CIHR BioEngineering of Skeletal Tissues Team, Mount Sinai Hospital, Canada M5G 1X5.
Acta Biomater. 2012 Apr;8(4):1603-15. doi: 10.1016/j.actbio.2011.12.022. Epub 2011 Dec 20.
A major challenge for cartilage tissue engineering remains the proper integration of constructs with surrounding tissues in the joint. Biphasic osteochondral constructs that can be anchored in a joint through bone ingrowth partially address this requirement. In this study, a methodology was devised to generate a cell-mediated zone of calcified cartilage (ZCC) between the in vitro-formed cartilage and a porous calcium polyphosphate (CPP) bone substitute in an attempt to improve the mechanical integrity of that interface. To do so, a calcium phosphate (CaP) film was deposited on CPP by a sol-gel process to prevent the accumulation of polyphosphates and associated inhibition of mineralization as the substrate degrades. Cartilage formed in vitro on the top surface of CaP-coated CPP by deep-zone chondrocytes was histologically and biochemically comparable to that formed on uncoated CPP. Furthermore, the mineral in the ZCC was similar in crystal structure, morphology and length to that formed on uncoated CPP and native articular cartilage. The generation of a ZCC at the cartilage-CPP interface led to a 3.3-fold increase in the interfacial shear strength of biphasic constructs. Improved interfacial strength of these constructs may be critical to their clinical success for the repair of large cartilage defects.
对于软骨组织工程来说，一个主要的挑战仍然是如何将构建物与关节中的周围组织进行适当的整合。能够通过骨向内生长而固定在关节中的双相骨软骨构建物部分满足了这一要求。在这项研究中，设计了一种方法来在体外形成的软骨和多孔磷酸钙（CPP）骨替代物之间产生细胞介导的钙化软骨（ZCC）区，以试图提高该界面的机械完整性。为此，通过溶胶-凝胶工艺在 CPP 上沉积了钙磷酸盐（CaP）膜，以防止聚磷酸盐的积累和相关的矿化抑制，因为基质降解。通过深区软骨细胞在 CaP 涂层 CPP 上体外形成的软骨在组织学和生物化学上与在未涂层 CPP 上形成的软骨相似。此外，ZCC 中的矿物质在晶体结构、形态和长度上与未涂层 CPP 和天然关节软骨形成的矿物质相似。在软骨-CPP 界面处产生 ZCC 可使双相构建物的界面剪切强度提高 3.3 倍。这些构建物的界面强度的提高对于它们在修复大的软骨缺损方面的临床成功可能至关重要。
