RESUMO
More insight into the biological fundamentals of leukocyte platelet-rich fibrin (L-PRF) guided healing is necessary to recommend its application, in particular in deficient bone sites that need to support implants. This study investigated the short-term bone healing effect of L-PRF treatment in cylindrical non-critical sized bone defects with 3 mm diameter and 6 mm depth in tibiae of 18 adult male New Zealand White rabbits. After a randomization process, 96 bone defects were prepared and half of them were filled with a L-PRF membrane, while untreated defects in the opposite tibia served as control group. The rabbits were euthanized after 7, 14 or 28 days of healing. The bone healing of the cortical and medullary areas was investigated by micro-CT, while the expression of molecular markers (RUNX2, VEGFA, COL1A2 and BMP2) was assessed by qRT-PCR. Treatment with L-PRF did not affect the micro-structural bone characteristics of the repaired bone tissue, except for a decrease in the trabecular connectivity at the cortical level after 14 days of healing. At this time, RUNX2 and VEGFA mRNA levels were significantly lower in the treated defects. L-PRF membranes thus had a temporary negative influence on the bone microarchitecture (Tb.Pf) and on the RUNX2 and VEGFA expression during early bone healing. Overall, L-PRF treatment did not enhance bone regeneration in these non-critical size defects after 28 days.