Titanium surface roughness alters responsiveness of MG63 osteoblast-like cells to 1 alpha,25-(OH)2D3

Biocompatibility and dimensional stability through the use of 3D-printed scaffolds made by polycaprolactone and bioglass-7: An in vitro and in vivo study

PURPOSE

This experiment aimed to observe the differences in biological properties by producing BGS-7 + PCL scaffolds with different weight fractions of BGS-7 through 3D printing and to confirm whether using the scaffold for vertical bone augmentation is effective.

MATERIALS AND METHODS

Cube-shaped bioglass (BGS-7) and polycaprolactone (PCL) scaffolds with different weight fractions (PCL alone, PCL with 15% and 30% BGS-7) are produced using 3D printing. The surface hydroxyapatite (HA) apposition, the pH change, proliferation and attachment assays, and various gene expression levels are assessed. After a 7-mm implant was inserted 3 mm into the rabbit calvaria, vertical bone augmentation is performed around the implant and inside the scaffold in four ways: scaffold only, scaffold+bone graft, bone graft only, and no graft. Sacrifice is performed at 6, 12, and 24 weeks, and the various parameters are compared radiographically and histologically.

RESULTS

HA apposition, cell proliferation, cell attachment, and expression of osteogenic genes increase as the proportion of BGS-7 increase. In the in vivo test, a higher bone-implant contact ratio, bone volume ratio, bone mineral density, and new bone area are observed when the scaffold and bone grafts were used together.

CONCLUSION

The 3D-printed scaffold, a mixture of BGS-7 and PCL, exhibit higher biological compatibility as the proportion of BGS-7 increase. Additionally, the use of scaffold is effective for vertical bone augmentation.

Osteoblastic Cell Behavior and Gene Expression Related to Bone Metabolism on Different Titanium Surfaces

The surface topography of titanium dental implants has a great influence on osseointegration. In this work, we try to determine the osteoblastic behavior and gene expression of cells with different titanium surfaces and relate them to the physicochemical properties of the surface. For this purpose, we have used commercial titanium discs of grade 3: as-received corresponds to machined titanium without any surface treatment (MA), chemically acid etched (AE), treated via sand blasting with Al₂O₃ particles (SB) and a sand-blasting treatment with acid etching (SB+AE). The surfaces have been observed using scanning electron microscopy (SEM) and the roughness, wettability and surface energy with dispersive and polar components have been characterized. Osteoblastic cultures were performed with SaOS-2 osteoblastic cells determining cell viability as well as alkaline phosphatase levels for 3 and 21 days, and osteoblastic gene expression was determined. The roughness values of the MA discs was 0.02 μm, which increases to 0.3 μm with acid attack and becomes the maximum for the sand-blasted samples, reaching values of 1.2 μm for SB and SB+AE. The hydrophilic behavior of the MA and AE samples with contact angles of 63° and 65° is superior to that of the rougher samples, being 75° for SB and 82° for SB+AE. In all cases, they show good hydrophilicity. GB and GB+AE surfaces present a higher polar component in the surface energy values, 11.96 and 13.18 mJ/m², respectively, than AE and MA, 6.64 and 9.79 mJ/m², respectively. The osteoblastic cell viability values at three days do not show statistically significant differences between the four surfaces. However, the viability of the SB and SB+AE surfaces at 21 days is much higher than that of the AE and MA samples. From the alkaline phosphatase studies, higher values were observed for those treated with sand blasting with and without acid etching compared to the other two surfaces, indicating a greater activity in osteoblastic differentiation. In all cases except in the Osterix (Ostx) -osteoblast-specific transcription factor-a decrease in gene expression is observed in relation to the MA samples (control). The most important increase was observed for the SB+AE condition. A decrease in the gene expression of Osteoprotegerine (OPG), Runt-related transcription factor 2 (Runx2), Receptor Activator of NF-κB Ligand (RANKL) and Alkaline Phosphatase (Alp) genes was observed in the AE surface.

