Do the fibrin architecture and leukocyte content influence the growth factor release of platelet concentrates? An evidence-based answer comparing a pure platelet-rich plasma (P-PRP) gel and a leukocyte- and platelet-rich fibrin (L-PRF).

Platelet concentrates for surgical use are tools of regenerative medicine designed for the local release of platelet growth factors into a surgical or wounded site, in order to stimulate tissue healing or regeneration. Leukocyte content and fibrin architecture are 2 key characteristics of all platelet concentrates and allow to classify these technologies in 4 families, but very little is known about the impact of these 2 parameters on the intrinsic biology of these products. In this demonstration, we highlight some outstanding differences in the growth factor and matrix protein release between 2 families of platelet concentrate: Pure Platelet-Rich Plasma (P-PRP, here the Anitua's PRGF - Preparation Rich in Growth Factors - technique) and Leukocyte- and Platelet-Rich Fibrin (L-PRF, here the Choukroun's method). These 2 families are the extreme opposites in terms of fibrin architecture and leukocyte content. The slow release of 3 key growth factors (Transforming Growth Factor ß1 (TGFß1), Platelet-Derived Growth Factor AB (PDGF-AB) and Vascular Endothelial Growth Factor (VEGF)) and matrix proteins (fibronectin, vitronectin and thrombospondin-1) from the L-PRF and P-PRP gel membranes in culture medium is described and discussed. During 7 days, the L-PRF membranes slowly release significantly larger amounts of all these molecules than the P-PRP gel membranes, and the 2 products display different release patterns. In both platelet concentrates, vitronectin is the sole molecule to be released almost completely after only 4 hours, suggesting that this molecule is not trapped in the fibrin matrix and not produced by the leukocytes. Moreover the P-PRP gel membranes completely dissolve in the culture medium after less than 5 days only, while the L-PRF membranes are still intact after 7 days. This simple demonstration shows that the polymerization and final architecture of the fibrin matrix considerably influence the strength and the growth factor trapping/release potential of the membrane. It also suggests that the leukocyte populations have a strong influence on the release of some growth factors, particularly TGFß1. Finally, the various platelet concentrates present very different biological characteristics, and an accurate definition and characterization of the different families of product is a key issue for a better understanding and comparison of the reported clinical effects of these surgical adjuvants.

Clinical evaluation of an enamel matrix protein derivative combined with a bioactive glass for the treatment of intrabony periodontal defects in humans.

BACKGROUND: The purpose of the present study was to compare the treatment of deep intrabony defects with a combination of an enamel matrix protein derivative (EMD) and a bioactive glass (BG) to BG alone. METHODS: Twenty-eight patients with chronic periodontitis, each of whom displayed 1 intrabony defect, were randomly treated with a combination of EMD and BG or with BG alone. Soft tissue measurements were made at baseline and at 1 year following therapy. RESULTS: No differences in any of the investigated parameters were observed at baseline between the 2 groups. Healing was uneventful in all patients. At 1 year after therapy, the sites treated with EMD and BG showed a reduction in mean probing depth (PD) from 8.07 +/- 1.14 mm to 3.92 +/- 0.73 mm and a change in mean clinical attachment level (CAL) from 9.64 +/- 1.59 mm to 6.42 +/- 1.08 mm (P < 0.0001). In the group treated with BG, the mean PD was reduced from 8.07 +/- 1.32 mm to 3.85 +/- 0.66 mm and the mean CAL changed from 9.78 +/- 1.71 mm to 6.71 +/- 1.89 mm (P < 0.0001). No statistically significant differences in any of the investigated parameters were observed between the test and control group. CONCLUSIONS: Within the limits of the present study, it can be concluded that both therapies led to significant improvements of the investigated clinical parameters, and the combination of enamel matrix derivative and bioactive glass does not seem to additionally improve the clinical outcome of the therapy.