5234772 and Kristin Werner are employees of Gambro Dialysatoren GmbH, Research & Development, Hechingen, Germany. Gambro AB (including all direct and indirect subsidiaries) is part of Baxter International Inc. Markus Pawlak and Michael Templin are employees of the NMI Technology Transfer GmbH. Financial support for this study comes in part from Gambro Dialysatoren GmbH, Hechingen. (http://www.gambro.de/). There are no patents, products in development or marketed products to declare. This does not alter our adherence to all the PLOS ONE policies on sharing data and materials.