A novel method for evaluating and quantifying cell types in platelet rich fibrin and an introduction to horizontal centrifugation

Platelet rich fibrin (PRF) has been utilized clinically as a platelet concentrate capable of stimulating tissue regeneration. Interestingly, several protocols have been proposed with little data obtained regarding the final cell counts following centrifugation. The aim of the present study was to compare different commercially available centrifuges and their respective protocols utilizing a novel method to quantify cells. One millimeter blood layers following centrifugation were sequentially pipetted from the upper layer downward until all 10 mL were harvested in sequential samples. Thereafter, each sample was sent for CBC analysis to accurately quantify precisely cell numbers within each separate blood layer following centrifugation. The results from this study revealed that L-PRF protocols (2700 rpm x 12 min) produced a clot with the majority of platelets and leukocytes concentrated within the buffy coat with relatively no cells found within the first 4 mL of L-PRF. Slower centrifugation protocols produced using the A-PRF protocols (1300 rpm x 8 min) produced a more evenly distributed number of platelets throughout PRF. Injectable-PRF (i-PRF) protocols produced the highest concentration of leukocytes/platelets, however, the total number of leukocytes and platelets were significantly lower owing to the decreased total volume collected. Horizontal centrifugation produced a significant increase in both the number and concentration of platelets and leukocytes (up to 3.5x higher for either solid/liquid PRF). When compared to either fixed or angled centrifuge (InstraSpin, Process for PRF). In conclusion, the present study revealed a novel/accurate method to quantify cells following PRF protocols. Furthermore, PRF produced via horizontal centrifugation accumulated a higher number and concentration of platelets/leukocytes when compared to either fixed-angle centrifugation.