The development of the collagen fibre network in tissue-engineered cartilage constructsin vivo. Engineered cartilage reorganises fibre network
1 Biomechanics Section, Hamburg University of Technology Hamburg, Germany
2 Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Hamburg, Germany
3 Department of Plastic and Hand Surgery, Technische Universität München, Munich, Germany
4 Department of Pediatric Orthopaedic Surgery, Children’s Hospital Hamburg-Altona, Hamburg, Germany
Abstract
For long term durability of tissue-engineered cartilage implantedin vivo, the development of the collagen fibre network orientation is essential as well as the distribution of collagen, since expanded chondrocytes are known to synthesise collagen type I. Typically, these properties differ strongly between native and tissue-engineered cartilage. Nonetheless, the clinical results of a pilot study with implanted tissue-engineered cartilage in pigs were surprisingly good. The purpose of this study was therefore to analyse if the structure and composition of the artificial cartilage tissue changes in the first 52 weeks after implantation. Thus, collagen network orientation and collagen type distribution in tissue-engineered cartilage-carrier-constructs implanted in the knee joints of Göttinger minipigs for 2, 26 or 52 weeks have been further investigated by processing digitised microscopy images of histological sections. The comparison to native cartilage demonstrated that fibre orientation over the cartilage depth has a clear tendency towards native cartilage with increasing time of implantation. After 2 weeks, the collagen fibres of the superficial zone were oriented parallel to the articular surface with little anisotropy present in the middle and deep zones. Overall, fibre orientation and collagen distribution within the implants were less homogenous than in native cartilage tissue. Despite a relatively low number of specimens, the consistent observation of a continuous approximation to native tissue is very promising and suggests that it may not be necessary to engineer the perfect tissue for implantation but rather to provide an intermediate solution to help the body to heal itself.
Keyword
- Collagen fibre organisation development in vivo; collagen distribution development in vivo; tissue-engineered cartilage; cartilage implant; polarisation microscopy; digital image analysis
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