Abstract 4701: Spatial resolution of tumor and immune cell lineages in the hypoxic microenvironment of pancreatic ductal adenocarcinoma (PDAC)

Understanding how the tumor microenvironment (TME) evolves during tumorigenesis and therapeutic response is crucial to developing personalized treatments with the goal of improving cancer therapy. With robust and comprehensive multiplexed imaging technologies, immune biomarker antibodies can be used to interrogate immune cell lineages and structures. When combined with specific oncology biomarker antibodies, this approach can capture the immune response within the TME in a variety of neoplasms. The Cell DIVETM Multiplex Imaging Solution allows probing and imaging of dozens of biomarkers on a whole single tissue section using an iterative staining and dye inactivation workflow. The broad portfolio of robust IHC-validated antibodies from Cell Signaling Technology (CST) enables the detection of key proteins in the TME, allowing immune cell detection and phenotyping in tissue. Here, we demonstrate multiplexed Cell DIVE imaging using a novel CST panel to probe pancreatic ductal adenocarcinoma (PDAC). These biomarker antibodies define the immune cell landscape in the hypoxic tumor. Development of the antibody panel required minimal optimization, enabled the identification of complex cell types and revealed their cell-to-cell interactions within the tumor microenvironment. The availability of cell type specific biomarkers, combined with the ability to interrogate using multiplexed tissue imaging, provides unprecedented and novel insights and spatial resolution of immune cell populations with many cell types in the TME.

Citation Format: Lisa Arvidson, Reginaldo Prioli, Samuel Jensen, Michael J. Smith, Katie O. White, Richard A. Heil-Chapdelaine, Chi-Chou Huang, Tuan H. Phan, Hideki Sasaki, Melinda L. Angus-Hill. Spatial resolution of tumor and immune cell lineages in the hypoxic microenvironment of pancreatic ductal adenocarcinoma (PDAC). [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4701.

Abstract 4698: Reproducibility in spatial biology: reducing variables to improve the reliability of insight generation

There is an ongoing crisis in reproducibility in scientific studies, and studies in spatial biology are no exception. Cell DIVETM Multiplex imaging solution (Leica Microsystems) provides reliable workflow solutions to minimize variability from study to study. Cell DIVE allows probing and imaging of dozens of biomarkers on a whole tissue section with an iterative staining and dye inactivation workflow. At its core, Cell DIVE is designed to provide methods reproducibility, from tissue preparation, antigen retrieval, and sample imaging and slide storage. Cell DIVE is designed to work with directly conjugated primary antibodies, another source of variability. However, conjugated antibodies from Cell Signaling Technology (CST) are rigorously validated using stringent acceptance criteria to reduce variability. In addition, the use of recombinant antibodies, the consistent conjugate brightness and antibody degree-of-labeling reduce lot to lot variability, ensuring reliable conjugated antibodies for spatial biology studies. High resolution imaging results are obtained by consistent round to round imaging, consistent calibration and corrections, and reduction of human error using the BAB 200 liquid handling solution (Advanced Solutions Life Sciences). We present here, an iterative biomarker study using adjacent tissue sections probed with distinct lots of CST antibody panels, imaged in temporally separated batches using a Cell DIVE imager fitted with a BAB200 liquid handler. Following robust analysis (segmentation, phenotyping and statistical analysis), we report the reproducibility findings across parameters. Methods and results reproducibility in spatial biology is essential for reliable insight generation, giving confidence in the quality of future studies aimed at improving patient outcomes.

Citation Format: Lisa Arvidson, Reginaldo Prioli, Samuel Jensen, James B. Hoying, Michael W. Golway, Michael J. Smith, Katie O. White, Richard A. Heil-Chapdelaine, Chi-Chou Huang, Tuan H. Phan, Hideki Sasaki, Melinda Angus-Hill. Reproducibility in spatial biology: reducing variables to improve the reliability of insight generation. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4698.

