Bone tissue engineering has become an alternative method to autograft or allograft procedures due to the lack of donor tissues, supply limitation, and rejection reactions by the recipients’ immune system. In bone tissue engineering porous materials are used as a matrix to provide a mimetic microenvironment. Thus, cells and biological components can be combined to a bioactive construct, which can be used as tissue replacement. Hydrogels are commonly used as supporting matrices because of their structural similarity to the native extracellular matrix, allowing cell encapsulation in a highly hydrated environment and enable solute molecules diffusion. However, hydrogels often lack biochemical cues to modulate the cellular response.
In order to functionalize hydrogels, plant virus nanoparticles are introduced in a novel approach to the cell-laden 3D hydrogel-based matrices. Plant virus nanoparticles exist in different sizes and shapes, and can be genetically modified to present thousands of functional peptides on their surfaces, which can positively influence the biological and the biochemical reactions of the cells and the environment as well as tuning the mechanical properties of the hydrogels (Figs. 1 and 2) . The aim of the project PlantVirusBone, which is financed by the German Research Foundation (DFG) and performed in collaboration with the Institute of Molecular Biotechnology of RWTH Aachen University, is to develop a novel regenerative strategy for mimetic bone replacement using biotechnologically modified plant virus nanoparticles. The synthesized bio-inspired hydrogel compounds will be analyzed for their mechanical characteristics, 3D bioprintability, and biological responses of human mesenchymal stem cells.
 Lauria I, Dickmeis C, Röder J, Beckers M, Rütten S, Lin YY, Commandeur U, Fischer H (2017). Engineered Potato virus X nanoparticles support hydroxyapatite nucleation for improved bone tissue replacement. Acta Biomater 62:317-327.