Optical fine-needle imaging biopsy of the brain

Using FDA-approved drugs as off-label fluorescent dyes for optical biopsies: from in silico design toex vivoproof-of-concept

Optical biopsies bring the microscope to the patient rather than the tissue to the microscope, and may complement or replace the tissue-harvesting component of the traditional biopsy process with its associated risks. In general, optical biopsies are limited by the lack of endogenous tissue contrast and the small number of clinically approvedin vivodyes. This study tests multiple FDA-approved drugs that have structural similarity to research dyes as off-labelin situfluorescent alternatives to standardex vivohematoxylin & eosin tissue stain. Numerous drug-dye combinations shown here may facilitate relatively safe and fastin situor possiblyin vivostaining of tissue, enabling real-time optical biopsies and other advanced microscopy technologies, which have implications for the speed and performance of tissue- and cellular-level diagnostics.

Micro-endoscopy for Live Small Animal Fluorescent Imaging

Intravital microscopy has emerged as a powerful technique for the fluorescent visualization of cellular- and subcellular-level biological processes in vivo. However, the size of objective lenses used in standard microscopes currently makes it difficult to access internal organs with minimal invasiveness in small animal models, such as mice. Here we describe front- and side-view designs for small-diameter endoscopes based on gradient-index lenses, their construction, their integration into laser scanning confocal microscopy platforms, and their applications for in vivo imaging of fluorescent cells and microvasculature in various organs, including the kidney, bladder, heart, brain, and gastrointestinal tracts, with a focus on the new techniques developed for each imaging application. The combination of novel fluorescence techniques with these powerful imaging methods promises to continue providing novel insights into a variety of diseases.

In vivo longitudinal depth-wise visualization of tumorigenesis by needle-shaped side-view confocal endomicroscopy

In vivo, longitudinal observation of tumorigenesis in a live mouse model over an extended time period has been actively pursued to obtain a better understanding of the cellular and molecular mechanism in a highly complex tumor microenvironment. However, common intravital imaging approaches based on a conventional laser scanning confocal or a two-photon microscope have been mostly limited to the observation of superficial parts of the solid tumor tissue. In this work, we implemented a small diameter needle-shaped side-view confocal endomicroscope that can be directly inserted into a solid tumor in a minimally-invasive manner in vivo. By inserting the side-view endomicroscope into the breast tumor from the surface, we achieved in vivo depth-wise cellular-level visualization of microvasculature and fluorescently labeled tumor cells located deeply inside the tumor. In addition, we successfully performed longitudinal depth-wise visualization of a growing breast tumor over three weeks in a live mouse model, which revealed dynamic changes in microvasculature such as a decreasing amount of intratumoral blood vessels over time.

In vivo fluorescence microscopy: lessons from observing cell behavior in their native environment

Microscopic imaging techniques to visualize cellular behaviors in their natural environment play a pivotal role in biomedical research. Here, we review how recent technical advances in intravital microscopy have enabled unprecedented access to cellular physiology in various organs of mice in normal and diseased states.