Abstract: A polysulfone-based hollow fiber membrane that purifies blood preparations, including a hydrophilic polymer on a surface thereof which contacts the blood preparation, wherein an abundance ratio of the hydrophilic polymer is from 40 to 60% by mass, and porosity at the surface is 8 to 30%.

Abstract: A hollow fiber membrane module is capable of producing washed platelets having a low total protein amount and a high total platelet count from a platelet suspension. The hollow fiber membrane module for washing platelets by removal of impurities from a platelet suspension includes a housing having a platelet suspension inlet, washed platelet outlet, and filtrate outlet; and a hollow fiber membrane for filtering the platelet suspension, wherein pores through which the platelets do not pass, while the impurities pass, are formed, which hollow fiber membrane is arranged inside the housing; wherein the capacity of the inlet-side space which communicates with the platelet suspension inlet and stores the platelet suspension before being filtered through the hollow fiber membrane in the housing is 30 to 400 mL, and the module water permeability is 50 to 300 mL/Pa/hr.

Abstract: A method of producing a platelet solution replaced with an artificial preservation solution includes a filtering step of carrying out cross-flow filtration of a platelet solution under the conditions of Formula (1) at an inlet wall shear rate of 25 to 1500 s?1 using a separation membrane whose surface which contacts with the platelet solution has an average pore size of not less than 0.1 ?m and less than 2.0 ?m, thereby obtaining a concentrated platelet solution; and a mixing step of mixing the concentrated platelet solution with an artificial preservation solution to obtain the platelet solution replaced with an artificial preservation solution: 1.0×1011<(A×B)/(?×?P)?2.5×1013 (platelets/(hr·m2·Pa))??(1) A: Concentration of platelets contained in the platelet solution (platelets/mL; with the proviso that the range is 8.0×107 to 200×107 platelets/mL) B: Filtration flow rate per unit area (mL/hr/m2) ?: Inlet wall shear rate (s?1) ?P: Viscosity of the platelet solution (Pa·s).

Abstract: A method of producing a platelet solution replaced with an artificial preservation solution includes a filtering step of carrying out cross-flow filtration of a platelet solution under the conditions of Formula (1) at an inlet wall shear rate of 25 to 1500 s?1 using a separation membrane whose surface which contacts with the platelet solution has an average pore size of not less than 0.1 ?m and less than 2.0 ?m, thereby obtaining a concentrated platelet solution; and a mixing step of mixing the concentrated platelet solution with an artificial preservation solution to obtain the platelet solution replaced with an artificial preservation solution: 1.0×1011<(A×B)/(?×?P)?2.5×1013 (platelets/(hr·m2·Pa))??(1) A: Concentration of platelets contained in the platelet solution (platelets/mL; with the proviso that the range is 8.0×107 to 200×107 platelets/mL) B: Filtration flow rate per unit area (mL/hr/m2) ?: Inlet wall shear rate (s?1) ?P: Viscosity of the platelet solution (Pa·s).

Abstract: A polysulfone-based hollow fiber membrane that purifies blood preparations, including a hydrophilic polymer on a surface thereof which contacts the blood preparation, wherein an abundance ratio of the hydrophilic polymer is from 40 to 60% by mass, and porosity at the surface is 8 to 30%.