Astrocytes alignment and reactivity on collagen hydrogels patterned with ECM proteins

Abstract

To modulate the surface properties of collagen and subsequent cell-surface interactions, a method was developed to transfer protein patterns from glass coverslips to collagen type I hydrogel surfaces. Two proteins and one proteoglycan found in central nervous system extracellular matrix as well as fibrinogen were patterned in stripes onto collagen hydrogel and astrocytes were cultured on these surfaces. The addition of the stripe protein patterns to hydrogels created astrocyte layers in which cells were aligned with underlying patterns and had reduced chondroitin sulfate expression compared to the cells grown on collagen alone. Protein patterns were covalently cross-linked to the collagen and stable over four days in culture with no visible cellular modifications. The present method can be adapted to transfer other types of protein patterns from glass coverslips to collagen hydrogels.

ECM hydrogel for the treatment of stroke: Characterization of the host cell infiltrate

“…Specifically, the abundance of ECM molecules, such as fibronectin and laminin, are thought to be pivotal in a repair response of neural stem cells [57,58] and might explain the relative preferential infiltration of neural and oligodendrocyte progenitors. In contrast, the high collagen content of these ECM hydrogels might serve as a deterrent to astrocytes [59,60], hence at this acute stage leading to a selective preference of neural progenitor infiltration. Nevertheless, the infiltration of a high proportion of neural progenitors is very encouraging to harness endogenous repair mechanisms into the lesion cavity and potentially promote the replacement of lost tissue using inductive biomaterials.…”

A Simple Modification Method to Obtain Anisotropic and Porous 3D Microfibrillar Scaffolds for Surgical and Biomedical Applications

“…[10][11][12] Moreover, in nonload-bearing tissues like the spinal cord, aligned organization of axons is ultimately needed to transfer stimuli in the correct direction. [13][14][15] These examples highlight that promoting cellular organization is a critical step in tissue engineering and reconstructive surgical applications in order to assure their long-term functionality and support the need for anisotropic 3D scaffolds. [16] Currently several methods have been developed to induce cellular alignment, [17] mostly exploiting the ability of cells to recognize surface topographies [18,19] where they align in the direction of fibers, ridges, and grooves.…”

“…Also in load‐bearing tissues such as tendons, vessels, and heart valves, alignment of extracellular matrix (ECM) fibers greatly improves the tensile strength of the tissues . Moreover, in nonload‐bearing tissues like the spinal cord, aligned organization of axons is ultimately needed to transfer stimuli in the correct direction . These examples highlight that promoting cellular organization is a critical step in tissue engineering and reconstructive surgical applications in order to assure their long‐term functionality and support the need for anisotropic 3D scaffolds …”

Control of Astrocyte Quiescence and Activation in a Synthetic Brain Hydrogel

“…Astrocytes constitute approximately 30% 1 of the cells within the mammalian brain and function as key producers and maintainers of the brain extracellular matrix (ECM) during brain tissue homeostasis. 2,3 During brain trauma 4 and inflammation 1,5 , changes in the ECM composition [6][7][8][9][10] , ECM stiffness 11 , and the introduction of cytokine molecules 12 transform astrocytes from a quiescent to a reactive state. This reactive state is typically characterized by the upregulation of the intermediate filament proteins glial fibrillary acidic protein (GFAP) 1-3 and vimentin 13 .…”

“…However, the close cell-cell contact in these organoid culture is an important drawback, as astrocyte processes only overlap in vivo during their reactive state. 2,17 Additionally, this culturing cells as organoids is time consuming 15,18 and does not allow for the customization of ECM cues like stiffness 6,19,20 and ligand density 7,20 present in real tissue. Protein and glycosaminoglycan-based 3D hydrogels, e.g.…”