Smart design of extracellular matrix scaffolds to evaluate immune cell migration and anti-tumoral function

Immune cell migration is a key step of the immune response, and its outcome depends on the efficient trafficking of leukocytes, such as dendritic cells (DCs) and T cells, which constantly patrol our body. Upon danger signal detection, leukocytes switch to a fast migration to reach the lymph nodes and start the T cell-mediated immune response. Importantly, the interaction with the microenvironment and other cells are main determinants of this migratory response, especially in pathological contexts, such as the tumor microenvironment where soluble molecules are released to impair proper immune cell function and migration. In addition, changes in the extracellular matrix, as those of the tumor microenvironment, trigger specific signaling pathways that impair proper immune cell migration and function. The Sáez lab investigates how different soluble factors control leukocyte migration by combining live-cell microscopy and microfluidics.

In order to decompose the contribution of the soluble factors released by the cancer cells of the tumor and the changes in the extracellular is necessary to develop physical and chemical methods to obtain matrices that mimick those found in the tumor microenvironment. The Sáez laboratory has therefore joined efforts with the Schroeter laboratory, which specializes in the synthesis of macro- and mesoporous matrices, so called “aerogels”, based on biopolymers. Since control and characterization of porous microstructures is crucial in the aerogel manufacturing process, combining the expertises of both laboratories provides a promising starting point for generation of extracellular matrices with the desired properties, their inclusion in microfluidic devices and therefore for determining the mechanisms of cell migration in tumor microenvironments.

The overall aim of this project is to develop extracellular matrices with controllable properties, to mimic the physical properties of the tumor microenvironment, and to study immune cell behavior on it in presence or absence of soluble molecules present in this context. Therefore we will develop a method to obtain biopolymer based gels for 3D cultures with specific particle sizes, pore structures and surface adhesivity.

We will generate gels from different biopolymers to reproduce the main features of the extracellular matrices observed in the tumor microenvironment. Therefore, in a first step biopolymer hydrogels will be produced from different proteins and polysaccharides (e.g. cellulose and alginate) and included into microfluidic chips. The microstructural properties will be controlled via different gelation techniques (e.g. variation of pH, temperature, biopolymer- and salt contents). Some of the hydrogels will be processed to aerogels via solvent exchange and supercritical CO₂ drying steps, which enables preservation and characterization of  the gel structure in dry state.    Main properties of the gels like pore size distributions and overall porosity  will be characterized using scanning electron microscopy and gas porosimetry. After identification of the most suitable matrix for cell migration, further modifications to the gels properties will be employed (e.g. change of surface adhesivity, inclusion of small spheres) in order to optimize the gels properties to mimic tumor microenvironments.

Then, we will characterize the behavior of immune cells in physiological and pathological conditions, such as the tumor microenvironment, by using 3D cultures, live-cell microscopy and image analysis. In parallel, we will analyze the effect of the main soluble molecules present in the tumor microenvironment over immune cell migration and cytotoxic activity. If successful, our project will advance deciphering the contribution of the soluble components of the tumor microenvironment and consequent cell communication, and the role of the extracellular matrix in such interaction.