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Elizabeth G. Loboa, PhD Assistant Professor

Joint Department of Biomedical Engineering
UNC-Chapel Hill & NC State University
North Carolina State University
433 Daniels Hall
Campus Box 7115
Raleigh, NC  27695-7115
919/513-4015
919/513-3814 fax

Cell Mechanics Laboratory website at UNC-Chapel Hill & NC State University

Degrees

PhD - Department of Mechanical Engineering, Stanford University, 2002

BS - Mechanical Engineering, UC Davis, 1995

MS - Biomechanical Engineering, Stanford University, 1997

Affiliations

Stanford University, Department of Mechanical Engineering

Graduate Women's Network, Stanford University

Mechanical Engineering Graduate Women's Group, Stanford University

Tau Beta Pi - National Engineering Honor Society

Student Member, Association for Women in Science - Palo Alto Chapter

Student Member, American Society of Mechanical Engineers

Student Member, Society of Women Engineers

Student Research Project

Mechanobiology of Tissue Differentiation - My project is concerned with the impact of mechanical stimuli on pluripotential tissue differentiation. Our research group has developed a tissue differentiation hypothesis relating hydrostatic stress and tensile strain to differentiation of pluripotential tissue into cartilage, bone, fibrocartilage, or fibrous tissue. In brief, it is our hypothesis that increasing negative hydrostatic stress (compression) induces development of chondroid tissue and increasing tensile strain induces fibrous tissue development. Bone development is permitted in regions of low stress and strain.

My research involves the application of this tissue differentiation concept to an analysis of non-union and pseudarthrosis (artificial joint) development. Using finite element analysis, I am investigating how the stresses and strains in a fracture callus can inhibit normal secondary fracture healing and, instead, induce pseudarthrosis formation.

Dissertation Abstract

Mesenchymal tissue is a multipotent tissue with the capability to differentiate into a variety of skeletal tissues including bone, cartilage, fibrocartilage, or fibrous tissue. Differentiation of mesenchymal tissue is dependent upon many biological factors including genetics, vascular supply, and various growth, differentiation, and angiogenic factors. However, it is also greatly dependent upon mechanobiology, i.e., the mechanical influences on the tissue through its biological mechanisms. A fascinating area of research with respect to mesenchymal tissue is the mechanobiological regulation of its differentiation to regulate the types and locations of new skeletal tissue formed during the regeneration process.

A tissue differentiation concept relating tensile strain and hydrostatic stress histories to skeletal tissue formation was previously developed by investigators in our laboratory. In that theory, it was proposed that hydrostatic pressure directs multipotent mesenchymal tissue down a chondrogenic (cartilage) pathway, significant tensile strain leads to fibrogenesis (fibrous tissue), a combination of hydrostatic pressure and significant tensile strain leads to fibrocartilage development, and, given adequate vascularity, low levels of hydrostatic stress and tensile strain allow direct intramembranous bone formation.

This research both implemented and expanded this tissue differentiation concept as it investigated the mechanobiology of multipotent mesenchymal tissue differentiation in new studies of skeletal tissue regeneration. Using experimental and computational approaches, analyses of oblique pseudarthrosis formation, mandibular distraction osteogenesis, and soft skeletal tissue regeneration were performed. Conclusions regarding the mechanical environments associated with 1) initial stages of oblique pseudarthrosis formation, 2) successful bone regeneration during mandibular distraction osteogenesis, and 3) time-dependent material property adaptations during the regeneration of cartilage, fibrocartilage, and fibrous tissue were made.

The results of this thesis verify the importance of mechanobiological factors in multipotent mesenchymal tissue differentiation during skeletal tissue regeneration. The relationships examined in this thesis are essential to understanding the time-dependent changes that occur during differentiation as a result of both physiologic and artificially imposed mechanical loads at a site of regenerating tissue.

Research Interests

• Mechanobiology of Delayed Fracture Healing and Non-union/Pseudarthrosis Formation
• Mechanical Regulation of Tissue Differentiation in Fracture Healing and Pseudarthrosis Development

Recent Publications

Papers:

Carter DR, Polefka EGL, GS Beaupré GS. Mechanical influences on skeletal regeneration and bone resorption. In: Bone Engineering (ed: Davies J). University of Toronto Press, Toronto, Canada, pp 358-368, 2000.

Carter, DR, Polefka EGL, Beaupré GS. Mechanical influences on skeletal regeneration. In: Human Biomechanics and Injury Prevention (eds: Kajzer J, Tanaka E, Yamada H). Springer-Verlag, Tokyo, pp 129-136, 2000.

Loboa EG, Beaupré GS, and Carter DR (in press), Mechanobiology of Initial Pseudarthrosis Formation with Oblique Fractures, Journal of Orthopaedic Research.

Sarin VK, Loboa Polefka EG, Beaupré GS, Kiratli BJ, Carter DR, and van der Meulen MCH (1999) DXA-derived section modulus and bone mineral content predict long-bone torsional strength. Acta Orthop Scand. 70(1):71-76.

Book Chapters:

Carter D.R., Loboa Polefka E.G., and Beaupré G.S. (2000) Mechanical influences on skeletal regeneration. In: Human Biomechanics and Injury Prevention, eds J. Kajzer, E. Tanaka, H. Yamada, pp. 129-136. Springer-Verlag, Tokyo.

Carter D. R., Loboa Polefka E. G., and Beaupré G. S. (2000) Mechanical influences on skeletal regeneration and bone resorption. In: Bone Engineering, ed JE Davies, pp. 358-368. University of Toronto, Toronto.

Abstracts:

Bouletreau PJ, Warren SM, Paccione MF, Greenwald JA, Nijher NS, McCarthy JG, Carter DR, Beaupre GS, Loboa E, Longaker MT. New developments in craniofacial distraction. 3rd Intl Congr Craniofacial and Maxillofacial Distraction, Paris, France, 2001.

Loboa Polefka EG, Beaupré GS, and Carter DR (2000) Stress and Strain Distributions are Correlated with Pseudarthrosis Development. ORS 46th Annual Meeting. Orlando, FL.

Loboa Polefka EG, Beaupré GS, and Carter DR (2000) Mechanobiology of Delayed Fracture Healing. VA Rehabilitation Research and Development Service, 2nd National Meeting. Arlington, VA.

Loboa EG, Sarin VK, Beaupré GS, Kiratli BJ, Carter DR, and van der Meulen MCH (1997) Fracture risk predictions using DXA imaging. National Bioengineering Career Symposium. Seattle, WA.

Loboa EG, Sarin VK, Beaupré GS, Kiratli BJ, Carter DR, and van der Meulen MCH (1997) Comparison of DXA-derived measurements of linear bone mineral content and section modulus as non-invasive predictors of bone strength. UC Davis Biomedical Engineering Symposium. Davis, CA.

Data Ready for Publication:

Wren TAL, Loboa EG, Beaupré GS, Carter DR. New concepts in the mechanobiology of skeletal tissue differentiation and regeneration.

Recent Presentations

Biomedical Computation at Stanford Symposium - 2001
Mechanobiology of Soft Skeletal Tissue Regeneration: A Mathematical Approach for describing Material Property Changes during Soft Skeletal Tissue Formation
Abstract

Biomedical Computation at Stanford Symposium - 2000
Mechanical Influences on Oblique Pseudarthrosis Formation
Abstract (page 60) - Figures

Mechanobiology of Delayed Fracture Healing, 2nd National Rehabilitation Research and Development Service Meeting, Arlington, VA, February 20 - 22, 2000.
Abstract

Links

Last updated 12/20/2004