Developing a Dielectrophoretic Method to Isolate Circulating Melanoma Cells: An Interview with AES Mid-Career Awardee Robbyn K. Anand

The award is to be presented at the annual SciX conference, which will be held this year from October 8 through October 13, in Sparks, Nevada. As part of an ongoing series of this year’s SciX conference honorees, Robbyn spoke to us about her work.

In a recent paper (2), you discuss a dielectrophoretic (DEP) method for selection of circulating melanoma cells (CMCs), which lack reliable identifying surface antigens and are extremely rare in blood. What motivated you to develop a DEP method rather than using a different technology?

Prevailing methods for circulating tumor cell isolation rely on either the presence of a specific antigen on the cell surface or on cell size. Narrowly defining cell type by expression of a surface antigen is overly selective, missing many of these rare cells, and for those arising from melanoma, a reliable surface marker has not been identified. Defining cell type by size alone is not selective enough–many white blood cells overlap circulating tumor cells in size.

The response of a cell to DEP is based on cell morphology and composition, such as the degree of cell membrane folding and glycosylation. What makes DEP so promising as a method for circulating tumor cell isolation is that it is more selective than cell size alone, but not so selective as targeting a single cell surface marker.

Your paper references previous work done which demonstrates the use of DEP at a wireless bipolar electrode (BPE) array, controlled by only two electrical leads, to address the need for selective single-cell capture (3,4). How did this previous work influence your current research and what new developments have you made?

Our previous work, which developed DEP-based selective cell capture at an array of wireless BPEs, has set the stage for individual cells to be isolated in chambers. Recent advancements in our group have incorporated single-cell assays for nucleic acids, enzymes, and secreted proteins into this device, and some assays are electrochemical, leveraging the BPE array. We are further developing methods to confirm the identity of captured cells in an automated fashion to save time and expense and to decrease reliance on user expertise.

Please summarize your findings and what surprised you most about the results.

In this work, we were most surprised to find that the biophysical properties of white blood cells were more variable among samples derived from patients diagnosed with melanoma than in those obtained from healthy donors. This means that the criteria for selection of circulating melanoma cells (such as the frequency of the applied electric field) can be optimized for each sample.

Were there any notable limitations or challenges you encountered in your work?

A major challenge in the field of single-cell analysis is that as you develop new methods, adoption of those methods by practitioners is a long road that requires demonstration of clinical relevance. For that reason, it is critical to forge and maintain connections with clinicians who are versed in cutting edge diagnostic and treatment approaches. They can help to prioritize analytical endpoints and collaborate on studies that correlate data obtained by these new methods to clinical outcomes.

Can you please summarize the feedback that you have received from others regarding this work?

This work has been highly cited and has generated enthusiasm because of its potential for impact in other areas, such as cell patterning, and a wide range of applications. We are often asked if this approach can be adapted to isolation of few or single bacterial cells or extracellular vesicles. Others ask if we can release a selected cell of interest for downstream analysis, such as by RNA sequencing. While none of these adaptations is easy, we think they are possible, and we’re excited for the potential for further innovation.

What are the next steps in this research?

We are now addressing a remaining limitation of this approach – which treats a cell’s response to the electric field as a binary, yes-or-no, response. There is a lot of valuable biophysical information represented in that response, and our new methods will extract and utilize that information.

What does your being named the recipient of the AES Mid-Career Award mean to you professionally? Personally?

I’m thrilled to have been selected for this honor by experts in the field, and I take it as a charge to support the community, especially students and early-career scientists.

References

(1) SciX. AES MID-CAREER AWARD. FACSS Analytical Science and Innovation 2023. https://scixconference.org/AES-MID-CAREER-AWARD/ (accessed 2023-09-06)

(2) Chen, H.; Osman, S. Y.; Moose, D. l.; Vanneste, M.; Anderson, J. L.; Hendry, M. D.; Anand, R. K. Quantification of Capture Efficiency, Purity, and Single-Cell Isolation in the Recovery of Circulating Melanoma Cells from Peripheral Blood by Dielectrophoresis. Lab Chip 2023, 23, 2586–2600. DOI: 10.1039/D2LC01113A

(3) Anand, R. K.; Johnson, E. S.; Chiu, D. T. Negative Dielectrophoretic Capture and Repulsion of Single Cells at a Bipolar Electrode: The Impact of Faradaic Ion Enrichment and Depletion. J. Am. Chem. Soc. 2015, 137, 776–783. DOI: 10.1021/ja5102689

(4) Li, M.; Anand, R. K. High-Throughput Selective Capture of Single Circulating Tumor Cells by Dielectrophoresis at a Wireless Electrode Array.J. Am. Chem. Soc. 2017, 139, 8950–8959. DOI: 10.1021/jacs.7b03288

About the Interviewee

Robbyn K. Anand is the Suresh Faculty Fellow and Carlyle G. Caldwell Endowed Chair in Chemistry at Iowa State University. Her group has developed methods for circulating tumor cell analysis, electrokinetic enrichment and separation of chemical species within water-in-oil droplets, and more sensitive bioanalysis at arrays of wireless bipolar electrodes. Prof. Anand also founded the Midwest Retreat for Diversity in Chemistry, an annual event aimed at the retention of underrepresented groups in the chemical enterprise.