrate head requires cell-cell and tissue-tissue interactions between derivatives of the three germ layers to coordinate morphogenetic movements in four dimensions (4D: x, y, z, t). The high spatial and temporal resolution offered by optical microscopy has made it the main imaging modularity for capturing the molecular and cellular dynamics of developmental processes. In this chapter, we highlight the challenges and new opportunities provided by emerging technologies that enable dynamic, high-information-content imaging of craniofacial development. We discuss the challenges of varying spatial and temporal scales encountered from the biological and technological perspectives. We identify molecular and fluorescence imaging technology that can provide solutions to some of the challenges. Application of the techniques described within this chapter combined with considerations of the biological and technical challenges will aid in formulating the best image-based studies to extend our understanding of the genetic and environmental influences underlying craniofacial anomalies.

Polymer-based mesh as supports for multi-layered 3D cell culture and assays

Three-dimensional (3D) culture systems can mimic certain aspects of the cellular microenvironment found in vivo, but generation, analysis and imaging of current model systems for 3D cellular constructs and tissues remain challenging. This work demonstrates a 3D culture system-Cells-in-Gels-in-Mesh (CiGiM)-that uses stacked sheets of polymer-based mesh to support cells embedded in gels to form tissue-like constructs; the stacked sheets can be disassembled by peeling the sheets apart to analyze cultured cells-layer-by-layer-within the construct. The mesh sheets leave openings large enough for light to pass through with minimal scattering, and thus allowing multiple options for analysis-(i) using straightforward analysis by optical light microscopy, (ii) by high-resolution analysis with fluorescence microscopy, or (iii) with a fluorescence gel scanner. The sheets can be patterned into separate zones with paraffin film-based decals, in order to conduct multiple experiments in parallel; the paraffin-based decal films also block lateral diffusion of oxygen effectively. CiGiM simplifies the generation and analysis of 3D culture without compromising throughput, and quality of the data collected: it is especially useful in experiments that require control of oxygen levels, and isolation of adjacent wells in a multi-zone format.

The third dimension bridges the gap between cell culture and live tissue

Moving from cell monolayers to three-dimensional (3D) cultures is motivated by the need to work with cellular models that mimic the functions of living tissues. Essential cellular functions that are present in tissues are missed by 'petri dish'-based cell cultures. This limits their potential to predict the cellular responses of real organisms. However, establishing 3D cultures as a mainstream approach requires the development of standard protocols, new cell lines and quantitative analysis methods, which include well-suited three-dimensional imaging techniques. We believe that 3D cultures will have a strong impact on drug screening and will also decrease the use of laboratory animals, for example, in the context of toxicity assays.

Tracking deforming aortas in two-photon autofluorescence images and its application on quantitative evaluation of aorta-related drugs

This paper describes a novel approach to an objective measurement of aorta samples of rats and a quantitative evaluation of aorta-related drugs. Two-photon fluorescence microscopy is used for recording image sequences of deforming aorta. Time sequence snake models are used to track the structural deformations of aorta walls caused by drug stimulation of the elastic lamina in the aorta. Several objective and quantitative biomarkers extracted from these models are used as diagnostic indicators. In a preliminary study, the technique was successfully used for evaluating the effect of a newly developed drug-human erythrocyte-derived depressing factor quantitatively and objectively.

Reconstruction of deforming aortas in two-photon autofluorescence image sequences

Information loss may occur frequently in the imaging of living tissues by using two-photon fluorescence microscopy due to the intensive deformation of the tissue. A landmark-based optical flow interpolation scheme is proposed for image reconstruction of living aorta walls in two-photon autofluorescence image sequences. Landmarks are extracted and evaluated by an active contour-based aorta model, and are aligned and reconstructed by use of a hierarchical algorithm. The accuracy of the calculation of optical flow is improved by applying landmark-based image warping. Experimental results show that the proposed scheme outperforms commonly used optical flow interpolation techniques for the reconstruction of intensively deforming tissues.