Relative centrifugal force (Rcf; g‐force) affects the distribution of tgf‐β in prf membranes produced using horizontal centrifugation

Abstract

Solid platelet‐rich fibrin (PRF) is produced with centrifugation tubes designed to accelerate clotting. Thus, activated platelets may accumulate within the fibrin‐rich extracellular matrix even before centrifugation is initiated. It can thus be assumed that platelets and their growth factors such as transforming growth factor‐β (TGF‐β) are trapped within PRF independent of their relative centrifugal force (RCF), the gravitation or g‐force. To test this assumption, we prepared PRF membranes with tubes where clotting is activated by a silicone‐coated interior. Tubes underwent 210 g, 650 g and 1500 g for 12 min in a horizontal centrifuge. The respective PRF membranes, either in total or separated into a platelet‐poor plasma and buffy coat fraction, were subjected to repeated freeze‐thawing to prepare lysates. Gingival fibroblasts were exposed to the PRF lysates to provoke the expression of TGF‐β target genes. We show here that the expression of interleukin 11 (IL11) and NADPH oxidase 4 (NOX4), and Smad2/3 signaling were similarly activated by all lysates when normalized to the size of the PRF membranes. Notably, platelet‐poor plasma had significantly less TGF‐β activity than the buffy coat fraction at both high‐speed protocols. In contrast to our original assumption, the TGF‐β activity in PRF lysates produced using horizontal centrifugation follows a gradient with increasing concentration from the platelet‐poor plasma towards the buffy coat layer.