Electrical Tissue Dissociation Outperforms Mechanical, Chemical Approaches
By Allison Proffitt
August 2, 2022 | A team of researchers from Brown University are in the process of developing a simple, inexpensive, portable device to electrically dissociate tissues into viable single cells. They’ve published the work in Scientific Reports, and foresee the approach being useful in both clinical diagnostics and basic scientific research.
While there are existing mechanical and chemical means researchers can use to dissociate tissues into viable, useful individual cells—vortexers, centrifuges, hot plates, the right combination of reagents, and/or specialty dissociation tools—the procedures are time consuming, laborious, and often expensive.
“This is much more streamlined, much more compact, much more efficient, and fast,” explains Cel Welch, first author on the paper (DOI: 10.1038/s41598-022-13068-6), and a Ph.D. candidate in the lab of Anubhav Tripathi, Professor of Biomedical Engineering at Brown University. “A couple hours it will take for traditional protocols—maybe 30 minutes if you’re lucky—but this is five minutes and you’re done.” The new technique also performs better, Welch adds.
In the proposed process, an electric field is applied between two parallel plate electrodes. The gap between the two electrodes is filled with liquid and a tissue biopsy core. “Then we’re applying the electric field between these two parallel plate electrodes, so it traverses through the cavity that is filled with liquid and the tissue core,” Welch says. The electric field breaks up the tissue into individual cells.
The authors of the paper report that electrical dissociation, “recovered slightly greater than five times as many live cells as traditional treatments in ¼ of the time. Cellular recovery was statistically significantly higher across all electrical treatments.”
Getting living cells is key, Welch says, and the study used several methods to ensure cellular integrity and viability in the dissociated cells. “The biggest application we have in mind here is using it as a sample preparation technology to go from… this complex tissue that you’re removing from a patient for cancer diagnostics, for example, and break that tissue up into individual component cells for downstream analysis by single-cell sequencing,” Welch says. For cancer diagnostics, transcriptome analysis is key, but Welch also foresees other applications. For instance, easy tissue dissociation could be useful in tissue engineering applications.
In designing the approach, the team tested many parameters: different electric fields, different tissue sources and cell types, and different fluid makeups. They found that a sucrose and ultrapure water solution (mimicking the cells’ own interior to prevent osmotic stress) outperformed both ultrapure water alone and DMEM media. Oscillating square-wave voltages produced “significantly” better results than DC linear electric fields. And the set up worked well across several tissue samples: bovine liver tissue from a local butcher, MDA-MB-231 triple-negative breast cancer cells cultured for use, and human clinical glioblastoma samples.
That’s not to say that these tissue samples are the same. The glioblastoma samples were “notably more complex and more difficult to dissociate when compared to the liver tissue,” the authors wrote. But the fact that the electrical dissociation worked for both is encouraging.
“There’s lots of different tissue types,” Welch says. “They’re coming from different organs, they have different sizes, they have different mechanical properties. It’s not like you can treat all tissues the same when you’re doing dissociation. I think that’s one of the main limitations of the current technology.”
Over the past several decades, Welch says, protocols have been developed for different tissue types, outlining the specific chemical reagents and dissociation paths for optimal outcomes. “Now we’re trying to create something that’s a little more streamlined. Instead of having to optimize these chemical parameters, these thermal parameters, these mechanical parameters, all you have to work with is optimization of the electrical parameters.”
It’s not going to be a one-size-fits all approach, Welch cautions, but expects a system that is, “a little bit more easily tuned and transferable to different tissue types without having to order 10 different reagents.”
The group is partnered with PerkinElmer to bring the technique into a commercialized product and holds as-yet-unlicensed intellectual property. The group is also exploring other novel physical mechanisms for dissociation.
“Within reason, I believe that this technique can be extrapolated to other kinds of tissues and cells,” by other researchers, Welch says, “but I think one thing to keep in mind is that with anything like this there’s going to be optimization required. I do think the technique is transferable in its nature, but I think some optimization is required for the different electrical parameters.”
The team is working on refining the device design, Welch says, making it portable, low cost, and ultra-high throughput. The characterization of the device itself is the subject of another forthcoming publication.