Microscopy with ultraviolet surface excitation for rapid slide-free histology.

Histologic examination of tissues is central to the diagnosis and management of neoplasms and many other diseases, and is a foundational technique for preclinical and basic research. However, commonly used bright-field microscopy requires prior preparation of micrometre-thick tissue sections mounted on glass slides, a process that can require hours or days, that contributes to cost, and that delays access to critical information. Here, we introduce a simple, non-destructive slide-free technique that within minutes provides high-resolution diagnostic histological images resembling those obtained from conventional haematoxylin-and-eosin-histology. The approach, which we named microscopy with ultraviolet surface excitation (MUSE), can also generate shape and colour-contrast information. MUSE relies on ~280-nm ultraviolet light to restrict the excitation of conventional fluorescent stains to tissue surfaces, and it has no significant effects on downstream molecular assays (including fluorescence in situ hybridization and RNA-seq). MUSE promises to improve the speed and efficiency of patient care in both state-of-the-art and low-resource settings, and to provide opportunities for rapid histology in research

Using spectral decomposition of the signals from laurdan-derived probes to evaluate the physical state of membranes in live cells

Background: We wanted to investigate the physical state of biological membranes in live cells under the most physiological conditions possible. Methods: For this we have been using laurdan, C-laurdan or M-laurdan to label a variety of cells, and a biphoton microscope equipped with both a thermostatic chamber and a spectral analyser. We also used a flow cytometer to quantify the 450/530 nm ratio of fluorescence emissions by whole cells. Results: We find that using all the information provided by spectral analysis to perform spectral decomposition dramatically improves the imaging resolution compared to using just two channels, as commonly used to calculate generalized polarisation (GP). Coupled to a new plugin called Fraction Mapper, developed to represent the fraction of light intensity in the first component in a stack of two images, we obtain very clear pictures of both the intra-cellular distribution of the probes, and the polarity of the cellular environments where the lipid probes are localised. Our results lead us to conclude that, in live cells kept at 37°C, laurdan, and M-laurdan to a lesser extent, have a strong tendency to accumulate in the very apolar environment of intra-cytoplasmic lipid droplets, but label the plasma membrane (PM) of mammalian cells ineffectively. On the other hand, C-laurdan labels the PM very quickly and effectively, and does not detectably accumulate in lipid droplets. Conclusions: From using these probes on a variety of mammalian cell lines, as well as on cells from Drosophila and Dictyostelium discoideum, we conclude that, apart from the lipid droplets, which are very apolar, probes in intracellular membranes reveal a relatively polar and hydrated environment, suggesting a very marked dominance of liquid disordered states. PMs, on the other hand, are much more apolar, suggesting a strong dominance of liquid ordered state, which fits with their high sterol contents

Multispectral analysis tools can increase utility of RGB color images in histology.

Multispectral imaging (MSI) is increasingly finding application in the study and characterization of biological specimens. However, the methods typically used come with challenges on both the acquisition and the analysis front. MSI can be slow and photon-inefficient, leading to long imaging times and possible phototoxicity and photobleaching. The resulting datasets can be large and complex, prompting the development of a number of mathematical approaches for segmentation and signal unmixing. We show that under certain circumstances, just three spectral channels provided by standard color cameras, coupled with multispectral analysis tools, including a more recent spectral phasor approach, can efficiently provide useful insights. These findings are supported with a mathematical model relating spectral bandwidth and spectral channel number to achievable spectral accuracy. The utility of 3-band RGB and MSI analysis tools are demonstrated on images acquired using brightfield and fluorescence techniques, as well as a novel microscopy approach employing UV-surface excitation. Supervised linear unmixing, automated non-negative matrix factorization and phasor analysis tools all provide useful results, with phasors generating particularly helpful spectral display plots for sample exploration

Real-time, High-resolution, In Vivo Characterization of Superficial Skin With Microscopy Using Ultraviolet Surface Excitation (MUSE).

BackgroundSkin care products make up the largest part (36%) of the cosmetic market globally, of which the United States plays the largest role. In 2015, approximately 115 billion USD was spent globally on skin care products. Skin care products, in contradistinction to pharmaceuticals, are not strictly regulated by the FDA. A key factor for evaluation of a skin care product or topical drug is skin barrier function and effect on super cial skin. Thus, it is critical to have quantitative and qualitative methods to study the effects of skin care products on skin barrier and the super cial skin. Currently, no imaging method exists that can evaluate and track super cial skin changes visually in real-time.ObjectiveTo report using a novel imaging modality, Microscopy using Ultraviolet Surface Excitation (MUSE), to provide real-time, high- resolution, in vivo characterization of super cial skin and moisturizing properties of topical moisturizer, and to highlight key bene ts of using MUSE to visualize the super cial skin and serve as an excellent complementary tool to current quantitative methods.Methods and materialsThe methodology of MUSE is based upon two main principles inherent to ultraviolet (UV) light and uorescent staining agents. In this study, the author's (JJ) index ngertip was imaged using the MUSE instrument without and with moisturizer.ResultsDermatoglyphics of the fingertip consists of ridges (cristae super ciales) and grooves (sulci super ciales) proved to be straightforward to visualize at high resolution. Desquamation of superficial corneocytes and opening of an acrosyringium (the most superficial portion of eccrine ducts) were visualized in high-resolution. Post-application of a moisturizer, a uniform layer of moisturizer could be seen superficial to the corneocytes along the ridges and CONCLUSIONS: Real-time, high-resolution, in vivo characterization of super cial skin and moisturizing properties of moisturizer using MUSE is feasible. Its utility can be enhanced with downstream quantification using imaging software. J Drugs Dermatol. 2016;15(11):1344-1346.

Pocket MUSE: an affordable, versatile and high-performance fluorescence microscope using a smartphone.

Smartphone microscopes can be useful tools for a broad range of imaging applications. This manuscript demonstrates the first practical implementation of Microscopy with Ultraviolet Surface Excitation (MUSE) in a compact smartphone microscope called Pocket MUSE, resulting in a remarkably effective design. Fabricated with parts from consumer electronics that are readily available at low cost, the small optical module attaches directly over the rear lens in a smartphone. It enables high-quality multichannel fluorescence microscopy with submicron resolution over a 10× equivalent field of view. In addition to the novel optical configuration, Pocket MUSE is compatible with a series of simple, portable, and user-friendly sample preparation strategies that can be directly implemented for various microscopy applications for point-of-care diagnostics, at-home health monitoring, plant biology, STEM education, environmental studies, etc