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Yuya Hayashi


We are interested in imaging life at the interface with nanotechnology. Seeing is believing. This is our belief, but nanomaterials are too small to be seen with the naked eye, especially when they are hidden inside our body. Starring zebrafish as a model organism to "see through" the tissues non-invasively, we explore how biological systems interact with nanoscale objects in real-time. We use a combination of genetic manipulation and microscopy approaches for in vivo imaging and screening at spatio-temporal resolutions unrivalled by existing mammalian models (see Figure and Movie).

Figure: Zebrafish model for nano-bioimaging

Zebrafish embryos as an emerging research model for bioimaging and screening of nanomaterials. Transgenic lines with a cell type-specific fluorescent protein reporter allow us to study the dynamic behaviour of e.g. macrophages and how injected nanomaterials are cleared from the bloodstream in a living organism. Transmission electron microscopy (TEM) approaches can then complement the real-time observations by visualising those processes at the nanoscale. A marriage of the two imaging approaches is correlative light-electron microscopy (CLEM), by which we can link the fluorescent reporters to ultrastructure of cells and nanomaterials at high-resolution. dpf, days post-fertilisation. mpi/hpi, minutes/hours post-injection (Image: Yuya Hayashi. Adapted from Hayashi et al. (2020) & Mohammad-Beigi et al. (2020) ACS Nano. Copyright 2020 American Chemical Society)

Movie: Visualising the interaction of macrophages with nanoparticles in the blood vessels

Macrophages (magenta) with internalised nanoparticles (cyan) crawling along the inner side of blood vessels (yellow). Tg(fli1a:eGFP); Tg(mpeg1:mCherry) embryos at 3 dpf were injected with Pacific Blue-labelled 70 nm SiO2 nanoparticles (2 ng). Time-lapse imaging was performed at the intervals of every 16 s for 15 min at 1-4 hpi. (Reprinted from Hayashi et al. (2020) ACS Nano. Copyright 2020 American Chemical Society)

Movie: Pro-inflammatory activation of macrophages visualised in real-time

Tg(tnfa:EGFP-F); Tg(mpeg1:mCherry) embryos at 3 dpf were injected with Pacific Blue-labelled 70 nm SiO2 nanoparticles (10 ng) with protein corona pre-formed of FBS. The caudal vein tissue of the embryos was imaged every 20 min for 1-12 hpi. Left panel shows Cy5-labelled protein coronas (cyan), macrophages (grey), and transcriptional activation of tumour necrosis factor-alpha (yellow). Right panel shows only the latter two after applying a mask created with the macrophage reporter signals. (Movie: Yuya Hayashi. Adapted from Mohammad-Beigi et al. (2020) ACS Nano. Copyright 2020 American Chemical Society)

Current projects

Biological recognition of nanomaterials through a protein corona

What lies at the interface of biological receptors and nanoparticles? Over the past decade, nanoscientists have studied complex biophysical interactions that take place between biomolecules and nanoparticles. Today, it is widely accepted that cells recognise the biomolecules adsorbed to nanoparticles rather than the bare surface. Proteins are among those biomolecules that form a "corona" around the nanoparticle, and the corona profile is translated into a biological identity that can determine the nanoparticle's fate within a biological milieu.

Our interest is to unravel how innate immunity fights against those nanomaterials through recognition of their biological identities. The zebrafish embryo model now opens up a new opportunity to tackle this scientific question with the power of in vivo imaging at the high spatio-temporal resolution.

We work with the collaboration partner Prof. Duncan Sutherland at iNANO Interdisciplinary Nanoscience Center, Aarhus University.

TRAPping long-distance extracellular RNA communication in action

From an organ to another organ, cells send signals to coordinate the physiology of the entire body. A well-known example is signalling by hormones, but what if cells instead wish to deliver more complex messages than signals? A striking new discovery is the packaged delivery of small RNA via extracellular vesicles (EVs) that enables cell-cell communication over a long distance. The meaning of this biological process is, however, still poorly understood today. This is largely due to technical difficulties in the isolation of EVs (and small RNA therein) from complex biological fluids. The EVs encompass a wide range of vesicular entities, among which exosomes and microvesicles are two major EV types of particular interest in biomedical applications such as diagnostics and drug delivery. They are nanoscale vesicles nature has created, and thus the approaches we use for bionanoscience have technical overlaps with EV research.

Using zebrafish as an in vivo model, we aim to develop a revolutionary method bypassing the technical difficulties by directly capturing the small RNA "in transit" from donor cells to recipient cells. Combined with genetic manipulation, we use omics approaches for global profiling of the small RNA "in transit" and mRNA "in translation" to identify the potential targets of the small non-coding messages sent out by the donor cells.

Our collaboration partner for this project is Prof. Jørgen Kjems at iNANO Interdisciplinary Nanoscience Center, Aarhus University.

Featured articles

"Differential Nanoparticle Sequestration by Macrophages and Scavenger Endothelial Cells Visualized in Vivo in Real-Time and at Ultrastructural Resolution" by Yuya Hayashi*, Masanari Takamiya, Pia Bomholt Jensen, Isaac Ojea-Jiménez, Hélicia Claude, Claude Antony, Kasper Kjær-Sørensen, Clemens Grabher, Thomas Boesen, Douglas Gilliland, Claus Oxvig, Uwe Strähle, and Carsten Weiss.
ACS Nano 14 (2020) pp. 1665-1681. https://doi.org/10.1021/acsnano.9b07233.

"Tracing the In Vivo Fate of Nanoparticles with a "Non-Self" Biological Identity" by Hossein Mohammad-Beigi, Carsten Scavenius, Pia Bomholt Jensen, Kasper Kjær-Sørensen, Claus Oxvig, Thomas Boesen, Jan J. Enghild, Duncan S. Sutherland, and Yuya Hayashi*.
ACS Nano 14 (2020) pp. 10666–10679. https://doi.org/10.1021/acsnano.0c05178.

Want to inject something in zebrafish embryos?

Please contact Yuya Hayashi (yuya.hayashi@mbg.au.dk) to discuss possibilities.