Fresenius is a competitor. It is possible they would want to buy CTSO, but in my opinion unlikely. They have what appears to be a technology already that is equivalent to or better than CTSO's.
To add to this, from Fresenius's 2010 annual report:
"By expanding our global network of clinics through acquisitions as well as procuring know-how and relevant technologies in the area of research and development, we are investing in our future growth. The close collaboration between our strategy and planning departments and the managers responsible for our acquisitions ensures that we are able to identify suitable potential acquisitions worldwide as early as possible."
"For Fresenius Medical Care’s research and development, this means quickly translating new insights into market-ready advances and innovations, thereby significantly contributing to gentler, safer and more individual patient treatment. Relevant technological trends include new developments in information technology, technologies that help to make products gradually smaller and simplify their use, the integration of various treatment elements into holistic therapy systems, and the application of promising procedures such as sorbent technology."
And going as far back as 2002:
"It is intended that the Adsorber Technology Division of Fresenius HemoCare will be transferred to Fresenius Medical Care. The combination of medical and technological know-how in the field of extracorporeal blood treatment will generate further therapy impulses. At the same time, this measure is in line with Fresenius Medical Care’s strategy to further strengthen extracorporeal therapies outside dialysis, both in the USA and internationally. Through this combination, Fresenius Medical Care’s worldwide network of dialysis clinics can be utilized for adsorber treatment – the extracorporeal removal of pathogenic substances from the blood – e.g. for patients suffering from rheumatoid arthritis."