Divisions of Orthopaedic Surgery and Surgical Research, Department of Surgery, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Alberta, Canada.
PLoS One. 2021 Mar 10;16(3):e0248292. doi: 10.1371/journal.pone.0248292. eCollection 2021.
Low oxygen and mechanical loading may play roles in regulating the fibrocartilaginous phenotype of the human inner meniscus, but their combination in engineered tissues remains unstudied. Here, we investigated how continuous low oxygen ("hypoxia") combined with dynamic compression would affect the fibrocartilaginous "inner meniscus-like" matrix-forming phenotype of human meniscus fibrochondrocytes (MFCs) in a porous type I collagen scaffold. Freshly-seeded MFC scaffolds were cultured for 4 weeks in either 3 or 20% O2 or pre-cultured for 2 weeks in 3% O2 and then dynamically compressed for 2 weeks (10% strain, 1 Hz, 1 h/day, 5 days/week), all with or without TGF-β3 supplementation. TGF-β3 supplementation was found necessary to induce matrix formation by MFCs in the collagen scaffold regardless of oxygen tension and application of the dynamic compression loading regime. Neither hypoxia under static culture nor hypoxia combined with dynamic compression had significant effects on expression of specific protein and mRNA markers for the fibrocartilaginous matrix-forming phenotype. Mechanical properties significantly increased over the two-week loading period but were not different between static and dynamic-loaded tissues after the loading period. These findings indicate that 3% O2 applied immediately after scaffold seeding and dynamic compression to 10% strain do not affect the fibrocartilaginous matrix-forming phenotype of human MFCs in this type I collagen scaffold. It is possible that a delayed hypoxia treatment and an optimized pre-culture period and loading regime combination would have led to different outcomes.
低氧和机械加载可能在调节人内半月板的纤维软骨表型方面发挥作用，但它们在工程组织中的组合仍未得到研究。在这里，我们研究了持续低氧（“缺氧”）与动态压缩相结合如何影响人半月板纤维软骨细胞（MFC）在多孔 I 型胶原支架中形成纤维软骨样“内半月板样”基质的表型。新鲜接种的 MFC 支架在 3%或 20%的 O2 中培养 4 周，或在 3%的 O2 中预培养 2 周，然后在有或没有 TGF-β3 补充的情况下进行 2 周的动态压缩（10%应变，1Hz，每天 1 小时，每周 5 天）。无论氧张力和应用动态压缩加载方案如何，TGF-β3 补充对于诱导 MFC 在胶原支架中形成基质都是必需的。静态培养下的缺氧或缺氧与动态压缩相结合对纤维软骨基质形成表型的特定蛋白和 mRNA 标志物的表达没有显著影响。在加载期间，机械性能显著增加，但在加载期后，静态和动态加载组织之间没有差异。这些发现表明，在支架接种后立即应用 3%的 O2 和 10%的应变进行动态压缩不会影响这种 I 型胶原支架中人 MFC 的纤维软骨基质形成表型。可能是延迟的缺氧处理和优化的预培养期和加载方案组合会导致不同的结果。
