Transgene enhancement of hyaluronan in human osteoarthritic cartilage

骨关节炎（OA）进展中的关键事件是蛋白聚糖聚集体从骨关节炎（OA）中的损失。 关节软骨细胞外基质。除了聚集蛋白聚糖，透明质酸（HA）的显著减少， 软骨蛋白聚糖聚集体的核心细丝，也在来自OA患者的软骨中观察到， 与正常的人类软骨相比。这些损失是由于居民代谢状态的变化， 软骨细胞在过去的研究中，我们已经验证了HA周转主要通过一个 内吞事件，由HA受体CD44介导。实验条件上调的损失， 聚集蛋白聚糖和HA也影响CD44表达的增强和HA的协同增加。 内吞作用此外，我们还测试了软骨细胞是否也使用CD44来"感知"和响应一种免疫应答。 通过启动信号级联而损失蛋白聚糖。直到最近，我们只能检测CD44 通过使用软骨细胞培养研究功能。这项新建议的核心假设是， 在受损软骨的细胞外基质（ECM）中的作用是有限的。因此，基质修复和聚集蛋白聚糖 保留无效。我们最近已经成功地将人类转基因导入完整的 通过使用人腺病毒和腺相关病毒的人、牛和小鼠软骨外植体 结构。这项建议包括若干创新办法。我们将使用基因转移的方法， 将HA合酶（HAS 2）转基因导入完整人OA软骨外植体。这种方法将 在ECM中产生HA的选择性和实质性增加，以解决是否存在 增加的局部合成的HA原位沉积提供了软骨修复， 聚集蛋白聚糖分解生物标志物作为驻留的软骨细胞被诱导进入静止状态。我们的第二个目标 将是确定HA诱导恢复稳态的机制，以及HA受体是否 CD44负责。我们的长期目标是确定HA对软骨稳态的重要性 以及如何改变体内尤其是人关节软骨中HA的代谢。

A key event in the progression of osteoarthritis (OA) is the loss of proteoglycan aggregate from the extracellular matrix of articular cartilage. In addition to aggrecan, a significant decrease in hyaluronan (HA), the core filament of the cartilage proteoglycan aggregate, is also observed in cartilage derived from OA patients as compared to normal human cartilage. These losses are due to changes in the metabolic state of resident chondrocytes. In past studies we have tested the hypothesis that HA turnover occurs primarily through an endocytosis event, mediated by the HA receptor CD44. Experimental conditions that upregulate the loss of aggrecan and HA, also affect an enhancement in CD44 expression and a coordinate increase in HA endocytosis. In addition we have tested whether chondrocytes also use CD44 to "sense" and respond to a loss of proteoglycan by initiating signaling cascades. Until recently we have only been able to examine CD44 functions by using chondrocyte cell-culture studies. The central hypothesis of this new proposal is that HA within the extracellular matrix (ECM) of damaged cartilage is limiting. As such, matrix repair and aggrecan retention are ineffective. We have been recently successful at introducing human transgenes into intact human, bovine and mouse cartilage explants through the use of human adenoviral and adeno-associated virus constructs. This proposal includes several innovative approaches. We will use a gene transfer approach to introduce a HA synthase (HAS2) transgene into intact human OA cartilage explants. This approach will generate a selective and substantial increase in HA within the ECM to address the question of whether an increased deposition of locally-synthesized HA in situ provides for cartilage repair and a diminution of aggrecanolysis biomarkers as resident chondrocytes are coaxed into a state of quiescence. Our second goal will be to determine the mechanism for the HA-induced return to homeostasis and whether HA receptors such as CD44 are responsible. Our long-term goal is to determine the importance of HA to cartilage homeostasis and, how to alter HA metabolism in vivo especially within human articular cartilage.