This project is about a new and innovative screening technology called “iSLICE” (immuno Spot Layer Imaging of Cell Excretions) developed by InterFluidics at the Medical Cell BioPhysics group (MCBP) at the University of Twente and applies chip array and 3D-imaging technology. In iSLICE, a relevant panel of different secreted molecules will be detected as cytokines, interleukins, endocrines, growth factors etc. from thousands of single cells in layers. The panel of all molecules secreted by a single cell is the so-called single cell secretome, which will be the ultimate challenge that we intend to tackle with this solution.

Currently ELISpot/FluoroSpot are the detection technologies for single cell secretion detection and using the new commercial IRIS technology of MabTech (2018) 4 compounds can be measured simultaneously using 4 Fluorophores. The iSLICE technology that will be developed in this ATTRACT project intends to at least double this number and provide a technical roadmap with a vision to even triple the number of detected molecules per single cell. The breakthrough approach is to image the secreted molecules in layers (SLICES) of capture molecule coated thin porous membranes on top of each other. So imaging can be performed in the third dimension. The lowest detection layer can be performed with Surface Plasmon Resonance imaging for real time and label free monitoring of the captured molecules secreted by a single cell for thousands of cells simultaneously.

In order to build a stack of coated capture membranes (SLICES) the cooperation with partner Xantec Bioanalytics is essential. The slices should have the right porosity, pore diameter, thickness and hydrogel thickness for capturing the ligands in high density. Xantec’s expertise regarding reliable coatings for SPRimaging applications is relevant and absolutely crucial for the development of the right stack of membrane slices. The first tests show a promising performance of untreated membranes that are commercially available with thicknesses down to 0.9 micron with respect to the size of a cell of about 5-15 micron in a 3D iSLICE.

Why is imaging of the secretome relevant? The main driver to develop the technology is in the cancer diagnostics area. In the labs of MCBP circulating tumour cells are characterised for monitoring metastasis formation. Cancer patients who receive cancer immunotherapy treatments are tested using ELISpot applying single cell secretions of Peripheral Blood Mononuclear Cells (PBMC). These PBMC samples are indicative to the response of the patient’s immune system. Interleukine 2 (IL2) and/or Interferon-gamma (IFN-ƴ) stimulated T-cells, but also IL6, IL8, VEGF play an important role in the characterisation of the immune response.

The primary focus of InterFluidics is therefore to develop cutting-edge technologies for these applications with greater multiplex data reliability. After all, the weight of clinical trial results depends on the accuracy, precision, and reliability of data generated from these PBMC samples. Huge cost savings are foreseen in immune-therapy when iSLICE technology becomes an approved diagnostic tool.