Tobacco Mosaic Virus Functionalized Alginate Hydrogel Scaffolds for Bone Regeneration in Rats with Cranial Defect

Plant viruses have been highlighted among material research due to their well-defined structures in nanoscale, monodispersity, stability, and chemical functionalities. Each of the thousands coat protein subunits on a viral nanoparticle can be homogeneously modified, chemically and genetically, with a functional ligand leading to a high-density and spatial distribution of ligands on each particle (multivalency). Previous reports from our group have evidenced that substrates coated with Tobacco mosaic virus (TMV) and its mutant promote early osteogenesis of mesenchymal stem cells (MSCs). We then fabricated a three-dimensional (3D) biopolymeric scaffold with rod-like TMV in the form of a sponge-like hydrogel for tissue engineering purposes. The hydrogel was functionalized with the cellular recognition peptide, arginine-glycine-aspartic acid (RGD), through an incorporation of an RGD mutant of TMV (TMV-RGD). The virus-functionalized hydrogel materials were shown to aid bone differentiation of MSCs in vitro. Herein, we performed an in vivo study based on the TMV and TMV-RGD hydrogels in Sprague-Dawley rats with cranial bone defects. This report substantiated the hypothesis that TMV-functionalized hydrogel scaffolds did not cause systemic toxicity when implanted in the defect site and that the TMV-based hydrogel platform can support cell localization and can be further optimized for bone regeneration and repair.