Glioblastomas are brain cancers with very poor patient prognosis. We have developed a Glioblastoma U87 MR model, using 4-dimensional imaging in multi-day tracking experiments. The cells have a tendency to form long-term cellular associations, and quantifying their motility by standard approaches is difficult. We cultured the cells in a structured environment (wound healing template), separated the X and Y information to define cumulative directionality plots providing a metric of the overall cell population movement analyzed by holographic imaging cytometry. With cellular tomography, we obtained 3D time lapse tomographs of cells at 0.2 um resolution, enabling sub-cellular analysis at levels not previously possible. Even in label-free cultures, sub-cellular components can be distinguished and color-coded based on differences of their refractive index values. We discovered that there are numerous mitochondria present, both single and also actively undergoing fission and fusion processes. Many thin mitochondrial networks are present within the cytoplasm, and also extending away from the cell in tunneling nanotubes. There is fusion of these networks to form larger structures that form connections between cells. Substances can be seen moving bi-directionally between cells. After several days of culture, the cells form large multicellular and highly connected spheroids. This is evident in widefield stitched images of the spheroids. While the tendency of U87 cells to form spheroids was previously known, the combined results from our multi-modality quantitative imaging platforms provide new insights into the cellular dynamics of glioblastoma cells, and the networks that they form. This knowledge is being applied to the development anti-glioblastoma treatments.
We rely on in vitro cellular cultures to evaluate the effects of the components of multifunctional nano-based formulations under development. We employ an incubator-adapted, label-free holographic imaging cytometer HoloMonitor M4® (Phase Holographic Imaging, Lund, Sweden) to obtain multi-day time-lapse sequences at 5- minute intervals. An automated stage allows hand-free acquisition of multiple fields of view.
Our system is based on the Mach-Zehnder interferometry principle to create interference patterns which are deconvolved to produce images of the optical thickness of the field of view. These images are automatically segmented resulting in a full complement of quantitative morphological features, such as optical volume, thickness, and area amongst many others. Precise XY cell locations and the time of acquisition are also recorded.
Visualization is best achieved by novel 4-Dimensional plots, where XY position is plotted overtime time (Z-directions) and cell-thickness is coded as color or gray scale brightness. Fundamental events of interest, i.e., cells undergoing mitosis or mitotic dysfunction, cell death, cell-to-cell interactions, motility are discernable. We use both 2D and 3D models of the tumor microenvironment.
We report our new analysis method to track feature changes over time based on a 4-sample version of the Kolmogorov-Smirnov test. Feature A is compared to Control A, and Feature B is compared to Control B to give a 2D probability plot of the feature changes over time. As a result, we efficiently obtain vectors quantifying feature changes over time in various sample conditions, i.e., changing compound concentrations or multi-compound combinations.
Brightfield Laser Scanning Imaging (BLSI) is available on Laser Scanning Cytometers (LSCs) from CompuCyte
Corporation. Briefly, digitation of photodetector outputs is coordinated with the combined motions of a small diameter
(typically 2 to 10 microns) laser beam scanning a specimen in the Y direction (directed by a galvanometer-driven
scanning mirror) and the microscope stage motion in the X direction. The output measurements are assembled into a
two-dimensional array to provide a "non-real" digital image, where each pixel value reports the amount of laser-scattered
light that is obtained when the laser beam is centered on that location. Depending on the detector positions, these images
are analogous to Differential Interference Contrast or Phase Contrast microscopy. We report the incorporation of the new
laser scattering capabilities into the workflow of a high-volume clinical cytology laboratory at University Health
Network, Toronto, Canada. The laboratory has been employing LSC technology since 2003 for immunophenotypic
fluorescence analysis of approximately 1200 cytological specimens per year, using the Clatch methodology. The new
BLSI component allows visualization of cellular morphology at higher resolution levels than is possible with standard
brightfield microscopic evaluation of unstained cells. BLSI is incorporated into the triage phase, where evaluation of
unstained samples is combined with fluorescence evaluation to obtain specimen background levels. Technical details of
the imaging methodology will be presented, as well as illustrative examples from current studies and comparisons to
detailed, but obscure, historical studies of cytology specimens based on phase contrast microscopy.
Background: Slide based cytometry (SBC) is a technology for the rapid stoichiometric analysis of cells fixed to surfaces. Its applications are highly versatile and ranges from the clinics to high throughput drug discovery. SBC is realized in different instruments such as the Laser Scanning Cytometer (LSC) and Scanning Fluorescent Microscope (SFM) and the novel inverted microscope based iCyte image cytometer (Compucyte Corp.). Methods: Fluorochrome labeled specimens were immobilized on microscopic slides. They were placed on a conventional fluorescence microscope and analyzed by photomultiplayers or digital camera. Data comparable to flow cytometry were generated. In addition, each individual event could be visualized. Applications: The major advantage of instruments is the combination of two features: a) the minimal sample volume needed, and b) the connection of fluorescence data and morphological information. Rare cells were detected, frequency of apoptosis by myricetin formaldehyde and H2O2 mixtures was determined;. Conclusion: LSC, SFM and the novel iCyte have a wide spectrum of applicability in SBC and can be introduced as a standard technology for multiple settings. In addition, the iCyte and SFM instrument is suited for high throughput screening by automation and may be in future adapted to telepathology due to their high quality images. (This study was supported by the IZKF-Leipzig, Germany and T 034245 OTKA, Hungary)
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