<p>Nano-Hydroxyapatite Coating Promotes Porous Calcium Phosphate Ceramic-Induced Osteogenesis Via BMP/Smad Signaling Pathway</p>

Abstract

BackgroundThe hierarchical porous structure and surface topography of calcium phosphate (CaP) bioceramics have a crucial impact on their osteoinductivity.PurposeTo fabricate a biomimetic bone graft with an interconnected porous structure analogous to that of trabecular bone and a bioactive nanostructured surface with excellent osteoinductive potential.Materials and methodsA biphasic CaP (BCP) substrate with highly porous structure was fabricated by an improved sponge replication method. Surface modification was performed by uniformly depositing a hydroxyapatite (HA) nanoparticle layer to create nHA-coated BCP scaffolds. The effects of these scaffolds on osteogenic differentiation of murine bone marrow-derived stem cells (BMSCs) were investigated in vitro, and their osteoinductivity was further assessed in vivo.ResultsThe BCP and nHA-coated BCP scaffolds had similar trabecular bone-like architectures but different surface structures, with mean grain sizes of ~55 nm and ~1 μm, respectively. Compared with the BCP substrate, the nHA-coated BCP scaffolds favored cell adhesion and promoted osteogenic differentiation of BMSCs, as evidenced by upregulated expression of osteogenic genes, enhanced alkaline phosphatase activity, and increased osteocalcin production. This could be attributed to activation of the BMP/Smad signaling pathway, as significantly higher expression levels of BMPRI, Smad1, Smad4, and Smad5 were observed in the nHA-coated BCP group. The nHA-coated BCP scaffold not only maintained scaffold integrity but also induced ectopic bone formation when implanted into rabbit dorsal muscle in vivo for 90 days, whereas the BCP substrate underwent marked biodegradation that led to severe inflammation with no sign of osteogenesis.ConclusionThe present study demonstrates the potential of this biomimetic bone graft with a trabecular framework and nanotopography for use in orthopedic applications.

<p>The Role of Tantalum Nanoparticles in Bone Regeneration Involves the BMP2/Smad4/Runx2 Signaling Pathway</p>

“…Hence, the Runx2 concentration is restricted to a baseline to maintain the inactivation of Smad4/Runx2 signaling. 43 Theoretically, the increased Smad4 and Runx2 amounts can be ascribed to two possible reasons: increased Smad4 production and decreased Smad4 degradation. 44,45 The mRNA expression of Smad4 was increased ( Figure 6A) by Ta NPs, indicating that the elevated total Smad4 level induced by the Ta NPs contributed, at least partially, to the increase in Smad4 production product levels.…”

Applications of PLA in modern medicine

“…The synthesized material is reported to encourage osteogenesis and angiogenesis with the neighboring tissues. However, several publications agree that the material utilized in these modalities suffer from a lack of physiological function [15] . Complications arise largely from a broad array of biological factors that must be considered before implantation of the biomaterial.…”

“…Concurrently, the material has to demonstrate an ability to integrate with the surrounding environment. Moreover, optimal performance is achieved when it can withstand immune responses and circumvent degradation into deleterious by-products [15] .…”

An efficient and inexpensive method for functionalizing metallic biomaterials used in orthopedic applications

“…The sub-micron topography observed in CaP+0.5 mM Si supports is consistent with the study by Da Silva et al who described a nanotopography induced by the incorporation of Si in hydroxyapatite tablets. Such a topography stimulates osteoblastic adhesion through the formation of numerous focal adhesion points [50] and stimulates osteogenic differentiation [51]. The supports' topography after steam sterilization was then analyzed.…”