Bone Induction By Biomimetic PLGA Copolymer Loaded With A Novel Synthetic RADA16-P24Peptide In Vivo

Objective: The novel RADA16-P24peptide was bound onto the surface of the PLGAscaffold to synthesize RADA16-P24-PLGA and its capacity of attaching bone marrowstromal cells (BMSCs) was evaluated in vitro and inducing ectopic bone formation wasobserved in vivoMethods: RADA16-P24peptide could self-assemble to form nanofibers demons-trated byAFM. Two methods of physisorbing and chemical cross-linking were used to bindRADA16-P24onto the surface of the copolymer PLGA to synthesize RADA16-P24-PLGAcomposite. The FTIR and Elemental analysis were used to calculate the binding rate ofRADA16-P24. The biocompatibility of RADA16-P24was demonstrated by evaluating theBMSCs adhesion and the proliferation activity on the surface of RADA16-P24-PLGAcomposite in vitro. The capacity of inducing ectopic bone formation was observed in vivo.Results:①The2g/L (2%by weight) RADA16-P24peptide solution could self-assembleto form nanofibers induced by divalent ion solution. The self-assembled nanofibers weredetected by AFM with a diameter of7-10nm and the length of the fiber could be as long asseveral hundreds of nm. These nano-fibers interweave to form a porous network structure.②The RADA16-P24-PLGA copolymer prepared by physisorbing or prepared by chemicalcross-linking had a peptide binding rate of（2.0180±0.5296）%or (10.0820±0.8405)%.The two differences had statistical significance, respectively (P<0.05).③The BMSCsproliferated vigorously in the RADA16-P24-PLGA biomaterials. Signi-ficantly thepercentage of BMSCs attached to RADA16-P24-PLGA composite prepared by chemicalcross-linking and physisorbing was (71.4±7.5)%or (46.7±5.8)%. The two differences hadstatistical significance (P<0.05).④Radiographic and Histological examination confirmedthat new bone formed4-8weeks after RADA16-P24-PLGA was implanted into rats.Conclusion: The PLGA copolymer is a good RADA16-P24carrier. This novelRADA16-P24-PLGA composite not only has good biocompatibility but has strong osteogenic capability.