Confinement primes cells for faster migration by polarizing active mitochondria

Mechanometabolism: recent findings on the intersection of cell adhesion, cell migration, and metabolism

Chemical and mechanical cues within the extracellular matrix (ECM) can initiate intracellular signaling that changes an array of fundamental cell functions. In recent work, studies of cell-ECM adhesion have deepened to include the influence of the physical ECM on cell metabolism. Since many biological processes involve metabolic programs, changes to cellular metabolism in response to cues in the ECM can have marked effects on cell health. In this review, we describe molecular mechanisms associated with cell-ECM adhesion that are key players in metabolism-induced changes to cell behaviors, including migration. We first review how changes to metabolite availability in the extracellular environment or manipulation of metabolic machinery in cells impact focal adhesions. We then connect this work to recent findings regarding the reverse relationship, namely, how the manipulation of focal adhesion proteins or integrins feeds back to alter cell metabolism. Finally, we consider the latest findings from studies that describe how the mechanical properties of the ECM, primarily stiffness and confinement, alter cellular metabolism. We identify key areas of future investigation that may elucidate the molecular drivers that permit cells to respond to mechanical and chemical ECM cues by reprogramming their metabolism to better inform future diagnostics and therapeutics for disease states.

Mechano-metabolism on the rise

Cells respond to the physical and geometrical tissue properties by multiple mechanotransduction mechanisms that can profoundly influence cells' decision-making, extending to cell metabolism. This review incorporates the most recent findings on this topic, organized along the idea that the mechano-metabolic connection serves three main functions, namely to inform systemic metabolism on the general functioning of a tissue/organ, to tune cells' energy production with the mechanical requirements imposed by their surroundings, and to coordinate cell metabolism with cell fate choices induced in response to mechanical cues. This connection highlights the pervasive influence of mechanical cues on cell activity, opens interesting questions on its physiological and pathological roles, and lays the foundations for exploiting the mechano-metabolism axis to design new therapeutic approaches.

Cell compression - relevance, mechanotransduction mechanisms and tools

From border cell migration during Drosophila embryogenesis to solid stresses inside tumors, cells are often compressed during physiological and pathological processes, triggering major cell responses. Cell compression can be observed in vivo but also controlled in vitro through tools such as micro-channels or planar confinement assays. Such tools have recently become commercially available, allowing a broad research community to tackle the role of cell compression in a variety of contexts. This has led to the discovery of conserved compression-triggered migration modes, cell fate determinants and mechanosensitive pathways, among others. In this Review, we will first address the different ways in which cells can be compressed and their biological contexts. Then, we will discuss the distinct mechanosensing and mechanotransducing pathways that cells activate in response to compression. Finally, we will describe the different in vitro systems that have been engineered to compress cells.

CAR-T cells are more affected than T lymphocytes by mechanical constraints: A microfluidic-based approach

AIMS

CAR-T cell therapy has attracted considerable attention in recent years owing to its well-known efficacy against haematopoietic malignancies. Nevertheless, this immunotherapy fails against solid tumours due to hostile conditions found in the tumour microenvironment. In this context, many relevant biochemical factors have been thoroughly studied, but crucial mechanical cues have been underestimated.

MAIN METHODS

We developed an innovative approach using microfluidic devices, which recreate the biomechanical aspects of solid tumours. Using these platforms, we quantified immune cell migration (T and CAR-T cells) under different confinement conditions.

KEY FINDINGS

We found that both CAR-T cell and T cell velocities are affected by the biomechanical and chemical cues studied, which are closely related to those found in solid tumours. Under biochemical stimulus-free conditions, the velocity of T cells is independent of the width of the microchannel, whereas the velocity of CAR-T cells is greatly reduced in the highest confinement channels. When chemoattractants or tumour cells are added, immune cells display increased confined migration velocity. However, in the presence of immunosuppressive chemokines, T cells become slower, whereas CAR-T cells significantly increase their velocity via a chimeric cytokine receptor.

SIGNIFICANCE

Our approach contributes to a better understanding of immune cell migration and the influence of mechanical constraints, which will allow the testing of new ways to improve CAR-T cell trafficking into solid tumours. Therefore, our study revealed that the migratory behaviour of CAR-T cells differs from that of T cells under confined conditions and that biomechanical cues, such as cell deformability caused by confinement, can influence the correct infiltration of immune cells into solid tumours during the immune response.

Mechanical signatures in cancer metastasis

The cancer metastatic cascade includes a series of mechanical barrier-crossing events, involving the physical movement of cancer cells from their primary location to a distant organ. This review describes the physical changes that influence tumour proliferation, progression, and metastasis. We identify potential mechanical signatures at every step of the metastatic cascade and discuss some latest mechanobiology-based therapeutic interventions to highlight the importance of interdisciplinary approaches in cancer diagnosis and treatment.

