Fig 2 - available from: Journal of Materials Science: Materials in Medicine
This content is subject to copyright. Terms and conditions apply.
Source publication
To find out the optimal porosity and pore size of porous titanium (Ti) regarding the cytocompatibility and osteogenic differentiation. Six groups of porous Ti samples with different porosities and pore sizes were fabricated by the powder metallurgy process. The microstructure and compressive mechanical properties were characterized. The cytocompati...
Context in source publication
Context 1
... elongated, square, and blunt pores were homogeneously distributed in all group samples and no cracks or defects were detected (Fig. 1). Open and interconnected pores were observed in Group AI, AII, BI, and BII, especially in Group BI, while pores were mostly isolated in Group AIII and BIII (Fig. ...
Citations
... This observation underscores the superior performance of gyroid samples compared to dense counterparts, attributable to their higher surface area and interconnected porosity, facilitating enhanced bone integration. 48 The bone volume fraction of the gyroid (9.6%) was 12-fold higher than that of the dense sample (0.8%). This indicates that the porous sample had improved structural integrity. ...
... For Ti2448-GelMA scaffolds, GelMA was incorporated into the porous interconnected structure of Ti2448 scaffolds ( Figure 1B) and formed a porous network with the mean pore size of 120.2 ± 25.1 μm ( Figures 1C,D). The interconnectivity and proper pore size (>100 μm) were crucially important for the transportation of oxygen/nutrients, cell attachment as well as the vascular growth, which were beneficial for the bone regeneration (Cimenoglu et al., 2011;Wu et al., 2014;Safaei-Yaraziz et al., 2021;Uiiah et al., 2021;Yao et al., 2021). Taking the advantages of 3D printing technology, the porous Ti2448-GelMA scaffolds provides the good interconnectivity with proper pore size (120.2 ...
Repair of large bone defects remains challenge for orthopedic clinical treatment. Porous titanium alloys have been widely fabricated by the additive manufacturing, which possess the elastic modulus close to that of human cortical bone, good osteoconductivity and osteointegration. However, insufficient bone regeneration and vascularization inside the porous titanium scaffolds severely limit their capability for repair of large-size bone defects. Therefore, it is crucially important to improve the osteogenic function and vascularization of the titanium scaffolds. Herein, methacrylated gelatin (GelMA) were incorporated with the porous Ti-24Nb-4Zr-8Sn (Ti2448) scaffolds prepared by the electron beam melting (EBM) method (Ti2448-GelMA). Besides, the deferoxamine (DFO) as an angiogenic agent was doped into the Ti2448-GelMA scaffold (Ti2448-GelMA/DFO), in order to promote vascularization. The results indicate that GelMA can fully infiltrate into the pores of Ti2448 scaffolds with porous cross-linked network (average pore size: 120.2 ± 25.1 μm). Ti2448-GelMA scaffolds facilitated the differentiation of MC3T3-E1 cells by promoting the ALP expression and mineralization, with the amount of calcium contents ∼2.5 times at day 14, compared with the Ti2448 scaffolds. Impressively, the number of vascular meshes for the Ti2448-GelMA/DFO group (∼7.2/mm²) was significantly higher than the control group (∼5.3/mm²) after cultivation for 9 h, demonstrating the excellent angiogenesis ability. The Ti2448-GelMA/DFO scaffolds also exhibited sustained release of DFO, with a cumulative release of 82.3% after 28 days. Therefore, Ti2448-GelMA/DFO scaffolds likely provide a new strategy to improve the osteogenesis and angiogenesis for repair of large bone defects.
... To optimize the elastic modulus and osseointegration performance of titanium alloy materials, several researchers have developed a porous technique. [17][18][19] The porous titanium alloy material has the following advantages over the dense solid: (i) The porous structural design not only satisfies the mechanical strength needs of the to-be-replaced bone tissue but also reduces the elastic modulus to accomplish biomechanical adaptation, thereby successfully reducing or eliminating the "stress shielding" phenomena. 20 (ii) Not only does the porous structure promote the adhesion, proliferation, and differentiation of human cells, but it also improves the movement of body fluids and nutrients. ...
