Cell–matrix interactions
In every tissue, cells are embedded in a microenvironment composed of a fibrillar extracellular matrix (ECM), neighboring cells and surrounding fluid. Cells dynamically sense the physical properties of the ECM (e.g. topographic features, stiffness), and mechanical forces from the solid phase (e.g. tensile and compressive) and fluid phase of the ECM (e.g. shear, hydrostatic and osmotic forces). These physical and mechanical signals are important for cell proliferation and differentiation. We are designing tailored environments that can mimic cell—matrix interactions to improve our understanding of cellular mechanotransduction in 3D and to develop disease models in tissue engineering and regenerative medicine.
Skin cancer models to replace xenografts
To study skin cancer and test potential therapies, researchers often use xenograft models, in which human skin cancer cells are transferred into mice, and the tumors are allowed to grow in the mice. This system relies heavily on animal experimentation. But alternatives exist, such as using hydrogels as 3D scaffolds for tumor spheroid growth. We are developing a biophysically and biochemically defined 3D in vitro models that would resemble a xenograft assay, allowing tumor growth and invasion. We are comparing different types of scaffolds, and will validate them by comparing the proteome of tumors in the different environments. The goal is then to use these assays to validate novel markers of tumor aggressivity.
People involved: Gabriela Da Silva André, Dr. Celine Labouesse.
[1] Da Silva André & Labouesse, 2024. Biophysical Reviews
[2] Da Silva André, Garau Paganella et al., 2024. Current Protocols, vol. 4: no. 1, pp. e966
Response of fibroblasts to mechanical
stresses in 3D
Skin is a 3D complex and hierarchical tissue, which plays a fundamental protective barrier role in the human body. We are developing 3D in vitro models to bridge the gap between animal studies and standard 2D cell culture. We use both synthetic hydrogels (e.g., poly(ethylene-glycol) based) and natural hydrogels (e.g., gelatin-based), of which we control the polymer weight and stiffness. We can trigger gelation after cell encapsulation using photosensitive initiators of cross-linking and/or enzymatic stiffening. These tools enable us to modulate the mechanical properties of the microenvironment and directly probe cellular response. We investigate how different physical and mechanical (stiffness, hydrostatic, and osmotic stress) stimuli affect the response of dermal fibroblasts. We combine expertise in hydrogel design with advanced biomechanics characterization to gain insight in the mechanisms underlying skin function and pathology.
People involved: Dr. Jaimie Mayner, Filippo Cuni, Jaime Pietrantuono Nepomuceno and Dr. Céline Labouesse.
Selected Publications:
[1] Garau Paganella et al., 2024. Biomaterials Advances, vol. 163, pp. 213933
[2] Da Silva André, Garau Paganella et al., 2024. Current Protocols, vol. 4: no. 1, pp. e966
[3] Sänger et al., 2023. Science Advances, vol. 9: no. 35, pp. eadh9219
[4] Kourouklis et al., 2023. Biomaterials Advances, vol. 145, pp. 213241
Models of tissue fibrosis
Fibrosis is a collection of diseases triggered by abnormal wound healing. In skin fibrosis, as in other organs, excessive matrix deposition and cross-linking results in a stiffening of the tissue, which is problematic for tissue function. This is often linked with hyperinflammation. We are developing an in vitro model of skin fibrosis in which we can control the stiffening and the inflammation. We focus on 3D models to better mimic the dimensionality of the dermis. This adds further challenges such as providing enough porosity for cell spreading. We are using granular biomaterials and photosensitive cross-linking chemistries to decouple control of porosity and stiffness.
People involved: Dr. Jaimie Mayner, Dr. Céline Labouesse
The role of the ECM in cell signaling
3D in vitro disease models are increasingly used as a tool to improve drug
development, as they fill the gap between 2D cell culture and animal models in pre-clinical research. One challenge is to understand how dosage of signaling molecules (growth factors, drugs) should be adjusted to the model used. There is mounting evidence that drug efficacy differs when used in 3D systems compared to 2D cell culture. Such discrepancies have been observed for cancer cells and fibrotic tissue. A key feature of 3D in vitro models is the presence of extracellular matrix (ECM). The role of the ECM in 3D is not fully understood. For example, are crowding effects important for cell signaling? We are developing systems to systematically test how the ECM regulates extracellular cell signaling in 3D.
People involved: Jaime Pietrantuono Nepomuceno, Dr. Céline Labouesse
Tissue engineering [completed]
To closely mimic the 3D in vivo niche, we encapsulate cells in tailored hydrogels and use acoustofluidics to apply spatial patterning. In addition to designing the hydrogel biomaterial, we optimize the cell culture conditions and nutrient supply necessary for specific cells. Currently, we are working on optimizing tissue engineering platforms for musculoskeletal tissue1 and to induce the formation of vascular networks.
Selected Publications:
[1] Deshmukh et al., Bioeng. & Transl. Med. 2020, 5, e10181.
[2] Guzzi et al., Biofabrication 2021, 13, 044105.
[3] Ragelle et al., Nat. Commun. 2018, 9, 1184.
Cell mechanotransduction in microniches
[completed]
Our collective knowledge of how cells sense their microenvironment through force-based interactions originates mostly from 2D studies. These have uncovered the mechanisms and pathways that control cell contractility, and mechano-regulation of gene expression, including the effect of mechanical memory1. In 3D contexts, cells develop lower forces and are under greater volumetric confinement.To understand the role of confinement in regulating cell function, we designed a microwell platform for 3D single cell niches of controlled size that can host single cells while restricting their spreading. We then measure how niche size and stiffness changes cell shape, cell adhesion, cell forces and downstream regulation of gene expression2. Cell-generated forces are estimated using Förster-based Energy Transfer (FRET) vinculin tension sensors. Ultimately, we will gain a better understanding of how mechano-transduction in 3D controls stem cell maintenance and differentiation.
Selected Publications:
[1] Yang and Tibbitt et al., Nat. Mater. 2014, 13, 645.
[2] Dudaryeva et al., Adv. Funct. Mater. 2021, 2104098.