Tissue-Engineered Cartilage for Nasal Reconstruction: Mechanical Stimulation Through Bidirectional Bending

In nasal reconstruction, cartilage struts are used to create the structural foundation of the nose. These struts, carved from autologous or allogeneic grafts of costal cartilage, are often limited by availability, warping, or resorption. This study aimed to investigate the mechanical and biochemical outcomes of applying dynamic bidirectional bending to tissue-engineered constructs, hypothesizing that such stimulation would improve matrix synthesis and mechanical properties.

Chondrocyte-seeded agarose struts were subjected to two weeks of dynamic bidirectional four-point bending at peak-to-peak strain amplitudes of 0, 2.5, 5, and 7.5%, for 1200 cycles at 1 Hz starting after a two-week pre-culture. Constructs were analyzed for DNA, proteoglycan, and collagen content, and evaluated via histology, polarized light microscopy, and four-point bending tests. Outcomes were compared to unstimulated controls, unidirectionally stimulated constructs, and native septal cartilage.

Bidirectional bending at a 2.5% strain amplitude increased collagen content by 74% and bending modulus by 72% relative to controls. Under 5% strain amplitudes, proteoglycan accumulation peaked with a 51% increase. Constructs stimulated unidirectionally showed reduced matrix deposition. Histological analysis demonstrated enhanced ECM deposition with region-specific proteoglycan and collagen distribution, partially resembling zonal patterns in native cartilage, although engineered constructs remained mechanically inferior to native septal cartilage.

Dynamic bidirectional bending enhances the biochemical and mechanical properties of tissue-engineered constructs. Lower strain amplitudes were most effective, supporting its consideration in developing mechanically robust grafts for nasal reconstruction. Further optimization of loading protocols and culture duration is needed to bridge the gap with native tissue performance.