Preparation of Platelet-Rich Plasma (PRP) Without Centrifugation

Since platelet-rich plasma (PRP) is a cocktail of various growth factors, it has been applied to enhance soft and hard tissue regeneration. Although the procedure for PRP preparation has been established, we feel there are still several problems. We found poly-L-glutamic acid (PGA) selectively precipitate erythrocyte without centrifugation. Objectives: The purpose of this study is to develop a simple method for PRP preparation with PGA. Methods: Blood was collected from arm vein and immediately mixed with citric acid. The aliquots of the blood in 1.5 ml plastic tubes were mixed with different amounts of PGA of various molecular weights. These tubes were left standing for 30 min and then the blood cells in the supernatant were characterized. We called this supernatant "sediment PRP (sPRP)". Finally, sPRP was applied to the incisions of the dorsal skin of immuno-deficient mice and the healing process was observed. Results: PGA precipitated erythrocyte selectively without centrifugation within 30 min resulting other blood cells in the supernatant. Increasing the amount and the molecular weight of PGA accelerated the precipitation. The degree of the precipitation reached the plateau at 2 mg /ml of PGA. The concentration of the platelets was approximately 1.9-fold and the efficiency of platelet recovery was 91.7%. After the activation with Ca2+ and thrombin, the supernatant formed gel. Application of sPRP to the skin incisions accelerated the healing compared to the control in which nothing was applied. Conclusion: PGA selectively precipitated erythrocytes and obtains platelets efficiently within 30 minutes without centrifugation. The final concentration of the platelets did not exceed 2.0 fold of the original blood; however, our sPRP accelerated the healing of skin incision. Although toxicity of PGA and optimal concentration of the platelets should be further clarified, the present results suggest a potentiality of our sPRP in promoting tissue regeneration.