Although a variety of injectable agents are available for soft tissue augmentation, no perfect filler material exists. The advantages and disadvantages of commonly used materials such as bovine collagen have been well documented. However, many newer injectables are still undergoing experimentation to determine their clinical efficacy and long-term safety. This article details recent scientific work to compare injectable materials from the following categories: xenografts (bovine collagen and hyaluronic acid derivatives), autografts (autologous fat, Isolagen, and Autologen), homografts (Dermalogen and Cymetra), and synthetic materials (fluid silicone and Artecoll).

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 tissueengineered neocartilage constructs. Furthermore, the age-associated variations in cartilage composition have implications for patient selection for reconstructive procedures.

The alterations of matrix composition produced by dedifferentiated chondrocytes may limit the mechanical stability of neocartilage constructs.

Of the systems compared, monolayer-expanded human septal chondrocytes demonstrated the greatest accumulation of sulfated glycosaminoglycans per cell when grown in alginate beads. Future research on cartilage tissue engineering may use alginate culture for reverting dedifferentiated cells back to the chondrocytic phenotype.