Improved bone healing by angiogenic factor-enriched platelet-rich plasma and its synergistic enhancement by bone morphogenetic protein-2.
OBJECTIVE
The purpose of this study was to modify the method of platelet-rich plasma (PRP) preparation for obtaining optimal angiogenic potential and accelerate bone healing. Also, the potential synergistic effect of a suboptimal concentration of bone morphogenic protein-2 (BMP-2) and modified PRP (mPRP) on bone healing was evaluated in vivo.


METHODS
The angiogenic factor-enriched PRP, which included peripheral blood mononuclear cells (mostly lymphocytes and monocytes, excluding polymorphonuclear leukocytes [PMNs], was achieved by lowering concentrations of thrombin and CaCl2, after pre-activation with shear stress using a table-top vortex machine and collagen. In vitro, endothelial cell migration activity in the mPRP group was compared to conventional PRP preparation using a modified Boyden chamber assay. In an animal study, PGA scaffold, PGA scaffold + mPRP, PGA scaffold + mPRP + rhBMP-2, and PGA scaffold + rhBMP-2 were applied to critical-sized calvarial defects in 28 nude rats. At 2 weeks, periosteal blood flow was measured using laser Doppler perfusion imaging, and bone formation was evaluated at 8 weeks by histology, dual energy x-ray absorptiometry, and micro-computed tomography.


RESULTS
mPRP induced faster migration of cord blood-derived outgrowth endothelial-like cells. In vivo, the group with mPRP with a low dose of rhBMP-2 showed significantly increased numbers of blood vessels at 2 weeks and notable synergistic effect on bone healing at 8 weeks as evaluated with histology, bone mineral density and bone mineral content, and muCT.


CONCLUSIONS
The mPRP used in this study improved vascular perfusion around the defect and resulted in enhanced bone healing. Also, combining mPRP with a suboptimal dosage of rhBMP-2 improved bone formation and enhanced bone density.
Park
Eun-Jin
EJ
Department of Dentistry, School of Medicine, Ewha Women's University, Seoul, South Korea.
Kim
Eun-Seok
ES
Weber
Hans-Peter
HP
Wright
Robert F
RF
Mooney
David J
DJ
D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology*; D001861:Bone Regeneration / Q000187:drug effects; D002498:Centrifugation; D017078:Laser-Doppler Flowmetry; D008214:Lymphocytes; D009000:Monocytes; D018919:Neovascularization, Physiologic; D053657:Platelet-Rich Plasma; D051381:Rats; D011923:Rats, Nude; D011994:Recombinant Proteins / Q000494:pharmacology; D012886:Skull / Q000601:surgery; D054457:Tissue Scaffolds; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*
D055396:Bone Morphogenetic Protein 2; D011994:Recombinant Proteins; D042461:Vascular Endothelial Growth Factor A