Gelatin-Methacryloyl (GelMA) Hydrogels with Defined Degree of Functionalization as a Versatile Toolkit for 3D Cell Culture and Extrusion Bioprinting.

Katharina Kruppa,Iliyana Pepelanova,Thomas Scheper,Antonina Lavrentieva

doi:10.3390/bioengineering5030055

Katharina Kruppa, Iliyana Pepelanova + Show 2 more

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https://doi.org/10.3390/bioengineering5030055

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Abstract

Gelatin-methacryloyl (GelMA) is a semi-synthetic hydrogel which consists of gelatin derivatized with methacrylamide and methacrylate groups. These hydrogels provide cells with an optimal biological environment (e.g., RGD motifs for adhesion) and can be quickly photo-crosslinked, which provides shape fidelity and stability at physiological temperature. In the present work, we demonstrated how GelMA hydrogels can be synthesized with a specific degree of functionalization (DoF) and adjusted to the intended application as a three-dimensional (3D) cell culture platform. The focus of this work lays on producing hydrogel scaffolds which provide a cell promoting microenvironment for human adipose tissue-derived mesenchymal stem cells (hAD-MSCs) and are conductive to their adhesion, spreading, and proliferation. The control of mechanical GelMA properties by variation of concentration, DoF, and ultraviolet (UV) polymerization conditions is described. Moreover, hAD-MSC cell viability and morphology in GelMA of different stiffness was evaluated and compared. Polymerized hydrogels with and without cells could be digested in order to release encapsulated cells without loss of viability. We also demonstrated how hydrogel viscosity can be increased by the use of biocompatible additives, in order to enable the extrusion bioprinting of these materials. Taken together, we demonstrated how GelMA hydrogels can be used as a versatile tool for 3D cell cultivation.

Highlights

Recapitulation of the in vivo-like microenvironment during in vitro cell cultivation remains a challenge for researchers
gelatin methacryloyl (GelMA) is a typical semi-synthetic hydrogel, which enables the exploitation of the biological signals inherent in the gelatin molecule, while allowing control of mechanical properties [1]
The hydrogel is obtained by the derivatization of gelatin with methacrylic anhydride, resulting in modification of lysine and hydroxyl residues with methacrylamide and methacrylate side groups [4]

Summary

Introduction

Recapitulation of the in vivo-like microenvironment during in vitro cell cultivation remains a challenge for researchers. Several important parameters/factors are usually neglected in conventional cell culture These include physiological concentrations of biologicals (e.g., cytokines), energy sources (e.g., glucose and fatty acids), as well as oxygen concentrations. The modification with methacryloyl side groups allows the GelMA molecule to undergo rapid polymerization in the presence of UV light and a photoinitiator (PI), resulting in covalent crosslinking through the creation of a methacryloyl backbone [4]. This feature gives GelMA stability at physiological temperature and allows fine-tuning of mechanical properties. The resulting material is transparent, which facilitates microscopic analysis

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