Porous construction and surface modification of titanium-based materials for osteogenesis: A review

Titanium and titanium alloy implants are essential for bone tissue regeneration engineering. The current trend is toward the manufacture of implants from materials that mimic the structure, composition and elasticity of bones. Titanium and titanium alloy implants, the most common materials for implants, can be used as a bone conduction material but cannot promote osteogenesis. In clinical practice, there is a high demand for implant surfaces that stimulate bone formation and accelerate bone binding, thus shortening the implantation-to-loading time and enhancing implantation success. To avoid stress shielding, the elastic modulus of porous titanium and titanium alloy implants must match that of bone. Micro-arc oxidation technology has been utilized to increase the surface activity and build a somewhat hard coating on porous titanium and titanium alloy implants. More recently, a growing number of researchers have combined micro-arc oxidation with hydrothermal, ultrasonic, and laser treatments, coatings that inhibit bacterial growth, and acid etching with sand blasting methods to improve bonding to bone. This paper summarizes the reaction at the interface between bone and implant material, the porous design principle of scaffold material, MAO technology and the combination of MAO with other technologies in the field of porous titanium and titanium alloys to encourage their application in the development of medical implants.

The modern Burch-Schneider antiprotrusio cage for the treatment of acetabular defects: is it still an option? A systematic review

BACKGROUND

A number of papers have been published about the clinical performance of modern rough-blasted titanium Burch-Schneider antiprotrusio cages (BS-APCs) for the treatment of acetabular bone defects. However, no systematic review of the literature has been published to date.

METHODS

The US National Library of Medicine (PubMed/MEDLINE), EMBASE, and the Cochrane Database of Systematic Reviews were queried for publications using keywords pertinent to Burch-Schneider antiprotrusio cage, revision THA, and clinical outcomes.

RESULTS

8 articles were found to be suitable for inclusion in the present study in which 374 cases (370 patients) had been treated with modern BS-APCs. Most acetabular bone defects were type 3 according to the Paprosky classification (type 2C: 18.1%, 3A: 51%, and 3B: 28.9%). The overall re-revision rate for the 374 acetabular reconstructions with modern BS-APCs was 11.5% (43 cases). The short-term survival rate of the modern BS-APC construct was 90.6% (339 out of 374 cases), while the mid-term survival rate was 85.6% (320 out of 374 cases), and the long-term survival rate 62% (54 out of 87 cases). The most common reasons for revision were aseptic loosening (5.6%), periprosthetic joint infection (3.8%), dislocation (2.7%), and acetabular periprosthetic fracture (1.9%).

CONCLUSIONS

There was moderate quality evidence to show that the use of modern rough blasted titanium BS-APCs in cases of acetabular bone loss has an unacceptably high failure rate (38%). Given that antiprotrusio cages do not provide any biological fixation, we would not recommend the routine use of modern BS-APCs in complex revision THA cases. By contrast, the satisfactory short- to mid-term outcome of modern BS-APCs in combination with their low cost compared to highly porous acetabular implants, make us feel that BS-APCs might still be used in selected elderly or low-demand patients without severe superomedial acetabular bone loss.

Novel insights into the coupling of osteoclasts and resorption to bone formation

Bone remodeling consists of resorption by osteoclasts (OCs) and formation by osteoblasts (OBs). Precise coordination of these activities is required for the resorbed bone to be replaced with an equal amount of new bone in order to maintain skeletal mass throughout the lifespan. This coordination of remodeling processes is referred to as the "coupling" of resorption to bone formation. In this review, we discuss the essential role for OCs in coupling resorption to bone formation, mechanisms for this coupling, and how coupling becomes less efficient or disrupted in conditions of bone loss. Lastly, we provide perspectives on targeting coupling to treat human bone disease.

The Surface Conditions and Composition of Titanium Alloys in Implantology: A Comparative Study of Dental Implants of Different Brands

The success of titanium dental implants depends on their osseointegration into the bone, which is determined by the composition and surface properties of the implant in close contact with the bone. There is a wide variety of implants on the market. Is it possible to identify the implant with the best composition and surface topography for optimal osseointegration? To this aim, 13 brands of dental implants from nine distinct manufacturers have been selected and their composition and surface topography determined. The obtained results show differences between these implants, in this case, the Ssk averages of the three measurements performed on each implant were positive, or 0.4 (0.1-0.8), indicating that the roughness of all implants analyzed was primarily textured and not flat. Like Sa, we found the highest Sdr for implants subjected only to sandblasting. In addition, only the ALS-active^® implant had a modified microstructure on its surface. However, analysis of the NANOTITE implant surface revealed a 1.40% presence of calcium which we consider too low to have an effect on bone formation around the implant. As a result, we have also highlighted the lack of a recognized independent standard for dental implant surface conditions and the lack of independent quality control vis-à-vis manufacturers. Of all the surface types studied, none proved more satisfactory than another.

