Development and validation of an in vitro short-time testing method for the prediction of the in vivo behavior of absorbable metallic implant materials

生物可吸收镁植入物被认为是外科医学学科中有前途的生物材料。镁的耐腐蚀性差在该特定应用中是有益的，因为植入物材料可以以这样的方式设计，即它们在限定的时间段内实现其功能并最终完全溶解，使得不需要进一步的手术来移除植入物。镁的广泛临床应用受到阻碍，因为腐蚀和降解行为以及相应的功能损失难以预测，气体作为腐蚀产物形成。在这种情况下，降解过程可以通过等离子体电解氧化（PEO）的涂层可调节地延迟。因此，镁材料作为生物材料的体外测试是一个很大的挑战，因为材料的行为必须在很长一段时间内预测。以前应用的腐蚀行为的评价方法是不一致的，几乎没有标准化。许多体外和体内研究认为细胞和生物相容性彼此独立。除了有效的体外试验外，还应通过镁样本的标准化细胞相容性分析来扩展方法，以可靠和完整地预测体内材料行为。此外，在模拟体液中长时间浸泡试验涉及细菌污染的风险。总之，在不涉及动物实验的情况下，通常对生物可吸收植入物应用材料的鉴定有很大的需求。因此，短期腐蚀疲劳试验方法将是可取的，与人体内的材料行为，可以估计时间加速以及在vitrial.Within计划的研究项目的框架内，这种测试方法应开发使用的有前途的镁合金WE43 MEO的例子。此外，应研究PEO涂层对细胞和生物相容性以及降解行为的影响。

Bioresorbable magnesium implants are considered as promising biomaterials of the future in surgical oriented disciplines of medicine. The poor corrosion resistance of magnesium is beneficial in this particular application, because implant materials can be designed in a way, that they fulfil their function for a defined period of time and eventually dissolve completely, so that there is no need for a further surgery to remove the implant.On the other hand, widespread clinical applications of magnesium are prevented because the corrosion and degradation behavior and the corresponding loss of function is difficult to predict as well as hydrogen gas is formed as a corrosion product. In this context, the degradation process can be adjustably delayed through coating by means of plasma electrolytic oxidation (PEO).Therefore, in vitro testing for qualification of magnesium materials as biomaterials is a big challenge, because the material behavior has to be predicted for a long period of time. Previously applied methods for the evaluation of the corrosion behavior are inconsistent and barely standardized. Many in vitro and in vivo studies consider the cyto- and biocompatibility independent from each other. Besides a valid in vitro testing, methods should be extended by standardized cytocompatibilty analyses of magnesium specimens to predict in vivo material behavior reliably and completely. Furthermore, immersion tests in simulated body fluids over long exposure times involve the risk of bacterial contamination.In summary, there is a generally great demand for qualification of materials for application as bioresorbable implants without referring to animal experiments. Therefore, a short-term corrosion fatigue testing method would be desirable with which the material behavior in the human body can be estimated time accelerated as well as in vitro.Within the framework of the planned research project such a testing method shall be developed using the example of the promising magnesium alloy WE43 MEO. Furthermore, the influence of a PEO-coating on the cyto- and biocompatibility as well as the degradation behavior shall be investigated.