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Biomedical Imaging and Instrumentation

Biomedical Imaging and Instrumentation - Poster Session A

Poster G5 - Chemotherapy induced cardiotoxicity analysis of oxaliplatin on human heart organoids using optical coherence tomography

Thursday, October 24, 2024

10:00 AM - 11:00 AM EST

Location: Exhibit Hall E, F & G

Presenting Author(s)

Joven C. Jose

Undergraduate student
Southeastern University, College of natural and health sciences
Bartow, Florida, United States

Co-Author(s)

Fei Wang

Graduate Student
Washington University in St. Louis
University City, Missouri, United States
RP

Ratul Paul

Post-doc
Washington University in st. Louis
Bethlehem, Pennsylvania, United States
JD

Junwei Du

Graduate Student
Washington University in St. Louis, United States
MB

Mikhail Berezin

Associate Professor of Radiology
Washington University in St. Louis, United States

Primary Investigator(s)

CZ

Chao Zhou

Professor
Washington university in St. louis, United States

Introduction: Cytotoxic chemotherapy drugs have clinically made effective progress in response rates for cancer patients. However, the benefits of modern cytostasis are accompanied by adverse toxicity particularly to cardiac cells. Oxaliplatin, a platinum based cytotoxic drug has been the standard treatment for advanced colorectal cancer. One of its least investigated side effects include cardiotoxicity as it causes rapid breathing, arrhythmia and tachycardia in various clinical cases. To determine the cardiotoxicity of drugs, various models use rodents and larger animals that have raised limitations due to the differences in cardiac function among species. Recent studies using two dimensional monocultured cardiomyocytes have also shown to lack efficiency in modelling the complex physiology of the human heart. Human heart organoids (hHOs) are three-dimensional (3D) miniature hearts developed from human induced pluripotent stem cells. They have phenomenal capabilities to recapitulate aspects of cardiac physiology making them a perfect fit for toxicity modelling. Optical coherence tomography (OCT) is a fast, non-invasive, and label-free imaging modality. It helps to overcome the limitations of tissue sectioning and immunostaining to effectively characterize an organoid's 3D morphological features throughout the experimental period. This study aims to postulate an efficient in-situ cardiotoxicity analysis model to determine cardiotoxic effects of oxaliplatin on self-assembling human heart organoids. The morphological and physiological parameters are characterized using customized Spectral Domain Optical coherence tomography (SD-OCT) and calcium imaging. To optimize chemotherapy treatments and reduce its long term cardiotoxic effects, efficient models as proposed in this study proves relevance in clinical application.

Materials and

Methods: Wild-type C human induced pluripotent stem cells (WTC hiPSCs), expressing calcium indicator GCaMP6f were used to fabricate hHOs. Calcium transients help to track contractile motion, an essential metric for cardiomyocyte health. Cardiomyocyte differentiation was achieved by activation and inhibition of the wnt signaling pathway by CHIR99021 and wnt-C59 respectively. After 20 days of organoid development, hHOs were exposed to various concentrations of oxaliplatin through the medium. The OCToScope setup provides an in-situ model that enables OCT, brightfield and fluorescence calcium imaging of organoids within the cell culture environment of the incubator. OCT morphological imaging of hHOs were performed for a week that provided 3D rendering, en face and cross-sectional views along with chamber segmentation. The resolution of the OCT was improved with a supercontinuum laser (Fianium SC450) having a 400-2000nm wavelength range. The number of A-scans was set as 600 per B-scan and exposure time was set to be 1µs to improve imaging depth. Calcium imaging was obtained by fluorescence microscopy (IX71, Olympus) at around 10 fps. Using a customized python program, total grayscale values were identified from which the normalized grayscale value per area of calcium transient were plotted. The detected peaks of calcium transients were plotted over time to obtain beats per minute along with the average peaks of fixed time range.

Results, Conclusions, and Discussions: Calcium transients play an essential role in coordinating heart functions and contractions that could be disrupted by cytotoxic drugs. Calcium imaging of heart organoids after oxaliplatin exposure indicates a steady decline in calcium transient duration. A significant increase in beats per minute was noted for organoids exposed to higher concentrations after the first day of drug exposure. However, the area of calcium signal propagation was found to be comparatively reduced than the control which could predict the disruption of electrical signaling. These organoids had a drastic decline of beats per minute in the later days. This decline is directly proportional to oxaliplatin concentration which is supported by the early onset cessation of beating for organoids exposed to 70μM and 100μM concentrations. The beating intensity of organoids exposed to higher oxaliplatin doses reduced over time along with a decrease in relaxation time. Segmentation and 3D rendering using OCT images indicate the deterioration of organoid cavities and structural deformation after oxaliplatin exposure that could be linked to decreased contractile functions observed.
Results from this study indicate the efficiency of a combined in situ model for cardiotoxicity analysis using human heart organoids, OCT and calcium imaging modality. Heart organoids are spontaneously beating from day 10 and acquire complete maturity by day 20 where the beating patterns and beats per minute tend to be stable. After exposure to the drug, organoids rapidly indicate morphological and beating changes. This helps to recapitulate the 3D tissue level effects of chemotherapy induced cardiotoxicity within a week. Due to imaging depth limitations, brightfield and fluorescence calcium imaging can monitor only the beating of the horizontal top layer of organoids. However, OCT recordings reveal the cross sectional beating patterns along with chamber and structural morphology of hHOs to analyse cardiotoxic effects. To further optimise this model, OCT M-mode scans along with immunostaining and confocal imaging could help observe effects of cytotoxic drugs on chamber contractions and blood vessel networks respectively. To maintain cardiac well-being of cancer patients after chemotherapy, a cardiotoxicity model as proposed by this study is essential to be done before clinical applications of cytotoxic drugs.

Acknowledgements (Optional):