骨软骨组织工程仿生梯度支架研究进展

骨软骨缺损是导致关节发病和残疾的重要原因，骨软骨组织工程是修复骨软骨缺损的方法之一。骨软骨组织工程方法涉及仿生梯度支架的制造，该支架需模仿天然骨软骨组织的生理特性（例如从软骨表面到软骨下骨之间的梯度过渡）。在许多研究中骨软骨仿生梯度支架表现为离散梯度或连续梯度，用于模仿骨软骨组织的特性，例如生物化学组成、结构和力学性能。连续型骨软骨梯度支架的优点是其每层之间没有明显的界面，因此更相似地模拟天然骨软骨组织。到目前为止，骨软骨仿生梯度支架在骨软骨缺损修复研究中已经取得了良好的实验结果，但是骨软骨仿生梯度支架与天然骨软骨组织之间仍然存在差异，其临床应用还需要进一步研究。本文首先从骨软骨缺损的背景、微尺度结构与力学性能、骨软骨仿生梯度支架制造相关的材料与方法等方面概述了离散和连续梯度支架的研究进展。其次，由于3D打印骨软骨仿生梯度支架的方法能够精确控制支架孔的几何形状和力学性能，因此进一步介绍了计算仿真模型在骨软骨组织工程中的应用，例如采用仿真模型优化支架结构和力学性能以预测组织再生。最后，提出了骨软骨缺损修复相关的挑战以及骨软骨组织再生未来研究的展望。例如，连续型骨软骨仿生梯度支架需要更相似地模拟天然骨软骨组织单元的结构，即力学性能和生化性能的过渡更加自然地平滑。同时，虽然大多数骨软骨仿生梯度支架在体内外实验中均取得了良好的效果，但临床研究和应用仍然需要进行进一步深入研究。

Research progress in biomimetic gradient scaffolds for osteochondral tissue engineering

Osteochondral defects are the main cause of joint morbidity and disability in elderly patients,and osteochondral tissue engineering is one of the methods to repair osteochondral defects.The method of osteochondral tissue engineering involves the manufacture of osteochondral biomimetic gradient scaffolds that should mimic the physiological properties of natural osteochondral tissue(e.g.,the gradient transition between cartilage surface and subchondral bone).The osteochondral biomimetic gradient scaffolds exhibit discrete gradients or continuous gradients to establish the characteristics of osteochondral tissue in many studies,such as biochemical composition,structure and mechanical properties.An advantage of the continuous osteochondral biomimetic gradient scaffold is that there is no obvious interface between each layer,therefore it more closely mimics the natural osteochondral tissue.Although promising results have been achieved so far on the regeneration of the osteochondral biomimetic gradient scaffold,there are still differences between the osteochondral biomimetic gradient scaffold and natural osteochondral tissue.Due to these differences,the current clinical treatment of osteochondral biomimetic gradient scaffolds to repair osteochondral defects needs further research.Firstly,the research progress on discrete and continuous gradient scaffolds from the background of osteochondral defects,the micro-scale structure and mechanical properties of osteochondral to the materials and methods related to the manufacture of osteochondral biomimetic gradient scaffolds was summarized in this article.Secondly,due to the 3D printing method of the osteochondral biomimetic gradient scaffold having the ability to precisely control the geometry of the scaffold hole and the mechanical properties of the scaffold,the application of computational simulation models in osteochondral tissue engineering was further introduced,for example,optimizing scaffold structure and mechanical properties are considered to predict tissue regeneration.Finally,the challenges related to the repair of osteochondral defects and prospects for the future research of osteochondral tissue regeneration were presented.For example,continuous osteochondral bionic gradient scaffolds need to more similarly simulate the structure of natural osteochondral tissue units,that is,the transition of mechanical properties and biochemical properties is more smooth naturally.At the same time,although most osteochondral biomimetic gradient scaffolds have achieved good results in in vivo and in vitro experiments,clinical research and application still need to be further studied.