Proliferation of meniscal fibrochondrocytes cultured on a new polyurethane scaffold is stimulated by TGF-β

The aim of this study was to investigate if newly developed polyurethane (PU) scaffolds are suitable as scaffold for cell-seeded meniscus tissue engineered constructs. Scaffolds were seeded with goat meniscal fibrochondrocytes and cultured to assess changes in biological and mechanical properties. Furthermore, the effect of TGF-beta on these properties was investigated. PU scaffolds were made from poly D/L lactide and caprolactone as soft segments and 1,4-butanediisocyanate for the urethane hard segments. The porosity of the scaffolds was 95%. Isolated goat meniscal fibrochondrocytes were seeded on the scaffolds and cultured with or without the addition of 10 ng/mL TGF-beta in standard culture medium. After 2, 4, and 6 weeks of culture, scaffolds were analyzed for cell proliferation, matrix synthesis, and mechanical properties. Scanning electron microscopy and histology showed that the scaffolds had an interconnected isotropic pore structure. Without the addition of TGF-beta, cells did not proliferate during the culture period and isolated meniscus fibrochondrocytes were more frequently located in the peripheral parts of the scaffold. Fibrochondrocytes supplemented with TGF-beta were distributed throughout the construct. Clustered cells were surrounded by matrix which stained slightly positive for glycosaminoglycans (GAGs). Also, collagen production was increased significantly after 4 and 6 weeks of culture compared to cultures without TGF-beta and also more GAG staining was found after 4 and 6 weeks in the sections of the TGF-beta stimulated cultures. Despite the increase in matrix production, the compressive stiffness of the constructs was not increased during the culture period. Meniscal fibrochondrocytes were able to adhere to the PU scaffold. However, the scaffold itself does not stimulate proliferation and matrix production. The addition of TGF-beta resulted in a strong induction of both proliferation and extracellular matrix production.