Abstract:

Objective To discuss the technological process of platelet rich fibrin （PRF）/hydroxyapatite （HA） complex prepared by the “sandwich” method， and to evaluate its properties. Methods The injectable PRF （I-PRF） and advanced PRF （A-PRF） were prepared with the centrifugation indexes of 700 r·min^－1×3 min and 1 300 r·min^－1×14 min，respectively， then they were combined with HA using the “sandwich” method. The microstructure of PRF/HA complex was observed under scanning electron microscope （SEM） after freeze drying； the material was immersed in the simulated body fluid （SBF）， and the growth of a bone-like layer on the surface of HA was observed on the 2nd， 4th， 8th，and 16th days， respectively，and its mineralization ability was evaluated；the PRF/HA complex extract solution co-cultured with preosteoblast MC3T3-E1 cells of the mice and complete culture medium were used as experimental group and control group；after cultured for 1， 3 and 5 d， respectively， the proliferation activities of the preosteoblast MC3T3-E1 cells were evaluated by CCK-8 method. Two full-thickness cranial defect areas with a diameter of 6 mm were symmetrically established on both the sides of the sagittal suture in the Japanese white rabbits； one side implanted with PRF/HA complex was regarded as experimental group， the other side without any material implantion was regarded as control group；X-ray and cone beam CT （CBCT） were used on the surgical area to evaluate the bone formation performance of the rabbits in two groups 4 and 8 weeks after surgery. Results The PRF/HA complex with a “sandwich” structure was successfully prepared， with the A-PRF on the outside and the I-PRF mixed with HA particles on the inside. The SEM observation results showed that the cross-section of the complex was an obvious three-layer structure， with the dense fibrin net on the outside and the porous HA particles attached by fibrin filaments on the inside. After being immersed in SBF，the mineralized nodules were formed on the surface of HA on the 2nd day， the bone-like layer was gradually established with the prolongation of the immersion time， and a lamellar structure was formed at the 16th day. The cell proliferation experiment results showed that compared with control group， the proliferation activities of the MC3T3-E1 cells in experimental group were significantly increased on the 1st， 3rd，and 5th days （P<0.05）. The imaging observation results showed that the cranial defect in experimental group had obvious marginal osteogenesis 4 weeks after surgery and the new bone had almost completely filled the bone defect area 8 weeks after surgery， while the new bone formation of the cranial defect in control group was significantly decreased than that in experimental group. Conclusion PRF/HA complex prepared by the “sandwich” method has a good mineralization ability and biocompatibility， and can promote the bone regeneration.

Key words: Platelet rich fibrin, Hydroxyapatite, Cell proliferation, Bone repair, Bone regeneration