Rapid Immunoaffinity-Based Method for Determination of Zearalenone in Corn by Fluorometry and Liquid Chromatography

An immunoaffinity-based method was developed to determine zearalenone in corn. Corn samples were extracted in acetonitrile-water (90 + 10, v/v), applied to an immunoaffinity column, and eluted with methanol. The isolated toxin was quantitated either by reaction with aluminum chloride hexahydrate (AlCl33.6H2O) prior to measurement with a fluorometer or injection into a liquid chromatographic (LC) system with a fluorescence detector. Performance was evaluated in terms of antibody specificity, limit of detection, percentage recovery, precision, column capacity, assay linearity, and comparison with AOAC Official Method 985.18. With the immunoaffinity column cleanup procedure, only zearalenone and its metabolites were recognized by the antibody (≥75% recovery). Limits of detection were 0.10 μg/g for the fluorometer and 0.10 or 0.0025 μg/g (sensitive method) for the LC method. Percentage recovery averaged 105% (fluorometer) and 93% (LC method), with average relative standard deviations (RSDs) of 15.7 and 9 .3%. Naturally contaminated samples gave comparable RSDs of 8.3 and 9.9% for the fluorometer and LC methods, respectively. Column capacity was 4.0 μg with 89% recovery. Assay linearity was comparable for both methods (r2 = 0.998). Optimum assay ranges were 0.10-5.0 μg/g for the fluorometer and 0.10-50 or 0.0025-5.0 μg/g (sensitive method) for the LC method. Comparative analysis of 17 naturally contaminated corn samples using ZearalaTest LC and the official AOAC LC method for detection of zearalenone showed that ZearalaTest is statistically comparable to the AOAC Official Method 985.18 (r2 = 0.747).

Velocity-dependent friction enhances tribomechanical differences between monolayer and multilayer graphene

The influence of sliding speed in the nanoscale friction forces between a silicon tip and monolayer and multilayer graphene were investigated with the use of an atomic force microscope. We found that the friction forces increase linearly with the logarithm of the sliding speed in a highly layer-dependent way. The increase in friction forces with velocity is amplified at the monolayer. The amplification of the friction forces with velocity results from the introduction of additional corrugation in the interaction potential driven by the tip movement. This effect can be interpreted as a manifestation of local thermally induced surface corrugations in nanoscale influencing the hopping dynamics of the atoms at the contact. These experimental observations were explained by modeling the friction forces with the thermally activated Prandtl-Tomlinson model. The model allowed determination of the interaction potential between tip and graphene, critical forces, and attempt frequencies of slip events. The latter was observed to be dominated by the effective contact stiffness and independent of the number of layers.

Gold nanoparticles on the surface of soda-lime glass: morphological, linear and nonlinear optical characterization

Materials presenting high optical nonlinearity, such as materials containing metal nanoparticles (NPs), can be used in various applications in photonics. This motivated the research presented in this paper, where morphological, linear and nonlinear optical characteristics of gold NPs on the surface of bulk soda-lime glass substrates were investigated as a function of nanoparticle height. The NPs were obtained by annealing gold (Au) thin films previously deposited on the substrates. Pixel intensity histogram fitting on Atomic Force Microscopy (AFM) images was performed to obtain the thickness of the deposited film. Image analysis was employed to obtain the statistical distribution of the average height of the NPs. In addition, absorbance spectra of the samples before and after annealing were measured. Finally, the nonlinear refractive index (n2) and the nonlinear absorption index (α2) at 800 nm were obtained before and after annealing by using the thermally managed eclipse Z-scan (TM-EZ) technique with a Ti:Sapphire laser (150 fs pulses). Results show that both n2 and α2 at this wavelength change signs after the annealing and that the samples presented a high nonlinear refractive index.

