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High School Student with a Traditionally Underrepresented Background

HS Poster

Poster 35 - Calcium Dynamics in Nuclei and Cytoplasm of Shockwave-Injured Astrocytes from an Alzheimer's Mouse Model

Saturday, October 26, 2024
10:00 AM - 12:00 PM EST
Location: Exhibit Hall E, F & G

    Presenting Author(s)

  • AL

    Angela Li (she/her/hers)

    Volunteer Research Intern
    University of California, San Diego: Institute of Engineering in Medicine
    San Diego, California, United States

    • Co-Author(s)

  • AL

    Albert Li

    volunteer research intern
    Outreach Program for Advancing Learning in STEM (OPALS), United States

  • AZ

    Austin Zhang

    Volunteer research intern
    University of California, San Diego: Institute of Engineering in Medicine, United States

    • Co-Author(s)

  • Sonia Kang

    Volunteer research intern
    University of California, San Diego: Institute of Engineering in Medicine
    San Diego, California, United States

  • Chengbiao Wu, PhD

    Professor
    University of California, San Diego: Department of Neurosciences, United States

    • Primary Investigator(s)

  • Linda Shi, PhD (she/her/hers)

    OPALS Program Director, Project Scientist, Co-director IEM
    University of California, San Diego: Institute of Engineering in Medicine
    La Jolla, California, United States

    • Last Author(s)

  • Veronica Gomez-Godinez, PhD (she/her/hers)

    Project Scientist
    Institute of Engineering in Medicine, UCSD, United States


Introduction: Alzheimer's disease (AD) is a neurodegenerative disorder affecting astrocytes, a glial cell type essential for regulating calcium ions in brain homeostasis. This experiment focuses exclusively on astrocytes derived from an AD model. Using Fluo-4 AM, a fluorescent calcium indicator, we visualized calcium dynamics in the nuclei and cytoplasm of these cells under a microscope. All astrocytes were subjected to a shockwave to induce cellular damage, simulating stress conditions. By comparing the calcium responses in the nuclei and cytoplasm, this study aims to provide insights into the cellular mechanisms of calcium regulation in Alzheimer's disease astrocytes under stress.

Materials and

Methods: Cells were obtained from the PSAPP mouse model, which carries mutations in both APP and presenilin1. A Coherent 1030 nm laser generated a shockwave on the cells to simulate stress conditions similar to traumatic brain injury. A rotating optical polarizer on a stepper-motor-controlled mount attenuated the laser power, and a mechanical shutter allowed a single pulse into the microscope. The laser beam diameter was adjusted to focus the laser 10 µm above the substrate. Prior to imaging, cells were loaded with Fluo-4 AM and dead red stain. Following the shockwave, 600 images were captured per sample at 3-second intervals. Brightness (pixel intensities) of cytoplasm and nuclei areas were measured before and after the shockwave to reflect calcium movement differences, analyzed using MATLAB peak analysis software. ImageJ was used to open the 600 images per sample, and MATLAB processed images to identify live and dead cells, saving brightness over time, half-life, and distances from the shockwave. Data was compiled into graphs and analyzed, with findings summarized in a poster and presentation.

Results, Conclusions, and Discussions:

Results:
The experiment examined calcium dynamics in astrocytes from an Alzheimer's disease (AD) model using the Fluo-4 AM calcium indicator. The analysis compiled results across all fields of view (FOVs), revealing significant differences between dead and live cells in both nuclei (t-statistic = 3.69, p-value = 0.00033) and cytoplasm (t-statistic = 0.77, p-value = 0.44008). Specifically, live nuclei exhibited higher average peak brightness (3.39) compared to live cytoplasm (3.12), whereas dead nuclei (2.73) showed lower average peaks than dead cytoplasm (3.00). Further comparisons between live cytoplasm and nuclei showed a significant difference (t-statistic = -2.07, p-value = 0.03981), whereas no significant difference was observed between dead cytoplasm and nuclei (t-statistic = 1.45, p-value = 0.15020).
Conclusions and Future Work:
The observed differences in calcium dynamics between the nuclei and cytoplasm of AD model astrocytes suggest impaired compartmental calcium regulation. This may contribute to cellular dysfunction in Alzheimer's disease. Significant differences were found between dead and live cells in both nuclei and cytoplasm. Live nuclei exhibited higher average peak brightness compared to live cytoplasm, while dead nuclei showed lower average peaks than dead cytoplasm. A significant difference was also noted between live cytoplasm and nuclei. Future work should expand the dataset and compare results with wild-type astrocytes to validate these observations and explore their implications for AD progression and treatment.

Acknowledgements (Optional): This work was supported by a generous gift from Beckman Laser Institute Inc. to L.S. and V.G.G. The high school students (*) participated in the UCSD IEM OPALS internship. Special thanks to Dr. Shu Chien from UCSD Bioengineering and Dr. Lizhu Chen from CorDx Inc. for their donations.

References (Optional):