Fresh platelet concentrates are used in many centers to treat recalcitrant wounds. To extend the therapeutic shelf-life of platelets, we analyzed the wound-healing effects of fresh-frozen and freeze-dried (FD) platelet-rich plasma (PRP) using a diabetic mouse model. Db/db mice with 1.0 cm2 dorsal excisional wounds (n = 15/group) were treated with a single application of FD PRP (1.2 x 10(6) platelets/microL) with or without a stabilization solution, and compared with wounds treated with fresh-frozen, sonicated PRP, and untreated wounds. Granulation tissue area, thickness, and wound size were analyzed 9 days posttreatment. Immunostained sections were quantified for vascularity and proliferation using antiplatelet endothelial cell adhesion molecule I and antiproliferating cell nuclear antigen antibodies. The results showed that all PRP preparations increased granulation tissue formation as assessed by surface coverage, thickness, and angiogenic response, when compared with untreated wounds. In addition, wounds treated with FD PRP, and biochemically stabilized FD PRP, exhibited higher proliferative levels. The possibility to deliver growth factors using platelets, and the potential to extend the shelf-life of platelet concentrates makes freeze-drying methods particularly suitable for enhanced wound care.