"I believe there are plasma donation centers that specialize in plasma protein therapies where virtually all of the donated plasma is separated into components JWs can accept transfusion of, which means JWs could theoretically donate to these centers given assurance that their donation would be used for this purpose."
At plasma donation centers, they separate the plasma out and that is 93% water and 7% the proteins and other stuff. Then the proteins and stuff they want to harvest is kept and the water is thrown out. Nothing wrong with that. Infact that is the same thing that the kidneys do. It pulls water and other stuff out of the circulatory system. Why do they not have a fit about urine collection?