In vitro effects of wool-derived keratin on human dental pulp-derived stem cells for endodontic applications.

In this study we examine the influence of wool-derived keratin intermediate filament proteins (kIFPs) on human dental pulp-derived stem cells (hDPSCs). kIFPs were diluted (10 mg/mL to 0.001 mg/mL) in cell culture media. Effects on hDPSCs proliferation were measured using Alamar blue assay. Keratin concentrations of 1 mg/mL and 0.1 mg/mL were tested for odontogenic differentiation and mineralisation. Alkaline phosphatase (ALP) quantification (7th, 14th, and 21st days), alizarin red S (AR-S) staining and calcium quantification (21st day), reverse transcription polymerase chain reaction (RT-PCR, collagen expression), and immunocytochemical staining for dentin matrix protein (DMP) were performed. hDPSCs showed higher proliferation with kIFPs of 0.1 mg/mL or less (p < 0.0001). The 0.1 mg/mL keratin concentration promoted odontogenic differentiation, confirmed by increased ALP activity, significant calcium deposits (AR-S staining, p < 0.05), up-regulated collagen expression (RT-PCR, p < 0.05), and positive DMP staining. These results suggest that kIFPs could be a potential biomaterial for pulp-dentin regeneration.

Effect of chitosan infiltration on hydroxyapatite scaffolds derived from New Zealand bovine cancellous bones for bone regeneration.

Hydroxyapatite (HA) derived from bovine bones garnered wider interest as a bone substitute due to their abundant availability as meat wastes and similarities in morphology and mineral composition to human bone. In our previous work, we developed an easy and reproducible method to prepare xenograft HA scaffolds from NZ bovine cancellous bones (BHA). However, the processing methodology rendered the material mechanically weak. The present study investigated the infiltration of chitosan (CS) into the bovine HA scaffolds (CSHA) to improve the mechanical properties of BHA. The presence of characteristic functional groups of HA and CS as detected by infrared spectroscopy confirmed the infiltration of CS into the BHA scaffolds. X-ray Diffraction study confirmed the presence of the hydroxyapatite phase in both BHA and CSHA scaffolds. SEM and µCT analyses showed the CSHA scaffolds presented adequate porosity and an interconnected porous architecture required for cell migration and attachment. CSHA scaffolds presented good thermal, chemical and structural stability while demonstrating sustained biodegradability in simulated body fluid. CSHA scaffolds presented mechanical properties significantly higher than the BHA scaffolds. CSHA scaffolds were biocompatible with Saos-2 osteoblast cells and supported cell proliferation significantly better than the BHA scaffolds indicating their potential in bone tissue engineering.

Development and characterization of a xenograft material from New Zealand sourced bovine cancellous bone.

A xenograft (bovine hydroxyapatite [BHA]) was developed from New Zealand sourced bovine cancellous bone by a successful defatting and deproteinizing procedure. The BHA was chemically, compositionally and structurally characterized. Fourier transform infrared spectroscopy confirmed the removal of organic matter from the bone matrix and the presence of carbonate ( CO32-), hydroxyl (OH- ), and phosphate ( PO43-) functional groups. X-ray diffraction analysis suggested that the processed bone corresponds characteristically to hydroxyapatite (HA). SEM analysis showed that the BHA has an interconnected porous architecture with a pore diameter ranging from 100 to 700 µm while µCT analysis calculated the total porosity as 73.46% ± 1.08. Furthermore, the BHA was stable up to 1000°C and lost only 1.8% of its weight. The Ca/P molar ratio of the BHA was 1.58, which is comparable with commercially available natural HA-Endobon® . After 28 days of incubation in simulated body fluid (SBF), the pH value only fluctuated between 7.1 and 7.5 and the BHA scaffold did not degrade significantly by weight indicating the scaffold had excellent chemical and structural stability. In vitro studies showed the BHA was cytocompatible and supported the proliferative growth of Saos-2 osteoblast cells. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1054-1062, 2017.

Substituted hydroxyapatites for bone regeneration: A review of current trends.

At present hydroxyapatite (HA) is been extensively investigated for biomedical applications, largely as a result of its similarity in composition to the mineral portion of bone. Although HA undergoes osseointegration and is bioactive and osteoconductive, the inherent brittleness and low fracture toughness limits its use under load bearing conditions, also once implanted in the body, HA takes a long time to resorb. The crystal structure of HA is conducive to a variety of ionic substitutions. To accurately mimic the calcium deficient and carbonate-containing nature of HA in bone, both cationic and anionic substituents have been incorporated to synthetic HA. This article focuses on the incorporation of both the well established (Zn, Si, Sr, F, and carbonate) and latest ions (Ag, citrate, iron, niobate, and tantalates) into the HA structure and aims to highlight the key effects of these substitutions in terms of their chemical, physical, and biological properties. It can be shown that a minor substituent cannot only alter the microstructure, stability and crystallinity of the HA structure in an implant, but also have a significant effect on bone cells colonizing the implant, which in turn can influence the new bone formation and bone remodeling processes. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1285-1299, 2017.