Lyophilized Platelet-rich Fibrin Promotes Craniofacial Bone Regeneration

Platelet-rich fibrin (PRF) is a second generation platelet concentrate developed as an scaffold for tissue repair and regeneration.  To improve storage and clinical applicability, lyophilized PRF was introduced as a novel aid in craniofacial tissue regeneration.  Objective:  To determine the effect of lyophilized PRF on osteogenic cell behavior and craniofacial tissue regeneration.  Methods:  PRF was generated from fresh blood after centrifugation, and fractions were lyophilized for comparison studies.  Fresh and lyophilized PRF was compared to either DMEM or fibrin in osteoblast cell cultures and in a craniofacial bone defect model.  Results:  Pore-size in lyophilized PRF was increased 18-fold over fresh PRF.   There was no significant difference between fresh and lyophilized PRF when comparing cell chemotaxis, alkaline phosphatase levels, and alizarin red mineralization staining in cultured osteoblasts.   However, application of lyophilized PRF significantly (p>0.001) increased cell proliferation 1.61-fold and Runx2 expression 1.29-fold in our osteoblast culture model.  The effect of both fresh and lyophilized PRF on osteoblast cell mineralization and alkaline phosphatase levels was more than 10-fold higher compared to that of DMEM culture medium alone.  When applied in a rat craniofacial defect model, application of lyophilized PRF resulted of 97% bony coverage of the defect, compared to 84% when using fresh PRF, 64% when using fibrin alone, and 16% when the defect was left without scaffold after 6 weeks.  Moreover, lyophilized PRF doubled the diameter of bone trabeculae compared to fresh PRF, and both lyophilized and fresh PRF resulted in long and interconnected bone trabeculae compared to short trabeculae after application of fibrin scaffold alone.  Conclusion:  Studies indicate that lyophilized PRF is a superior biomimetic scaffold for craniofacial bone regeneration when compared to fresh PRF or fibrin.  Funding for these studies was provided by NIDCR grant DE 15425 to TGHD.