The goal of tissue engineering is to use substitutes to repair and restore organ function. Bioreactors are an indispensable tool for monitoring and controlling the unique environment for engineered constructs to grow. However, in order to determine the biochemical properties of engineered constructs, samples need to be destroyed. In this study, we developed a novel technique to nondestructively online-characterize the water content and fixed charge density of cartilaginous tissues. A new technique was developed to determine the tissue mechano-electrochemical properties nondestructively. Bovine knee articular cartilage and lumbar annulus fibrosus were used in this study to demonstrate that this technique could be used on different types of tissue. The results show that our newly developed method is capable of precisely predicting the water volume fraction (less than 3% disparity) and fixed charge density (less than 16.7% disparity) within cartilaginous tissues. This novel technique will help to design a new generation of bioreactors which are able to actively determine the essential properties of the engineered constructs, as well as regulate the local environment to achieve the optimal conditions for cultivating constructs.

1.
Grodzinsky
,
A. J.
, 1983, “
Electromechanical and Physicochemical Properties of Connective Tissue
,”
Crit Rev. Biomed. Eng.
,
9
(
2
), pp.
133
199
.
2.
Maroudas
,
A.
, 1979, “
Physicochemical Properties of Articular Cartilage
,”
Adult Articular Cartilage
, 2nd ed.,
M. A. R.
Freeman
, ed.,
Pitman Medical
,
London, UK
, pp.
215
290
.
3.
Mow
,
V. C.
,
Ratcliffe
,
A.
, and
Poole
,
A. R.
, 1992, “
Cartilage and Diarthrodial Joints as Paradiams for Hierarchical Materials and Structures
,”
Biomaterials
,
13
(
2
), pp.
67
97
.
4.
Muir
,
H.
, 1983, “
Proteoglycons as Organizers of the Extracellular Matrix
,”
Biochem. Soc. Trans.
,
11
(
6
), pp.
613
622
.
5.
Muir
,
H.
, 1980, “
The Chemistry of the Ground Substance of Joint Cartilage
,”,
The Joints and Synovial Fluid
,
L.
Sokolff
, ed.,
Academic
,
New York
, pp.
27
94
.
6.
Eisenberg
,
S. R.
, and
Grodzinsky
,
A. J.
, 1985, “
Swelling of Articular Cartilage and Other Connective Tissues: Electromechanochemical Forces
,”
J. Orthop. Res.
,
3
(
2
), pp.
148
159
.
7.
Lai
,
W. M.
,
Hou
,
J. S.
, and
Mow
,
V. C.
, 1991, “
A Triphasic Theory for the Swelling and Deformation Behaviors of Articular Cartilage
,”
J. Biomech. Eng.
,
113
(
3
), pp.
245
258
.
8.
Urban
,
J. P.
, and
Maroudas
,
A.
, 1981, “
Swelling of the Intervertebral Disc in vitro
,”
Connect. Tissue Res.
,
9
(
1
), pp.
1
10
.
9.
Urban
,
J. P.
, and
McMullin
,
J. F.
, 1985, “
Swelling Pressure of the Intervertebral Disc: Influence of Proteoglycan and Collagen Contents
,”
Biorheology
,
22
(
2
), pp.
145
157
.
10.
Urban
,
J. P.
, and
McMullin
,
J. F.
, 1988, “
Swelling Pressure of the Lumbar Intervertebral Discs: Influence of Age, Spinal Level, Composition, and Degeneration
,”
Spine
,
13
(
2
), pp.
179
187
.
11.
Donnan
,
F. G.
, 1924, “
The Theory of Membrane Equilibria
,”
Chem. Rev.
,
1
, pp.
73
90
.
12.
Eisenberg
,
S. R.
, and
Grodzinsky
,
A. J.
, 1987, “
The Kinetics of Chemically Induced Nonequilibrium Swelling of Articular Cartilage and Corneal Stroma
,”
J. Biomech. Eng.
,
109
(
1
), pp.
79
89
.
13.
Gu
,
W. Y.
,
Lai
,
W. M.
, and
Mow
,
V. C.
, 1997, “
A Triphasic Analysis of Negative Osmotic Flows Through Charged Hydrated Soft Tissues
,”
J. Biomech.
,
30
(
1
), pp.
71
78
.
14.
Gu
,
W. Y.
,
Lai
,
W. M.
, and
Mow
,
V. C.
, 1993, “
Transport of Fluid and Ions Through a Porous-Permeable Charged-Hydrated Tissue, and Streaming Potential Data on Normal Bovine Articular Cartilage
,”
J. Biomech.
,
26
(
6
), pp.
709
723
.
15.
Darling
,
E. M.
, and
Athanasiou
,
K. A.
, 2003, “
Articular Cartilage Bioreactors and Bioprocesses
,”
Tissue Eng.
