implanting-glass-spinal-cord-windows-adult-mice-with-experimental

Implanting Glass Spinal Cord Windows in Adult Mice with Experimental Autoimmune Encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) in adult rodents is the standard experimental model for studying autonomic demyelinating diseases such as ...

intravital-microscopy-imaging-liver-following-leishmania-infection-an

Intravital Microscopy Imaging of the Liver following <em>Leishmania</em> Infection: An Assessment of Hepatic Hemodynamics

Intravital microscopy (IVM) is a powerful optical imaging technique that has made possible the visualization, monitoring and quantification of various ...

Aix Marseille University

University of Aix-Marseille

Testicular sperm extraction is widely used in the treatment of male infertility in cases of non-obstructive azoospermia. Identifying spermatogenetic foci within the testes is critical for testicular sperm extraction. Two-photon laser scanning microscopy (TPLSM) is an autofluorescence-based microscopy technique that allows observation at a cellular level in the depth of fresh living tissues and does not require any histological processing (fixation or staining). The wavelengths previously used have shown no phototoxicity on sperm. We used TPLSM to detect spermatogenetic foci in fresh mouse testicular parenchyma without disrupting the tunica albuginea. Fresh surgically retrieved testes were observed using TPLSM within 1 h after extraction. Contralateral testes for each animal were observed using standard histology. Using TPLSM we were able to observe and measure the diameter of seminiferous tubules through the tunica albuginea, similar to the histological control. Structures within epithelial tubules were also observed, although their nature has yet to be identified. TPLSM is a real-time microscopy technique that could detect spermatogenetic foci.

High-magnification observation of seminiferous tubules through the tunica albuginea by two-photon laser scanning microscopy.

Repeated in vivo two-photon imaging of adult mammalian spinal cords, with subcellular resolution, would be crucial for understanding cellular mechanisms under normal and pathological conditions. Current methods are limited because they require surgery for each imaging session. Here we report a simple glass window methodology avoiding repeated surgical procedures and subsequent inflammation. We applied this strategy to follow axon integrity and the inflammatory response over months by multicolour imaging of adult transgenic mice. We found that glass windows have no significant effect on axon number or structure, cause a transient inflammatory response, and dramatically increase the throughput of in vivo spinal imaging. Moreover, we used this technique to track retraction/degeneration and regeneration of cut axons after a ‘pin-prick' spinal cord injury with high temporal fidelity. We showed that regenerating axons can cross an injury site within 4 days and that their terminals undergo dramatic morphological changes for weeks after injury. Overall the technique can potentially be adapted to evaluate cellular functions and therapeutic strategies in the normal and diseased spinal cord.

Long-term in vivo imaging of normal and pathological mouse spinal cord with subcellular resolution using implanted glass windows.

Two-photon microscopy (2PM) has become a gold standard for deep-tissue observations in the living animal as well as on thick samples. Using 2PM, the endofluorescence properties of biomolecules have shown an interesting potential for the imaging of tissues without any staining. In this short communication, we report a method to observe the different layers of mouse small intestine explants with subcellular resolution and without any staining or clearing. This method allows rapid observations of samples with little to no preparation thanks to the endofluorescence properties of biomolecules such as NAD(P)H or flavins and second-harmonic generation. Finally, we show different three-dimensional reconstructions of the mouse small intestine anatomy obtained with this approach to show the potential of this method in morphological studies.

Three-dimensional imaging of small intestine morphology using non-linear optical microscopy and endogenous signals.

The culture of fastidious microorganisms is a critical step in infectious disease studies. As a proof-of-concept experiment, we evaluated an empirical medium containing eukaryotic cell extracts for its ability to support the growth of Coxiella burnetii. Here, we demonstrate the exponential growth of several bacterial strains, including the C. burnetii Nine Mile phase I and phase II strains, and C. burnetii isolates from humans and animals. Low-oxygen-tension conditions and the presence of small hydrophilic molecules and short peptides were critical for facilitating growth. Moreover, bacterial antigenicity was conserved, revealing the potential for this culture medium to be used in diagnostic tests and in the elaboration of vaccines against C. burnetii. We were also able to grow the majority of previously tested intracellular and fastidious bacterial species, including Tropheryma whipplei, Mycobacterium bovis, Leptospira spp., Borrelia spp., and most putative bioterrorism agents. However, we were unable to culture Rickettsia africae and Legionella spp. in this medium. The versatility of this medium should encourage its use as a replacement for the cell-based culture systems currently used for growing several facultative and putative intracellular bacterial species.

Cell extract-containing medium for culture of intracellular fastidious bacteria.

After spinal cord injury (SCI), resident and peripheral myelomonocytic cells are recruited to the injury site and play a role in injury progression. These cells are important for clearing cellular debris, and can modulate the retraction and growth of axons in vitro. However, their precise spatiotemporal recruitment dynamics is unknown, and their respective roles after SCI remain heavily debated. Using chronic, quantitative intravital two-photon microscopy of adult mice with SCI, here we show that infiltrating lysozyme M (LysM(+)) and resident CD11c(+) myelomonocytic cells have distinct spatiotemporal recruitment profiles, and exhibit changes in morphology, motility, phagocytic activity and axon interaction patterns over time. This study provides the first in vivo description of the influx of inflammatory and resident myelomonocytic cells into the injured spinal cord and their interactions with cut axons, and underscores the importance of precise timing and targeting of specific cell populations in developing therapies for SCI.

Pascal Weber

Developmental Biology Institute of Marseille-Luminy (IBDML)

Aix Marseille University

Implanting Glass Spinal Cord Windows in Adult Mice with Experimental Autoimmune Encephalomyelitis

Intravital Microscopy Imaging of the Liver following Leishmania Infection: An Assessment of Hepatic Hemodynamics