构建关节软骨的滚压加载装置

A rolling depression loading device for articular cartilage construction

背景:通常使用的加载装置或反应器有灌流式生物反应器、液压系统、直接动态压缩装置、剪切系统、拉伸装置或其中部分的组合。以上每一种载荷单独作用都没有实现软骨功能化培养,但即使是这几种的组合也不足以表征软骨的力学状态,构建的软骨功能与天然软骨仍有较大差距。目的:首次提出和研制了一种用于关节软骨构建的滚压加载装置,并在滚压加载条件下分析软骨的受力状态。方法:该装置包括滚动控制系统和压缩调节机构。滚动控制系统通过步进电机、丝杠控制辊子滚动速度,由齿轮和齿条啮合形成辊子纯滚动,辊子能够以均匀速度滚过培养物。压缩调节机构通过楔形滑块的相对滑动可以保证工作面平行升降,从而可以对培养物产生均匀、可调的压缩量。结果与结论:该装置对培养物提供了滚压的力学条件,使培养物处于动态压缩变形和剪切变形的复合加载过程。在滚压的力学条件下,有限元分析表明培养物受到复杂力学状态。培养物浅表层受到交替出现的压力、拉应力;中层在滚动方向平面内应力与表面有一定夹角,角度由-45°～+45°呈周期变化;深层处应力都为压应力,与3个坐标轴方向接近。该装置的加载运动方式与关节的运动方式一致,滚压加载可能有利于功能化关节软骨结构、功能的构建。

BACKGROUND：Hynamic mechanical loading devices or bioreactors contain perfusion bioreactor,hydraulic system,and dynamic compression device,shear system,stretching device or the combination of some devices.However,all these devices can not characterize the mechanical state of cartilage,and the function of constructed cartilage is far from natural cartilage.OBJECTIVE：A novel loading device for articular engineering construction was firstly proposed,and to analyze the mechanical behavior of chondrocytes under this loading device.METHODS：The rolling depression loading device comprised roll controlling system and compression-adjusting system.In roll controlling system,the roller could roll over tissue engineered constructs with uniform velocity via controlling stepper motor and gear.The compressive subsystem could produce uniform,controlled compressions by relatively sliding of two wedge blocks.RESULTS AND CONCLUSION：Under the device,constructs would endure the dynamical compressive deformation and stress deformation.Finite element analysis showed that the rolling depression load provided constructs with complex mechanical conditions,namely,pressure-tensile stress presented alternately on the superficial zone of tissue engineered constructs,-45° to ＋ 45° periodic changed angles could be found between rolling-direction plane and surface in the mesopelagic zone,and compressive stress presented in the deep layer,which closely to the X,Y,Z-directions.The loading mode of this device is consistent with articular mode,thus,it may benefit the functional construction of engineered cartilage.