Tissue response to partially in vitro predegraded poly-L-lactide implants
Tissue response to partially in vitro predegraded poly-L-lactide implants
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DOI：
10.1016/j.biomaterials.2004.06.026
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发表时间：
2005-05-01
期刊：
影响因子：
14
通讯作者：
Bos, RRM
中科院分区：
文献类型：
--
作者：
De Jong, WH;Bergsma, JE;Bos, RRM
用组织学方法观察了由96%L-丙交酯和4%D-丙交酯组成的聚L-丙交酯（PLA 96）植入大鼠皮下后2、13和26周的局部反应。为了模拟可能的终末阶段反应，还在体外预降解PLA 96，直至约50%的重量损失。将预降解PLA（PLA 96（168））的局部反应与聚乙烯（PE）和非预降解PLA（PLA 96）的局部反应进行比较。对于PE和PLA 96，在所有时间点均观察到轻度局部反应，包括植入物界面处的最小层巨噬细胞样细胞和偶然的多核巨细胞，周围有轻度结缔组织囊。对于PLA 96，在第13周和第26周，观察到细胞降解和向内生长方面的一些最小变化。PLA 96（168）的体外孵育（90 ℃，168小时）导致0.2 mm薄样品完全降解。植入并评价了预降解的0.5、1.0和2.0圈PLA 96（168）样品。可在研究的所有时间点评价1.0 mm和2.0 mm样本。但是一些0.5mm的PLA 96168样品在植入后第2周已经完全吸收。一般来说，在第2、13和26周发现的预降解的PLA 96（168）的反应与含有双折射材料的显著巨噬细胞浸润相似。聚合物碎片的包囊，以及由聚合物和细胞残余物组成的碎片区域的存在。在淋巴结中，仅在具有预降解的PLA 96的淋巴结引流部位观察到具有双折射物质的泡沫状巨噬细胞（168）。在非降解PE和PLA 96的植入界面处，鉴定了ED 1和OX 6（MHC 11类）阳性细胞。在被膜中，巨噬细胞Eke细胞表达所有三种巨噬细胞标志物ED 1、ED 2和ED 3。CD 4和CD 8阳性细胞。分别表示T辅助细胞和T抑制细胞/细胞毒性细胞。可以观察到低数量，CD 4多于CD 8。在降解的PLA 96（168）植入物中偶尔观察到CD 4和CD 8。植入后2周主要观察到多形核嗜中性粒细胞，表明预降解可作为研究后期组织对聚合物反应的一种手段。完全降解可以用相对较薄的种植体进行研究，但这可能导致对吸收期的解释相当乐观。当材料预期用于骨固定的螺钉和/或接骨板时，应使用厚度至少为1.0-2.0 mm的植入物，因为这些植入物可以更真实地代表研究材料的再吸收特征。(C)2004 Elsevier Ltd.保留所有权利。
The in vivo local reaction of as-polymerized poly-L-lactide composed of 96% L-lactide and 4% D-lactide (PLA96) was investigated by histology at 2, 13 and 26 weeks after subcutaneous implantation in rats. In order to simulate possible end stage reactions the PLA96 was also predegraded in vitro until approximately 50% weight loss. The local reaction of predegraded PLA (PLA96(168)) was compared to the local reaction of polyethylene (PE) and non-predegraded PLA (PLA96).For PE and PLA96 a mild local reaction was observed at all time points consisting of a minimal layer of macrophage like cells with incidentally multinucleated giant cells at the implant interface, surrounded by a mild connective tissue capsule. For PLA96 at weeks 13 and 26 some minimal alterations in terms of degradation and ingrowth of cells was noted. The in vitro incubation (90degreesC for 168 h) of PLA96(168) resulted for the thin 0.2 mm samples in complete degradation. Predegraded 0.5, 1.0 and 2.0 turn PLA96(168) samples were implanted and evaluated. The 1.0 and 2.0 mm samples could be evaluated for all time points investigated. but some 0.5 mm PLA96168 samples were already completely resorbed at week 2 after implantation. In general, responses found for the predegraded PLA96(168) at weeks 2, 13 and 26 were similar with a pronounced macrophage infiltrate containing birefringent material. encapsulation of polymer fragments, and the presence of a debris area consisting Of Polymer and cellular remnants. in lymph nodes foamy macrophages with birefringent material were only observed in lymph nodes draining sites with predegraded PLA96(168).Immunohistochemistry was performed for further characterization of the cellular infiltrate. At the implant interface of the nondegrading PE and PLA96, ED1 and OX6 (MHC class 11) positive cells were identified. In the capsule macrophage Eke cells expressed all three macrophage markers ED1, ED2, and ED3. CD4 and CD8 positive cells. indicating T helper and T supressor/cytotoxic cells, respectively. could be observed in low numbers, CD4 more than CD8. Both CD4 and CD8 were occasionally observed within the degrading PLA96(168) implant. Polymorphonuclear neutrophilic granulocytes were mainly observed at 2 weeks after implantation.We showed that predegradation Could be used as a means to study late tissue reactions to polymers. Complete degradation may be studied with relatively thin implants, but this may lead to rather optimistic interpretation of resorption periods. When materials are intended to be used for screws and/or plates for bone fixation, implants of at least 1.0-2.0 mm thickness should be used as these May show a more realistic representation of the resorption characteristics of the material under investigation. (C) 2004 Elsevier Ltd. All rights reserved.