Micro-/Nano-Structured Ceramic Scaffolds That Mimic Natural Cancellous Bone.

Micro-/nano-structured scaffolds with a weight composition of 46.6% α-tricalcium phosphate (α-TCP)-53.4% silicocarnotite (SC) were synthesized by the polymer replica method. The scanning electron microscopy (SEM) analysis of the scaffolds and natural cancellous bone was performed for comparison purposes. Scaffolds were obtained at three cooling rates via the eutectoid temperature (50 °C/h, 16.5 °C/h, 5.5 °C/h), which allowed the surface nanostructure and mechanical strength to be controlled. Surface nanostructures were characterized by transmission electron microscopy (TEM) and Raman analysis. Both phases α-TCP and SC present in the scaffolds were well-identified, looked compact and dense, and had neither porosities nor cracks. The non-cytotoxic effect was evaluated in vitro by the proliferation ability of adult human mesenchymal stem cells (ah-MSCs) seeded on scaffold surfaces. There was no evidence for cytotoxicity and the number of cells increased with culture time. A dense cell-hydroxyapatite layer formed until 28 days. The SEM analysis suggested cell-mediated extracellular matrix formation. Finally, scaffolds were functionalized with the alkaline phosphatase enzyme (ALP) to achieve biological functionalization. The ALP was successfully grafted onto scaffolds, whose enzymatic activity was maintained. Scaffolds mimicked the micro-/nano-structure and chemical composition of natural cancellous bone by considering cell biology and biomolecule functionalization.

High temperature CaSiO3-Ca3(PO4)2 ceramic promotes osteogenic differentiation in adult human mesenchymal stem cells.

Silicophosphate calcium ceramics are widely used in orthopedic and oral surgery applications because of their properties for stimulating bone formation and bone bonding. These bioceramics, together with multipotent undifferentiated adult human mesenchymal stem cells, are serious candidates in the field of bone tissue engineering and regenerative medicine. For this reason, the influence of a novel 30 wt%CaSiO3 - 70 wt%Ca3(PO4)2 ceramic over a primary adult human mesenchymal stem cells culture has been investigated in this study, observing a total colonization of the biomaterial by cells at 21 days. The osteoinductive capacity of the materials was also studied: alkaline phosphatase activity, gene quantification of osteoblastic genes and calcium deposits stained by Alizarin Red test, showed evidences of osteogenic differentiation of adult human mesenchymal stem cells seeded with this bioceramic both in growth medium and osteogenic medium. Therefore, the 30 wt%CaSiO3 - 70 wt%Ca3(PO4)2 bioceramic represents a potential scaffold which could be used in the field of biomaterials for bone tissue engineering, allowing cell adhesion, proliferation and promoting osteogenic differentiation of adult human mesenchymal stem cells.

Demineralized Bone Matrix Coating Si-Ca-P Ceramic Does Not Improve the Osseointegration of the Scaffold.

The aim of this study was to manufacture and evaluate the effect of a biphasic calcium silicophosphate (CSP) scaffold ceramic, coated with a natural demineralized bone matrix (DBM), to evaluate the efficiency of this novel ceramic material in bone regeneration. The DBM-coated CSP ceramic was made by coating a CSP scaffold with gel DBM, produced by the partial sintering of different-sized porous granules. These scaffolds were used to reconstruct defects in rabbit tibiae, where CSP scaffolds acted as the control material. Micro-CT and histological analyses were performed to evaluate new bone formation at 1, 3, and 5 months post-surgery. The present research results showed a correlation among the data obtained by micro-CT and the histomorphological results, the gradual disintegration of the biomaterial, and the presence of free scaffold fragments dispersed inside the medullary cavity occupied by hematopoietic bone marrow over the 5-month study period. No difference was found between the DBM-coated and uncoated implants. The new bone tissue inside the implants increased with implantation time. Slightly less new bone formation was observed in the DBM-coated samples, but it was not statistically significant. Both the DBM-coated and the CSP scaffolds gave excellent bone tissue responses and good osteoconductivity.

Nurse's A-Phase Material Enhance Adhesion, Growth and Differentiation of Human Bone Marrow-Derived Stromal Mesenchymal Stem Cells.

