Synergistic Effects of a Novel Multifunctional Bionic Scaffold and Electrical Stimulation Promote Bone Tissue Regeneration

Abstract

Electrical stimulation (ES) can effectively regulate cell behavior and promote bone tissue regeneration, and conductive biomaterials can further enhance this effect by enhancing the conduction of electrical signals between cells. In this study, poly(lactic-co-glycolic acid) (PLGA) and poly(l-lactide)-aniline pentamer triblock copolymer (PAP) were used as raw materials to prepare a conductive bionic scaffold (PLGA/PAP). Subsequently, bone morphogenetic protein 2 mimetic peptide containing a DOPA tag (DBMP2MP) was loaded on the scaffold surface. The prepared scaffold (DBMP2MP@PLGA/PAP) had a porosity of 79.17% and a porous structure similar to that of natural cancellous bone. After PAP was added, the mechanical strength and electrical conductivity of the scaffold were increased to 2.79 ± 0.1 kPa and 1.29 ± 0.023 × 10−6 s/cm. The addition of DBMP2MP significantly improved the hydrophilicity of the scaffold material, and the contact Angle of the scaffold material decreased from 102.45 ± 7.67° to 30.36 ± 5.25°. At the same time, DBMP2MP and scaffold surface bonding ability increased by two times compared with commercial BMP2. The polypeptide DBMP2MP can bind to the surface of scaffolds and exhibit long-lasting biological effects. In vitro cell experiments revealed that the DBMP2MP@PLGA/PAP scaffold could significantly promote the proliferation and adhesion of MC3T3-E1 cells and that the combination of DBMP2MP@PLGA/PAP with pulsed ES could further synergistically induce cell mineralization and osteogenic differentiation. The results of the rabbit radius defect experiments revealed that grafting the DBMP2MP@PLGA/PAP scaffold at the defect site significantly promoted the formation of new bone and collagen fibers. When the DBMP2MP@PLGA/PAP scaffold was combined with ES, the regeneration rate of bone tissue further improved, and the newborn collagen tissue is close to normal bone collagen. Therefore, this bionic scaffold with excellent electrical and biological activity shows considerable potential in the field of bone defect repair.