StarPEG/heparin-hydrogel based in vivo engineering of stable bizonal cartilage with a calcified bottom layer

Biofabrication. 2018 Oct 30;11(1):015001. doi: 10.1088/1758-5090/aae75a.

Abstract

Repaired cartilage tissue lacks the typical zonal structure of healthy native cartilage needed for appropriate function. Current grafts for treatment of full thickness cartilage defects focus primarily on a nonzonal design and this may be a reason why inferior nonzonal regeneration tissue developed in vivo. No biomaterial-based solutions have been developed so far to induce a proper zonal architecture into a non-mineralized and a calcified cartilage layer. The objective was to grow bizonal cartilage with a calcified cartilage bottom zone wherein main tissue development is occurring in vivo. We hypothesized that starPEG/heparin-hydrogel owing to the glycosaminoglycan heparin contained as a building-block would prevent mineralization of the upper cartilage zone and be beneficial in inhibiting long-term progression of calcified cartilage into bone. MSCs were pre-cultured as self-assembling non-mineralized cell discs before a chondrocyte-seeded fibrin- or starPEG/heparin-hydrogel layer was cast on top directly before ectopic implantation. Bizonal cartilage with a calcified bottom-layer developed in vivo showing stronger mineralization compared to in vitro samples, but the hydrogel strongly determined outcome. Zonal fibrin-constructs lost volume and allowed non-organized expansion of collagen type X, ALP-activity and mineralization from the bottom-layer into upper regions, whereas zonal starPEG/heparin-constructs were of stable architecture. While non-zonal MSCs-derived discs formed bone over 12 weeks, the starPEG/heparin-chondrocyte layer prevented further progression of calcified cartilage into bone tissue. Conclusively, starPEG/heparin-hydrogel-controlled and cell-type mediated spatiotemporal regulation allowed in vivo growth of bizonal cartilage with a stable calcified cartilage layer. Altogether our work is an important milestone encouraging direct in vivo growth of organized cartilage after biofabrication.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcification, Physiologic
  • Cartilage, Articular / cytology
  • Cartilage, Articular / growth & development*
  • Cartilage, Articular / metabolism
  • Cell Proliferation
  • Cells, Cultured
  • Chondrocytes / cytology*
  • Chondrocytes / metabolism
  • Collagen Type X / metabolism
  • Glycosaminoglycans / chemistry
  • Heparin / chemistry*
  • Hydrogels / chemistry*
  • Mesenchymal Stem Cells / cytology
  • Mesenchymal Stem Cells / metabolism
  • Polyethylene Glycols / chemistry*
  • Swine
  • Swine, Miniature
  • Tissue Engineering / instrumentation
  • Tissue Engineering / methods*
  • Tissue Scaffolds / chemistry*

Substances

  • Collagen Type X
  • Glycosaminoglycans
  • Hydrogels
  • Polyethylene Glycols
  • Heparin