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

TLDR

Gelatin‑methacryloyl (GelMA) is a semi‑synthetic hydrogel derived from gelatin with methacrylamide and methacrylate groups that offers RGD motifs for cell adhesion and can be rapidly photo‑crosslinked to provide shape fidelity and stability at physiological temperature. This study demonstrates how GelMA hydrogels can be synthesized with a defined degree of functionalization and tailored to serve as a 3D cell culture platform that promotes human adipose‑derived mesenchymal stem cell adhesion, spreading, and proliferation. Mechanical properties are tuned by varying GelMA concentration, degree of functionalization, and UV polymerization conditions, while cell viability and morphology are assessed across stiffnesses, viscosity is increased with biocompatible additives to enable extrusion bioprinting, and hydrogels can be digested to release encapsulated cells. The resulting hydrogels can be digested to recover viable encapsulated cells, and collectively demonstrate that GelMA hydrogels are a versatile tool for 3D cell cultivation.

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.