Porous structure is an efficient tool for optimizing the elastic modulus and osseointegration properties of titanium alloy materials. However, the investigations on pore shape remain scarce. In this study, we created porous Ti6Al4V scaffolds with a pore size of 600 μm but different lattices (cubic pentagon, diamond, cuboctahedron). The mechanical and biological properties of the scaffolds were investigated in static simulation analysis, in vitro mechanical compression test, computational fluid dynamics, as well as cell and animal experiments. The results demonstrated that the calculated yield strength difference between the three Ti6Al4V porous scaffolds was negligible, at approximately 140 MPa, allowing them to match the strength requirements of human bones. The diamond scaffold has the lowest calculated elastic modulus (11.6 GPa), which is conducive for preventing stress shielding. The shear stress was largely concentrated in the diamond scaffold, and the stress range of 120–140 MPa accounted for the greatest share. The mouse MC3T3-E1 cells were found to attach to all three scaffolds, with the diamond scaffold displaying a higher degree of cell adherence. There was more proliferating cells on the diamond and cubic pentagon scaffolds than on the cuboctahedron scaffolds (P < 0.05). The diamond scaffold exhibited the highest alkaline phosphatase activity and calcium salt accumulation in cell differentiation tests. Besides, the expression of osteogenic genes on the diamond scaffold was higher than that on the cuboctahedron scaffold, the cubic pentagon scaffold displaying the lowest expression. The in vivo studies revealed that all three scaffolds fused well with the surrounding bone and that there was no loosening or movement of the prosthesis. Micro-computed tomography, corroborated by the staining results of hard tissues, revealed that the level of new bone formation was the highest in the diamond scaffold, followed by the cuboctahedron scaffold (P < 0.05). Taken together, the diamond scaffold is comparatively better at optimizing the elastic modulus and osseointegration properties of titanium alloy materials, and thus is a preferred choice for porous design.
... Research suggests that higher porosity can enhance bone ingrowth, but it can also lead to a decrease in mechanical characteristics such as young's modulus and hardness. Several studies have indicated that increased porosity can enhance bone ingrowth, but this may come at the cost of reduced mechanical properties of the implant, including young's modulus and hardness [62]. As displayed in Figure 10, both the average pore size and porosity decrease with the increasing of Fe content. ...
... Researchers also put high values on the correlation of pore size and porosity [70][71][72][73][74]. Therefore, the correlation of these parameters and mechanical characteristics of the fabricated hydrogels, obtained from the resultant stress-strain curves under uniaxial compressive loading, were depicted by a series of contour plots. ...
The purpose of this study is to design and evaluate a series of porous hydrogels by considering three independent
variables using the Box-Behnken method. Accordingly, concentrations of the constituent macromolecules of the
hydrogels, Polyvinyl Alcohol and Gelatin, and concentration of the crosslinking agent are varied to fabricate sixteen different porous samples utilizing the lyophilization process. Subsequently, the porous hydrogels are subjected to a battery of tests, including Fourier Transform Infrared spectroscopy, morphology assessment, pore-size
study, porosimetry, uniaxial compression, and swelling measurements. Additionally, in-vitro cell assessments are
performed by culturing mouse fibroblast cells (L-929) on the hydrogels, where viability, proliferation, adhesion,
and morphology of the L-929 cells are monitored over 24, 48, and 72 h to evaluate the biocompatibility of these
biomaterials. To better understand the mechanical behavior of the hydrogels under compressive loadings, Deep
Neural Networks (DNNs) are implemented to predict and capture their compressive stress-strain responses as a
function of the constituent materials' concentrations and duration of the performed mechanical tests. Overall,
this study emphasizes the importance of considering multiple variables in the design of porous hydrogels, provides a comprehensive evaluation of their mechanical and biological properties, and, particularly, implements
DNNs in the prediction of the hydrogels' stress-strain responses.
... Cells are subjected to and influenced by various biomechanical stimuli present in their physiological microenvironment [1]: several studies have shown that localized stresses, such as the stiffness [2][3][4][5][6][7], micropatterning [8][9][10][11], porosity [12,13], and geometry of the substrate [14][15][16], strongly influence cell proliferation and differentiation. ...
Cells are influenced by several biomechanical aspects of their microenvironment, such as substrate geometry. According to the literature, substrate geometry influences the behavior of muscle cells; in particular, the curvature feature improves cell proliferation. However, the effect of substrate geometry on the myogenic differentiation process is not clear and needs to be further investigated. Here, we show that the 3D co-printing technique allows the realization of substrates. To test the influence of the co-printing technique on cellular behavior, we realized linear polycaprolactone substrates with channels in which a fibrinogen-based hydrogel loaded with C2C12 cells was deposited. Cell viability and differentiation were investigated up to 21 days in culture. The results suggest that this technology significantly improves the differentiation at 14 days. Therefore, we investigate the substrate geometry influence by comparing three different co-printed geometries—linear, circular, and hybrid structures (linear and circular features combined). Based on our results, all structures exhibit optimal cell viability (>94%), but the linear pattern allows to increase the in vitro cell differentiation, in particular after 14 days of culture. This study proposes an endorsed approach for creating artificial muscles for future skeletal muscle tissue engineering applications.
