A 3-dimensional fibre scaffold as an investigative tool for studying the morphogenesis of isolated plant cells
Background: Cell culture methods allow the detailed observations of individual plant cells and their internal processes. Whereas cultured cells are more amenable to microscopy, they have had limited use when studying the complex interactions between cell populations and responses to external signals associated with tissue and whole plant development. Such interactions result in the diverse range of cell shapes observed in planta compared to the simple polygonal or ovoid shapes in vitro. Microfluidic devices can isolate the dynamics of single plant cells but have restricted use for providing a tissue-like and fibrous extracellular environment for cells to interact. A gap exists, therefore, in the understanding of spatiotemporal interactions of single plant cells interacting with their three-dimensional (3D) environment. A model system is needed to bridge this gap. For this purpose we have borrowed a tool, a 3D nano- and microfibre tissue scaffold, recently used in biomedical engineering of animal and human tissue physiology and pathophysiology in vitro. Results: We have developed a method of 3D cell culture for plants, which mimics the plant tissue environment, using biocompatible scaffolds similar to those used in mammalian tissue engineering. The scaffolds provide both developmental cues and structural stability to isolated callus-derived cells grown in liquid culture. The protocol is rapid, compared to the growth and preparation of whole plants for microscopy, and provides detailed subcellular information on cells interacting with their local environment. We observe cell shapes never observed for individual cultured cells. Rather than exhibiting only spheroid or ellipsoidal shapes, the cells adapt their shape to fit the local space and are capable of growing past each other, taking on growth and morphological characteristics with greater complexity than observed even in whole plants. Confocal imaging of transgenic Arabidopsis thaliana lines containing fluorescent microtubule and actin reporters enables further study of the effects of interactions and complex morphologies upon cytoskeletal organisation both in 3D and in time (4D). Conclusions: The 3D culture within the fibre scaffolds permits cells to grow freely within a matrix containing both large and small spaces, a technique that is expected to add to current lithographic technologies, where growth is carefully controlled and constricted. The cells, once seeded in the scaffolds, can adopt a variety of morphologies, demonstrating that they do not need to be part of a tightly packed tissue to form complex shapes. This points to a role of the immediate nano- and micro-topography in plant cell morphogenesis. This work defines a new suite of techniques for exploring cell-environment interactions.
© 2015 Luo et al. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Online Date August 2015. This work is funded by the Gatsby Charitable Trust through Fellowships GAT3272/C and GAT3273-PR1 to E.M.M. and the European Research Council grant EMATTER 280078 to S.S. Authors' contributions: Concept, CJL, RW; methodology, CJL, RW; acquisition of data, CJL, RW; analysis and interpretation, CJL, RW, SS, EM; drafting and editing of the manuscript, CJL, RW, SS, EM. All authors read and approved the manuscript. Competing interest: C.J.L., R.W., E.M.M. declare no competing interest. S.S. serves on Xanofi's board of directors and declares financial interest in the scaffolds used in this work.
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