STUDY OF THE MUTUAL INTERACTION BETWEEN EXTRACELLULAR MATRIX AND CELLS IN PERITONEAL METASTASIS

This thesis project is related to the field of mechanobiology, a novel and emerging area of biology. The work is mainly focused on the biomechanical interaction of cancer cells with extracellular matrix extracted from human patients during peritoneal metastasis. AFM microscopy with large colloidal probes was used as the main experimental tool. Presented results of mechanical characterization of ECM, together with additional biotechnological studies, revealed that signs of forming pre-metastatic niche are already present in normal derived tissue, which gives a chance to use the nano- and microscale characterization of the mechanical properties of tissues as a cancer diagnosis tool. It was also demonstrated that the decellularized peritoneal ECM can be adapted as a scaffold for culture of organoids to create ex vivo model of human peritoneal metastasis lesion. AFM nanoindentation measurements revealed significant stiffening over time of both normal and neoplastic ECM repopulated with neoplastic organoids. It revealed that tumour derived organoids introduced to microenvironment of different elastic modulus and biological characteristics are expressing different behaviour. Part of the work presented in this thesis was focused in investigating the mechanical properties of biological tissue after applying different freezing protocols. Additionally, steps for tissue sample preparation were optimized to allow for AFM measurements. Spheroids were investigated as 3D models with the main target to characterize their mechanical properties and understand possible applications in cancer research. First, protocol for AFM measurements was optimized. The versality of AFM and its probes allowed to study elasticity of spheroids in different terms. Finally, measurements of spheroids were carried out also with microfluidic cytometry showing a parallel method to measure their viscoelasticity.