Rational Design and Development of Anisotropic and Mechanically Strong Gelatin‐Based Stress Relaxing Hydrogels for Osteogenic/Chondrogenic Differentiation

Abstract

Rational design and development of tailorable simple synthesis process remains a centerpiece of investigational efforts toward engineering advanced hydrogels. In this study, a green and scalable synthesis approach is developed to formulate a set of gelatin‐based macroporous hybrid hydrogels. This approach consists of four sequential steps starting from liquid‐phase pre‐crosslinking/grafting, unidirectional freezing, freeze‐drying, and finally post‐curing process. The chemical crosslinking mainly involves between epoxy groups of functionalized polyethylene glycol and functional groups of gelatin both in liquid and solid state. Importantly, this approach allows to accommodate different polymers, chitosan or hydroxyethyl cellulose, under identical benign condition. Structural and mechanical anisotropy can be tuned by the selection of polymer constituents. Overall, all hydrogels show suitable structural stability, good swellability, high porosity and pore interconnectivity, and maintenance of mechanical integrity during 3‐week‐long hydrolytic degradation. Under compression, hydrogels exhibit robust mechanical properties with nonlinear elasticity and stress‐relaxation behavior and show no sign of mechanical failure under repeated compression at 50% deformation. Biological experiment with human bone marrow mesenchymal stromal cells (hMSCs) reveals that hydrogels are biocompatible, and their physicomechanical properties are suitable to support cells growth, and osteogenic/chondrogenic differentiation, demonstrating their potential application for bone and cartilage regenerative medicine toward clinically relevant endpoints.

Impedance-Based Monitoring of Mesenchymal Stromal Cell Three-Dimensional Proliferation Using Aerosol Jet Printed Sensors: A Tissue Engineering Application

“…Only from a measuring perspective, the reproducibility and sensitivity could be improved through an enhanced standardization of the scaffold characteristics (e.g., porosity and dimensions) and of the conductivity of the overall system. On the other hand, results obtained from these scaffolds, non-conductive but already validated for regenerative medicine purposes in terms of cytocompatibility and porosity [10,11], are really promising and may lead to the direct adoption of this monitoring strategy for the optimization of 3D seeded scaffold ready for in vivo implantation.…”

“…Hybrid gelatin-chitosan hydrogel scaffold were prepared following the procedure described in [10], cut, sterilized using gamma irradiation with Cobalt 60 gamma rays using 27-33 kGy following UNI EN ISO 11137 (Sterilization of Health Care Products) and stored in sealed bags until use. Before sterilization, scaffolds were cut into standard cylinders of 4 mm in diameter and 2 mm in height, in order to ensure the correct fitting within the wells, considering their volumetric expansion when wet.…”

“…In particular, gelatin and chitosan have been extensively used for tissue engineering applications, since they are biocompatible, biodegradable, non-antigenic, non-toxic and present antimicrobial activity [6,7]. Starting from this evidence and aiming to regenerate bone, recent literature has provided examples of optimized combinations of these materials to realize hybrid hydrogel scaffolds, presenting a structure that mimics native ECM constituents and reporting morphological and mechanical properties suitable to support cell growth, osteo-differentiation and mineralization [8][9][10][11].…”

Chitosan-Hydrogel Polymeric Scaffold Acts as an Independent Primary Inducer of Osteogenic Differentiation in Human Mesenchymal Stromal Cells

“…Chitosan is a biomimetic, biodegradable, biocompatible, non-immunogenic, and versatile polymer presenting appropriate mechanical strength and anti-bacterial properties [16]. It is also able to support growth factor activity [32,34].…”

“…Biocompatiblility and non-immunogenicity are also desirable features. Scaffolds should also be versatile concerning manufacturing methods, functionalization potential, and control of three-dimensional microarchitecture [3,16]. It is important to understand that the bio-physiological and chemical 3D organization of cells is fundamental for a successful design and maturation of new tissues.…”