Date of Award

5-2010

Document Type

Thesis

Degree Name

Master of Science (MS)

Program

Biomedical Engineering and Imaging

Research Advisor

Denis Diangelo, Ph.D.

Committee

Joel Bumgardner, Ph.D. Satoru Nishimoto, Ph.D. Yunzhi Yang, Ph.D.

Abstract

Bone grafts are commonly used for the treatment of large bone defects. Biodegradable, synthetic bone grafts combined with cells and growth factors as a tissue engineered construct can provide benefits over the common autografts and allografts currently used. Calcium phosphate (CaP) materials offer high biocompatibility and chemical similarity to natural bone tissue. Biodegradable beta-tricalcium phosphate (β-TCP) scaffolds with an interconnected porous network have been created to promote tissue ingrowth and regeneration in vitro and in vivo. Extracellular matrix (ECM) coated on titanium and polymer scaffolds has been shown to improve cell response to those material surfaces. Here, we attempted to further improve the biocompatibility of the interconnected β-TCP ceramic scaffolds by generating a cell derived ECM on the ceramic surface in vitro. Cell derived ECM was generated on scaffolds for 1, 7, 14, 21, or 28 days of culture. Scaffolds were decellularized and sterilized to isolate the ECM coating on the β-TCP scaffolds. Osteogenic medium-soaked scaffolds treated for the same time periods as ECM coated scaffolds and autoclaved, untreated scaffolds were used as controls. The behavior of preosteoblasts seeded onto each scaffold was examined over a 28 day period. Cellular assays for cell number, alkaline phosphatase (ALP), and total protein (TP) were measured. Cell morphology changes on the scaffold were observed by scanning electron microscopy. The cell count on all scaffolds reached a plateau after 14 days. Specific ALP and specific TP slowly increased during the 28 days for all groups. New ECM was visible after 14 days of generation time on all groups. No significant difference was seen between the untreated scaffold control, the 1, 7, 14, 21, or 28 day ECM-coated scaffolds, or the 1, 7, 14, 21, or 28 day medium-soaked scaffolds (eleven groups). This study verifies the high biocompatibility of β-TCP scaffolds and suggests that a cell derived biological coating on the β-TCP scaffolds offers no significant changes to the attachment rates or differentiation rate of seeded cells. Future studies will seek to find other benefits of the ECM coating, like use as a bioactive agent delivery vehicle.

DOI

10.21007/etd.cghs.2010.0366

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