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Armed Forces Biomedical Research Institute (IRBA) and IPS2: collaboration for mutual benefit

When animal and plant research join forces to develop new common methods in cytology and histology.

As part of a fruitful collaboration with the Institut de Recherche Biomédicale des Armées (IRBA), IPS2 (FLOCAD team) has contributed to the implementation of a cytology technique, detailed in the article published jointly in the FASEB Journal at the end of 2020 and titled « Hybridization-chain-reaction is a relevant method for in situ detection of M2d-like macrophages in a mini-pig model »

Unlike traditional in situ hybridization approaches, in situ amplification by the HCR (Hybridization – Chain - Reaction) technique allows the localization of the expression of several mRNAs simultaneously. This technique is based on the combined use of an initiator probe and two invariable amplifying probes at the heart of the labeling reaction. Thus, the choice of targets can be much wider than in the context of other in situ hybridization techniques and therefore makes it possible to target any nucleic acid sequence of interest.

In this article, this new technique is validated on M2 macrophage cells in regenerating muscle with the expression of three probes simultaneously. Macrophages are very heterogeneous cell groups, which until now could not be detected in vivo by subtypes with classical techniques.

This new technology, highly sensitive, is also interesting in crop plants and is available within the framework of the EPITRANS platform activity. (IPS2, FLOCAD team). It is closely linked to a second innovative imaging project, which consists in making plant organs transparent, such as flowers (to localize in situ the expression of several genes at the same time. These technologies


Identification of M2 macrophages in a muscle by HCR. Detection of TGF-β1b, TNFα, and CD68 in four representative zones (Zone 1, Zone 2, Zone 3, Zone 4). Zone 4-Expanded view: high magnification image of the area within the red rectangle in Zone 4. Probe-TGF-β1b (Alexa488, yellow fluorescence), Probe-TNFα (Alexa546, turquoise fluorescence), Probe-CD68 (Alexa647, red fluorescence), nuclear staining with DAPI (blue fluorescence).


Nikovics K, Morin H, Riccobono D, Bendahmane A, Favier AL. Hybridization-chain-reaction is a relevant method for in situ detection of M2d-like macrophages in a mini-pig model. FASEB J. 2020 Dec;34(12):15675-15686.