Multifunctional Properties of Quercitrin-Coated Porous Ti-6Al-4V Implants for Orthopaedic Applications Assessed In Vitro

(1) One strategy to improve the outcome of orthopedic implants is to use porous implants with the addition of a coating with an antibacterial biomolecule. In this study, we aimed to produce and test the biocompatibility, the osteopromotive (both under normal conditions and under a bacterial challenge with lipopolysaccharide (LPS)) and antibacterial activities of a porous Ti-6Al-4V implant coated with the flavonoid quercitrin in vitro. (2) Porous Ti-6Al-4V implants were produced by 3D printing and further functionalized with quercitrin by wet chemistry. Implants were characterized in terms of porosity and mechanical testing, and the coating with quercitrin by fluorescence staining. Implant biocompatibility and bioactivity was tested using MC3T3-E1 preosteoblasts by analyzing cytotoxicity, cell adhesion, osteocalcin production, and alkaline phosphatase (ALP) activity under control and under bacterial challenging conditions using lipopolysaccharide (LPS). Finally, the antibacterial properties of the implants were studied using Staphylococcus epidermidis by measuring bacterial viability and adhesion. (3) Porous implants showed pore size of about 500 µm and a porosity of 52%. The coating was homogeneous over all the 3D surface and did not alter the mechanical properties of the Young modulus. Quercitrin-coated implants showed higher biocompatibility, cell adhesion, and osteocalcin production compared with control implants. Moreover, higher ALP activity was observed for the quercitrin group under both normal and bacterial challenging conditions. Finally, S. epidermidis live/dead ratio and adhesion after 4 h of incubation was lower on quercitrin implants compared with the control. (4) Quercitrin-functionalized porous Ti-6Al-4V implants present a great potential as an orthopedic porous implant that decreases bacterial adhesion and viability while promoting bone cell growth and differentiation.

In Vitro Cell Adhesion, Proliferation and Differentiation of Adipose Derived Stem Cells on Tulbaghia violacea Loaded Polycaprolactone (PCL) Nanofibers

Tissue engineering has been used for decades to restructure, replace and repair damaged tissue in the body. However, there are a number of challenges that have been identified, with the biggest one currently being the development of scaffolds with the ideal properties that can promote cell-scaffold interactions to enhance cell proliferation and differentiation. There is currently very little research on the incorporation of extracts of medicinal plants in scaffold fabrication with the aim of enhancing the surface properties of the scaffold. For this study, Tulbaghia violacea-based PCL scaffolds were fabricated and evaluated for their osteogenic potential on adipose derived stem cells (ADSCs) in osteogenic media. The short-term studies illustrated enhanced cell adhesion and proliferation with low levels of toxicity as well as the formation of elongated cells in the T. violacea-based scaffolds when compared to the control PCL scaffold. The long term studies indicated increased alkaline phosphate activity (ALP) in the T. violacea scaffolds when compared to PCL and overall higher levels of osteocalcin production over a period of 3 weeks. Immunofluorescence imaging of marker proteins also illustrated that the T. violacea incorporated scaffolds supported better osteocalcin production which is a specific extracellular matrix (ECM) marker for cartilaginous tissue. These results support the incorporation of T. violacea plant extracts for the enhancement of nanofiber scaffolds with the potential for tissue engineering applications.

Influence of Inclusion of Apatite-based Microparticles on Osteogenic Cell Pheonotype and Behavior

ABSTRACTThe proximity of minerals found in human hard tissues may influence cell phenotype. Since cells respond to a range of environmental cues, this study sought to identify the influence of two apatite-based microparticles, hydroxyapatite (HA) and fluoroapatite (FA), upon dental and bone cells. After bone marrow stromal cells (BMSCs), 7F2 osteoblasts and dental pulp stem cells (DPSCs) were plated into media with or without HA or FA particles, the cells were analyzed for alkaline phosphatase (ALP) production, collagen I production, osteocalcin production, and mineralization for two weeks. The BMSCs and DPSCs in media without any microparticles produced more ALP compared to those with microparticles from Day 5 forward. In addition, the collagen I and osteocalcin production in cultures without microparticles was higher than in cultures containing either HA or FA particles. While some studies have shown increased osteogeonic differentiation in the presence of mineral particles, those studies used nanoparticles that were able to be internalized by the cells and were smaller than the microparticles used in this study.

Effect of nanoparticulate bioactive glass particles on bioactivity and cytocompatibility of poly(3-hydroxybutyrate) composites

This work investigated the effect of adding nanoparticulate (29 nm) bioactive glass particles on the bioactivity, degradation and in vitro cytocompatibility of poly(3-hydroxybutyrate) (P(3HB)) composites/nano-sized bioactive glass (n-BG). Two different concentrations (10 and 20 wt %) of nanoscale bioactive glass particles of 45S5 Bioglass composition were used to prepare composite films. Several techniques (Raman spectroscopy, scanning electron microscopy, atomic force microscopy, energy dispersive X-ray) were used to monitor their surface and bioreactivity over a 45-day period of immersion in simulated body fluid (SBF). All results suggested the P(3HB)/n-BG composites to be highly bioactive, confirmed by the formation of hydroxyapatite on material surfaces upon immersion in SBF. The weight loss and water uptake were found to increase on increasing bioactive glass content. Cytocompatibility study (cell proliferation, cell attachment, alkaline phosphatase activity and osteocalcin production) using human MG-63 osteoblast-like cells in osteogenic and non-osteogenic medium showed that the composite substrates are suitable for cell attachment, proliferation and differentiation.