A composition, method, and use of microporous particles such as polysaccharide hemostat particle gels activates platelet rich plasma (PRP) or other platelet-containing substances. The composition may contain microporous polysaccharaide hemostats (MPH) mixed with platelet-rich plasma, platelet-poor plasma, blood, or the like. The method may contain mixing the MPH with platelet-rich plasma or other platelet-containing substance either by hand, in a device, or by applying the MPH directly to the wound before or after application of the platelet-containing substance. Alternatively, MPH can by applied directly to the bleeding wound, using the blood as a source of platelets.