Date of Completion

1-21-2013

Embargo Period

1-21-2013

Keywords

stem cell, progenitor cell, odontoblast, osteoblast, dental pulp, perivascular cell, GFP, αSMA, αSMAGFP

Major Advisor

Ivo Kalajzic

Associate Advisor

Mina Mina

Associate Advisor

William Upholt

Field of Study

Biomedical Science

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

It has been proposed that perivascular cells of the dental pulp are a source of odontoblast-like cells. However, the differentiation potential of perivascular cells remained undefined. In the present study we utilized αSMAGFP and αSMACreERT2xAi9 models to define the ability of perivascular cells to give rise to second generation of odontoblasts secreting dentin.

Dental pulp cells were collected from unerupted molars of P5-P7 neonatal pups. The αSMAGFP+ dental pulp cells were a small population residing in close proximity to endothelial cells in vivo. During growth and mineralization of primary pulp cultures, there was a significant increase in the number of αSMAGFP+ cells resulting from both the acquisition of GFP in new cells, and from the mitotic activity of αSMAGFP+ cells.

Sorted αSMAGFP+ cells derived from fresh tissue digests had the ability to differentiate into a mineralizing cell type that expressed osteocalcin and collagen type 1a1, and significantly less dentin sialophosphoprotein (Dspp). In contrast, the αSMAGFP- population represented an enriched odontoblast progenitor cell population that expressed high levels of CD90 and Dspp.

The role of the perivascular cell expressing αSMA during the process of reparative dentinogenesis was examined using a red fluorescent protein (tdTomato) reporter expressed by perivascular cells and their progeny after pulp exposure. Our findings provide evidence that perivascular cells expressing αSMA constitute one of the progenitor populations in the dental pulp able to differentiate into odontoblast-like cells giving rise to reparative dentin.

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