Engineered cell culture microenvironments for mechanobiology studies of brain neural cells

Abstract

The biomechanical properties of the brain microenvironment, which is composed of different neural cell types, the extracellular matrix, and blood vessels, are critical for normal brain development and neural functioning. Stiffness, viscoelasticity and spatial organization of brain tissue modulate proliferation, migration, differentiation, and cell function. However, the mechanical aspects of the neural microenvironment are largely ignored in current cell culture systems. Considering the high promises of human induced pluripotent stem cell- (iPSC-) based models for disease modelling and new treatment development, and in light of the physiological relevance of neuromechanobiological features, applications of in vitro engineered neuronal microenvironments should be explored thoroughly to develop more representative in vitro brain models. In this context, recently developed biomaterials in combination with micro- and nanofabrication techniques 1) allow investigating how mechanical properties affect neural cell development and functioning; 2) enable optimal cell microenvironment engineering strategies to advance neural cell models; and 3) provide a quantitative tool to assess changes in the neuromechanobiological properties of the brain microenvironment induced by pathology. In this review, we discuss the biological and engineering aspects involved in studying neuromechanobiology within scaffold-free and scaffold-based 2D and 3D iPSC-based brain models and approaches employing primary lineages (neural/glial), cell lines and other stem cells. Finally, we discuss future experimental directions of engineered microenvironments in neuroscience.

Micro 3D Printing Elastomeric IP-PDMS Using Two-Photon Polymerisation: A Comparative Analysis of Mechanical and Feature Resolution Properties

“…For conventional PDMS, Wang et al [31] reported YMs ranging from 570 kPa to 3.7 MPa. Furthermore, for applications in which the Young's modulus is important, such as cell microenvironments and deformable structures, it is essential to measure it in aqueous environments to unveil possible correlations (e.g., for studies about the relationship between a material's Young's modulus and cell differentiation [22,32,33]). The effect of swelling on the Young's modulus is indeed crucial for biological applications, as, in such circumstances, the IP-PDMS is in contact with liquids.…”

“…The ability to tune the Young's modulus, in this case, was limited to 2PP polymers featuring GPa Young's moduli, which have already been extensively used for cell mechanobiology [17][18][19] and in vitro disease modelling applications [20,21]. The main focus of the present work is, on the other hand, to focus on the tuneable mechanical properties and the achievable feature resolution of a soft (kPa-MPa YM) elastomeric material, IP-PDMS, which could find application in the context of neuronal engineered microenvironments [22] as the brain is one of the softest tissues in the body.…”

“…IP-PDMS is, thus, approximately 100 times softer compared with other proprietary Nanoscribe materials [8]. Microscale architectures made from soft elastomeric (bio)materials like hydrogels and PDMS, are extremely interesting for biomedical applications, such as cell scaffolding and mechanobiological studies, as cells can deform the material, thus not generating large tension forces and retaining their shapes [8,22]. In addition, soft polymeric materials can also be employed in other fields, such as microfluidics, sensors, and actuators.…”

Novel Approaches to the Establishment of Local Microenvironment from Resorbable Biomaterials in the Brain In Vitro Models

“…The development of an appropriate microenvironment for the long-term in vitro culture of brain cells is still an unresolved question in neurobiology and tissue engineering [10,11]. It relates to the complexity of the extracellular composition in the brain tissue, different metabolic profiles and requirements in neuronal, glial, and endothelial cells, significant effects of developmental aspects, and the variability of current brain tissue in vitro models (isolated cells cultured in a 2D-or 3D-environment, brain-on-chip microfluidic models, organotypic slices, cerebral organoids, etc.).…”

Micro‐Vessels‐Like 3D Scaffolds for Studying the Proton Radiobiology of Glioblastoma‐Endothelial Cells Co‐Culture Models

“…A 3D cell culture approach allows to recreate the specific environment that cells require in a controlled in vitro setting. [ 1,2 ] There are many additive manufacturing approaches to create polymeric or hydrogel “scaffolds”, which are structures that support cells in 3D. [ 3 ] Among these methods, two‐photon polymerization (2PP) is a technique widely used in the cell mechanobiology field [ 4,5 ] since it can manufacture structures in the submicrometric range.…”