Cell–cell interactions: Quantifying cellular binding strength and isolating potent
lymphocytes from a heterogeneous cell population
In this proof of concept, researchers cultured a target cell line inside the z-Movi Chip and introduced three lymphocyte populations with high affinity (red), intermediate (green) and low affinity (cyan) against the target cell line.
Next, a force ramp was applied. At the low force regime, the low affinity lymphocytes were separated from the mixed population, resulting in an enriched target-specific lymphocyte population inside the chip. By increasing the force further we quantified the binding strength of each class of lymphocytes (Figure 1), but also screened and collected lymphocytes based on their target cell avidity.
In these types of experiments, it becomes possible to identify, examine, collect, and ultimately expand for further research the most potent cells. As the z-Movi uses non-invasive forces to probe cells, their viability is not affected, enabling us to perform further analysis to the collected enriched cell population fractions, such as sequencing, mass spectrometry, flow cytometry, and functional (cytotoxicity) assays.
Cell–cell avidity enhanced by antibodies: Screening of bispecific antibodies
Screening of therapeutic antibodies that enhance the killing properties of the T cells is crucial for the development of immunotherapies against cancer or other diseases. With the z-Movi we can determine the effect of the bispecific antibody on T cell binding to target tumor cells.
In this pilot study, we investigated the interactions of bispecific antibodies bound to T cells against target tumor cells.
Figure 2 shows the total number of T cells bound to tumor cells under increasing applied forces, in the presence and absence of bispecific antibodies. The results demonstrated that in the presence of the antibodies the interaction strength between T cells and tumor cells was significantly enhanced. Similar experiments can be performed to test the selectivity and efficiency of different compounds against a target and determine the compound with the highest binding enhancing properties.
Cell–extracellular matrix interactions: Unraveling the kinetics and strength of cellular adhesion
The z-Movi is a useful tool to obtain insights into the cell adhesion process. Here, Kamsma et al. used the z-Movi to resolve the adhesion forces and kinetics
of CD4+ T lymphocytes (CD4) to fibronectin.
They identified three interaction states of the cells: unbound, binding, and bound. Interaction strengths below 30 pN were defined for unbound cells, below 55 pN for transiently binding and crawling cells, and from 55 pN and above for bound cells (Figure 3).
The researchers then investigated how these properties are influenced by interleukin-7 (IL7), the main regulatory cytokine of CD4 cells. The results demonstrated that while IL7 accelerates CD4 adhesion, it does not influence CD4 binding strength (Figures 4 and 5).