Triple-negative breast cancer (TNBC) is a highly aggressive subtype with a high metastatic rate, making it one of the leading causes of cancer-related mortality [ 1]. Imaging methods, including both non-optical and optical approaches, play a crucial role in breast cancer research, from initial diagnosis in the clinic to in-depth in vivo and in vitro studies, providing essential insights into the interactions of carcinoma cells within and beyond their microenvironment. Synchronizing in vitro metastatic models with imaging technologies has always been challenging in monitoring different steps of metastasis due to size limitations and the lack of co-culture capabilities in traditional models [ 2]. Microphysiological systems bridge the gap between in vitro and in vivo metastasis models by providing confined spaces and transparent devices suitable for static and dynamic imaging. These systems can be integrated with tumor cells, organoids, and vascular elements to capture the complex, real-time processes involved in metastasis, particularly in understanding the role of small extracellular vesicles (sEVs) in promoting distant metastasis [ 3]. Herein, we investigated the impact of metastatic-site-derived sEVs on the metastasis of carcinoma cells toward brain organoids within microphysiological systems, using static and dynamic imaging techniques.
The microphysiological metastatic model enables the formation of vascular lumens as blood-brain barrier (BBB) models, facilitating high-resolution, live confocal imaging of the TNBC cell line (MDA-MB-231 cells) as they interact with an endothelial lumen and extravasate toward brain organoids, revealing the effect of metastatic-site-derived sEVs ( Fig. 1). In addition, microphysiological systems are ideal tools for capturing the dynamic interactions between endothelial cells and early brain organoids through time-lapse confocal imaging ( Fig. 2).
Fig 1.
Time-lapse imaging of CMP-TX-labeled HUVECs (red) and GFP-labeled MDA-MB-231 cells (green) showing carcinoma cell attachment, endothelial disruption, angiogenesis, and metastasis over a 12-hour period. Scale bar = 100 µm.
Fig 2.
Time-lapse imaging of brain organoids interacting with CMP-TX-labeled HUVECs in a microfluidic system. Nuclei stained with Hoechst (blue). Images show HUVEC sprouting and integration into brain organoids from 24 to 36 hours. Scale bar = 50 µm.
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