Preliminary studies for the development of a second generation granulocytapheresis (G-CAP) column. Part II: in vitro and ex vivo studies.

Our previous studies concluded Egyptian cotton was the most appropriate material for making a second generation granulocytapheresis (G-CAP) column as structural dimensions of the cotton fibers are able to attract granulocytes. Unfortunately, it is considered to be blood incompatible as its fibers are of non-synthetic origins. In this study we examined the alteration of the removal rates of blood cells with different surface modifications of Egyptian cotton to enhance its blood compatibility. The surface-modified cotton fibers were compared after three kinds of combination treatments. There were no differences in the removal rates of white blood cells (WBCs) and particularly neutrophils with the use of three kinds of biolized cottons. Next, an ex vivo animal study with a healthy dog was performed with the prototype of the G-CAP column. The dog's blood pressure (BP) decreased to approximately 80% of the initial values of BP at 20 min after the start of the extracorporeal circulation. The decrease in BP gradually reverted to normal. WBCs and particularly neutrophils decreased significantly at 15 min after the start of the extracorporeal circulation and remained low during the extracorporeal circulation. The ability of this column to remove WBCs was maintained during extracorporeal circulation. Especially, neutrophils at the inlet of the column were thoroughly removed for 1 h. Based upon these results, a second generation G-CAP column could be fabricated with Egyptian cotton and applied for clinical use on the condition that the biocompatibility of the Egyptian cotton needs to be improved by the appropriate biolization method.