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Thursday, February 6, 2003

Mechanical properties of engineered cartilage from adult human chondrocytes undergo maturation

Poster No. P160

Cartilage tissue engineered from adult human chondrocytes exhibits time-dependent changes in mechanical properties typical of maturing cartilage, report investigators for Scientific Poster P160.

Synthesized cartilaginous tissue can be implanted and used to treat focal articular cartilage defects. Various methods are used to develop this tissue, including the "alginate-recovered chondrocyte" or ARC method. This method can use adult human chondrocytes, which are pre-cultured in alginate, recovered, and further cultured. Researchers wanted to quantify the biomechanical properties of ARC cartilaginous tissue and to investigate the dependence of these mechanical properties on matrix composition.

Constructs were synthesized from eight adult (range 22 to 78 years old) human articular chondrocytes using the ARC method. The culture medium was supplmented with 20 percent Fetal Bovine Serum and 200ng/ml Osteogenic Protein-1. After 2 or 4 weeks of culture, researchers performed biomechanical tests on the samples to determine confined compression modulus, hydraulic permeability and tensile strength. A biochemical analysis was also performed to determine proteoglycan and collagen content. Data were analyzed by ANOVA and linear regression and are expressed as a mean figure (plus/minus standard deviation).

The resulting cartilage constructs were easy to handle and white and opaque in appearance. Between 2 and 4 weeks, the compressive modulus increased 153 percent, from 3.4 kilopascals (kPa) (± 2.5) to 8.6 kPa (± 6.9) (p<0.05). Tensile strength increased 290 percent, from 30 kPa (± 18) to 119 kPa (±74) (p<0.05). Proteoglycan content increased 37 percent, from 9.8 mg/ml (±4.2) to 13.5 mg/ml (±2.9) (p<0.05). Collagen content increased 64 percent, from 7.2 mg/ml (±2.7) to 11.8 mg/ml (±3.3) (p<0.05). Increasing proteoglycan and collagen content were correlated significantly to increasing compressive modulus (each p<0.05, R2=0.70, R2=0.85, respectively).

This study provides the first assessment of the biomechanical properties of cartilaginous tissue engineered from chondrocytes of adult humans rather than from the chondrocytes of animals or immature human donors. The time-dependent changes in mechanical properties and correlation with composition are typical of maturing cartilage. Such human ARC tissue potentially can be derived from patients in an autogenic procedure or from donors in an allogenic procedure, and used as a moldable press-fit orthopaedic implant material for filling chondral defects.

Researchers included Albert C Chen, PhD, and Robert L. Sah, MD, ScD, both of La Jolla, Calif.; Koichi Masuda, MD, Koichi Nakagawa, MD, Michiaki Yamada, MD, and Eugene J. Thonar, PhD, all of Chicago; and Brian E Pfister, PhD, of Northbrook, Ill., a consultant/employee of Articular Engineering. Dr. Masuda is a consultant/employee and stockholder of Articular Engineering. Dr. Thonar is also a stockholder in Articular Engineering.

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Last modified 20/January/2003