Spatiotemporal Profiling of Human Development Using Multiplexed Imaging

QC 2024-04-12

Abstract

Human development is complex and intricate, where the positions of cells, expression of key markers, and cell-cell interactions contribute to the development of various organs from different germ layers and the establishment of the body axis. Therefore, understanding human development within spatial and temporal aspects is crucial. Spatial and temporal aspects can be studiedthrough multiplexed imaging, which enables the assessment of multiple markers on the same tissue, offering critical insights into protein expressions in the cells and tissues. Within the scope of this thesis, we focused on the spatial and single-cell profiling of cell types during the first trimester of human development, both at the systemic and organ levels, using multiplexed imaging. Paper I of this thesis presents a spatial and single-cell map of the developing human lung in the first trimester. We used multiplexed imaging on post-conception week 6 to 13 lungs employing a 30-plex antibody panel and, as a result, analyzed nearly 1 million cells. We provide a spatially resolved cell type composition of the developing human lung, focusing on spatiotemporal changes in the cell types, such as immune cells, endothelial cells, lymphatic cells, and proliferative cell states. Key findings of the first paper are that the proliferation patterns in the epithelium reveal differences in the elongation of smaller and larger distal and proximal airways and the presence of some immune cells around arteries, highlighting location-function relationships. Additionally, this paper represents the first application of multiplexed imaging on the developing human lung. Paper II aimed to systematically investigate human development in whole embryos by focusing on cell types such as immune and endothelial cells. We analyzed human whole embryo tissues from week 3 to 5 using a 28-plex multiplexed antibody panel. A key finding of the paper is the appearance of liver immune cells as early as week 4 and differences in their marker expression profiles compared to the other immune cells. In Paper III, we proposed a simple and flexible open-source method for visualizing in situ expressions of hundreds of genes, which can be combined with other methods, such as multiplexed imaging. In Paper IV, we explored the spatial dynamics of the developing human heart at the cellular and subcellular levels. In conclusion, this thesis elucidates the spatiotemporal changes during the first trimester of human development by presenting spatial maps of developing organs and whole embryos at various stages. The objective is to illustrate the characteristics of a healthy state, contributing to a better understanding of abnormalities associated with congenital diseases.

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