In situ atomic force microscopy and image analysis of dentine submitted to acid etching

The effect of acid etching on root dentine was analyzed with Atomic Force Microscopy using a liquid cell that allowed image acquisition while the sample was kept in contact with the etching solution. The time evolution of the etching process was evaluated both qualitatively and quantitatively. Image sequences against etching time were obtained showing a clear trend of surface cleaning and opening of dentine tubules. Image analysis methods were employed to quantify the changes on the dentine surface, through the detection and morphological measurement of dentine tubules over time. The measurements indicated an overall increase in the diameter of the tubules against time, with a saturation value between 3.5 and 5.5 microm reached after approximately 300 seconds.

Real-time atomic force microscopy of root dentine during demineralization when subjected to chelating agents

AIM

To explore the potential of atomic force microscopy (AFM) for the examination of changes to dentine surfaces during demineralization and evaluate qualitatively the effect of EDTA, EDTAC and citric acid.

METHODOLOGY

Nine canine teeth were sectioned transversely at the cemento-enamel junction, and the crowns discarded. Subsequently, each root was embedded in an epoxy cylinder and discs approximately 5 mm thick were cut. A standard metallographic procedure was then used to prepare the surfaces for observation. From the central portion of these samples, two specimens were symmetrically prepared per tooth so that a total number of 18 samples was produced. To allow the use of a liquid cell during AFM, the samples were embedded in silicone rubber and were then randomly divided into three groups, as follows: group 1: 17% EDTA (pH 7.7), group 2: 17% EDTAC (pH 7.7) and group 3: 10% citric acid (pH 1.4). Topographical images were acquired during the demineralization process, allowing real-time observation of the dentine surface. Two operators assigned scores to the AFM images using a double-blind method. anova analysis with random effects (P < 0.05) was used to compare the results.

RESULTS

The average scores were 6.13 +/- 0.35 for EDTAC, 7.36 +/- 0.23 for EDTA and 14.55 +/- 1.21 for citric acid. Citric acid was statistically different from EDTA and EDTAC while EDTA and EDTAC were not statistically different.

CONCLUSIONS

The most effective demineralizing substance was citric acid. The methodology developed for real-time observation of dentine surfaces is a valuable method to evaluate demineralization.

Lateral force microscopy profiles for amorphous potentials

In this work, the lateral force profiles of the scanning force microscope tip on an amorphous surface were simulated with the use of an independent oscillator model. The correlation between the lateral force profiles and the surface potential were studied as a function of the tip-surface normal force and relative scanning velocity. It is shown that the microscope resolution is governed by the quotient between the average potential interaction energy and the average elastic energy stored before the jumps. We show that there is an optimal velocity with which the scanning tip better senses the surface potential and we present its scaling laws.

Grain size distribution analysis in polycrystalline LiF thin films by mathematical morphology techniques on AFM images and X-ray diffraction data

The influence of the deposition temperature on the grain size of polycrystalline lithium fluoride (LiF) thin films is studied using a mathematical morphology method. On atomic force microscopy images of the LiF surface, the grain sizes and shapes are determined by applying the watershed technique, together with a shape factor algorithm. Also, the domain size of the film structure, determined by an X-ray diffraction data analysis, is compared and correlated with the mean grain size as a function of the deposition temperature. In both cases a linear increase with temperature and a very good agreement among the two structural parameters (grain and domain size) was found.

Rapid immunoaffinity-based method for determination of zearalenone in corn by fluorometry and liquid chromatography

