A compositional analysis of human nasal septal cartilage.

BACKGROUND: Nasal septal cartilage is well established as an autograft material. Tissue engineering methods are now being developed to synthesize cartilage constructs with the properties of this type of cartilage. However, important baseline data on the composition of native septal cartilage is sparse. OBJECTIVES: To characterize quantitatively the major biochemical constituents of native adult human septal cartilage and determine age- or sex-related variation in composition. METHODS: Cartilage was harvested from the inferior region of the nasal septum in 33 patients (mean +/- SD age, 47.0 +/- 13.5 years; range, 24-80 years) during routine septoplasty or septorhinoplasty. Biochemical assays were used to determine the quantities, relative to wet weight, of the major constituents of cartilage: water, collagen (from hydroxyproline), sulfated glycosaminoglycan (sGAG), and chondrocytes (from DNA). RESULTS: On average, each gram of wet cartilage contained 77.7% water, 7.7% collagen, 2.9% sGAG, and 24.9 million cells. Hydration and collagen content showed no significant age variation. Advancing age was associated with a reduction in sGAG content (7.7% per decade, P =.02) and cellularity (7.4% per decade, P =.05). No significant sex differences were found in any of these cartilage constituents. CONCLUSIONS: This study represents the first biochemical characterization of the composition of native human septal cartilage. The data serve as a baseline for future comparison of the properties of tissue-engineered neocartilage constructs. Furthermore, the age-associated variations in cartilage composition have implications for patient selection for reconstructive procedures.

Effect of gravity on localization of chondrocytes implanted in cartilage defects.

The transplantation of autologous chondrocytes under a periosteal flap has been used to treat focal cartilage defects. Results have been promising but occasionally involve complications ranging from graft hypertrophy to detachment. The objective of this study was to determine if gravitational forces affect the uniformity of cell distribution within the defect. Using an ex vivo bovine model, the orientation relative to gravity of a repaired full-thickness articular cartilage defect was found to affect the initial distribution of transplanted chondrocytes, prelabeled with 3H-thymidine. After 4 hours, the injected cells (3H-radioactivity) were primarily at the base of the defect (79%) in samples oriented in the up position, primarily at the dependent semicylindrical half of the defect (83%) in samples oriented to the side, and primarily at the periosteal top of the defect (78%) in samples oriented upside-down. Subsequently, the cell distribution remained unchanged after reorientation into other positions. These results indicate that injected chondrocytes localize under the influence of gravity within the initial few hours after injection. Therefore, the defect orientation during this time can be an important factor in the uniformity of cell distribution in the autologous chondrocyte implantation procedure and may be an important determinant of the ultimate clinical outcome.