Wataha J C, Hanks C T, Craig R G
Department of Prosthodontics, University of Michigan School of Dentistry, Ann Arbor.
Dent Mater. 1993 May;9(3):172-6. doi: 10.1016/0109-5641(93)90116-8.
The effect of cell density (number of cells per unit area of a monolayer culture) on the in vitro cytotoxicity of metal ions which are known to be released from dental materials was investigated. The effects of cell density (1) may explain previous discrepancies in in vitro tests, (2) may be important in wound healing where cell density changes over time, and (3) may help clarify the mechanisms of cytotoxicity of metal ions. Balb/c 3T3 fibroblasts were plated at cell densities ranging from 10,000-80,000 cells/cm2 and were exposed to 8 concentrations of 10 different metal ions. After 24 h, the succinic dehydrogenase activity and DNA synthesis were measured to quantify the cytotoxic effect. Higher cell densities markedly reduced the sensitivity of these fibroblasts to all metal ions except Al+3 and Zn+2, but the magnitude of the reduction was metal dependent. In addition, the DNA synthesis was inhibited more than the succinic dehydrogenase activity for all metal ions except Zn+2. The unique effect of cell density on each metal ion supported the hypothesis that the effect was not simply caused by a dilution of the number of metal ions per cell. Given these results, the effect of cell density should be carefully selected in in vitro cytotoxicity tests.
研究了细胞密度（单层培养物单位面积的细胞数量）对已知从牙科材料中释放的金属离子体外细胞毒性的影响。细胞密度的影响：（1）可能解释先前体外试验中的差异；（2）在伤口愈合中可能很重要，因为细胞密度会随时间变化；（3）可能有助于阐明金属离子的细胞毒性机制。将Balb/c 3T3成纤维细胞以10,000 - 80,000个细胞/cm²的细胞密度接种，并暴露于10种不同金属离子的8种浓度下。24小时后，测量琥珀酸脱氢酶活性和DNA合成以量化细胞毒性作用。较高的细胞密度显著降低了这些成纤维细胞对除Al+3和Zn+2之外的所有金属离子的敏感性，但降低的幅度因金属而异。此外，除Zn+2外，所有金属离子对DNA合成的抑制作用均大于对琥珀酸脱氢酶活性的抑制作用。细胞密度对每种金属离子的独特影响支持了这样一种假设，即这种影响并非仅仅是由于每个细胞中金属离子数量的稀释所致。鉴于这些结果，在体外细胞毒性试验中应仔细选择细胞密度的影响。
