Date of Award

8-9-2014

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

Sub-Department

Chemistry

First Advisor

Qian Wang

Abstract

Plant viruses have been highlighted among material research due to their well-defined structures in nanoscale, mono-dispersity, stability, and chemical functionalities. Each of the thousands coated protein subunits on a viral nanoparticle can be homogenously modified, chemically, and genetically with a functional ligand leading to a high-density and spatial distribution of ligands on each particle (multivalency). Many reports from our group have clearly shown that virus coated substrates induced the acceleration of bone marrow stromal cells differentiation into bone cells. We hypothesized that this phenomenon could rely on the multivalency that the viral nanoparticle has to offer. Moving to a more clinical relevant application, we fabricated three-dimensional (3D) biopolymeric scaffolds with functionalized rod-like Tobacco mosaic virus (TMV) for tissue engineering. The virus-functionalized hydrogel materials were developed and characterized. The first three chapters present in vitro and in vivo data based on the sponge-like preformed hydrogel functionalized with the cellular recognition peptide, arginine-glycine-aspartic acid (RGD), through an incorporation of RGD mutant of TMV (TMV-RGD1). Chapter 6 describes the development of an in situ crosslinking injectable hydrogel using cysteine-addition mutant of TMV (TMV-1Cys).

First chapter includes the fabrication method for TMV-incorporated porous alginate hydrogel, in vitro stem cell culture in 3D, and in vitro bone differentiation of stem cell in the hydrogel. TMV-RGD1 was non-covalently incorporated to introduce the biofunctionality into the hydrogel. This hydrogel was a preformed scaffold in which stem cells were seeded after the gel was fabricated. Cell attachment, viability were then characterized to assure the presence and accessibility of the RGD peptide on the virus scaffold. Osteogenic differentiation of bone marrow stromal cells was assessed in the composite hydrogels. The virus and its mutant modification with bio-adhesive peptide (RGD) significantly improved cell attachments and afforded a higher level of calcium depositions in comparison to the unmodified hydrogel. The TMV-functionalized hydrogel scaffolds were also used to study cartilage differentiation of bone marrow stromal cells in chapter 5. In chapter 2, in vivo biocompatibility studies of the hydrogel scaffolds, functionalized with wild-type and RGD-mutant TMV, showed no systemic toxicity and insignificant immune response against virus-modified hydrogel implants in the BALB/c mice. Chapter 3 confirms the in vivo biocompatibility of the hydrogel scaffolds with TMV and its RGD-mutant when bone marrow stromal cells were incorporated in the implants. Moreover, the implanted hydrogels guided the bone regeneration and could consequently repaired cranial defects in laboratory rats, as presented in chapter 4.

In chapter 6, cys-mutant of TMV was used to covalently link the virus particles with methacrylated polymer backbone through Michael addition reaction in the injectable hydrogel. In this system, physical properties of the hydrogel; for example, gelation time and gel moduli could be finely tuned via the degree of methacrylation and/or the addition of the virus. This in situ crosslinking method and the resulting hydrogel was cytocompatible for encapsulation and cultivation of bone marrow stromal cells.

Taken together, this dissertation articulates the application of using virus nanoparticles in functionalization and development of hydrogels as biomaterials for 3D cell culture and differentiation, as well as bone substitute matrix. These findings demonstrated that the virus-functionalized hydrogels can be promising materials for tissue engineering.

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