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Biomedical Engineering Faculty

Xiaodu Wang, Ph.D.
Professor
Department of Mechanical Engineering

Educational Background:
B.S., Beijing Institute of Aeronautics & Astronautics
M.S., Beijing Institute of Aeronautics & Astronautics
Ph.D.,Yokohama National University
Postdoctoral,UTHSCSA

Areas of Research Interest:
Dr. Wang's research interests are in the areas of hard tissue biomechanics, age-related bone fractures, contribution of collagen to bone quality, bone remodeling and bone quality, nano scale characterization of materials properties, nano/micro mechanics modeling of damage formation in bone, cell culture model of bone formation, and interfacial fracture mechanics. The NIH, Air Force Office Scientific Research, and NSF have continuously supported his research.

1. Age-related effect of bone remodeling on the toughness of bone
This project is based on the hypothesis that age-dependent changes in the collagen matrix are related to changes in the bone remodeling process, and such changes weaken the collagen network, and consequently cause decreased bone toughness. Three specific aims will be addressed: Aim 1: to determine age-related changes in the mechanical integrity of secondary osteons and interstitial bone. Aim 2: to determine age-related changes in the collagen matrix within secondary osteons and interstitial bone. Aim 3: To determine if age-related decreases in collagen integrity are correlated with decreased bone toughness (as a tissue) in aging. This study will provide insights into the underlying mechanism of age-related deterioration in bone quality and will facilitate future studies in the prevention and treatment of age- and disease-related bone fractures.

2. Modeling of microdamage formation in bone
The hypothesis of this study is that microdamage formation (microcrack or diffuse damage) in bone is dependent on the ultrastructural and material properties of collagen fibrils and mineral matrix in the tissue. Two specific aims will be addressed as follows: Aim1: To develop a probabilistic failure model of mineral-collagen fibril composite to predict the mechanisms of damage formation in bone (i.e., either microcrack or diffuse damage) as a function of ultrastructural and material properties of mineral and collagen constituents; Aim 2: To verify the probabilistic failure model using bone samples from several mice models.

3. Osteoblast cell culture system for study of bone formation
The overall objective of this study is to elucidate molecular mechanism behind the action of intermittent PTH in bone formation. The central hypothesis to be tested is that intermittent PTH increases the activity of hemichannels formed by connexin 43 (Cx43), which in turn promotes bone formation. We plan to test our central hypothesis by pursuing the following two specific aims. Aim 1: Determine the Activity of Hemichannels and Quality of the Bone Formed With and Without Intermittent PTH Treatment. Aim 2: Determine the Effects of Dosage and Duration of Intermittent PTH Treatment on Hemichannel Activities and Quality of the Bone.

4. Nano scale characterization of in situ tissue properties of bone
The objective of this study is to develop and validate a novel and simple nano-scratch technique to evaluate the in situ post-yield behavior of bone tissues in lamellae, osteon, and interstitial bone regions (e.g., at the nano/micro length scales). To address the issue, the following two specific aims will be addressed: Aim 1: To develop a novel nano-scratching technique that is capable of assessing the post-yield energy dissipation in both osteonal and interstitial regions of bone. Aim 2: To validate the nano-scratch methodology by comparing the nano-scratching data with those obtained from the conventional techniques (i.e., tensile test).

Selected Publications:

X. Wang, J.S. Nyman: A novel approach to assess post-yield energy dissipation of bone in tension, J. Biomech. 40 (2007) 674-7.

X. Wang, Y.J. Yoon, & H. Ji: A novel scratching approach for measuring age-related changes in the in situ toughness of bone, J. Biomech. 40 (2007) 1401-4.

J.S. Nyman, A. Roy, J.H. Tyler, R. Acuna, H.J. Gayle, and X. Wang: Age-related factors affecting the post-yield energy dissipation of human cortical bone. J. Orhtop. Res. 25 (2007) 646-655.

