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Background Tissue engineering focuses on reconstructing the damaged meniscus by mimicking the native meniscus. The application of mechanical loading on chondrocyte-laden decellularized whole meniscus is providing the natural microenvironment. The goal of this study was to evaluate the effects of dynamic compression and shear load on chondrocyte-laden decellularized meniscus. Material and methods The fresh samples of rabbit menisci were decellularized, and the DNA removal was confirmed by histological assessments and DNA quantification. The biocompatibility, degradation and hydration rate of decellularized menisci were evaluated. The decellularized meniscus was injected at a density of 1 × 105 chondrocyte per scaffold and was subjected to 3 cycles of dynamic compression and shear stimuli (1 h of 5% strain, ± 25°shear at 1 Hz followed by 1 h rest) every other day for 2 weeks using an ad hoc bioreactor. Cytotoxicity, GAG content, ultrastructure, gene expression and mechanical properties were examined in dynamic and static condition and compared to decellularized and intact menisci. Results Mechanical stimulation supported cell viability and increased glycosaminoglycan (GAG) accumulation. The expression of collagen-I (COL-I, 10.7-folds), COL-II (6.4-folds), aggrecan (AGG, 3.2-folds), and matrix metalloproteinase (MMP3, 2.3-folds) was upregulated compared to the static conditions. Furthermore, more aligned fibers and enhanced tensile strength were observed in the meniscus treated in dynamic condition with no sign of mineralization. Conclusion Compress and shear stimulation mimics the loads on the joint during walking and be able to improve cell function and ultrastructure of engineered tissue to recreate a functional artificial meniscus.

The scientist does not study nature because it is useful; he studies it because he delights in it, and he delights in it because it is beautiful. Henri Poincaré In this essay, we briefly survey the contemporary scientific and philosophical debates on emergence and conclude that this notion has become a dilemma. We argue that the reason for this dilemma is metaphysical. Subsequently, we investigate some fundamental philosophical methods in science, such as Cartesian reduction and objectivism, as the main sources of scientific drawbacks. Eventually, we suggest some refinements in philosophical methods for improvement of scientific insight and propose the method of transcendentionism as a metaphysical panacea to encounter the dilemma of emergence. © 2011 Wiley Periodicals, Inc. Complexity, 17,10–18, 2011