Quantitative Diagnosis of Malignant Pleural Effusions by Single-Cell Mechanophenotyping
Science Translational Medicine
In this paper, we conducted the first large scale clinical study evaluating the use of cellular mechanical biomarkers from thousands of single-cells as a diagnostic. The report provides evidence that the approach could reduce the need for diagnostic procedures associated with body fluid cytological analysis and the associated costs while improving accuracy over currently used methods. In a highlight article, Guck et al. describe the impact of our work “…this study marks a quantum leap in the clinical application of mechanical phenotyping… Tse and colleagues have opened a door to merging mechanics with medicine; now, it is well worth stepping through to explore what lies behind.”
The clinical study focused on pleural fluid samples from more than 100 patients in which we aimed to identify patients with malignant cells using our high-throughput mechanical phenotyping approach. Current screening of pleural fluid for cancer is costly, time-consuming, and often inconclusive. The detailed biophysical metrics we obtained from profiles of many single cells, along with machine learning approaches, allowed improved sensitivity over traditional cytology. Some patient samples that were not identified as cancerous via traditional methods were found to be so through deformability cytometry, and these results were verified six months later. Because our approach does not require a trained pathologist, its potential benefits are even greater in areas where there is a lack of such specialists, such as rural areas or developing nations.
Hydrodynamic stretching of single cells for large population mechanical phenotyping
Proceedings of the National Academy of Sciences
This work is the first to introduce the concept of measuring mechanical properties of cells at rates similar to flow cytometry (>1,000 cells/sec), enabling statistically robust conclusions and sub-population analyses. The deformability cytometer that we describe in the paper consists of a miniaturized microfluidic chip that sequentially aligns cells so that they impact on a wall of fluid at rates of thousands per second. A high-speed camera takes microscopic images of these cells at higher intervals of 250,000 pictures per second, and these images are automatically analyzed by custom software to extract information about cell physical properties. This approach provides a rapid and unambiguous integrative measure of the viscoelastic properties of cells. Viscous and elastic properties of cells are related to the membrane surrounding the cell, internal cytoskeletal structural elements, and the packed DNA arrangement in the nucleus. Variations in these properties can be indicative of disease such as sepsis or cancer.
Using this platform data indicating the ability to identify inflammation, malignant cell populations and other cell states without costly chemical tags is reported, supporting diagnostic application areas where rapid analysis of the mechanical response of cells is important. While previous researchers have shown the relevance of the physical properties of cells to their health, the speed of our technique allows these findings to be clinically relevant.
A Mechanical Biomarker of Cell State in Medicine
This review highlights the opportunities to improve clinical diagnostics using mechanical measurements of populations of single-cells as unique biomarkers. These biomarkers are argued to that have some advantages over molecular markers which require labeling and sample preparation, which can increase the complexity and cost of an assay. The manuscript highlights the body of historical work using slow, manual, and complex techniques (e.g. AFM, micropipette aspiration, and optical stretching) to measure the mechanical stiffness of cells and connect these metrics to changes in cell state and disease. The work also poses that throughput and robust quantitative instrumentation similar to flow cytometry will be necessary to achieve an impact in medicine using these historically established biomarkers. Clinical and drug discovery application areas from immunology, oncology, and regenerative medicine, are covered where a rapid mechanical measurement may have significant value. Finally, the technological advances needed to achieve rapid and robust measurements are reviewed.
- Scientific Reports - Introducing the Cell Mechanome
- Microengineering and Nanosystems - Biophysical Classification of Cell Differentiation State
- Lab Chip - Measuring Mechanics of Circulating Tumor Cells
- Annual Review of Biomedical Engineering - New Opportunities for Rapid Mechanical Measurement of Cells
- Biomicrofluidics - Preparing and Analyzing Exosomes
- Current Opinion in Biotechnology - Single-cell Analysis from Molecules to Mechanics
- Analytical Chemistry - Continuous Flow Sample Preparation
- Lab Chip - Continuous Flow Cell Staining and Cytology
- Lab Chip - Squeezing Cells with Co-flows
- Small - Focusing Cells to Single Streams
- Small - Rapid Solution Exchange
- Analytical Chemistry - Focusing Cells at High Rates