Date of Completion

8-14-2020

Embargo Period

6-10-2022

Advisors

Dr. Bahar Houshmand and Dr. Bina Katechia

Field of Study

Dental Science

Degree

Master of Dental Science

Open Access

Open Access

Abstract

Identification of the mesenchymal stem cell (MSC) population capable of giving rise to odontoblasts secreting dentin during growth (primary dentinogenesis)and repair (reparative dentinogenesis) is critical for the development of improved pulp therapy, regeneration of dentin and ultimately, the bioengineering of functional teeth. Recent lineage tracing studies have led to the identification of several new MSCs and their associated niche referred to as the neurovascular bundle, located at the apical end of the incisor. This newly identified niche contains several populations of MSCs including Gli1+(glioma-associated oncogene homolog 1), cells that are activated by Shh secreted by sensory nerves. Furthermore, these studies showed contribution of Gli1+cells to odontoblasts during growth and repair, in incisors. Despite significant progress in the identification of MSCs within the mouse incisors in vivo, we know much less about MSCs in mouse molars that, unlike incisors, are not continuously growing and are more similar to human dentition. Therefore, the long-term goal of our studies is to gain insight into the roles of neurovascular niche and Gli1 expressing cellsin primary and reparative dentinogenesis in mice molars.

As the first step in the present study we evaluated the neurovascular niche and Gli1 expressing in adult mice molars using Gli1-CreERT2/Ai9 tomato reporter mice. The expression of transgenes was correlated with the expression of vascular marker CD31 and neuronal marker CGRP. The results show that Gli1+ expressing cells were identified in close proximity to CD31+ blood vessels and CGRP+ nerve fibers in the apical portion of mature mouse molars, thereby indicating a close association of Gli1+ reporter cells to the neurovascular bundle. Understanding the supporting niche of Gli1+ cells within the dental pulp is an important step in identifying these MSCs and their further lineage commitment to odontoblast-like cells, which could serve as a valuable cell source for the generation of reparative dentin after tooth injury.

Major Advisor

Dr. Mina Mina

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