Van der Meijden, R. H. M. | bioRxiv Science

bioRxiv2024

Development of an Organ-on-a-Chip for Correlative Microscopy: Visualizing Early Osteogenesis in 3D with High Resolution

Correlative microscopy approaches offer powerful means to study tissue development across spatial scales, but combining 3D light and electron imaging remains technically challenging. Here, we present a practical workflow that integrates organ-on-a-chip culture with longitudinal fluorescence imaging and volume electron microscopy. By modifying an existing chip platform designed for aligned tissue growth, we demonstrate the feasibility of extended 3D live imaging and subsequent high-pressure freezing of intact microtissues. Fluorescence-guided targeting enables focused ion beam/scanning electron microscopy (FIB/SEM) of selected regions, revealing ultrastructural features such as cellular organization, collagen alignment, and matrix mineralization. While not aimed at new biological discoveries, this study highlights the compatibility and potential of this pipeline for future high-resolution, multiscale studies of tissue morphogenesis and pathology in controlled microenvironments.

bioengineering↗

bioRxiv2022

A 3D CELL-FREE BONE MODEL SHOWS COLLAGEN MINERALIZATION IS A PHYSICOCHEMICAL PROCESS DRIVEN AND CONTROLLED BY THE MATRIX

Osteons, the main organizational components of human compact bone, are cylindrical structures composed of layers of mineralized collagen fibrils, called lamellae. These lamellae have different orientations, different degrees of organization and different degrees of mineralization where the intrafibrillar and extrafibrillar mineral is intergrown into one continuous network of oriented crystals. While cellular activity is clearly the source of the organic matrix, recent in vitro studies call into question whether the cells are also involved in matrix mineralization, and suggest that this process could be simply driven by the interactions of the mineral with extracellular matrix. Through the remineralization of demineralized bone matrix, we demonstrate the complete multiscale reconstruction of the 3D structure and composition of the osteon without cellular involvement. We then explore this cell-free in vitro system as a realistic, functional model for the in situ investigation of matrix-controlled mineralization processes. Combined Raman and electron microscopy indicates that glycosaminoglycans play a more prominent role than generally assumed in the matrix-mineral interactions. Our experiments also show that the organization of the collagen is in part a result of its interaction with the developing mineral.

biochemistry↗