An adhesive bone marrow scaffold and bone morphogenetic-2 protein carrier for cartilage tissue engineering.

A chondroitin sulfate-bone marrow (CS-BM) adhesive hydrogel was used to localize rhBMP-2 to enhance articular cartilage tissue formation. Chondrocyte pellet culture revealed that 0.1 and 1 µg/mL of rhBMP-2 enhanced sulfated-GAG content. rhBMP-2 localization within the hydrogels was investigated, and it was found that BM, CS-NHS, and rhBMP-2 levels and time affected rhBMP-2 retention. Retention was modulated from 82 to 99% over a 3-week period for the material formulations investigated. To evaluate carrier efficacy, rhBMP-2 and bovine articular chondrocytes were encapsulated within CS-BM, and biochemical evaluation revealed significant increases in total collagen production with rhBMP-2. Histological analysis revealed more robust tissue formation and greater type-II collagen production with encapsulated rhBMP-2. Subsequently, a subcutaneous culture of hydrogels revealed increased total collagen, type-II to type-I collagen ratio, and sulfated GAG in samples carrying rhBMP-2. These findings indicate the development of a multifunctional system capable of localizing rhBMP-2 to enhance repair tissue quality.

Bonding and fusion of meniscus fibrocartilage using a novel chondroitin sulfate bone marrow tissue adhesive.

The weak intrinsic meniscus healing response and technical challenges associated with meniscus repair contribute to a high rate of repair failures and meniscectomies. Given this limited healing response, the development of biologically active adjuncts to meniscal repair may hold the key to improving meniscal repair success rates. This study demonstrates the development of a bone marrow (BM) adhesive that binds, stabilizes, and stimulates fusion at the interface of meniscus tissues. Hydrogels containing several chondroitin sulfate (CS) adhesive levels (30, 50, and 70 mg/mL) and BM levels (30%, 50%, and 70%) were formed to investigate the effects of these components on hydrogel mechanics, bovine meniscal fibrochondrocyte viability, proliferation, matrix production, and migration ability in vitro. The BM content positively and significantly affected fibrochondrocyte viability, proliferation, and migration, while the CS content positively and significantly affected adhesive strength (ranged from 60±17 kPa to 335±88 kPa) and matrix production. Selected material formulations were translated to a subcutaneous model of meniscal fusion using adhered bovine meniscus explants implanted in athymic rats and evaluated over a 3-month time course. Fusion of adhered meniscus occurred in only the material containing the highest BM content. The technology can serve to mechanically stabilize the tissue repair interface and stimulate tissue regeneration across the injury site.

Lubricin distribution in the human intervertebral disc.

BACKGROUND: Previous studies have identified lubricin (also known as superficial zone protein) as a lubricating glycoprotein present in several musculoskeletal tissues including articular cartilage, meniscus, and tendon. In this immunohistochemical study, we determined the presence and distribution of lubricin in the cells, extracellular matrix, and tissue surfaces of human nucleus pulposus and anulus fibrosus tissues. METHODS: Twenty-eight human intervertebral discs were resected at autopsy from fourteen cadavers. Disc specimens were fixed in formalin, processed, and paraffin-embedded prior to sectioning. Tissue sections were immunohistochemically stained for lubricin, the extent of extracellular matrix staining was evaluated semiquantitatively, and cellular staining was assessed quantitatively with use of a survey method. RESULTS: Lubricin staining was evident in the extracellular matrix and at select surfaces of the nucleus pulposus and anulus fibrosus tissues. The extent of lubricin staining of the extracellular matrix was contingent on the disc region (nucleus pulposus, inner anulus fibrosus, or outer anulus fibrosus), with the greatest extent of matrix staining found in the nucleus pulposus, but it was not contingent on the Thompson grade. A subset of disc cells within the nucleus, inner anulus, and outer anulus also stained positively for lubricin, suggesting intrinsic cell synthesis of the glycoprotein. The disc region significantly affected the percentage of lubricin-staining cells, with the greatest percentage of cells staining for lubricin (nearly 10%) found in the nucleus pulposus. The percentage of cells staining for lubricin correlated with the extent of extracellular matrix staining for lubricin. CONCLUSIONS: The results of this study confirm the presence of lubricin in the human intervertebral disc and demonstrate a unique distribution compared with that in the goat. The presence of lubricin in asymptomatic discs provides a foundation for future research regarding the role of lubricin in pathological disc conditions.