Master's Theses

Date of Award

2011

Document Type

Thesis

Department

Biomedical Engineering

Keywords

Bone, Osteoporosis, Vascular Porosity

Abstract

"Osteoporosis is a skeletal disease that currently affects 10 million Americans, and is characterized by low bone mass and increased skeletal fragility (National Osteoporosis Foundation, 2011). Estrogen loss, which begins during menopause, is the leading cause of osteoporosis in women. Recent research has focused on changes in cortical bone microporosity due to estrogen loss, which is important for bone health; load-induced interstitial fluid flow within the lacunar-canalicular porosity surrounding osteocytes is thought to play an important role in bone maintenance, while the vascular porosity provides a pressure relaxation mechanism for the fluid flow in the lacunar-canalicular porosity. Recent high-resolution micro-CT studies show that the cortical vascular porosity and average vascular canal diameter increase in the tibia metaphysis of ovariectomized (OVX) rats (Larriera et al., 2010). The present study investigated whether osteoclast resorption is responsible for the increased canal diameter, and if changes in the cortical blood vessel morphology occur due to estrogen loss. Alterations in the vascular porosity and bone vasculature were assessed using the rat OVX model at one and two weeks post-OVX, and analyzed histologically using TRAP enzyme and Goldner’s Trichrome staining. No differences in TRAP activity or vasculature morphology between OVX and sham-operated animals were found for all measurements one and two weeks post-surgery, signifying that osteoclast resorption may not be the primary mechanism for the increased canal diameter demonstrated previously. These results also suggest that cortical blood vessel morphology is unchanged at these time points. All parameters quantified in this thesis will be analyzed six weeks post-OVX to see if there are changes at the time point corresponding to the previous micro-CT analyses. While additional research is needed, this study begins to unveil the ways in which postmenopausal osteoporosis affects the microporosity in cortical bone."

 
 

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