Abstract: Osteocytes, the most abundant bone cell, form an interconnected network throughout bone tissue.  When bone is mechanically loaded during physical activity, fluid pressure gradients produce interstitial fluid flow in the lacunar-canalicular pore space surrounding osteocytes.  This load-induced interstitial fluid movement enhances solute transport that ensures the metabolic function of osteocytes;  it is also believed to play a role in bone’s mechanosensory system by translating whole-body motion to the cellular level.  It has been proposed that an alteration in osteocyte viability during postmenopausal osteoporosis could alter the interconnectedness of the osteocyte network.  This seminar will highlight our recent investigations of how reduced estrogen levels affect the osteocyte microenvironment as well as the interstitial space surrounding bone blood vessels.  While it is established that estrogen deficiency reduces bone mass, our recent studies using high-resolution microscopy and micro-CT imaging demonstrate that estrogen deficiency also alters the submicron lacunar-canalicular porosity surrounding osteocytes as well as the vascular porosity that houses the bone vasculature.  We have also demonstrated that reduced estrogen increases solute movement due to applied mechanical loading in cancellous bone.  Modification of the canalicular surface surrounding osteocytes might disrupt the connections that attach osteocytes to the bone matrix and could reduce the transduction of mechanical forces via interstitial fluid flow.  In this way the sensitivity of osteocytes to mechanical loading may be reduced in the estrogen-deficient state, which could contribute to the bone loss that occurs during postmenopausal osteoporosis. 

Biosketch: Susannah P. Fritton graduated summa cum laude from Tulane University in 1988, receiving a BSE in biomedical engineering.  She spent her junior year at the University of Leeds, UK, as part of the Tulane Junior Year Abroad honors program. After completing a PhD in biomedical engineering from Tulane in 1994, she became a postdoctoral research fellow in the Department of Orthopaedics at the State University of New York at Stony Brook.  In 1996 she joined the faculty of the Department of Mechanical Engineering at the City College of New York (CCNY), where she helped to establish BS, MS, and PhD degree programs in biomedical engineering.  In 2002 Dr. Fritton was a founding member of CCNY’s Department of Biomedical Engineering;  she currently acts as the department’s Deputy Chair.  Dr. Fritton’s research focuses on the effects of mechanical loading on bone;  recent work supported by the NIH and NSF involves investigating the effects of osteoporosis on bone interstitial fluid flow and mechanotransduction.  Dr. Fritton is a Catell Research Fellow at CCNY, and in 2008 she received the Grove School of Engineering Outstanding Teacher Award.  She has served on numerous NSF, NASA, and NIH grant review panels and was recently a Nominating Committee member and Topic Chair for the Orthopaedic Research Society.

~BME Faculty Host: Russell Main~

***Coffee and juice will be provided at West Lafayette***

(via teleconference to SL165 at IUPUI)