3-D printed Ti-6Al-4V scaffolds for supporting osteoblast and restricting bacterial functions without using drugs: Predictive equations and experiments

Abstract

Conditions resulting from musculoskeletal deficiencies (MSDs) are wide-ranging and retain the likelihood for restricting motion or producing pain, especially in the lower back, neck, and upper limbs. Engineered scaffold devices are being produced to replace antiquated modalities that suffer from structural and mechanical deficiencies in the treatment of MSDs. Here, as-fabricated Ti-6Al-4V-based Hive™ interbody fusion scaffolds, commercialized by HD Lifesciences LLC, were assayed for their osteogenicity and antibacterial potential using a series of characterization and in vitro tests, as well as by quantitative analyses. A topographical assessment of the Hive™ meshes indicated that the elementally pure substrates are microscopically porous and rough, in addition to displaying structural heterogeneity. Roughness estimations and static contact angle measurements recommended the use of the as-fabricated Ti-6Al-4V substrates for supporting osteoblast attachment, especially, due to the improved surface roughness and wettability values of these scaffolds relative to the unembellished Ti-6Al-4V surfaces. Quantitative correlations relating the surface properties of roughness and energy were applied to predict cellular behaviors. Cell growth suppositions were experimentally corroborated. Critical in vitro data indicated the competencies of the Hive™ scaffolds for promoting the adhesion and proliferation of human fetal osteoblasts (hFOBs), accumulating substantial calcium deposition from metabolizing hFOBs, and restricting the attachment of bacteria. The model system that investigated the pre-adsorption of casein proteins along the Hive™ test substrates additionally furthered the notion that bacterial attachment may be restricted, with short-scale adhesion dynamics serving as the theoretical basis for this hypothesis. In this manner, this study showed that through predictive models and experiments, these novel 3D printed Ti-based scaffolds can increase bone cell while decreasing bacteria functions without using drugs. STATEMENT OF SIGNIFICANCE: Sintered Ti-6Al-4V spinal fusion devices (Hive™) manufactured and marketed by HD Lifesciences LLC were assessed for their biocompatibility and antibacterial performance. A mixed methods approach was employed, whereby quantitative measures were used to predict the ability for Hive™ substrates to adsorb specialized proteins and to restrict bacterial surface colonization. In vitro tests that evaluated bone cell and bacterial adhesion, calcium deposition, and protein adsorption supported quantitative predictions. The data herein presented demonstrate the following: (1) surface energy is an important predictor of implant-cell interactions, (2) strong correlations exist between surface energy and surface roughness, (3) mathematical models can be used to improve and predict implant device perofrmance, and (4) porous, rough, 3D-printed materials perform well in terms of biocompatibility and antimicrobial efficacy.

Keywords: Antibacterial; Mesh scaffold; Nanotopography; Osteogenesis; Surface energy; Ti-6Al-4V.