title: Quantitative ultrasound can assess the regeneration process of tissue-engineered cartilage using a complex between adherent bone marrow cells and a three-dimensional scaffold.
abstract: Articular cartilage (hyaline cartilage) defects resulting from traumatic injury or degenerative joint disease do not repair themselves spontaneously. Therefore, such defects may require novel regenerative strategies to restore biologically and biomechanically functional tissue. Recently, tissue engineering using a complex of cells and scaffold has emerged as a new approach for repairing cartilage defects and restoring cartilage function. With the advent of this new technology, accurate methods for evaluating articular cartilage have become important. In particular, in vivo evaluation is essential for determining the best treatment. However, without a biopsy, which causes damage, articular cartilage cannot be accurately evaluated in a clinical context. We have developed a novel system for evaluating articular cartilage, in which the acoustic properties of the cartilage are measured by introducing an ultrasonic probe during arthroscopy of the knee joint. The purpose of the current study was to determine the efficacy of this ultrasound system for evaluating tissue-engineered cartilage in an experimental model involving implantation of a cell/scaffold complex into rabbit knee joint defects. Ultrasonic echoes from the articular cartilage were converted into a wavelet map by wavelet transformation. On the wavelet map, the percentage maximum magnitude (the maximum magnitude of the measurement area of the operated knee divided by that of the intact cartilage of the opposite, nonoperated knee; %MM) was used as a quantitative index of cartilage regeneration. Using this index, the tissue-engineered cartilage was examined to elucidate the relations between ultrasonic analysis and biochemical and histological analyses. The %MM increased over the time course of the implant and all the hyaline-like cartilage samples from the histological findings had a high %MM. Correlations were observed between the %MM and the semiquantitative histologic grading scale scores from the histological findings. In the biochemical findings, the chondroitin sulfate content increased over the time course of the implant, whereas the hydroxyproline content remained constant. The chondroitin sulfate content showed a similarity to the results of the %MM values. Ultrasonic measurements were found to predict the regeneration process of the tissue-engineered cartilage as a minimally invasive method. Therefore, ultrasonic evaluation using a wavelet map can support the evaluation of tissue-engineered cartilage using cell/scaffold complexes.
authors.affiliation: Department of Orthopaedic Surgery, Nara Medical University, Nara, Japan. hattori@naramed-u.ac.jp
authors.forename: Koji
authors.initials: K
authors.lastname: Hattori
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Takakura
authors.forename: Hajime
authors.initials: H
authors.lastname: Ohgushi
authors.forename: Takashi
authors.initials: T
authors.lastname: Habata
authors.forename: Kota
authors.initials: K
authors.lastname: Uematsu
authors.forename: Jun
authors.initials: J
authors.lastname: Yamauchi
authors.forename: Kenji
authors.initials: K
authors.lastname: Yamashita
authors.forename: Takashi
authors.initials: T
authors.lastname: Fukuchi
authors.forename: Masao
authors.initials: M
authors.lastname: Sato
authors.forename: Ken
authors.initials: K
authors.lastname: Ikeuchi
mesh_terms: D000818:Animals; D001698:Biomedical Engineering / Q000379:methods*; D001854:Bone Marrow Cells / Q000000981:diagnostic imaging* / Q000502:physiology; D001861:Bone Regeneration / Q000502:physiology*; D002358:Cartilage, Articular / Q000000981:diagnostic imaging* / Q000502:physiology; D002478:Cells, Cultured; D008297:Male; D011817:Rabbits; D023822:Tissue Engineering / Q000379:methods*; D014463:Ultrasonography