Finding intracellular lipid droplets from the single-cell biolens' signature in a holographic flow-cytometry assay

In recent years, intracellular LDs have been discovered to play an important role in several pathologies. Therefore, detection of LDs would provide an in-demand diagnostic tool if coupled with flow-cytometry to give significant statistical analysis and especially if the diagnosis is made in full non-invasive mode. Here we combine the experimental results of in-flow tomographic phase microscopy with a suited numerical simulation to demonstrate that intracellular LDs can be easily detected through a label-free approach based on the direct analysis of the 2D quantitative phase maps recorded by a holographic flow cytometer. In fact, we demonstrate that the presence of LDs affects the optical focusing lensing features of the embracing cell, which can be considered a biological lens. The research was conducted on white blood cells (i.e., lymphocytes and monocytes) and ovarian cancer cells. Results show that the biolens properties of cells can be a rapid biomarker that aids in boosting the diagnosis of LDs-related pathologies by means of the holographic flow-cytometry assay for fast, non-destructive, and high-throughput screening of statistically significant number of cells.

Automated summary

Intracellular lipid droplets (LDs) play a vital role in various pathologies, and their detection through label-free analysis of 2D quantitative phase maps recorded by a holographic flow cytometer can provide a non-invasive and statistically significant diagnostic tool. The research conducted on white blood cells and ovarian cancer cells shows that the optical focusing lensing features of cells, considered as biological lenses, are influenced by the presence of LDs. The biolens properties of cells can serve as a rapid biomarker that aids in the diagnosis of LDs-related pathologies through holographic flow cytometry.