ABSTRACT
Current immunological issues in bone grafting regarding the transfer of xenogeneic donor bone cells into the recipient are challenging the industry to produce safer acellular natural matrices for bone regeneration. The aim of this study was to investigate the efficacy of a novel decellularization technique for producing bovine cancellous bone scaffold and compare its physicochemical, mechanical, and biological characteristics with demineralized cancellous bone scaffold in an in-vitro study. Cancellous bone blocks were harvested from a bovine femoral head (18-24 months old) subjected to physical cleansing and chemical defatting, and further processed in two ways. Group I was subjected to demineralization, while Group II underwent decellularization through physical, chemical, and enzymatic treatments. Both were then freeze-dried, and gamma radiated, finally producing a demineralized bovine cancellous bone (DMB) scaffold and decellularized bovine cancellous bone (DCC) scaffold. Both DMB and DCC scaffolds were subjected to histological evaluation, scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), fourier-transform infrared spectroscopy (FTIR), quantification of lipid, collagen, and residual nucleic acid content, and mechanical testing. The osteogenic potential was investigated through the recellularization of scaffolds with human osteoblast cell seeding and examined for cell attachment, proliferation, and mineralization by Alizarin staining and gene expression. DCC produced a complete acellular extracellular matrix (ECM) with the absence of nucleic acid content, wider pores with extensive interconnectivity and partially retaining collagen fibrils. DCC demonstrated a higher cell proliferation rate, upregulation of osteogenic differentiation markers, and substantial mineralized nodules production. Our findings suggest that the decellularization technique produced an acellular DCC scaffold with minimal damage to ECM and possesses osteogenic potential through the mechanisms of osteoconduction, osteoinduction, and osteogenesis in-vitro.
Subject(s)
Nucleic Acids , Osteogenesis , Animals , Cattle , Humans , Infant , Child, Preschool , Osteogenesis/physiology , Tissue Scaffolds/chemistry , Tissue Engineering/methods , Cancellous Bone , Collagen , Cell DifferentiationABSTRACT
In the past years, high entropy alloys (HEAs) witnessed great interest because of their superior properties. Phase prediction using machine learning (ML) methods was one of the main research themes in HEAs in the past three years. Although various ML-based phase prediction works exhibited high accuracy, only a few studied the variables that drive the phase formation in HEAs. Those (the previously mentioned work) did that by incorporating domain knowledge in the feature engineering part of the ML framework. In this work, we tackle this problem from a different direction by predicting the phase of HEAs, based only on the concentration of the alloy constituent elements. Then, pruned tree models and linear correlation are used to develop simple primitive prediction rules that are used with self-organizing maps (SOMs) and constructed Euclidean spaces to formulate the problem of discovering the phase formation drivers as an optimization problem. In addition, genetic algorithm (GA) optimization results reveal that the phase formation is affected by the electron affinity, molar volume, and resistivity of the constituent elements. Moreover, one of the primitive prediction rules reveals that the FCC phase formation in the AlCoCrFeNiTiCu family of high entropy alloys can be predicted with 87% accuracy by only knowing the concentration of Al and Cu.
ABSTRACT
Molecular dynamics was applied to simulate ECAP of single-crystal magnesium at room temperature. Four samples with different orientations were processed, and the grain structure, grain fragmentation, slip systems, strain, and twin formation were analyzed. The initial orientation played a substantial role in the strain and deformation experienced by the samples during both stages of deformation. Compressions initially occurred before extrusion, and simple shear occurred in the deformation zone during extrusion. The samples nucleated a { 10 1 ¯ 2 } tension twin during compression, and the tension twin grew to immediately cover the entire sample, effectively changing the orientation of the sample. Additionally, stacking faults acted as a precursor for the { 10 1 ¯ 2 } tension twin. The strain was strongly correlated with the shear factor, that is, a high shear factor resulted in low strain. Moreover, discrepancy occurred between theoretical and actual shear strain due to two factors. First, theoretical shear is considered to be simple shear occurring entirely in the deformation zone; it does not consider the shear strain due to the normal stress in the compression phase. Second, deformation is considered to be homogenous and isotropic, and it does not take into account the initial grain orientation and the anisotropic nature of magnesium.
ABSTRACT
PURPOSE: Not all elements with ß-stabilizing properties in titanium alloys are suitable for biomaterial applications, because corrosion and wear processes release the alloying elements to the surrounding tissue. Chromium and molybdenum were selected as the alloying element in this work as to find balance between the strength and modulus of elasticity of ß-titanium alloys. This study aimed to investigate the effect of Titanium-10Molybdenum-10Chromium (Ti-10Mo-10Cr), Titanium-10Chromium (Ti-10Cr) and Titanium-10Molybdenum (Ti-10Mo) on the elemental leachability in tissue culture environment and their effect on the viability of human gingival fibroblasts (HGFs). METHODS: Each alloy was immersed in growth medium for 0-21 days, and the elution was analyzed to detect the released metals. The elution was further used as the treatment medium and exposed to seeded HGFs overnight. The HGFs were also cultured directly to the titanium alloy for 1, 3 and 7 days. Cell viability was then determined. RESULTS: Six metal elements were detected in the immersion of titanium alloys. Among these elements, molybdenum released from Ti-10Mo-10Cr had the highest concentration throughout the immersion period. Significant difference in the viability of fibroblast cells treated with growth medium containing metals and with direct exposure technique was not observed. The duration of immersion did not significantly affect cell viability. Nevertheless, cell viability was significantly affected after 1 and 7 days of exposure, when the cells were grown directly onto the alloy surfaces. CONCLUSIONS: Within the limitation of this study, the newly developed ß-titanium alloys are non-cytotoxic to human gingival fibroblasts.