Differential Effects of Neurectomy and Botox-induced Muscle Paralysis on Bone Phenotype and Titanium Implant Osseointegration

Metabolic bone is highly innervated by both sensory and sympathetic nerves. In addition to skeletal development, neural regulation participates in local bone remodeling, which is important for successful osseointegration of titanium implants. Neurectomy is a model used to investigate the lack of neural function on bone homeostasis, but the relative impacts of direct denervation to bone or denervation-induced muscle paralysis are less well defined. To investigate this difference, we used two nerve intervention models, sciatic and femoral neurectomy (SFN) v. botox-induced muscle paralysis (BTX) and assessed the resulting femoral bone phenotype and Ti implant osseointegration. Male Sprague Dawley rats (19) were randomly divided into three groups: implant control (n = 5), SFN (n = 7), and BTX (n = 7). Ti implants (microrough/hydrophilic [modSLA], Institut Straumann AG) were placed in the distal metaphysis of each femur on day 24 post-SFN or BTX. Bone and muscle were examined on day 28 after implant insertion. Both nerve intervention models impaired osseointegration. MicroCT and histology indicated that both models had reduced trabecular bone formation. Only BTX reduced cortical bone formation and increased cortical bone porosity. BTX resulted in more bone loss characterized by the least trabecular and cortical bone, as well as osseointegration. Osteoblasts isolated from the tibia exhibited a model-specific phenotype when they were grown on Ti substrates in vitro. Neurectomy caused more severe muscle atrophy than botox injection. These results indicate that neural regulation directly modulates bone formation and osseointegration. Muscle paralysis modulated the effects of loss of neural inputs into bone, supporting the hypothesis that mechanical loading of bone is a factor in achieving successful osseointegration. The different effects of botox and neurectomy on bone phenotype indicated that the sensory and sympathetic nerves had a role in the osseointegration process.

Vacuum plasma sprayed porous titanium coating on polyetheretherketone for ACDF improves the osteogenic ability: An in vitro and in vivo study

Cervical degenerative disease is a common and frequently occurring disease, which seriously affects the health and quality of the life of patients worldwide. Anterior cervical decompression and interbody fusion is currently recognized as the gold standard for the treatment of degenerative cervical spondylosis. Polyetheretherketone (PEEK) has become the prevailing material for cervical fusion surgery. Although PEEK has excellent biocompatibility, it is difficult to form bone connection at its bone-implant interface due to its low surface hydrophilicity and conductivity. It is widely accepted that Ti has excellent osteogenic activity and biocompatibility. In this study, a Ti-PEEK composite cage was prepared by coating Ti on the surface of a PEEK cage using a vacuum plasma spraying technique to enhance the osteogenic property of PEEK. The Ti-PEEK samples were evaluated in terms of their in vitro cellular behaviors and in vivo osteointegration, and the results were compared to a pure PEEK substrate. The skeleton staining and MTS assay indicated that the MC3T3-E1 cells spread and grew well on the surface of Ti-PEEK cages. The osteogenic gene expression and western blot analysis of osteogenic protein showed upregulated bone-forming activity of MC3T3-E1 cells in Ti-PEEK cages. Furthermore, a significant increase in new bone formation was demonstrated on Ti-PEEK implants in comparison with PEEK implants at 12 weeks in a sheep cervical spine fusion test. These results proved that the Ti-PEEK cage exhibited enhanced osseointegrative properties compared to the PEEK cage both in vitro and in vivo.

