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Fehri, A.

Publications and source records attributed to Fehri, A..

2 recordsLinked to original sources

Contrastive learning for cell division detection and tracking in live cell imaging data

Fluorescent live-cell microscopy is essential for understanding cellular dynamics by imaging specific molecules, their interactions, and biochemical states in live samples. It is crucial for biological research and drug screening. However, live-cell imaging often requires balancing temporal resolution with cell viability (i.e. conditions enabling cells to thrive) because of photo-toxicity. Consequently, there is increasing interest in lowering temporal resolution to allow for extended observation periods and to study event sequences that uncover causal relationships and mechanistic insights. Tracking cells in video microscopy with low temporal resolution remains a challenge. We introduce a new integrated methodology that uses contrastive learning and graph-based approaches to improve cell division detection and tracking. Our approach employs contrastive learning models to create cell representations that facilitate the detection of cell divisions and enhance cell tracking. Of note, we propose a weakly-supervised constrastive learning approach to build robust temporal cell representations through time-based augmentations. Additionally, we introduce an innovative graph optimization technique to identify cell tracks based on these representations and observed division events. We evaluate our methods on an in-house dataset and public datasets from the Cell Tracking Challenge, achieving substantial performance improvements in both native and reduced temporal resolutions. Our methodology thus enhances adaptability to various temporal resolutions, improving precision and efficiency in live-cell microscopy analysis. This advancement is particularly beneficial for extended drug screening studies, ensuring cell viability and maintaining normal cell homeostasis, which is vital for therapeutic research.

bioinformatics↗

Cell Segmentation in Images Without Structural Fluorescent Labels

High-content screening (HCS) provides an excellent tool to understand the mechanism of action of drugs on disease-relevant model systems. Careful selection of fluorescent labels (FLs) is crucial for successful HCS assay development. HCS assays typically comprise (1) FLs containing biological information of interest, and (2) additional structural FLs enabling instance segmentation for downstream analysis. However, the limited number of available fluorescence microscopy imaging channels restricts the degree to which these FLs can be experimentally multiplexed. In this paper, we present a segmentation workflow that overcomes the dependency on structural FLs for image segmentation, typically freeing 2 fluorescence microscopy channels for biologically relevant FLs. It consists in extracting structural information encoded within readouts that are primarily biological, by fine-tuning pre-trained state-of-the-art generalist cell segmentation models for different combinations of individual FLs, and aggregating the respective segmentation results together. Using annotated datasets that we provide, we confirm our methodology offers improvements in performance and robustness across several segmentation aggregation strategies and image acquisition methods, over different cell lines and various FLs. It thus enables the biological information content of HCS assays to be maximized without compromising the robustness and accuracy of computational single-cell profiling. Impact StatementThis methodological paper describes a framework enabling cell segmentation for datasets without structural fluorescent labels to highlight cell organelles. Such capabilities favorably impact costs and possible discoveries in single-cell downstream analysis by improving our ability to incorporate more biological read-outs into a single assay. The perspective of computational and experimental biologist coauthors ensures a multidisciplinary viewpoint and accessibility for a wide readership.

bioinformatics↗