Affiliations: [a] Institute for Human Science and Biomedical Engineering, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan | [b] Department of Radiological Science, Graduate School of Human Health Science, Tokyo Metropolitan University, Arakawa-ku, Tokyo, Japan | [c] Department of Cartilage and Bone Regeneration, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
Correspondence:
[*]
Corresponding author: Masaki Misawa, Institute for Human Science and Biomedical Engineering, National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564, Japan. Tel.: +81 29 861 7106; Fax: +81 29 861 7905; E-mail:m.misawa@aist.go.jp
Abstract:
BACKGROUND:
Transmission and tomographic X-ray measurements are useful in assessing bone
structures, but only a few studies have examined cartilage growth because of
the poor contrast in conventional X-ray imaging.
OBJECTIVE:
In this study, we attempted to use the linear attenuation coefficient (LAC)
as a metric of tissue-engineered cartilage development, which would be
useful in high-throughput screening of cartilage products.
METHODS:
Assuming that the LAC is related to the amount of extracellular matrix (ECM)
in terms of the density and its atomic components, we measured X-ray
absorption through tissue-engineered cartilage constructs. Characteristic
X-ray beams from a molybdenum microfocus X-ray tube were employed to avoid
beam hardening. The correlation of the LAC with mechanical properties was
analyzed for verification.
RESULTS:
The LAC was higher for chondrocyte constructs and lower for
fibroblast-dominant constructs and was consistent with the quantification of
toluidine blue staining, which is a proof of ECM production. The LAC was
positively correlated with the bending modulus but negatively correlated
with the dynamic elastic modulus and stiffness, possibly because of the
remaining scaffold.
CONCLUSIONS:
The LAC has the potential to be used as a metric of development of
tissue-engineered cartilage. However, the calcified regions should be
excluded from analysis to avoid decreasing the correlation between the LAC
and the amount of ECM.