Q. Ni, J.S. Nyman, X. Wang, A. De Los Santos, and D.P. Nicolella: Assessment of water distribution changes in human cortical bone by nuclear magnetic resonanceMeas. Sci. Technol. 18 (2007) 1–9..

J.S. Nyman, A. Roy, R.L. Acuna, H.J. Gayle, M.J. R eyes, J.H. Tyler, D.D. Dean, and X. Wang: Age-related effect on the concentration of collagen crosslinks in human osteonal and interstitial bone tissue, Bone, 39 (2006) 1210-1217.

K.S. Chan, H, Ji, X. Wang, S.J. Hudak, B.R. Lanning: Mechanical properties and interface toughness of FeCo thin film on Ti-6Al-4V, Materials Science and Engineering, A 422 (2006) 298-308.

J.G. Fleischli, T.J. Laughlin, K.A. Athanasiou, D.R. Lanctot, L. Lavery, X. Wang, and C.M. Mauli: Effect of diabetes mellitus on the material properties of the distal tibia. Journal of the American Podiatric Association, (2006) 96(2) 91-95.

J. Nyman, A. Roy, X. Shen, and X. Wang: The influence of water distribution on the strength and toughness of cortical bone, J. Biomech. (2006) 39(5) 931–938

X. Wang and C.J. Qian: Prediction of microdamage formation using a mineral-collagen composite model of bone, J. Biomech. (2006) Vol. 39(4) 595-602.

Jeffry S. Nyman, Michael Reyes, X. Wang: Effect of ultrastructural changes on the toughness of bone, Micron 36 (2005) 566-582.

Q. Ni, J.D. King, and X. Wang: The characterization of human compact bone structure changes by low-field nuclear magnetic resonance, Measurement Sci. & Tech. 15 (2004) 58-66.

X. Wang and S. Puram: The toughness of cortical bone and its relationship with age, Annals of Biomed. Engineering, 32 (2004) 123-135.

X. Wang, X. Li, X. Shen, CM Agrawal: Age-related changes of non-calcified collagen in cortical bone, Annals of Biomed. Engineering, 31 (2003) 1365-1371.

X. Li, C.M. Agrawal, and X. Wang: Age-dependence of in situ thermostability of collagen in human bone. Calcif. Tissue Intel. 72 (2003) 513-518.

X. Wang and Q. Ni: Determination of cortical bone porosity and pore size distribution using a low field NMR approach, J. Orthop. Res. 21 (2003) 312-319.

X. Wang, X. Shen, X. Li, and C.M. Agrawal: Age-related changes in the collagen network and the toughness of bone, Bone, Vol. 31 (2002) 1-7.

X. Wang, R.A. Bank, J.M. TeKoppele, and C.M. Agrawal: The role of collagen in determining bone mechanical properties. Journal of Orthopaedic Research, Vol. 19 (2001) 1021-1026.

Yamashita, J.; Furman, B.R.; Rawls, H.R.; Wang, X.; Agrawal, C.M.: The use of dynamic mechanical analysis to assess the viscoelastic properties of human cortical bone. J Biomed Mater Res., 58(1) (2001) 47-53.

X. Wang and C.M. Agrawal: Mixed mode fracture toughness test of bone-biomaterial interfaces, Journal of Biomedical Materials Research (Applied Biomaterials), Vol 53 (2000) 664-672.

J.P. Phelps, G.B. Hubbard, X. Wang, C.M. Agrawal: Microstructural heterogeneity and the fracture toughness of bone. J. Biomed. Mater. Res. 51 (2000) 735-741.

X. Wang, R.A. Bank, J.M. te Koppele, Gene B. Hubbard, K.A. Athanasiou, and C.M. Agrawal: Effect of collagen denaturation on the toughness of bone. Clin. Orthop. Rel. Res. No. 371 (2000) 228-239.

Contact Information:

College of Engineering, Room EB 3.04.52
Department of Mechanical Engineering
University of Texas at San Antonio
Phone: 210-458-5565
Fax: 210-458-6504
Xiaodu.Wang@utsa.edu

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