Date of Award

5-2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Bioengineering

Advisor

Dean, Delphine

Committee Member

Kennedy , Marian S

Committee Member

Nagatomi , Jiro

Abstract

Human teeth are very complex structures that are susceptible to many different pathologies due to poor dental health. Currently, there are many restorative methods to reestablish some of the function that teeth have, but the materials used in these methods all have drawbacks and cannot fully mimic the native teeth. Tissue engineering research groups have begun to explore regenerating bone or dental tissue using mesenchymal stem cells derived from the bone marrow. However, our group focuses on regenerating dental tissues using multipotent stem cells from dental pulp.
Dental pulp stem cells (DPSCs) have shown similarities to bone marrow stem cells in in that they can differentiate into many cell types. Also, stem cells in general have shown that differentiation can be induced with microenvironmental factors such as growth factors and substrate properties. If enough is known about the cues that cells receive that induces differentiation, tissues could be engineered using the constructs and growth conditions necessary.
To determine the effect of substrate stiffness on human DPSCs, cells were placed on polyacrylamide gels of varying stiffness and in varying growth factor conditions. The cells were then observed with light and confocal microscopy, and the amount of alkaline phosphatase (ALP) activity was measured. These tests gave an indication of growth and differentiation. It was seen that the growth patterns were different on the gels than they were on a glass control, but there was little difference between the two gels. Also, the growth factors did not appear to have a significant contribution to differentiation.
Much work has been done to determine the effects of mechanical compression muscleoskeletal tissues, such as cartilage and bone. Dental tissues are also subject to loading throughout the day. Therefore, it was hypothesized that if dental pulp stem cells are compressed with pressure similar to that seen physiologically, it will induce differentiation to a bone or tooth-like lineage.
To determine the effects of static compression on dental pulp stem cells, a custom compressive device was fabricated. The device was tested for usability and it was deemed acceptable for use. ALP assays were performed similar to the previous studies. Preliminary results showed that that after only 1 day of culture time, the compression did not have much of an effect on dental pulp stem cells, while it did have an effect on osteoblasts. More work is to be done to determine the effects of compressive forces on dental pulp stem cells.

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