Gleghorn J P, Jones A R C, Flannery C R, Bonassar L J
Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA.
Eur Cell Mater. 2007 Aug 4;14:20-8; discussion 28-9. doi: 10.22203/ecm.v014a02.
Despite the fact that lubrication is a primary function of articular cartilage, there is little information on the frictional properties of cartilaginous engineered tissues. A biochemical mediator of cartilage frictional properties in boundary lubrication, lubricin, has been shown to be secreted from chondrocyte-hydrogel constructs. In the current studies we utilized articular chondrocytes (CON), meniscal fibrochondrocytes (MEN), and mesenchymal stem cells (MSC) in alginate cultures to determine lubricin localization and the inherent boundary lubrication friction coefficient. Additionally, we investigated the ability of these tissues to be lubricated by synovial fluid and the reversibility of this lubrication. Cell-alginate constructs were cultured over six weeks, culture medium assayed for lubricin release by ELISA and constructs analyzed with immunohistochemical (IHC) methods to investigate the localization of lubricin. Engineered tissues were tested in a custom friction instrument to determine the equilibrium friction coefficient (microeq) in boundary lubrication mode, following incubation with equine synovial fluid (SF), and subsequent extraction in l.5M NaCl. MSCs released 10 fold more lubricin than CON or MEN cultures. IHC analysis showed no localization of lubricin to alginate, minimal focal staining of engineered constructs at six weeks in culture, and the ability of all engineered tissues to localize lubricin when exogenously treated with SF. Frictional characterization showed no difference in microeq over culture for all engineered tissues, while incubation in SF decreased microeq for all tissues over culture duration, and extraction of lubricin resulted in a loss of lubrication of all engineered tissues.
尽管润滑是关节软骨的主要功能，但关于软骨工程组织的摩擦特性的信息却很少。润滑素作为边界润滑中软骨摩擦特性的一种生化介质，已被证明可从软骨细胞 - 水凝胶构建体中分泌出来。在当前的研究中，我们在藻酸盐培养物中利用关节软骨细胞（CON）、半月板纤维软骨细胞（MEN）和间充质干细胞（MSC）来确定润滑素的定位以及固有的边界润滑摩擦系数。此外，我们还研究了这些组织被滑液润滑的能力以及这种润滑的可逆性。细胞 - 藻酸盐构建体培养六周，通过酶联免疫吸附测定法（ELISA）检测培养基中润滑素的释放情况，并用免疫组织化学（IHC）方法分析构建体以研究润滑素的定位。在定制的摩擦仪器中对工程组织进行测试，以确定在与马滑液（SF）孵育后，在边界润滑模式下的平衡摩擦系数（microeq），随后在1.5M NaCl中提取。间充质干细胞释放的润滑素比软骨细胞或半月板纤维软骨细胞培养物多10倍。免疫组织化学分析表明，润滑素在藻酸盐中无定位，培养六周时工程构建体有极少的局灶性染色，并且当用滑液进行外源性处理时，所有工程组织都有定位润滑素的能力。摩擦特性表征显示，所有工程组织在培养过程中的microeq没有差异，而在滑液中孵育会使所有组织在培养期间的microeq降低，并且提取润滑素会导致所有工程组织失去润滑作用。
