Label-Free and Quantitative Dry Mass Monitoring for Single Cells during In Situ Culture.

Ya Su,Xianbo Luo,Wenli Du,Li Ma,Rongxin Fu,Ruliang Wang,Han Yang,Xiangyu Jin,Xue Lin,Xiaohui Shan,Wenqi Lv,Guoliang Huang

doi:10.3390/cells10071635

Abstract

Quantitative measurement of single cells can provide in-depth information about cell morphology and metabolism. However, current live-cell imaging techniques have a lack of quantitative detection ability. Herein, we proposed a label-free and quantitative multichannel wide-field interferometric imaging (MWII) technique with femtogram dry mass sensitivity to monitor single-cell metabolism long-term in situ culture. We demonstrated that MWII could reveal the intrinsic status of cells despite fluctuating culture conditions with 3.48 nm optical path difference sensitivity, 0.97 fg dry mass sensitivity and 2.4% average maximum relative change (maximum change/average) in dry mass. Utilizing the MWII system, different intrinsic cell growth characteristics of dry mass between HeLa cells and Human Cervical Epithelial Cells (HCerEpiC) were studied. The dry mass of HeLa cells consistently increased before the M phase, whereas that of HCerEpiC increased and then decreased. The maximum growth rate of HeLa cells was 11.7% higher than that of HCerEpiC. Furthermore, HeLa cells were treated with Gemcitabine to reveal the relationship between single-cell heterogeneity and chemotherapeutic efficacy. The results show that cells with higher nuclear dry mass and nuclear density standard deviations were more likely to survive the chemotherapy. In conclusion, MWII was presented as a technique for single-cell dry mass quantitative measurement, which had significant potential applications for cell growth dynamics research, cell subtype analysis, cell health characterization, medication guidance and adjuvant drug development.

Highlights

The ability to quantitatively measure single-cell dry mass with femtogram sensitivity at the ultrastructural level is of great significance in the fields of cell growth, mass transport, cancer diagnosis and tumor therapy research
We found that multichannel wide-field interferometric imaging (MWII) has significant potential applications for cell growth dynamics research, cell-level diagnosis, cell metabolism detection and cellular health characterization
We demonstrated a quantitative MWII technique for single-cell dry mass measurement during long-term culture, which could reveal intrinsic cellular conditions at an ultrastructural level

Summary

Introduction

The ability to quantitatively measure single-cell dry mass with femtogram sensitivity at the ultrastructural level is of great significance in the fields of cell growth, mass transport, cancer diagnosis and tumor therapy research. There is an age-old debate about how cell growth is coordinated with cell cycle progression to maintain cell size [1]. Another example is that the necessity for active transport is especially acute, as in the case of the transport of the large objects up and down the axonal [2]. These phenomena could be better understood through quantitative mass analysis.

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Conclusion