Hossainy S F, Hubbell J A
Department of Chemical Engineering, University of Texas at Austin 78712.
Biomaterials. 1994 Sep;15(11):921-5. doi: 10.1016/0142-9612(94)90118-x.
In vivo calcification of polyethylene glycol diacrylate (PEG DA) hydrogels of molecular weight (MW) 400, 1000, 4000, 6000 and 10,000 and polyethylene glycol tetraacrylate (PEG TA) of MW 18,500 was investigated using a rat subcutaneous model. This study was performed in 4-wk-old rats for durations of 1, 3, 6 and 8 wk. The results indicate a strong dependence of calcification upon the MW of the PEG precursor or the MW between crosslinks. Results for gels implanted for 6 wk show that calcification was maximal at a PEG MW of 1000 (224 mg/g +/- 12.8, n = 4) (mean +/- SEM) with less at MW = 400 (23.0 mg/g +/- 9.30, n = 4) and considerably less at higher MWs, e.g. for MW = 10,000 (0.23 mg/g +/- 0.01, n = 4). Results for other time periods indicate a similar calcification trend. The extent of calcification of gels from PEG TA (MW = 18,500) was intermediate (1.09 mg/g +/- 0.43, n = 3) between PEG DA (MW = 6000) (1.39 mg/g +/- 0.42, n = 6) and PEG DA (MW = 10,000) at 6 wk, i.e. calcification depended upon the PEG MW between crosslinks. When composite gels were implanted, such that a highly calcifying gel (MW = 400 or 1000) was encapsulated within a gel of low calcification (MW = 4000), the gel inside calcified to at least the same extent as if it had not been encapsulated. Thus, direct contact with tissues is apparently not necessary for calcification to occur. Energy dispersive X-ray spectroscopy was performed on the mineral deposits in the gels and a P:Ca ratio of 0.67 +/- 0.04 (95% confidence interval) for MW 1000 gels and 0.60 +/- 0.07 for MW 400 gels was found to be consistent with deposition of Ca3(PO4)2.
使用大鼠皮下模型研究了分子量（MW）为400、1000、4000、6000和10,000的聚乙二醇二丙烯酸酯（PEG DA）水凝胶以及MW为18,500的聚乙二醇四丙烯酸酯（PEG TA）的体内钙化情况。本研究在4周龄大鼠中进行，持续时间为1、3、6和8周。结果表明钙化强烈依赖于PEG前体的MW或交联之间的MW。植入6周的凝胶结果显示，PEG MW为1000时钙化最大（224 mg/g±12.8，n = 4）（平均值±标准误），MW = 400时较少（23.0 mg/g±9.30，n = 4），MW更高时显著减少，例如MW = 10,000时（0.23 mg/g±0.01，n = 4）。其他时间段的结果显示出类似的钙化趋势。PEG TA（MW = 18,500）凝胶的钙化程度在6周时介于PEG DA（MW = 6000）（1.39 mg/g±0.42，n = 6）和PEG DA（MW = 10,000）之间（1.09 mg/g±0.43，n = 3），即钙化取决于交联之间的PEG MW。当植入复合凝胶时，即高钙化凝胶（MW = 400或1000）被包裹在低钙化凝胶（MW = 4000）内，内部凝胶的钙化程度至少与未被包裹时相同。因此，钙化发生显然不需要与组织直接接触。对凝胶中的矿物质沉积物进行了能量色散X射线光谱分析，发现MW为1000的凝胶的P:Ca比为0.67±0.04（95%置信区间），MW为400的凝胶的P:Ca比为0.60±0.07，这与Ca3(PO4)2的沉积一致。