The purpose of this study was to evaluate the bioactivity and cell response of a well-characterized Nurse's A-phase (7CaO·P2O5·2SiO2) ceramic and its effect compared to a control (tissue culture polystyrene-TCPS) on the adhesion, viability, proliferation, and osteogenic differentiation of ahMSCs in vitro. Cell proliferation (Alamar Blue Assay), Alizarin Red-S (AR-s) staining, alkaline phosphatase (ALP) activity, osteocalcin (OCN), and collagen I (Col I) were evaluated. Also, field emission scanning electron microscopy (FESEM) images were acquired in order to visualise the cells and the topography of the material. The proliferation of cells growing in a direct contact with the material was slower at early stages of the study because of the new environmental conditions. However, the entire surface was colonized after 28 days of culture in growth medium (GM). Osteoblastic differentiation markers were significantly enhanced in cells growing on Nurse's A phase ceramic and cultured with osteogenic medium (OM), probably due to the role of silica to stimulate the differentiation of ahMSCs. Moreover, calcium nodules were formed under the influence of ceramic material. Therefore, it is predicted that Nurse's A-phase ceramic would present high biocompatibility and osteoinductive properties and would be a good candidate to be used as a biomaterial for bone tissue engineering.

Revising the Subsystem Nurse's A-Phase-Silicocarnotite within the System Ca3(PO4)2-Ca2SiO4.

The subsystem Nurse's A-phase-silicocarnotite within the system Ca3(PO4)2-Ca2SiO4 was conducted as a preliminary step toward obtaining new biomaterials with controlled microstructures. Phase composition of the resulting ceramics was studied by X-ray diffraction, differential thermal analysis, and scanning electron microscopy with attached wavelength dispersive spectroscopy. The results showed that the sub-system presents an invariant eutectoid point at 1366 ± 4 °C with a composition of 59.5 wt % Ca3(PO4)2 and 40.5 wt % Ca2SiO4, and typical eutectoid microstructure of lamellae morphology. These results are in disagreement with the previous reported data, which locate the invariant eutectoid point at 1250 ± 20 °C with a composition of 55 wt % Ca3(PO4)2 and 45 wt % Ca2SiO4. In addition, cell attachment testing showed that the new eutectoid material supported the mesenchymal stem cell adhesion and spreading, and the cells established close contact with the ceramic after 28 days of culture. These findings indicate that the new ceramic material with eutectoid microstructure of lamellae morphology possesses good bioactivity and biocompatibility and might be a promising bone implant material.

Novel Resorbable and Osteoconductive Calcium Silicophosphate Scaffold Induced Bone Formation.

This aim of this research was to develop a novel ceramic scaffold to evaluate the response of bone after ceramic implantation in New Zealand (NZ) rabbits. Ceramics were prepared by the polymer replication method and inserted into NZ rabbits. Macroporous scaffolds with interconnected round-shaped pores (0.5-1.5 mm = were prepared). The scaffold acted as a physical support where cells with osteoblastic capability were found to migrate, develop processes, and newly immature and mature bone tissue colonized on the surface (initially) and in the material's interior. The new ceramic induced about 62.18% ± 2.28% of new bone and almost complete degradation after six healing months. An elemental analysis showed that the gradual diffusion of Ca and Si ions from scaffolds into newly formed bone formed part of the biomaterial's resorption process. Histological and radiological studies demonstrated that this porous ceramic scaffold showed biocompatibility and excellent osteointegration and osteoinductive capacity, with no interposition of fibrous tissue between the implanted material and the hematopoietic bone marrow interphase, nor any immune response after six months of implantation. No histological changes were observed in the various organs studied (para-aortic lymph nodes, liver, kidney and lung) as a result of degradation products being released.

Assessment of Effects of Si-Ca-P Biphasic Ceramic on the Osteogenic Differentiation of a Population of Multipotent Adult Human Stem Cells.

A new type of bioceramic with osteogenic properties, suitable for hard tissue regeneration, was synthesised. The ceramic was designed and obtained in the Nurse's A-phase-silicocarnotite subsystem. The selected composition was that corresponding to the eutectoid 28.39 wt % Nurse's A-phase-71.61 wt % silicocarnotite invariant point. We report the effect of Nurse's A-phase-silicocarnotite ceramic on the capacity of multipotent adult human mesenchymal stem cells (ahMSCs) cultured under experimental conditions, known to adhere, proliferate and differentiate into osteoblast lineage cells. The results at long-term culture (28 days) on the material confirmed that the undifferentiated ahMSCs cultured and in contact with the material surface adhered, spread, proliferated, and produced a mineralised extracellular matrix on the studied ceramic, and finally acquired an osteoblastic phenotype. These findings indicate that it underwent an osteoblast differentiation process. All these findings were more significant than when cells were grown on plastic, in the presence and absence of this osteogenic supplement, and were more evident when this supplement was present in the growth medium (GM). The ceramic evaluated herein was bioactive, cytocompatible and capable of promoting the proliferation and differentiation of undifferentiated ahMSCs into osteoblasts, which may be important for bone integration into the clinical setting.