Doctoral Dissertations

Date of Award

5-2014

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Polymer Engineering

Major Professor

Roberto Benson

Committee Members

Madhu Dhar, Kevin Kit, Wei He, Deidra Mountain

Abstract

A very promising approach to quickly and safely restore normal function to extensively damages and diseases bone and cartilage tissues is the regeneration of these injured tissues using an engineered support scaffold. This dissertation research focuses on the development and evaluation of native bacterial cellulose (BC) and chemically modified BCs as potential biomaterials for bone and cartilage regeneration using equine-derived bone marrow mesenchymal stem cells (EqMSCs).

The ability of native BC scaffold to maintain cell proliferation, viability, and in vitro differentiation of the seeded EqMSCs for application in bone and cartilage tissue engineering was studied. BC morphology was characterized using Scanning Electron Microscopy (SEM). Fluorescence microscopy and MTS assay were used to evaluate cell viability and expansion on the BC scaffolds. EqMSCs differentiation into osteocytes and chondrocytes were assessed using alizarin red and alcian blue differentiation assays, respectively.

Biodegradable, microporous and surface modified BC scaffolds were developed to mimic native bone and cartilage tissues. Microporous BC scaffolds were synthesized using natural wax microspheres. BC scaffolds were chemically modified with periodate oxidation to generate biodegradable BCs. To mimic bone tissue, BCs were mineralized with calcium-deficient hydroxyapatite (CdHAP). Surface amination and carboxylation of BCs were performed to simulate the glycosaminoglycans present in the native cartilage tissue. Native and modified BC scaffolds were characterized using Fourier Transform Infrared Spectroscopy (FTIR), SEM, and mechanical testing. Resulting scaffolds were also characterized for their ability to support and maintain the proliferation, osteogenic and chondrogenic differentiation of EqMSCs using fluorescence microscopy, confocal microscopy, MTS assay, and cell differentiation assays.

Biodegradable, CdHAP tubular-shaped BC composites with oriented nanofibers were developed and evaluated to mimic the hydroxyapatite minerals and inherent oriented collagen fibers in native bone. Tubular-shaped BCs were synthesized under static culture in oxygen-permeable silicone tubes. The scaffolds were characterized using SEM and mechanical testing. The ability of the tubular-shaped BC scaffolds to support and maintain EqMSCs proliferation and osteogenic differentiation were also assessed.

In summary, the material properties and in vitro results acquired from the research demonstrate that native and specifically biodegradable microporous BC scaffolds have the ideal properties for bone and cartilage tissue regeneration therapies.

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