... 1,3,8,21,22,35,[41][42][43][44][45][46][47] Larger pores have been reported to facilitate nutrient-residue exchange, vascularization, and optimize cell adhesion, but larger pores decrease implant hardness, compressive strength, and modulus of elasticity. 6,42,[48][49][50][51][52] Initial adhesion of osteogenic cells, influenced by the presence of pores on the surface, contributes to bone tissue neoformation and enables better implant outcomes. 6,42,53,54 Thus, the present systematic review aimed to identify the influence of the presence of pores on the titanium surface obtained from AM and its correlation with osteoblastic cell adhesion. ...
... 44 The presence of pores influences the adhesion of osteogenic cells on titanium surfaces produced by AM, as all selected studies showed that porous surfaces increased the cell attachment area by the presence of greater free space, wettability, and a decrease in the elasticity modulus of the implant due to lower density on the surface. [1][2][3]8,21,22,35,[41][42][43][44][45][46][47][48]51 AM can control the diameter, quantity, and interconnectivity of the pores responsible for cell adhesion, migration, and colonization, the promotion of blood capillary formation, and the passage of oxygen and nutrients to the tissues. 17,45,47,52 In the absence of interconnectivity, reduced oxygen flow (hypoxia) and cell necrosis occur, which hinders vascularization and tissue growth. ...
... to maintain its integrity and larger ones near the surface to allow cell activity, prevent occlusion of these pores, and provide adequate yield and compressive strength, hardness, and modulus of elasticity while promoting good cell adhesion and activity. 45 The effect of pores on cell adhesion has been directly related to the density of the titanium alloy used 47,48 ; the lower the density of the structure, the smaller the pore size. 29,47,48 The presence of pores on titanium surfaces improves cellular activity for bone matrix deposition because the pores increase the area of fixation through the larger free space. ...
Statement of problem:
Titanium dental implants produced by additive manufacturing have pores that, depending on their size and quantity, may improve osteogenic cell adhesion without impairing mechanical properties. A systematic review of in vitro studies on this topic is lacking.
Purpose:
The purpose of this systematic review was to answer the question "What is the influence of pores on osteogenic cell adhesion on titanium surfaces produced by additive manufacturing?".
Material and methods:
The study was designed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) 2020 standards and registered in the Open Science Framework (OSF) (osf.io/baw59). A manual search of published articles without language or time restrictions was conducted in November 2022 in the electronic databases PubMed, Scopus, ScienceDirect, Embase, and in the nonpeer-reviewed literature via Google Scholar.
Results:
A total of 1338 initial results were found, and after removing duplicates and applying eligibility criteria, 13 articles were included in this review that, according to the Joanna Briggs Institute (JBI) tool, presented a low risk of bias. Pores with larger diameters provide greater a surface area that favors cell filopodia adhesion and has interconnection that optimizes the transport of nutrients and oxygen and bone cell activity.
Conclusions:
The presence of pores on the surface of titanium produced by additive manufacturing increases the adhesion, migration, proliferation, and viability of osteogenic cells.
... Therefore, additives were omitted in this study to demonstrate a possible effect of the embroidery pattern (porosity and pore size) and functionalization with collagen foam as well as gas-phase fluorination on the differentiation but also on the maintenance of the cellular phenotype. Other studies have also shown that porosity has a significant influence on the differentiation of stem cells [86,87]. Although the filaments were partially covered by a collagen foam, it could be seen not only in the immunocytochemical staining but also in the histological analysis that the migrating cells orientate themselves to the direction of the filaments in order to build up an ordered ECM structure. ...
Successful anterior cruciate ligament (ACL) reconstructions strive for a firm bone-ligament integration. With the aim to establish an enthesis-like construct, embroidered functionalized scaffolds were colonized with spheroids of osteogenically differentiated human mesenchymal stem cells (hMSCs) and lapine (l) ACL fibroblasts in this study. These triphasic poly(L-lactide-co-ε-caprolactone) and polylactic acid (P(LA-CL)/PLA) scaffolds with a bone-, a fibrocartilage transition- and a ligament zone were colonized with spheroids directly after assembly (DC) or with 14-day pre-cultured lACL fibroblast and 14-day osteogenically differentiated hMSCs spheroids (=longer pre-cultivation, LC). The scaffolds with co-cultures were cultured for 14 days. Cell vitality, DNA and sulfated glycosaminoglycan (sGAG) contents were determined. The relative gene expressions of collagen types I and X, Mohawk, Tenascin C and runt-related protein (RUNX) 2 were analyzed. Compared to the lACL spheroids, those with hMSCs adhered more rapidly. Vimentin and collagen type I immunoreactivity were mainly detected in the hMSCs colonizing the bone zone. The DNA content was higher in the DC than in LC whereas the sGAG content was higher in LC. The gene expression of ECM components and transcription factors depended on cell type and pre-culturing condition. Zonal colonization of triphasic scaffolds using spheroids is possible, offering a novel approach for enthesis tissue engineering.
