A Beginner’s Guide to the Characterization of Hydrogel Microarchitecture for Cellular Applications

Abstract

The extracellular matrix (ECM) is a three-dimensional, acellular scaffold of living tissues. Incorporating the ECM into cell culture models is a goal of cell biology studies and requires biocompatible materials that can mimic the ECM. Among such materials are hydrogels: polymeric networks that derive most of their mass from water. With the tuning of their properties, these polymer networks can resemble living tissues. The microarchitectural properties of hydrogels, such as porosity, pore size, fiber length, and surface topology can determine cell plasticity. The adequate characterization of these parameters requires reliable and reproducible methods. However, most methods were historically standardized using other biological specimens, such as 2D cell cultures, biopsies, or even animal models. Therefore, their translation comes with technical limitations when applied to hydrogel-based cell culture systems. In our current work, we have reviewed the most common techniques employed in the characterization of hydrogel microarchitectures. Our review provides a concise description of the underlying principles of each method and summarizes the collective data obtained from cell-free and cell-loaded hydrogels. The advantages and limitations of each technique are discussed, and comparisons are made. The information presented in our current work will be of interest to researchers who employ hydrogels as platforms for cell culture, 3D bioprinting, and other fields within hydrogel-based research.

Hydrogel for the Controlled Delivery of Bioactive Components from Extracts of Eupatorium glutinosum Lam. Leaves

“…The difference in color between the hydrogel without the extracts, when compared to EG-methanolic/NRC, EG-methanolic/MCC, EG-ethanolic/NRC, and EG-ethanolic/MCC, indicated encapsulation of the extract inside the polymeric matrix [ 44 ]. Unique features such as the surface topology of the loaded hydrogels developed in this research may limit their biomedical applications [ 45 ]. The physical integrity of the extract-loaded hydrogels could also be related to their mechanical strength, functionality, and adaptability [ 46 ].…”

Assessing cell migration in hydrogels: An overview of relevant materials and methods

“…A harsh treatment is required to dry and coat the sample with a thin metal layer. [ [40] , [41] , [42] , [43] ] Optical Microscopy Brightfield Affordable; Reduced phototoxicity; Simple to use Low contrast; Poor resolution; Difficult to distinguish different cell types; mainly limited to hydrogel surface [ 42 , 44 , 45 ] Epifluorescence Fast imaging of hydrogel network structure and content Dynamics of the hydrogel network Photo bleaching Out-of-focus background. Photo toxicity Laser-scanning confocal microscopy High-resolution imaging of hydrogel 3D network structure and dynamics Photobleaching Time-consuming for large z-stacks.…”

Production and Utility of Extracellular Vesicles with 3D Culture Methods

“…Pore sizes are important in enabling adequate tissue growth and are dependent on the specific type of cell. For example, hydrogels with pore sizes of 25–500 µm are required for cartilage growth, ~166 µm for vascular network formation, and 50–200 μm for the growth of smooth muscle cells [ 147 , 148 ].…”