Kim H M, Kim Y S, Woo K M, Park S J, Rey C, Kim Y, Kim J K, Ko J S
Laboratory of Molecular Biointerface, Department of Oral Anatomy and Dental Research Institute, Seoul National University, 28 YeonKun-Dong, ChongRo-Ku, Seoul, 110-749, Korea.
J Biomed Mater Res. 2001 Aug;56(2):250-6. doi: 10.1002/1097-4636(200108)56:2<250::aid-jbm1092>3.0.co;2-s.
Poorly crystalline apatite (PCA) crystals introduced into bone tissue should be stable for a definite period before they are dissolved as a result of a host response. In this report, the dissolution of PCA crystals by the action of osteoclasts was studied on artificial thin films. These consisted of PCA crystals having similar crystallographic properties to bone crystals which were developed for assaying the osteoclast activity in vitro. The dissolution of minerals by osteoclasts decreased along with the decreased amount of labile phosphate and hydrogen phosphate domains of apatite crystals, which were caused by the crystal maturation temperature. A profound effect on mineral dissolution by pH in the culture medium was also shown. Low acidity considerably increased mineral dissolution, whereas a slight alkalinity totally blocked mineral dissolution. There was little difference in the mineral dissolution behavior of osteoclasts near the physiologic pH. In addition, it was determined whether mineral dissolution by osteoclasts was dependent on the destruction of the organic matrix. Nocodazole was introduced to inhibit the secretion of hydrolytic enzymes, and acetazolamide was added to inhibit acid production by the osteoclasts. There was no significant change as a result of nocodazole addition on mineral dissolution or by the addition of acetazolamide on degradation of collagen. These results indicate that small changes in the physicochemical properties of apatite crystals can decrease resorption by osteoclasts, which can be highly activated at low pH. These results also suggest that mineral dissolution and organic degradation by osteoclasts are self-regulating.
引入骨组织的 poorly crystalline apatite (PCA) 晶体在因宿主反应而溶解之前，应在一定时期内保持稳定。在本报告中，研究了破骨细胞作用下 PCA 晶体在人工薄膜上的溶解情况。这些人工薄膜由与骨晶体具有相似晶体学性质的 PCA 晶体组成，这些晶体是为体外测定破骨细胞活性而开发的。破骨细胞对矿物质的溶解随着磷灰石晶体中不稳定磷酸根和磷酸氢根域数量的减少而降低，而这种减少是由晶体成熟温度引起的。还显示了培养基中的 pH 值对矿物质溶解有深远影响。低酸度显著增加矿物质溶解，而轻微的碱度则完全阻止矿物质溶解。在生理 pH 值附近，破骨细胞的矿物质溶解行为几乎没有差异。此外，还确定了破骨细胞对矿物质的溶解是否依赖于有机基质的破坏。引入诺考达唑以抑制水解酶的分泌，并添加乙酰唑胺以抑制破骨细胞产酸。添加诺考达唑对矿物质溶解或添加乙酰唑胺对胶原蛋白降解均未产生显著变化。这些结果表明，磷灰石晶体物理化学性质的微小变化会降低破骨细胞的吸收，破骨细胞在低 pH 值下可被高度激活。这些结果还表明，破骨细胞对矿物质的溶解和对有机物质的降解是自我调节的。
