Lorenc, E. | Search bioRxiv

bioRxiv2022

The nanomechanical fingerprint of colorectal-derived peritoneal metastasis

Peritoneal metastases (PM) are one of the most common routes of dissemination for colorectal cancer (CRC) and remain a lethal disease with a poor prognosis. The compositional, mechanical and structural properties of the extracellular matrix (ECM) play an important role in cancer development; studying how these properties change during the progression of the disease is crucial to understand CRC-PM development. The elastic properties of ECMs derived from human samples of normal and neoplastic PM in different pathological conditions were studied by atomic force microscopy (AFM); results were correlated to patients clinical data and to the expression of ECM components related to metastatic spread. Our results show that PM progression is accompanied by stiffening of ECM as a common feature; spatially resolved mechanical analysis highlighted significant spatial heterogeneity of the elastic properties of both normal and neoplastic ECMs, which show significant overlap in the two conditions. On the micrometre scale, ECMs that are considered normal according to the pathological classification possess stiffer spatial domains, which are typically associated with cancer associated fibroblasts (CAF) activity and tumour development in neoplastic matrices; on the other hand, softer regions are found in neoplastic ECMs on the same scales. Our results support the hypothesis that local changes (stiffening) in the normal ECM can create the ground for growth and spread from the tumour of invading metastatic cells. Mechanical changes correlate well with the presence of CAF and an increase in collagen deposition, which are well known markers of cancer progression. Furthermore, we have found correlations between the mechanical properties of the ECM and patients clinical data like age, sex, presence of mutations in BRAF and KRAS genes and tumour grade. Overall, our findings suggest that the mechanical phenotyping of the PM-ECM has the potential for predicting tumour development.

biophysics↗

bioRxiv2022

Force sensing on cells and tissues by atomic force microscopy

Biosensors are aimed to detect tiny physical and chemical stimuli in biological systems. Physical forces are ubiquitous, being implied in all cellular processes, including cell adhesion, migration, and differentiation. Given the strong interplay between cells and their microenvironment, the extracellular matrix (ECM), the structural and mechanical properties of the ECM play an important role in the transmission of external stimuli to single cells within the tissue. Vice versa, also cells themselves use self-generated forces to probe the biophysical properties of the ECM. ECM mechanics influences cell fate, regulates tissue development and show peculiar features in health and disease conditions of living organisms. Force sensing in biological systems is therefore crucial to dissect and understand complex biological processes, such as mechanotransduction. Atomic Force Microscopy (AFM), which can both sense and apply forces at the nanoscale, with sub-nanoNewton sensitivity, represents an enabling technology and a crucial experimental tool in biophysics and mechanobiology. In this work, we report on the application of AFM to study of biomechanical fingerprints of different components of biological systems, such as the ECM, the whole cell, and cellular components, like the nucleus and the glycocalyx. We show that physical observables like the (spatially resolved) Youngs modulus of elasticity of ECMs or cells, and the effective thickness and stiffness of the glycocalyx, can be quantitatively characterised by AFM. Their modification can be correlated to changes of the microenvironment, physio-pathological conditions, or gene regulation.

biophysics↗