Humanoid Robotic Loading Enhances Mechanotransduction in Tendon Tissue Engineering
PMC13009534
· 10.34133/cbsystems.0542
Gap Declaration
This innovative approach allows for the application of torsion, compressive, and tensile stresses through a non-load-bearing membrane. These advancements have led to significant improvements in cellular orientation and pronounced activation of mechanosensitive signaling pathways, particularly PI3K/Akt, compared to the uniaxial platform. Our approach has demonstrated promising results; however, several limitations must be addressed in future work. The present study was intentionally designed to interrogate early mechanotransductive and cellular responses to complex loading, rather than long-term tissue maturation or construct-level functionality. First, although the robotic platform is capable of 3 kinematic DOF, only a single DOF was employed in this study, which, while relevant to supraspinatus loading, does not fully reproduce the complex motion patterns present in daily and skilled activities. [...] The present study was intentionally designed to interrogate early mechanotransductive and cellular responses to complex loading, rather than long-term tissue maturation or construct-level functionality. First, although the robotic platform is capable of 3 kinematic DOF, only a single DOF was employed in this study, which, while relevant to supraspinatus loading, does not fully reproduce the complex motion patterns present in daily and skilled activities. Future work will incorporate additional joint rotations to more accurately simulate physiological loading. Second, periodic media replacement does not adequately mimic the dynamic nutrient and waste exchange seen in vivo. A continuous perfusion system will be integrated to better simulate the native tissue environment and address potential challenges like continuous media supply and hypoxia during long-term culture. [...] While passive shear or torsional deformation may occur within the bioreactor chamber, these components were not quantified in the present study. Finally, although the MEF sensor exhibits reliable performance, its measured strain does not represent the strain of the scaffold or embedded cells, as it is not perfectly attached to the matrix. Future work will address these limitations through full integration of the sensor and matrix.
Abstract
Mechanical stimulation is essential in tissue engineering and regenerative medicine for proper tissue maturation. However, conventional uniaxial platforms fail to reproduce the multiaxial loading experienced in vivo. In this study, we present a humanoid robotic bioreactor capable of delivering human-like shoulder motions to engineered tendon constructs, enabling controlled multiaxial stimulation with real-time strain monitoring. Human mesenchymal stem cells were cultured on decellularized tendon scaffolds and subjected to adduction–abduction loading at peak strains of approximately 3.5% and 9.5% under external forces of 25 and 50 N, respectively. Strain levels were directly quantified in situ using a flexible sensor integrated within the bioreactor. The transparent bioreactor membrane allo…
Conclusions / Discussion
Discussion Equipping flexible bioreactor chambers with soft sensors has enabled the precise application and monitoring of mechanical dynamic stimulation on growing cells with both the multiaxial robotic and uniaxial platforms. We have also successfully monitored cell growth noninvasively by performing confocal microscopy directly through the thin transparent TPU membrane. Our experiments have identified distinct transcriptomic and protein-level responses under matched peak tensile strain conditions, with multiaxial stimulation inducing greater changes in mechanosensitive signaling pathways compared with uniaxial loading. Remarkably, the integrated strain sensor verified that the applied strain magnitudes were comparable between platforms. Therefore, the distinct biological responses are likely associated with differences in mechanical load delivery mode rather than strain magnitude alone. Under mechanical stimulation, a similar decrease in cell viability is noted in both platforms, particularly at 3.5% strain. However, this decrease should not necessarily be interpreted solely as evidence of acute cytotoxic damage. Although metabolic activity declined, microscopic observations and …
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Structural Hole
40% bridge
Technique originates in neuroscience; functional analogues in psychology, criminal justice literature are absent.
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