... Taking advantages of high specific strength, excellent corrosion resistance, and outstanding biocompatibility, titanium and its alloys are widely applied in orthopedics and dental implants [18]. Some previous studies [19,20] have shown that porous titanium is beneficial to the proliferation and differentiation of bone cells, promoting the combination of bone cells and implants. For example, Su et al. reported that the nanoporous structures on the Ti6Al4V surface improved the adhesion of osteogenic cells [21]. ...
Manipulating materials at nanoscale is challenging but rewarding. Nanostructures exhibit some unique properties distinguished from macroscopic bulk materials, so fabrication of nanostructures on the material surface is beneficial to broaden their functional applications. In this study, by nanosecond pulse laser irradiation in nitrogen atmosphere, it was found that unique nanoporous structures could be formed on the Ti6Al4V surface. The effects of laser parameters including the laser power, overlap rate, scanning speed, and repetition frequency on the formation and evolution of the nanoporous structures were systematically investigated. By changing the laser parameters, the nanoporous structures with various porosities could be easily achieved on the Ti6Al4V surface. According to the structural evolution and chemical composition, the formation mechanism of the nanoporous structures was discussed. Furthermore, by characterizing the micro-mechanical properties and wettability, it was found that the surface with nanoporous structures exhibited similar surface hardness but improved tribological performances compared to the original Ti6Al4V surface, and the surface wettability could be tuned. This study provides a simple method for fabricating nanoporous structures on the Ti6Al4V surface, which would broaden its functional applications.
... Fluorescent live/dead assays are able to discriminate between live and dead cells by evaluating plasma membrane integrity and the activity of the esterase enzyme, both maintained only in viable cells [54,55,60,62,70,74,75,[77][78][79][80][81][82][83][84]. Other commercial colorimetric assays for the evaluation of cell viability are available on the market and, among the most widely used are the cell counting kit-8 (CCK-8) assay that allows a sensitive colorimetric measure of viable cells, using a water-soluble tetrazolium salt that produces, in presence of active dehydrogenases in living cells, an orange formazan product, and the amount of formazan produced is directly proportional to the number of viable cells [55,57,58,62,73,76,80,81,[85][86][87][88][89]. Moreover, the Alamar Blue assay method is frequently used to assess the metabolic activity of proliferating cells: the active resazurin compound, upon entering living cells, is reduced to resorufin, a red fluorescent molecule that can be quantified [14,59,64,72,75,90,91]. ...
... Different cell lines also find an approved use in the field: the most used is the mouse calvarial preosteoblast MC3T3-E1 cell line [52,54,62,63,71,78,80,82,[85][86][87]90,114]. Other reported cell lines are: human osteosarcoma SaOS-2 cells [56,64,88], the mouse osteoblastic KUSA-A1 cell line [84], the human osteoblast NHOst-Osteoblasts OGM cell line [66], and the human osteosarcoma MG63 osteoblast-like cells [58,95,97]. ...
... In the vast majority of papers in the literature, the expression levels of one or more genes associated with osteoblast differentiation are usually evaluated by quantitative realtime PCR (qRT-PCR) and/or Western blot and/or immunofluorescence analysis and/or ELISA assay [14,55,57,58,60,62,64,65,[68][69][70]72,73,76,77,79,80,[82][83][84]86,87,[89][90][91]94,96,98,100,108,109,113]. Table 3 reports the most representative osteogenic genes usually analyzed. ...
In the last 20 years, bone regenerative research has experienced exponential growth thanks to the discovery of new nanomaterials and improved manufacturing technologies that have emerged in the biomedical field. This revolution demands standardization of methods employed for biomaterials characterization in order to achieve comparable, interoperable, and reproducible results. The exploited methods for characterization span from biophysics and biochemical techniques, including microscopy and spectroscopy, functional assays for biological properties, and molecular profiling. This review aims to provide scholars with a rapid handbook collecting multidisciplinary methods for bone substitute R&D and validation, getting sources from an up-to-date and comprehensive examination of the scientific landscape.