One-Step Fabrication of Low-Cost, Autoclavable, and Multifunctional Silk-Based Nanofibrous Permeable Hanging Cell Culture Inserts for Various Biological Applications

Hanging cell culture inserts are most widely used in vitro cell culture devices, which provide a freestanding multichamber setup for various co-culture and triculture systems. Apart from being costly, the commercial inserts do not provide enough choices regarding polymer types and pore sizes. Most importantly, commercially available inserts are two-dimensional multiporous membrane-based devices. Herein, we report a one-step fabrication process of the multifunctional nanofiber-based permeable hanging cell culture insert using electrospinning. These fabricated nanofibrous membranes' attached inserts have advantages such as low cost, ready availability, easy fabrication, tunable porosity, autoclavability, and biomaterial-based nanofibrous membranes. The inserts without nanofibrous membrane can also be reused by autoclaving them and electrospun nanofibrous membrane on it according to the application. We have also confirmed its suitability for extensive use in the field of in vitro cell culture by analyzing its adherence and toxicity results on breast cancer cell line (MCF-7). These hanging cell culture inserts are thus a potent product for various cell culture assays such as cell migration for wound healing, cancer metastasis, and other tissue engineering applications.

Molecular Mechanisms of Topography Sensing by Osteoblasts: An Update

Bone is a specialized tissue formed by different cell types and a multiscale, complex mineralized matrix. The architecture and the surface chemistry of this microenvironment can be factors of considerable influence on cell biology, and can affect cell proliferation, commitment to differentiation, gene expression, matrix production and/or composition. It has been shown that osteoblasts encounter natural motifs in vivo, with various topographies (shapes, sizes, organization), and that cell cultures on flat surfaces do not reflect the total potential of the tissue. Therefore, studies investigating the role of topographies on cell behavior are important in order to better understand the interaction between cells and surfaces, to improve osseointegration processes in vivo between tissues and biomaterials, and to find a better topographic surface to enhance bone repair. In this review, we evaluate the main available data about surface topographies, techniques for topographies’ production, mechanical signal transduction from surfaces to cells and the impact of cell–surface interactions on osteoblasts or preosteoblasts’ behavior.

Mechanical and Physical Regulation of Fibroblast-Myofibroblast Transition: From Cellular Mechanoresponse to Tissue Pathology

Fibroblasts are cells present throughout the human body that are primarily responsible for the production and maintenance of the extracellular matrix (ECM) within the tissues. They have the capability to modify the mechanical properties of the ECM within the tissue and transition into myofibroblasts, a cell type that is associated with the development of fibrotic tissue through an acute increase of cell density and protein deposition. This transition from fibroblast to myofibroblast-a well-known cellular hallmark of the pathological state of tissues-and the environmental stimuli that can induce this transition have received a lot of attention, for example in the contexts of asthma and cardiac fibrosis. Recent efforts in understanding how cells sense their physical environment at the micro- and nano-scales have ushered in a new appreciation that the substrates on which the cells adhere provide not only passive influence, but also active stimulus that can affect fibroblast activation. These studies suggest that mechanical interactions at the cell-substrate interface play a key role in regulating this phenotype transition by changing the mechanical and morphological properties of the cells. Here, we briefly summarize the reported chemical and physical cues regulating fibroblast phenotype. We then argue that a better understanding of how cells mechanically interact with the substrate (mechanosensing) and how this influences cell behaviors (mechanotransduction) using well-defined platforms that decouple the physical stimuli from the chemical ones can provide a powerful tool to control the balance between physiological tissue regeneration and pathological fibrotic response.

Quantitative Investigation of the Process Parameters of Electrohydrodynamic Direct-Writing and Their Effects on Fiber Surface Roughness and Cell Adhesion

Electrohydrodynamic (EHD) direct-writing has been widely used to fabricate micro/nanofibers that can serve as a building block in tissue engineering scaffolds. However, the application of EHD direct-writing in tissue engineering is limited by the lack of fundamental knowledge in the correlations among the process parameters, the fiber surface roughness, and the cell adhesion performance. Without a standardized experimental setting and the quantitative database, inconsistent results have been reported. Here, we quantitatively investigate the process–structure–property relationships as the first step towards a better understanding of the EHD direct-writing technology for tissue engineering. Polycaprolactone (PCL) solution is used as a model ink material, and human mesenchymal stem cells (hMSCs) are used to study cell adhesion on PCL fibers. We investigate the different jetting modes defined by the applied voltage, the feed rate, and the nozzle–collector distance. The quantitative effects of process parameters on the fiber surface roughness and the cell adhesion performance are experimentally determined. The quantitative process–structure–property relationships revealed in this study provide guidelines for controlling the surface roughness and the cell adhesion performance of EHD direct-written fibers. This study will facilitate the application of EHD direct-writing in tissue engineering.

