ABSTRACT
The aim of this study was to evaluate and compare the mechanical resistance of platelet-rich fibrin (PRF) membrane when submitted to resistance traction on longitudinal axis. Blood collection of a healthy individual was collected with an amount of 300 mL and divided into 30 tubes containing 10 mL each one. The samples were divided into three groups, according to the g-force protocols: (1) F200 g: (2) F400 g; (3) F800 g. Membranes of each g-force group were divided into subgroups, according to waiting time after centrifugation: (T0) immediate use and (T30) use after 30 min. Considering these intervals of time, the concentrate was removed from tubes and inserted in a PRF metallic box to confection of the membrane. The PRF membranes were submitted to mechanical tension on a universal testing machine and obtained to a resistance force of each membrane. The centrifugation time showed no statistically significant difference for membrane resistance for any force applied (P > 0.05; Student's t-test). For T0 group results demonstrated no influence for membrane resistance (P = 0.357; Student's t-test), therefore T30 showed statistically significant difference (P = 0.040; Student's t-test) for membrane resistance for centrifugation forces applied, with highest value when applied greatest force. The findings suggest that the waiting time for centrifugation could be determined according to demand of application, and for immediate use of the membrane, the centrifugation did not influence the resistance, on the other hand, after 30 min, the application of higher force resulted in a membrane with considerable resistance.
ABSTRACT
Blood Concentrates (BCs) are autologous non-transfusional therapeutical preparations with biological properties applied in tissue regeneration. These BCs differ in the preparation method, in fibrin network architecture, growth factors release as well as in platelet/cell content. Methodological changes result in distinct matrices that can compromise their clinical effectiveness. The present study evaluated the influence of different g-forces and types of tubes in the release of vascular endothelial growth factor (VEGF) from platelet-rich fibrin (PRF) as a function of time. The PRF-like samples were obtained with three g-forces (200, 400, and 800 x g) for 10 minutes in pure glass tubes or in polystyrene-clot activator tubes. Scanning and Transmission electron microscopy was used to morphometric analyzes of PRF's specimens and flow cytometry was used to quantify VEGF slow release until 7 days. Our results showed that platelets were intact and adhered to the fibrin network, emitting pseudopods and in degranulation. The fibrin network was rough and twisted with exosomic granulations impregnated on its surface. An increase in the concentration of VEGF in the PRF supernatant was observed until 7 days for all g forces (200, 400 or 800 xg), with the highest concentrations observed with 200 x g, in both tubes, glass or plastic. Morphological analyzes showed a reduction in the diameter of the PRF fibers after 7 days. Our results showed that g-force interferes with the shape of the fibrin network in the PRF, as well as affect the release of VEGF stored into platelets. This finding may be useful in applying PRF to skin lesions, in which the rapid release of growth factors can favor the tissue repair process. Our observations point to a greater clarification on the methodological variations related to obtaining PRF matrices, as they can generate products with different characteristics and degrees of effectiveness in specific applications.
