Label-Free Tomographic Imaging of Lipid Droplets in Foam Cells for Machine-Learning-Assisted Therapeutic Evaluation of Targeted Nanodrugs

Abstract

Lipid droplet (LD) accumulation, a key feature of foam cells, constitutes an attractive target for therapeutic intervention in atherosclerosis. However, despite advances in cellular imaging techniques, current noninvasive and quantitative methods have limited application in living foam cells. Here, using optical diffraction tomography (ODT), we performed quantitative morphological and biophysical analysis of living foam cells in a label-free manner. We identified LDs in foam cells by verifying the specific refractive index using correlative imaging comprising ODT integrated with three-dimensional fluorescence imaging. Through time-lapse monitoring of threedimensional dynamics of label-free living foam cells, we precisely and quantitatively evaluated the therapeutic effects of a nanodrug (mannose−polyethylene glycol−glycol chitosan−fluorescein isothiocyanate−lobeglitazone; MMR-Lobe) designed to affect the targeted delivery of lobeglitazone to foam cells based on high mannose receptor specificity. Furthermore, by exploiting machine-learning-based image analysis, we further demonstrated therapeutic evaluation at the single-cell level. These findings suggest that refractive index measurement is a promising tool to explore new drugs against LD-related metabolic diseases.

CD45 pre-exclusion from the tips of microvilli establishes a phosphatase-free zone for early TCR triggering

“…We used an antigen-specific system, OTII x Rag2 -/-(KO) TCR-transgenic CD4 + T cells specific for ovalbumin (OVA), which were loaded with the Ca 2+ indicator Fluo-4 AM and stimulated with OVA peptide-pulsed B cell APCs. The maximum theoretical lateral resolutions of the ODT system can reach ~110 nm (Lauer, 2002;Park et al, 2020). The practical lateral resolution of the system was reported to be 172 nm (Shin et al, 2018).…”

Detection of intracellular monosodium urate crystals in gout synovial fluid using optical diffraction tomography

“…By measuring the 3D RI, ODT can visualize the intracellular components of live cells. ODT has been recently applied in diverse fields to monitor label-free morphological changes in live cells during drug treatment 5 , disease progression 6 , nanoparticle tracking 7 , and photodynamic therapy 8 . However, it has not yet been used as a diagnostic tool to evaluate clinical samples despite its usefulness.…”

Holotomographic microscopy: A new approach to detect apoptotic cell features

“…Then, the optical diffraction tomography (ODT) reconstructs the 3D distribution of RI values, then providing structural and chemical information of the specimen (Figure 1). Therefore, it enables quantitative and label-free analysis of volume and subcellular components on live unstained cells and tissue slices (Debailleul, Georges, Simon, Morin, & Haeberlé, 2009;Kim et al, 2016;Park et al, 2020). In particular, information about dry mass, morphology, and dynamics of the cellular membrane, can be obtained.…”

“…Therefore, it enables quantitative and label‐free analysis of volume and subcellular components on live unstained cells and tissue slices (Debailleul, Georges, Simon, Morin, & Haeberlé, 2009; Kim et al, 2016; Park et al, 2020). In particular, information about dry mass, morphology, and dynamics of the cellular membrane, can be obtained.…”