Controlling Fibroblast Proliferation with Dimensionality-Specific Response by Stiffness of Injectable Gelatin Hydrogels

Abstract

We report an injectable hydrogel system with tunable stiffness for controlling the proliferation rate of human fibroblasts (HFF-1) in both two-dimensional (2D) and three-dimensional (3D) culture environments for potential use as a wound dressing material. The hydrogel composed of gelatin–hydroxyphenylpropionic acid (Gtn–HPA) conjugate was formed by the oxidative coupling of HPA moieties catalyzed by hydrogen peroxide (H₂O₂) and horseradish peroxidase (HRP). The stiffness of the hydrogels was controlled well by varying the H₂O₂ concentration. The effects of hydrogel stiffness on the proliferation rate of HFF-1 in both 2D and 3D were investigated. We found that the proliferation rate of HFF-1 using Gtn–HPA hydrogels was strongly dependent on the hydrogel stiffness, with a dimensionality-specific response. In the 2D studies, the HFF-1 exhibited a higher proliferation rate when the stiffness of the hydrogel was increased. In contrast, the HFF-1 cultured inside the hydrogel remained non-proliferative for 12 days before a stiffness-dependent proliferation profile was shown. The proliferation rate decreased with an increase in stiffness of the hydrogel in a 3D culture environment, unlike in a 2D environment.