The in vivo and in vitro studies for the effect of mechanical loads on the temporomandibular joint disc

有关TMJ关节盘的粘弹性行为的信息是理解其功能以及例如其组织工程所必需的。因此，本研究的目的是检测TMJ圆盘的动态粘弹性和TMJ中的润滑能力。利用猪TMJ圆盘，研究了其拉伸、压缩和剪切的动态粘弹性能。动弹模数随加载频率的增加而增大。在构成TMJ盘的成分中，蛋白多糖在决定盘的粘弹性特性方面起着重要作用，因此使盘具有更大的分布和降低应力的能力。对于TMJ的润滑，我们进行了第一次调查，以澄清完整的TMJ的润滑能力。在50 N恒定载荷作用下，完整猪颞下颌关节在5个S时间内的平均摩擦系数为0.0145，随着载荷持续时间的延长摩擦系数增大，1小时后摩擦系数为0.022。此外，添加高相对分子质量的透明质酸可以在一定程度上恢复因类OA结构而降低的润滑能力。考虑到这些发现，我们开始对TMJ椎间盘进行组织工程学研究。考虑到细胞外基质的组成和细胞类型，血小板衍生生长因子(PDGF)对TMJ间盘细胞的增殖和代谢可能是有效的。因此，我们研究了添加剂PDGF对TMJ间盘细胞增殖和细胞外基质合成的影响。结果表明，高剂量的PDGF对培养的椎间盘细胞的增殖、胶原和透明质酸的合成有明显的影响。提示PDGF在治疗腰椎间盘退变，特别是在组织工程治疗方面具有潜在的应用前景。

Information about the viscoelastic behavior of the temporomandibular joint (TMJ) disc is required for its function to be understood and, for instance, for its tissue engineering. The aim of this research was, thus, to examine the dynamic viscoelastic properties of the TMJ discs and the lubricating ability in the TMJ. Using the porcine TMJ discs, the dynamic viscoelastic properties in tension, compression and shear were examined. The dynamic moduli increased as the loading frequency increased. Of the components constructing TMJ disc, the proteoglycans play an important role in determining the viscoelastic properties of the disc and, therefore, give the disc a greater capacity for distributing and reducing stresses. With respect to the TMJ lubrication, we conducted the first investigation for clarifying the lubricating ability of the intact TMJ. The mean frictional coefficient of porcine intact TMJ was 0.0145 after a constant load of 50 N during 5 s. The frictional coefficient increased with the length of the preceding load duration and 0.022 after 1 hr. Furthermore, the reduced lubricating ability by OA-like structure could be restored by the addition of hyaluronic acid with high molecular weight to a certain extent. Considering these findings, we started to do the tissue engineering, of the TMJ disc. Considering the composition of extracellular matrix and the cell types, Platelet derived growth factor (PDGF) may be effective for TMJ disc cell proliferation and metabolism. Thus, we investigate the effect of additive PDGF on the TMJ disc cell proliferation and synthesis of extracellular matrix. As the result, high doses of PDGF had the major effects on cultured disc cell proliferation, collagen and hyaluronic acid syntheses. This implies that the administration of PDGF may have future therapeutic potential in the treatment of disc degeneration, especially in tissue engineering of TMJ disc