Bisphosphonates inhibit surface-mediated osteogenesis

Bisphosphonates (BPs) target osteoclasts, slowing bone resorption thus providing rationale to support osseointegration. However, BPs may negatively affect osteoblasts, impairing peri-implant bone formation. The goal of this study was to assess the effects BPs have on surface-mediated osteogenesis of osteoblasts. MG63 cells were cultured on 15-mm grade 2 titanium disks: smooth, hydrophobic-microrough, or hydrophilic-microrough (Institut Straumann AG, Basel, Switzerland). Tissue culture polystyrene (TCPS) was used as a control. At confluence, cells were treated with 0, 10^-8 , 10^-7 , and 10^-6 M of alendronate, zoledronate, or ibandronate for 24 hr. Sprague Dawley rats were also treated with 1 μg/kg/day ibandronate or phosphate-buffered saline control for 5 weeks. Calvarial osteoblasts (rat osteoblasts [rOBs]) were isolated, characterized, and cultured on surfaces. Osteogenic markers in the media were quantified using ELISAs. BP treatment reduced osteocalcin, osteoprotegerin, osteopontin, bone morphogenetic protein-2, prostaglandin E₂ , transforming growth factor β1, interleukin 10, and vascular endothelial growth factor in MG63 cells. The effect was more robust on rough surfaces, and higher concentrations of BPs stunted production to TCPS/PT levels. Ibandronate conditioned rOBs produced less osteogenic markers similar to direct BP treatment. These results suggest that BP exposure jeopardizes the pro-osteogenic response osteoblasts have to microstructured surfaces. Their effects persist in vivo and negatively condition osteoblast response in vitro. Clinically, BPs could compromise osseointegration.

In Situ Controlled Surface Microstructure of 3D Printed Ti Alloy to Promote Its Osteointegration

It is well known that three-dimensional (3D) printing is an emerging technology used to produce customized implants and surface characteristics of implants, strongly deciding their osseointegration ability. In this study, Ti alloy microspheres were printed under selected rational printing parameters in order to tailor the surface micro-characteristics of the printed implants during additive manufacturing by an in situ, controlled way. The laser path and hatching space were responsible for the appearance of the stripy structure (S), while the bulbous structure (B) and bulbous⁻stripy composite surface (BS) were determined by contour scanning. A nano-sized structure could be superposed by hydrothermal treatment. The cytocompatibility was evaluated by culturing Mouse calvaria-derived preosteoblastic cells (MC3T3-E1). The results showed that three typical microstructured surfaces, S, B, and BS, could be achieved by varying the 3D printing parameters. Moreover, the osteogenic differentiation potential of the S, B, and BS surfaces could be significantly enhanced, and the addition of nano-sized structures could be further improved. The BS surface with nano-sized structure demonstrated the optimum osteogenic differentiation potential. The present research demonstrated an in situ, controlled way to tailor and optimize the surface structures in micro-size during the 3D printing process for an implant with higher osseointegration ability.

The impact of implant abutment surface treatment with TiO2 on peri-implant levels of angiogenesis and bone-related markers: a randomized clinical trial

The goal of this randomized, blinded, split-mouth controlled clinical trial was to assess the influence of abutment surface treatment on tissue healing. Fifteen patients received two implants distributed randomly to two groups: test (TiO₂ abutment surface), control (standard abutment surface). Levels of epidermal growth factor (EGF), bone morphogenetic protein 9 (BMP-9), endothelin 1 (ET-1), fibroblast growth factor (FGF), placental growth factor (PlGF), and vascular endothelial growth factor (VEGF) were quantified in the peri-implant fluid after 3, 14, 30, and 60 days. Inter-group comparisons indicated higher levels of EGF, BMP-9, ET-1, FGF, and PlGF in the test group after 30days (P<0.05). PlGF levels were also higher in the test group after 60 days. In the test group, intra-group analysis revealed different levels of ET-1 and FGF between days 3 and 30, and days 3 and 60 (P<0.05); furthermore, VEGF levels were significantly higher on day 60 than on day 3 (P <0.05). In the control group, intra-group analysis demonstrated significantly different levels of ET-1, FGF, and PlGF between days 3 and 60 and of PlGF between days 14 and 60 (P<0.05). In conclusion, abutment surfaces treated with TiO₂ influenced the levels of angiogenesis and bone-related markers.

