Transcript Diapositivo 1

Introdução à Engenharia Biomédica
"An assessment of bone mineral and organic phases in
osteoporosis and rheumatoid arthritis and their influence on
the mechanical integrity of the bone.”
Prof. Patrícia Figueiredo
Prof. Fernando Lopes da Silva
Coelho, João[1]; Rocha, Ricardo[2]; Silva, Pedro[3]
Prof. João E. Fonseca
[1][email protected]; [2][email protected]; [3] [email protected]
Key Facts
Rheumatoid Arthritis
“…is a systemic and autoimmune chronic disease,
which causes inflammation
and tissue damage in joints
and tendons.”
Osteoporosis
“…is defined as a skeletal disorder
characterized by compromised
bone strength predisposing a
person to an increased risk of
fracture. Bone strength primarily
reflects the integration of bone
density and bone quality.”
In RA, the RANK/OPG
ratio is increased,
leading to osteoporosis
Hypothesis
Objectives
In OP and RA, as bone remodelling is increased, bone
formation is not able to keep the pace of bone resorption...
1
To characterise bone mineral and organic phases of OP, RA and healthy
bone in human and animal models, using AFM, SEM, SAXS and MPM
2
To characterise the influence of alterations of the mineral-organic
matrix on the architecture of bone as a result of OP and RA in human
and animal models (and compared to healthy controls) using X-ray
computed tomography
3
To assess the effects of those changes on bone strength by evaluating
the intrinsic mechanical properties of healthy and diseased bone
from human and animal models using nanoindentation (small sample
compression test).
The bone does not have time to mature, because the osteoblast
activity is interrupted by a new cycle of osteoclast destruction.
… immature collagen type I fibril segments will constitute
part of the matrix, disturbing the pattern of hydroxyapatite
crystals growth and apposition, thus affecting bone
structure and bone mechanical properties.
Imaging Techniques
Collagen Fibers
(dyed blue in the
left image and
green on the
image below)
organization by
Multi-photon
microscopy.
Human fractured
femur (left) and
with coxoarthrosis
(below) by
Scanning Electron
Microscopy.
BMMD and
trabeculae may be
analyzed.
Healthy femur
DXA (Left) femur
with osteoporosis
(below). Whiter
areas are denser.
Dual X-ray
Absorptiometry is
used to measure
BMDD
Mechanical properties
Normal
Bone
Decalcified
bone
The mechanical properties of bone
are determined by:
- the amount of mineral in the tissue;
- its density distribution;
- collagen composition and content;
- orientation of the collagen fibres;
- bonding between the mineral and
collagen phases;
- accumulation of micro-cracks in the
bone matrix.
Micro-computed
Tomography of a
healthy bone (Left)
and of a bone with
osteoporosis
(below).
Trabecular
architecture is
visible.
Hydroxyapatite
crystals size and
orientation
(yellow lines),
obtained by SAXS,
superimposed on
a bone SEM
image (below).
Collagen fibers
topology is seen by
Atomic Force
Microscopy, in left
and below images .
Gap and overlap
zones are visible.
Conclusions
In the Future…
Nanoidentation compression
test on a femur sample (Left)
and the graphic that can be
obtained (Above).
Evaluation of trabecular mechanical and microstructural properties in human calcaneal bone of advanced age using mechanical testing, mCT, and DXA, Mittraa E., Rubinb C., Gruberc B., Qinb Y. | Efeito da osteoporose e da osteoartrose nas Propriedades mecânicas e estruturais do Osso trabecular, Lúcio M. | SAXS Studies at the Bone-Cartilage Interface, W.
Kaabar1, E. Che Ismail1, O. Gundogdu1, O. Bunk2, F. Pfeiffer2, M.J | In vivo Delivery of Fluoresceinated Dextrans to the Murine Growth Plate: Imaging of Three Vascular Routes by Multiphoton Microscopy, Farnum, C., Lenox, M., Zipfel, W., Horton, W., Williams, R. | Mechanical analysis of bone and its microarchitecture based on in vivo voxel images, Ulrich D.,
Rietbergen B., Laib A., Rüegsegger P. | Application of micro-CT assessment of 3-D bone microstructure in preclinical and clinical studies, Jiang Y., Zhao J., Liao E.Y., Dai R.C., Wu X.P., Genant H.K. | Topography and Mechanical Properties of Single Molecules of Type I Collagen Using Atomic Force Microscopy, Bozec, L. and Horton, M. | Measurement of human
trabecular bone by nove ultrasonic bone densitometry based on fast and slow waves, T. Yamamoto ; T. Otani; H. Hagino; H. Katagiri; T. Okano; I. Mano; R. Teshima | Microstructural Stresses And Strains Associated With Trabecular Bone Microdamage, Srinidhi Nagaraja | Osteoimmunology, M. Rauner; W. Sipos; P. Pietschman; | Everolimus suppresses cancellous
bone loss, bone resorption, and cathepsin K expression by osteoclasts; M. Kneissela, N. Luong-Nguyena, M. Baptista, R. Cortesia, S. Zumstein-Meckerb, S. Kossidac, T. O’Reillyb, H. Laneb, M. Susaa, | Effect of mineral dissolution from bone specimens on the viscoelastic properties of cortical bone, Sasaki,N.,et al. | Osteoclasts: What Do They Do and How Do They
Do It?, Teitelbaum, S. | Evaluation of trabecular mechanical and microstructural properties in human calcaneal bone of advanced age using mechanical testing, mCT, and DXA, E. Mittraa, C. Rubinb, B. Gruberc, Y. Qinb
Critical initial changes in bone matrix that lead
with high probability to global bone weakness
will be identified, and therefore allow:
We are grateful to:
Joana and her team (IMM)
Prof. Fátima Vaz and André Saraiva (IST)