Lee W D, Hurtig M B, Pilliar R M, Stanford W L, Kandel R A
Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, Ontario M5S 3G9, Canada.
Ontario Veterinary College, University of Guelph, 50 McGilvray Street, Guelph, Ontario N1G 2W1, Canada.
Osteoarthritis Cartilage. 2015 Aug;23(8):1307-15. doi: 10.1016/j.joca.2015.04.010. Epub 2015 Apr 17.
In healthy joints, a zone of calcified cartilage (ZCC) provides the mechanical integration between articular cartilage and subchondral bone. Recapitulation of this architectural feature should serve to resist the constant shear force from the movement of the joint and prevent the delamination of tissue-engineered cartilage. Previous approaches to create the ZCC at the cartilage-substrate interface have relied on strategic use of exogenous scaffolds and adhesives, which are susceptible to failure by degradation and wear. In contrast, we report a successful scaffold-free engineering of ZCC to integrate tissue-engineered cartilage and a porous biodegradable bone substitute, using sheep bone marrow stromal cells (BMSCs) as the cell source for both cartilaginous zones.
BMSCs were predifferentiated to chondrocytes, harvested and then grown on a porous calcium polyphosphate substrate in the presence of triiodothyronine (T3). T3 was withdrawn, and additional predifferentiated chondrocytes were placed on top of the construct and grown for 21 days.
This protocol yielded two distinct zones: hyaline cartilage that accumulated proteoglycans and collagen type II, and calcified cartilage adjacent to the substrate that additionally accumulated mineral and collagen type X. Constructs with the calcified interface had comparable compressive strength to native sheep osteochondral tissue and higher interfacial shear strength compared to control without a calcified zone.
This protocol improves on the existing scaffold-free approaches to cartilage tissue engineering by incorporating a calcified zone. Since this protocol employs no xenogeneic material, it will be appropriate for use in preclinical large-animal studies.
在健康关节中，钙化软骨区（ZCC）在关节软骨和软骨下骨之间提供机械整合。重现这一结构特征应有助于抵抗关节运动产生的持续剪切力，并防止组织工程软骨分层。以往在软骨-基质界面创建ZCC的方法依赖于对外源支架和粘合剂的策略性使用，而这些易因降解和磨损而失效。相比之下，我们报告了一种成功的无支架工程化ZCC方法，以整合组织工程软骨和多孔可生物降解骨替代物，使用绵羊骨髓基质细胞（BMSC）作为两个软骨区的细胞来源。
将BMSC预分化为软骨细胞，收获后在存在三碘甲状腺原氨酸（T3）的情况下在多孔聚磷酸钙基质上培养。撤去T3，将额外的预分化软骨细胞置于构建体顶部并培养21天。
该方案产生了两个不同的区域：积累蛋白聚糖和II型胶原蛋白的透明软骨，以及与基质相邻的钙化软骨，其还积累了矿物质和X型胶原蛋白。具有钙化界面的构建体与天然绵羊骨软骨组织具有相当的抗压强度，并且与没有钙化区的对照相比具有更高的界面剪切强度。
该方案通过纳入钙化区改进了现有的无支架软骨组织工程方法。由于该方案不使用异种材料，因此适用于临床前大型动物研究。