,
9
(
1
), pp.
9
26
.
16.
Schulz
,
R. M.
, and
Bader
,
A.
, 2007, “
Cartilage Tissue Engineering and Bioreactor Systems for the Cultivation and Stimulation of Chondrocytes
,”
Eur. Biophys. J.
,
36
(
4–5
), pp.
539
568
.
17.
Mow
,
V. C.
,
Wang
,
C. C.
, and
Hung
,
C. T.
, 1999, “
The Extracellular Matrix, Interstitial Fluid and Ions as a Mechanical Signal Transducer in Articular Cartilage
,”
Osteoarthritis Cartilage
,
7
(
1
), pp.
41
58
.
18.
Helfferich
,
F.
,
Ion Exchange
(
McGraw Hill Book Company, Inc.
,
New York
, 1962).
19.
Katchalsky
,
A.
, and
Curran
,
P. F.
, 1975, “
Nonequilibrium Thermodynamics in Biophysics
,” 4th ed.,
Harvard University
,
Cambridge, MA
.
20.
Maroudas
,
A.
, 1968, “
Physicochemical Properties of Cartilage in the Light of Ion Exchange Theory
,”
Biophys. J.
,
8
(
5
), pp.
575
595
.
21.
Gu
,
W. Y.
,
Yao
,
H.
,
Vega
,
A. L.
, and
Flagler
,
D.
, 2004, “
Diffusivity of Ions in Agarose Gels and Intervertebral Disc: Effect of Porosity
,”
Ann. Biomed. Eng.
,
32
, pp.
1710
1717
.
22.
Gu
,
W. Y.
, and
Justiz
,
M. A.
, 2002, “
Apparatus for Measuring the Swelling Dependent Electrical Conductivity of Charged Hydrated Soft Tissues
,”
J. Biomech. Eng.
,
124
,
790
793
.
23.
Gu
,
W. Y.
,
Mao
,
X. G.
,
Foster
,
R. J.
,
Weidenbaum
,
M.
,
Mow
,
V. C.
, and
Rawlins
,
B. A.
, 1999, “
The Anisotropic Hydraulic Permeability of Human Lumbar Anulus Fibrosus. Influence of Age, Degeneration, Direction, and Water Content
,”
Spine
,
24
(
23
), pp.
2449
2455
.
24.
Gu
,
W. Y.
,
Mao
,
X. G.
,
Rawlins
,
B. A.
,
Iatridis
,
J. C.
,
Foster
,
R. J.
,
Sun
,
D. N.
,
Weidenbaum
,
M.
, and
Mow
,
V. C.
, 1999, “
Streaming Potential of Human Lumbar Anulus Fibrosus is Anisotropic and Affected by Disc Degeneration
,”
J. Biomech.
,
32
(
11
),
1177
1182
.
25.
Gu
,
W. Y.
,
Justiz
,
M. A.
, and
Yao
,
H.
, 2002, “
Electrical Conductivity of Lumbar Annulus Fibrosis: Effects of Porosity and Fixed Charge Density
,”
Spine
,
27
, pp.
2390
2395
.
26.
Huang
,
C. Y.
,
Deitzer
,
M. A.
, and
Cheung
,
H. S.
, 2007, “
Effects of Fibrinolytic Inhibitors on Chondrogenesis of Bone-Marrow Derived Mesenchymal Stem Cells in Fibrin Gels
,”
Biomech. Model. Mechanobiol.
,
6
(
1–2
), pp.
5
11
.
27.
Bashir
,
A.
,
Gray
,
M. L.
,
Hartke
,
J.
, and
Burstein
,
D.
, 1999, “
Nondestructive Imaging of Human Cartilage Glycosaminoglycan Concentration by MRI
,”
Magn. Reson. Med.
,
41
(
5
), pp.
857
865
.
28.
Lesperance
,
L. M.
,
Gray
,
M. L.
, and
Burstein
,
D.
, 1992, “
Determination of Fixed Charge Density in Cartilage Using Nuclear Magnetic Resonance
,”
J. Orthop. Res.
,
10
(
1
), pp.
1
13
.
29.
Maroudas
,
A.
,
Muir
,
H.
, and
Wingham
,
J.
, 1969, “
The Correlation of Fixed Negative Charge With Glycosaminoglycan Content of Human Articular Cartilage
,”
Biochim. Biophys. Acta
,
177
(
3
), pp.
492
500
.
30.
Wilson
,
C. G.
,
Bonassar
,
L. J.
, and
Kohles
,
S. S.
, 2002, “
Modeling the Dynamic Composition of Engineered Cartilage
,”
Arch. Biochem. Biophys.
,
408
(
2
), pp.
246
254
.
You do not currently have access to this content.