Usefulness of Photoacoustic Measurements for Evaluation of Biomechanical Properties of Tissue-Engineered Cartilage

Abstract

There is a demand in the field of regenerative medicine for measurement technology that enables functions of engineered tissue to be determined. For meeting this demand, we previously proposed a noninvasive method for determination of the viscoelasticity of a tissue phantom based on photoacoustic measurements. The purpose of this study was to verify the usefulness of the photoacoustic measurement method for evaluation of the viscoelastic properties of actual engineered tissue and to determine the correlation between biochemical characteristics and photoacoustic signals. The relaxation times measured by the photoacoustic method agreed well with the intrinsic viscoelastic parameters with a correlation coefficient of 0.98 when tissue-engineered cartilage tissues cultured for various periods (up to 12 weeks) were used as samples. By comparison of the results of biochemical analyses and biomechanical studies, we proved that the photoacoustic signal is a good indicator for evaluating extracellular matrix formation in order to determine the characteristics of tissue-engineered cartilage. To our knowledge, this is the first report on noninvasive and time-dependent viscoelastic evaluation of engineered tissue for determining functions of engineered tissues.

A Pilot Feasibility Study for Ultrasound Evaluation of Living Human Wrist Cartilage: Site-Specific Differences in Acoustic Properties

“…With respect to use of laser light, Ishihara et al 14 evaluated the viscoelastic properties of cartilage based on photoacoustic measurements. Naka et al 15 assessed the cartilage surface lubrication based on evanescent waves.…”

Recent technological advancements related to articular cartilage regeneration

“…This photoacoustic measurement method can be used not only for evaluating engineered tissue both in vitro and in vivo, but also for the diagnosis of the disease and for surgical treatment planning [13,18]. After transplantation of tissue-engineered cartilage and chondrocyte sheet, the subchondral bone of the joints would also have to be evaluated.…”

“…It was shown that there was no need to consider the diffraction effect when measuring the articular cartilage with only a few millimeters in thickness in comparison to the diffraction length ([20 mm). The tissue-engineered cartilage with the ACHMS scaffold was measured using a photoacoustic measurement system [13,18].…”

“…2a-c) [7][8][9][10][11][12][13][14][15] (diameter 6 mm, thickness 2 mm) in 96-well plates (Sumitomo Bakelite Corp., Tokyo, Japan) by centrifugation at 500 rpm (45 g) for 5 min and then were cultured in F12/DMEM supplemented with a 10% fetal bovine serum (Iwaki) and 50 g/ml of ascorbic acid (Sigma Corp., St Louis, MO) at 37°C in an atmosphere of 5% CO 2 in air and 100% relative humidity.…”

Nondestructive Techniques to Evaluate the Characteristics and Development of Engineered Cartilage

“…63 A strong inverse correlation (0.98) between viscoelastic properties (tan δ) and relaxation times over a twelve week culture period was found. This suggests that the tissue was becoming more elastic and less viscous over the culture period.…”