Functional cartilage repair capacity of de-differentiated, chondrocyte- and mesenchymal stem cell-laden hydrogels in vitro.

OBJECTIVE: The long-term performance of cell-seeded matrix-based cartilage constructs depends on (1) the development of sufficient biomechanical properties, and (2) lateral integration with host tissues, both of which require cartilage-specific matrix deposition within the scaffold. In this study, we have examined the potential of tissue-engineered cartilage analogs developed using different cell types, i.e., mesenchymal stem cells (MSCs) vs chondrocytes and de-differentiated chondrocytes, in an established "construct in cartilage ring" model. DESIGN: Cell-laden constructs of differentiated chondrocytes, de-differentiated chondrocytes after two, five or eight population doublings, and MSCs were either implanted into a native cartilage ring immediately after fabrication (immature group) or pre-treated for 21 days in a transforming growth factor-ß3 (TGF-ß3) containing medium prior to implantation. After additional culture for 28 days in a serum-free, chemically defined medium, the extent of lateral integration, and biochemical and biomechanical characteristics of the implants as hybrid constructs were assessed. RESULTS: The quality of integration, the amount of accumulated cartilage-specific matrix components and associated biomechanical properties were found to be highest when using differentiated chondrocytes. De-differentiation of chondrocytes negatively impacted the properties of the implants, as even two population doublings of the chondrocytes in culture significantly lowered cartilage repair capacity. In contrast, MSCs showed chondrogenic differentiation with TGF-ß3 pre-treatment and superior integrational behavior. CONCLUSIONS: Chondrocyte expansion and de-differentiation impaired the cell response, resulting in inferior cartilage repair in vitro. With TGF-ß3 pre-treatment, MSCs were able to undergo sustained chondrogenic differentiation and exhibited superior matrix deposition and integration compared to de-differentiated chondrocytes.

Primary nasopharyngeal tuberculosis mimicking exacerbation of chronic rhinosinusitis.

OBJECTIVE: Nasopharyngeal tuberculosis is a rare condition, even in endemic tuberculosis areas. We report a case of primary nasopharyngeal tuberculosis from a non-endemic area, which presented with symptoms resembling exacerbation of previously diagnosed chronic rhinosinusitis. CASE REPORT: A 48-year-old man presented with extreme postnasal drip and an unpleasant nasal odour. Endoscopic examination revealed irregular thickening of the left lateral and posterior wall of the nasopharynx, partially covered with crusts and necrotic tissue. Histopathological study showed typical giant cell epithelioid granulomas with caseous necrosis. Direct examination after Ziehl-Neelsen staining was positive for tuberculosis. After six months of antituberculous triple therapy, endoscopic examination revealed a completely normal nasopharynx. CONCLUSION: To our best knowledge, this is the first published report of primary nasopharyngeal tuberculosis in a patient previously diagnosed with chronic rhinosinusitis. The difficulties in obtaining a proper diagnosis in such a case are discussed.