Hung Clark T, Mauck Robert L, Wang Christopher C B, Lima Eric G, Ateshian Gerard A
Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
Ann Biomed Eng. 2004 Jan;32(1):35-49. doi: 10.1023/b:abme.0000007789.99565.42.
Deformational loading represents a primary component of the chondrocyte physical environment in vivo. This review summarizes our experience with physiologic deformational loading of chondrocyte-seeded agarose hydrogels to promote development of cartilage constructs having mechanical properties matching that of the parent calf tissue, which has a Young's modulus E(Y) = 277 kPa and unconfined dynamic modulus at 1 Hz G* = 7 MPa. Over an 8-week culture period, cartilage-like properties have been achieved for 60 x 10(6) cells/ml seeding density agarose constructs, with E(Y) = 186 kPa, G* = 1.64 MPa. For these constructs, the GAG content reached 1.74% ww and collagen content 2.64% ww compared to 2.4% ww and 21.5% ww for the parent tissue, respectively. Issues regarding the deformational loading protocol, cell-seeding density, nutrient supply, growth factor addition, and construct mechanical characterization are discussed. In anticipation of cartilage repair studies, we also describe early efforts to engineer cylindrical and anatomically shaped bilayered constructs of agarose hydrogel and bone (i.e., osteochondral constructs). The presence of a bony substrate may facilitate integration upon implantation. These efforts will provide an underlying framework from which a functional tissue-engineering approach, as described by Butler and coworkers (2000), may be applied to general cell-scaffold systems adopted for cartilage tissue engineering.
变形加载是体内软骨细胞物理环境的主要组成部分。本综述总结了我们对接种软骨细胞的琼脂糖水凝胶进行生理性变形加载的经验，以促进具有与小牛母体组织相匹配机械性能的软骨构建体的发育，该母体组织的杨氏模量E(Y)=277 kPa，1 Hz时的无侧限动态模量G* = 7 MPa。在8周的培养期内，接种密度为60×10⁶个细胞/ml的琼脂糖构建体实现了类软骨特性，E(Y)=186 kPa，G* = 1.64 MPa。对于这些构建体，糖胺聚糖（GAG）含量达到1.74%（湿重），胶原蛋白含量为2.64%（湿重），而母体组织的相应含量分别为2.4%（湿重）和21.5%（湿重）。讨论了有关变形加载方案、细胞接种密度、营养供应、生长因子添加和构建体力学表征等问题。预期进行软骨修复研究，我们还描述了构建琼脂糖水凝胶和骨的圆柱形及解剖学形状双层构建体（即骨软骨构建体）的早期工作。骨基质的存在可能有助于植入时的整合。这些工作将提供一个基础框架，从中可以将Butler及其同事（2000年）描述的功能性组织工程方法应用于软骨组织工程采用的一般细胞支架系统。
