Decellularized tissue and cell-derived extracellular matrices as scaffolds for orthopaedic tissue engineering

Abstract

The reconstruction of musculoskeletal defects is a constant challenge for orthopaedic surgeons. Musculoskeletal injuries such as fractures, chondral lesions, infections and tumor debulking can often lead to large tissue voids requiring reconstruction with tissue grafts. Autografts are currently the gold standard in orthopaedic tissue reconstruction; however, there is a limit to the amount of tissue that can be harvested before compromising the donor site. Tissue engineering strategies using allogeneic or xenogeneic decellularized bone, cartilage, skeletal muscle, tendon and ligament have emerged as promising potential alternative treatment. The extracellular matrix provides a natural scaffold for cell attachment, proliferation and differentiation. Decellularization of in vitro cell-derived matrices can also enable the generation of autologous constructs from tissue specific cells or progenitor cells. Although decellularized bone tissue is widely used clinically in orthopaedic applications, the exciting potential of decellularized cartilage, skeletal muscle, tendon and ligament cell-derived matrices has only recently begun to be explored for ultimate translation to the orthopaedic clinic.

Keywords: Articular cartilage; Bone; Decellularized matrix; Extracellular matrix; Ligaments; Skeletal muscle; Tendons; Tissue engineering; Tissue scaffolds.

Figure 1

Bone tissue engineering with decellularized trabecular bone cultured in a bioreactor. (a) DNA content per wet weight (ww) of tissue constructs seeded with human embryonic stem cell H9 cell line after 3 and 5 weeks of culture in a bioreactor (br) compared to static (st) cultures. Both cultures were also compared to tissue constructs seeded with bone marrow-derived MSC (BMSC) cultured in a bioreactor. Values are expressed as percent of the initial value. (b) Alkaline phosphatase (AP) activity measured after 3 and 5 weeks of culture. (c) Cumulative osteopontin (OPN) content in culture medium after 2 weeks of culture. Data for DNA content, AP activity and OPN are expressed as averages ± standard deviation (n = 3–5). Statistical significance when P <0.05. Statistical significance between H9 static and H9 bioreactor at the same time point indicated by “*” and between H9 static and BMSC bioreactor group at the same time point indicated by “#”. Statistically significant difference within the same group but at different time points indicated by “$”. (d) Histological staining with hematoxylin and eosin to visualize tissue morphology, Masson’s trichrome and Goldner’s trichrome to visualize bone matrix deposition and osteocalcin immunohistochemistry on tissue constructs seeded with H9 human embryonic stem cell line cultured statically or in a bioreactor and on tissue constructs seeded with bone marrow-derived stem cells cultured in bioreactor for 3 and 5 weeks. Reprinted from Marolt et al. 2012 with permission from Proceedings of the National Academy of Science.

Figure 2

Tissue engineered cartilage after in vitro culture (4 and 16 weeks) or after in vitro culture for 4 weeks follow by in vivo implantation (4 and 12 weeks). (a) Macroscopic view and histology of tissue engineered cartilage stained with hematoxylin and eosin, Safranin O, Toluidine blue and type II collagen immunohistochemistry. Arrows show non-degraded acellular cartilage sheets. Scale bars: 100 mm. (b) Wet weight of tissue engineered cartilage at different time points expressed in milligram (mg). (c)Young’s modulus of tissue engineered cartilage at different time points compared with normal porcine auricular cartilage. Reprinted from Gong Yi Yi et al. 2011 with permission from Elsevier Publisher, Ltd.

Figure 3

Decellularized and untreated ACL and its tibial insertion site in porcine samples stained with hematoxylin and eosin at 20× magnification. (a) Untreated ACL with collagen fibers (F) passing through fibrocartilage (FC), mineralized cartilage (MC) and bone (B). (b) ACL treated with Triton–SDS. (c) ACL treated with Triton–Triton. (d) ACL treated with Triton–TnBP. Scale bars: 100 μm. Reprinted from Woods et al. 2005 with permission from Elsevier Publisher, Ltd. Porcine tibial insertion of decellularized and untreated Anterior Cruciated Ligaments.