Release Kinetics of rhBMP-2 Using E-PRF as an Autologous Carrier: An in Vitro Analysis

Innovations in biomedicine and recombinant protein technology show promising advances for the regeneration of advanced alveolar defects. Recombinant growth factors and biologics encourage minimally invasive procedures with improved clinical outcomes/healing times in complex oral surgery procedures. Recombinant human bone morphogenic protein-2 (rhBMP-2) is a morphogen that is a well-known regulator of bone formation1 and has been widely studied for bone reconstructive treatments.2-6 RhBMP-2 is currently commercially available and loaded on an absorbable collagen sponge (ACS). This recombinant growth factor has been approved by the US Food and Drug Administration as an alternative to autogenous bone grafting in sinus augmentation and localized alveolar ridge augmentation for defects associated with extraction sockets. It is also used off-label for vertical bone augmentation. However, there are limitations of the ACS as a carrier because it is compressible and does not ideally support soft tissues to maintain space for osteogenesis to occur. Furthermore, the release kinetics of rhBMP-2 in a standardized in vitro environment from its ACS carrier are unknown and it is further unknown how such release would compare to the use of other carriers. Subcutaneous implantation in rats and implantation at orthotropic sites in rats and rabbits has also revealed that rhBMP-2-loaded ACS has a release of rhBMP-2 over 21 days with a half-life of 2 days. The use of an alternative delivery system may retain and sequester rhBMPs at the target site and extend its growth factor release over time. This may be clinically relevant as prolonging tissue exposure to an osteoinductive growth factor like rhBMP-2 could extend the period of osteoblastic bone deposition and improve repair at regenerative sites. E-PRF as an autologous carrier for rhBMP-2 may be advantageous based on its resorption properties of up to 4-6 months, as well as its ability to support the healing process due to the slow and gradual release of several growth factors including, PDGF-AA, PDGF-BB, TGF- β1,VEGF, IGF, and EGF. This study aims to quantify the release of rhBMP-2 over a 120 day period with the use of a novel delivery system, E-PRF.