Vacuum extraction enhances rhPDGF-BB immobilization on nanotubes to improve implant osseointegration in ovariectomized rats

Nanotube morphology has been previously applied to improve osseointegration in osteoporosis, but the osteogenic capability of the technique requires further improvements. This study aimed to investigate the effects of vacuum extraction on the loading of rhPDGF-BB on nanotube arrays as well as its effects on the osseointegration of ovariectomized (OVX) rats. More rhPDGF-BB protein particles aggregated on the nanotube surface and into the nanotube after vacuum extraction for 10 min. The immobilized protein could be slowly released for at least 14 days and still kept its biological activity. In vitro, the immobilized rhPDGF-BB enhanced cell adhesion, proliferation and osteogenic differentiation. In vivo, more rhPDGF-BB immobilized on the nanotube surface also promoted the osseointegration. These results suggest that the enhanced immobilization of rhPDGF-BB on nanotube arrays can potentially be used in the future as an implant surface modification strategy in dental and orthopedic applications in osteoporotic patients. From the Clinical Editor: This study presents convincing evidence that enhanced immobilization of recombinant human PDGF-BB protein particles on nanotubes lead to improved osteogenic differentiation in an experimental system. When used as a surface modification strategy for dental or orthopedic implants, this method was able to promote osseointegration even in an osteoporotic animal model, raising the likelihood for potential future clinical applications. (C) 2014 Elsevier Inc. All rights reserved.