Trafficking in cancer: from gene deregulation to altered organelles and emerging biophysical properties

Intracellular trafficking supports all cell functions maintaining the exchange of material between membrane-bound organelles and the plasma membrane during endocytosis, cargo sorting, and exocytosis/secretion. Several proteins of the intracellular trafficking machinery are deregulated in diseases, particularly cancer. This complex and deadly disease stays a heavy burden for society, despite years of intense research activity. Here, we give an overview about trafficking proteins and highlight that in addition to their molecular functions, they contribute to the emergence of intracellular organelle landscapes. We review recent evidence of organelle landscape alterations in cancer. We argue that focusing on organelles, which represent the higher-order, cumulative behavior of trafficking regulators, could help to better understand, describe and fight cancer. In particular, we propose adopting a physical framework to describe the organelle landscape, with the goal of identifying the key parameters that are crucial for a stable and non-random organelle organization characteristic of healthy cells. By understanding these parameters, we may gain insights into the mechanisms that lead to a pathological organelle spatial organization, which could help explain the plasticity of cancer cells.

Mechanobiology of 3D cell confinement and extracellular crowding

Cells and tissues are often under some level of confinement, imposed by the microenvironment and neighboring cells, meaning that there are limitations to cell size, volume changes, and fluid exchanges. 3D cell culture, increasingly used for both single cells and organoids, inherently impose levels of confinement absent in 2D systems. It is thus key to understand how different levels of confinement influences cell survival, cell function, and cell fate. It is well known that the mechanical properties of the microenvironment, such as stiffness and stress relaxation, are important in activating mechanosensitive pathways, and these are responsive to confinement conditions. In this review, we look at how low, intermediate, and high levels of confinement modulate the activation of known mechanobiology pathways, in single cells, organoids, and tumor spheroids, with a specific focus on 3D confinement in microwells, elastic, or viscoelastic scaffolds. In addition, a confining microenvironment can drastically limit cellular communication in both healthy and diseased tissues, due to extracellular crowding. We discuss potential implications of extracellular crowding on molecular transport, extracellular matrix deposition, and fluid transport. Understanding how cells sense and respond to various levels of confinement should inform the design of 3D engineered matrices that recapitulate the physical properties of tissues.

Engineering approaches for understanding mechanical memory in cancer metastasis

Understanding cancer metastasis is crucial for advancing therapeutic strategies and improving clinical outcomes. Cancer cells face dynamic changes in their mechanical microenvironment that occur on timescales ranging from minutes to years and exhibit a spectrum of cellular transformations in response to these mechanical cues. A crucial facet of this adaptive response is the concept of mechanical memory, in which mechanosensitive cell behavior and function persists even when mechanical cues are altered. This review explores the evolving mechanical landscape during metastasis, emphasizing the significance of mechanical memory and its influence on cell behavior. We then focus on engineering techniques that are being utilized to probe mechanical memory of cancer cells. Finally, we highlight promising translational approaches poised to harness mechanical memory for new therapies, thereby advancing the frontiers of bioengineering applications in cancer research.

Principles of organelle positioning in motile and non-motile cells

Cells are equipped with asymmetrically localised and functionally specialised components, including cytoskeletal structures and organelles. Positioning these components to specific intracellular locations in an asymmetric manner is critical for their functionality and affects processes like immune responses, tissue maintenance, muscle functionality, and neurobiology. Here, we provide an overview of strategies to actively move, position, and anchor organelles to specific locations. By conceptualizing the cytoskeletal forces and the organelle-to-cytoskeleton connectivity, we present a framework of active positioning of both membrane-enclosed and membrane-less organelles. Using this framework, we discuss how different principles of force generation and organelle anchorage are utilised by different cells, such as mesenchymal and amoeboid cells, and how the microenvironment influences the plasticity of organelle positioning. Given that motile cells face the challenge of coordinating the positioning of their content with cellular motion, we particularly focus on principles of organelle positioning during migration. In this context, we discuss novel findings on organelle positioning by anchorage-independent mechanisms and their advantages and disadvantages in motile as well as stationary cells.

A Vicsek-type model of confined cancer cells with variable clustering affinities

Clustering of cells is an essential component of many biological processes from tissue formation to cancer metastasis. We develop a minimal, Vicsek-based model of cellular interactions that robustly and accurately captures the variable propensity of different cells to form groups when confined. We calibrate and validate the model with experimental data on clustering affinities of four lines of tumor cells. We then show that cell clustering or separation tendencies are retained in environments with higher cell number densities and in cell mixtures. Finally, we calibrate our model with experimental measurements on the separation of cells treated with anti-clustering agents and find that treated cells maintain their distances in denser suspensions. We show that the model reconstructs several cell interaction mechanisms, which makes it suitable for exploring the dynamics of cell cluster formation as well as cell separation. Insight: We developed a model of cellular interactions that captures the clustering and separation of cells in an enclosure. Our model is particularly relevant for microfluidic systems with confined cells and we centered our work around one such emerging assay for the detection and research on clustering breast cancer cells. We calibrated our model using the existing experimental data and used it to explore the functionality of the assay under a broader set of conditions than originally considered. Future usages of our model can include purely theoretical and computational considerations, exploring experimental devices, and supporting research on small to medium-sized cell clusters.