Mechanical and electrical environments to stimulate bone cell development

Hannay, Gwynne George (2006) Mechanical and electrical environments to stimulate bone cell development. PhD thesis, Queensland University of Technology.

Abstract

Healthy bone is bombarded with many different mechanical strain derived signals during normal daily activities. One of these signals is present as a direct connective tissue strain on the cells. However, there is also the presence of an electrically charged streaming potential during this straining. The electrical potential is created from the movement of charged fluid through the small bone porosities. To date, little focus has been applied to elucidating the possible synergistic effects of these two stimulants.

The aim of this project was to evaluate the effects of mechanical strain and indirect electrical stimulation upon the development of bone forming osteoblast cells and any possible synergistic effects of the two stimulants. This aim was achieved by using a novel device, designed and developed with the capability of creating a cell substrate surface strain along with an exogenous electrical stimulant individually or at the same time. Proliferation and differentiation were determined as a measure of cellular development.

The indirect electrical stimulation was achieved through the use of a pulsed electromagnetic field (PEMF) while the mechanical strain was produced from dynamic stretching of a deformable cell substrate. Strain and strain rate were modelled from recent studies proposing that relatively high frequency, low strain osteogenic mechanical stimulants are more indicative of what healthy bone would be experiencing during normal activities. The PEMF signal mimicked a clinically available bone growth stimulator signal.

Results showed a PEMF stimulus on monolayers of SaOS-2 and MG-63 osteoblast-like cells leads to a depression in proliferation. A concomitant increase in alkaline phosphatase production was also observed for the SaOS-2 cultures, but not for the MG-63 cell line. It was hypothesised that this was due to the MG-63's lack of phenotypic maturity compared to the SaOS-2 cells. Mechanical strain of the cell substrate alone, at a relatively high frequency (5Hz) but small strain, did not significantly effect either cell proliferation or differentiation for the MG-63 cells.

However, when the electrical and mechanical stimulants were combined a significant increase in cellular differentiation occurred with MG-63 cultures, revealing a possible synergistic effect of these two stimulants on the development of bone cells.

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ID Code: 16285
Item Type: QUT Thesis (PhD)
Supervisor: Pearcy, Mark & Leavesley, David
Keywords: PEMF, pulsed electromagnetic fields, electrical stimulation, mechanical stimulation, mechanical strain, cell substrate stretch, biophysical stimuli, dual stimuli, osteoblast, bone healing, electrical currents in bone, cell proliferation, cell differentiation, cell adhesion, surface characteristics
Divisions: Past > QUT Faculties & Divisions > Faculty of Built Environment and Engineering
Past > Schools > School of Engineering Systems
Department: Faculty of Built Environment and Engineering
Institution: Queensland University of Technology
Copyright Owner: Copyright Gwynne George Hannay
Deposited On: 03 Dec 2008 04:00
Last Modified: 28 Oct 2011 19:45

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