Osseointegration and current interpretations of the bone-implant interface

Complex physical and chemical interactions take place in the interface between the implant surface and bone. Various descriptions of the ultrastructural arrangement to various implant design features, ranging from solid and macroporous geometries to surface modifications on the micron-, submicron-, and nano- levels, have been put forward. Here, the current knowledge regarding structural organisation of the bone-implant interface is reviewed with a focus on solid devices, mainly metal (or alloy) intended for permanent anchorage in bone. Certain biomaterials that undergo surface and bulk degradation are also considered. The bone-implant interface is a heterogeneous zone consisting of mineralised, partially mineralised, and unmineralised areas. Within the meso-micro-nano-continuum, mineralised collagen fibrils form the structural basis of the bone-implant interface, in addition to accumulation of non-collagenous macromolecules such as osteopontin, bone sialoprotein, and osteocalcin. In the published literature, as many as eight distinct arrangements of the bone-implant interface ultrastructure have been described. The interpretation is influenced by the in vivo model and species-specific characteristics, healing time point(s), physico-chemical properties of the implant surface, implant geometry, sample preparation route(s) and associated artefacts, analytical technique(s) and their limitations, and non-compromised vs compromised local tissue conditions. The understanding of the ultrastructure of the interface under experimental conditions is rapidly evolving due to the introduction of novel techniques for sample preparation and analysis. Nevertheless, the current understanding of the interface zone in humans in relation to clinical implant performance is still hampered by the shortcomings of clinical methods for resolving the finer details of the bone-implant interface. STATEMENT OF SIGNIFICANCE: Being a hierarchical material by design, the overall strength of bone is governed by composition and structure. Understanding the structure of the bone-implant interface is essential in the development of novel bone repair materials and strategies, and their long-term success. Here, the current knowledge regarding the eventual structural organisation of the bone-implant interface is reviewed, with a focus on solid devices intended for permanent anchorage in bone, and certain biomaterials that undergo surface and bulk degradation. The bone-implant interface is a heterogeneous zone consisting of mineralised, partially mineralised, and unmineralised areas. Within the meso-micro-nano-continuum, mineralised collagen fibrils form the structural basis of the bone-implant interface, in addition to accumulation of non-collagenous macromolecules such as osteopontin, bone sialoprotein, and osteocalcin.

The effect of surface topography and porosity on the tensile fatigue of 3D printed Ti-6Al-4V fabricated by selective laser melting

Additive manufacturing (3D printing) is emerging as a key manufacturing technique in medical devices. Selective laser melted (SLM) Ti-6Al-4V implants with interconnected porosity have become widespread in orthopedic applications where porous structures encourage bony ingrowth and the stiffness of the implant can be tuned to reduce stress shielding. The SLM technique allows high resolution control over design, including the ability to introduce porosity with spatial variations in pore size, shape, and connectivity. This study investigates the effect of construct design and surface treatment on tensile fatigue behavior of 3D printed Ti-6Al-4V. Samples were designed as solid, solid with an additional surface porous layer, or fully porous, while surface treatments included commercially available rotopolishing and SILC cleaning. All groups were evaluated for surface roughness and tested in tension to failure under monotonic and cyclic loading profiles. Surface treatments were shown to reduce surface roughness for all sample geometries. However, only fatigue behavior of solid samples was improved for treated as compared to non-treated surfaces Irrespective of surface treatment and resulting surface roughness, the fatigue strength of 3D printed samples containing bulk or surface porosity was approximately 10% of the ultimate tensile strength of identical 3D printed porous material. This study highlights the relative effect of surface treatment in solid and porous printed samples and the inherent decrease in fatigue properties of 3D printed porous samples designed for osseointegration.

