Bone morphogenetic protein-2-encupsulated PEG-grafted-poly-lactic acid-polycaprolactone nanoparticles promote bone repair

Abstract

To explore the efficacy of a novel tissue engineered bone in repairing bone defects using poly-lactic acid-polycaprolactone (PLA-PCL) scaffolding seeded with PEG-bone morphogenetic protein-2 (BMP-2) transfected rBMSCs (rabbit bone marrow stromal cells). rBMSCs were harvested, transfected with PEG/BMP-2 or liposome/BMP-2 and then implanted into PLA-PCL tissue engineered bone. The protein level of BMP-2 was assessed by Western blot and immunohistochemistry. Enzyme-linked immunosorbent assay (ELISA) was employed to measure the amount of BMP-2 in culture media. The mRNA levels of BMP-2 and osteocalcin were assayed quantitatively by real-time polymerase chain reaction (PCR). The middle portion of bilateral radius in New Zealand rabbits was excised and implanted with tissue engineered bone. And the modified areas were monitored by radiology, hematoxylin-eosin staining and immunohistochemical staining of BMP-2. PEG-BMP-2 nanoparticles (NPs) and BMP-2 loaded PEG-PLA-PCL tissue engineered bones were successfully constructed. The novel PEG-PLA-PCL NPs/DNA complex was superior for transfecting BMP-2 in rBMSCs compared to traditional liposomes. Moreover, the mRNA level of osteocalcin and alkaline phosphatase activity also increased after a transfection of BMP-2 encapsulated NPs. PEG-PLA-PCL NPs/BMP-2 complex facilitates bone repair so that it provides theoretic rationales for potential clinical treatments.