Purification and characterization of a new highly pure, double virus inactivated von Willebrand factor concentrate
Desmopressin-unresponsive von Willebrand disease patients are treated with substitutive therapy, with both pure von Willebrand factor (vWF) and factor VIII/vWF concentrates. We developed a new purification process, easily scalable to industrial level, to obtain a double virus inactivated highly pure vWF. VWF was purified starting from a waste fraction of already in use human plasma-derived factor VIII manufacturing procedure, using only one anionic-exchange chromatographic step. After chromatography, the product was dialyzed, lyophilized, and heat treated. The process resulted in a very highly purified vWF, with a mean specific activity of 95.3 IU of vWF:ristocetin cofactor assay/mg of total proteins. The obtained vWF had a whole structure, as showed by the triplet bands analysis. The residual content of contaminating proteins such as immonoglobulin M and factor VIII was very low. Immunoglobulin A, immunoglobulin G, and fibronectin were totally absent. Notably, the lyophilized highly pure vWF was stable, without the addition of stabilizing proteinaceous material. A new simple purification method was performed, starting from a waste fraction of in use plasma-derived factor VIII process, using one single chromatographic step to obtain a highly pure and double virus inactivated vWF.