“Are these cells potent enough?” is a major question in cell therapy. It’s a challenging question to answer with the traditional methods for cell function analysis. The issue lies in the heterogeneity of cell populations. A single-cell view of immune cell activities, such as cytokine or antibody secretion, is critical to determine the potency of an immune cell population intended for therapeutic use.
Bulk functional assays of mammalian cells can only deliver average readouts for the heterogeneous population. This masks the view of individual cell activity. This can be due to the cross-talk between immune cells with different activities in the bulk solution. Furthermore, when it comes to natural killer cells, bulk assays won’t reveal the presence of “serial killers” in the population.
Advancements in single-cell analysis
Transcriptomics can give this single-cell insight, but the cells are killed in the workflow, leaving researchers with no possibility to recover and expand the cells with the right properties.
Droplet microfluidics technology has proven to be the solution to this challenge. Samplix has developed the ®Xdrop products based on a unique approach to droplet microfluidics with applications for cell therapy research. The company’s goal has been to make Xdrop accessible to every lab and straightforward to use.
Double-emulsion droplets: a breakthrough approach
The core of Samplix’s unique approach to droplet microfluidics is the production of double-emulsion droplets. Also called water-in-oil-in-water droplets, these act as picoliter-sized reaction chambers that are stable and suitable for incubation, flow cytometry, sorting, and other downstream analyses. Xdrop can generate millions of droplets in just eight minutes, encapsulating the living cells. The oil shell is permeable to gases and small molecules, but not to large proteins. That means that the cells can stay alive for a long time within the droplets, with simple nutrients, oxygen, carbon dioxide, and water passing between the inner and outer media.
The double-emulsion droplets produced by Xdrop also have one other key benefit in answering the question about cell function. Cytokines, antibodies, and enzymes produced by the captured cell cannot pass out of the droplet. They build up quickly in the small volume, enabling rapid differentiation of the active secretors from the inactive ones. Assays for the detection of compounds like IFN-γ, TNF-α, and granzyme B have already been tested, with the secretors with the desired activity then sorted from the rest of the population and recovered alive for expansion. Similarly, experiments with the co-encapsulation of natural killer cells and their target lymphoblasts have allowed the identification and recovery of the cells with the desired activity level.
This identification and recovery of cells with the desired function has applications beyond those mentioned. For example, in molecular biology workflows, double-emulsion droplets will support the identification and recovery of the microbial cells with the right enzyme secretion levels. In addition, Xdrop double-emulsion droplets have established applications in gene editing validation, with workflows to identify on- and off-target CRISPR edits as well as to map CAR cassette integration. These workflows depend on the encapsulation of DNA fragments and primers rather than on the encapsulation of living cells. Their application for engineered gene therapy research is clear.
Unlocking the full potential of cell and gene therapies is a major goal in medical research. Now, it seems Xdrop double-emulsion droplets are the key to that goal.
Learn more about Xdrop at https://samplix.com.