An immunoaffinity-based method was developed to determine zearalenone in corn. Corn samples were extracted in acetonitrile-water (90 + 10, v/v), applied to an immunoaffinity column, and eluted with methanol. The isolated toxin was quantitated either by reaction with aluminum chloride hexahydrate (AlCl3.6H2O) prior to measurement with a fluorometer or injection into a liquid chromatographic (LC) system with a fluorescence detector. Performance was evaluated in terms of antibody specificity, limit of detection, percentage recovery, precision, column capacity, assay linearity, and comparison with AOAC Official Method 985.18. With the immunoaffinity column cleanup procedure, only zearalenone and its metabolites were recognized by the antibody (> or = 75% recovery). Limits of detection were 0.10 microgram/g for the fluorometer and 0.10 or 0.0025 microgram/g (sensitive method) for the LC method. Percentage recovery averaged 105% (fluorometer) and 93% (LC method), with average relative standard deviations (RSDs) of 15.7 and 9.3%. Naturally contaminated samples gave comparable RSDs of 8.3 and 9.9% for the fluorometer and LC methods, respectively. Column capacity was 4.0 micrograms with 89% recovery. Assay linearity was comparable for both methods (r2 = 0.998). Optimum assay ranges were 0.10-5.0 micrograms/g for the fluorometer and 0.10-50 or 0.0025-5.0 micrograms/g (sensitive method) for the LC method. Comparative analysis of 17 naturally contaminated corn samples using Zearala Test LC and the official AOAC LC method for detection of zearalenone showed that Zearala Test is statistically comparable to the AOAC Official Method 985.18 (r2 = 0.747).

Quantification of deoxynivalenol in wheat using an immunoaffinity column and liquid chromatography

A simple and accurate method to quantify the mycotoxin deoxynivalenol (DON) in wheat is described. The method uses immunoaffinity chromatography for DON isolation and liquid chromatography (LC) for toxin detection and quantification. Wheat samples are extracted in water, filtered twice and applied to an immunoaffinity column. Following a water wash, DON is eluted from the column with methanol and injected onto an LC system with a UV detector for quantification. Test performance was evaluated in terms of antibody specificity, limit of detection, percentage recovery, precision, column capacity, assay linearity and comparison with the GC-electron-capture detection (ECD) method of Tacke and Casper. Specificity of the immunoaffinity column cleanup procedure was confirmed with only DON (>80%) and its 15-C derivatives (40-50%) being recognized by the antibody while 3-C DON derivatives, nivalenol, T-2 and fusarenon-X did not bind. The limit of detection is at least 0.10 microg/g. Percentage recovery for the entire assay range averages 90% with an average relative standard deviation of 8.3%. Naturally contaminated samples showed comparable precision. Column capacity was determined to be 3.3 microg. The assay showed a high degree of linearity (r2=0.999) and an optimum assay range of 0.10 to 10.0 microg/g. Comparative analysis of 28 naturally or artificially contaminated wheat samples using DONtest-HPLC and the GC-ECD method of Tacke and Casper showed that DONtest-HPLC is a statistically significant predictor of the GC-ECD method (r2=0.982).

Improved fluorometric and chromatographic methods for the quantification of fumonisins B(1), B(2) and B(3)

Fumonisins pose serious health risks to humans and livestock, making their detection imperative in foods and feedstuffs. This detection can be accomplished quickly, precisely and accurately in a two-step chromatographic process. In the first step, fumonisins are extracted from a sample and isolated on an immunoaffinity column. In the second step, fumonisins are converted to fluorescent derivatives and quantified either through high-performance liquid chromatography (HPLC) or by fluorometer. These methods offer significant improvements in performance compared to earlier technology: limits of detection as low as 0.016 micrograms/g with HPLC-based detection and 0.25 micrograms/g for fluorometer-based detection; greater assay linearity (with HPLC, r = 0.997; with fluorometer, r = 0.998); larger immunoaffinity column capacity (77% recovery at 12.5 micrograms) and extended assay range (0-10 micrograms/g) for methods. The percentage recovery of fumonisins over the entire assay range averaged 83% for both the fluorometer and HPLC methods. Precision studies were performed for both the fluorometer and the HPLC methods. The average coefficient of variation was 14% for the fluorometer method and 8.3% for the HPLC method. As a result of the efficient separation, the improved HPLC method offers the advantage of precise individual quantification of FB1, FB2 and FB3. The two methods were compared using 33 naturally or artificially contaminated corn samples. Linear regression analysis demonstrated an excellent correlation (r = 0.996) between the two techniques. Higher recoveries of fumonisins were obtained using this HPLC method than with the official AOAC method.