VEGF-A regulates angiogenesis during osseointegration of Ti implants via paracrine/autocrine regulation of osteoblast response to hierarchical microstructure of the surface

Establishment of a patent vasculature at the bone-implant interface plays a significant role in determining overall success of orthopedic and dental implants. Osteoblasts produce vascular endothelial growth factor-A (VEGF-A), an important regulator of angiogenesis during bone formation and healing, and the amount secreted is sensitive to titanium (Ti) surface microtopography and surface energy. The purpose of this study was to determine if surface properties modulate cellular response to VEGF-A. MG63 osteoblast-like cells were transfected with shRNA targeting VEGF-A at >80% knockdown. Cells stably silenced for VEGF-A secreted reduced levels of osteocalcin, osteoprotegerin, FGF-2, and angiopoietin-1 when cultured on grit-blasted/acid-etched (SLA) and hydrophilic SLA (modSLA) Ti surfaces and conditioned media from these cultures caused reduced angiogenesis in an endothelial tubule formation assay. Treatment of MG63 cells with 20 ng/mL rhVEGF-A₁₆₅ rescued production in silenced cells and increased production of osteocalcin, osteoprotegerin, FGF-2, and angiopoietin-1, with greatest effects on control cells cultured on modSLA. Addition of a neutralization antibody against VEGF receptor 2 (VEGFR2; Flk-1) resulted in a significant increase in VEGF-A production. Overall, this study indicates that VEGF-A has two roles in osseointegration: enhanced angiogenesis and an autocrine/paracrine role in maturation of osteoblast-like cells in response to Ti surface properties. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 423-433, 2019.

Human osteoblasts exhibit sexual dimorphism in their response to estrogen on microstructured titanium surfaces

BACKGROUND

Osseointegration is dependent on the implant surface, surrounding bone quality, and the systemic host environment, which can differ in male and female patients. Titanium (Ti) implants with microstructured surfaces exhibit greater pullout strength when compared to smooth-surfaced implants and exhibit enhanced osteogenic cellular responses in vitro. Previous studies showed that 1α,25-dihydroxyvitamin D3 [1α,25(OH)₂D₃] has a greater effect on rat osteoblast differentiation on microstructured Ti compared to smooth Ti surfaces and tissue culture polystyrene (TCPS). The stimulatory effect of 17β-estradiol (E₂) on differentiation is observed in female osteoblasts on micro-rough Ti, but it is not known if male osteoblasts behave similarly in response to E₂ and microtopography. This study assessed whether human male and female osteoblasts exhibit sex-specific differences in response to E₂ and 1α,25(OH)₂D₃ when cultured on microstructured Ti surfaces.

METHODS

Osteoblasts from three male and three female human donors were cultured on Ti discs with varying surface profiles: a smooth pretreatment (PT), a coarse grit-blasted/acid-etched (SLA), and an SLA surface having undergone modification in a nitrogen environment and stored in saline to maintain hydrophilicity (modSLA). Cells cultured on these surfaces were treated with E₂ or 1α,25(OH)₂D₃.

RESULTS

Male and female human osteoblasts responded similarly to microstructure although there were donor-specific differences; cell number decreased, and osteocalcin (OCN), osteoprotegerin (OPG), and latent and active transforming growth factor 1 increased on SLA and modSLA compared to TCPS. Female osteoblasts had higher alkaline phosphatase activity and OCN production than male counterparts but produced less OPG. Both sexes responded similarly to 1α,25(OH)₂D₃. E₂ treatment reduced cell number and increased osteoblast differentiation and factor production only in female cells.

CONCLUSIONS

Male and female human osteoblasts respond similarly to microstructure and 1α,25(OH)₂D₃ but exhibit sexual dimorphism in substrate-dependent responses to E₂. E₂ affected female osteoblasts, suggesting that signaling is sex-specific and surface-dependent. Donor osteoblasts varied in response, demonstrating the need to test multiple donors when examining human samples. Understanding how male and female cells respond to orthopedic biomaterials will enable greater predictability post-implantation as well as therapies that are more patient-specific.

The impact of photofunctionalized gold nanoparticles on osseointegration

OBJECTIVES

The aims of this study were to create a new surface topography using simulated body fluids (SBF) and Gold Nanoparticles (GNPs) and then to assess the influence of UV Photofunctionalization (PhF) on the osteogenic capacity of these surfaces.

MATERIALS AND METHODS

Titanium plates were divided into six groups All were acid etched with 67% Sulfuric acid, 4 were immersed in SBF and 2 of these were treated with 10 nm GNPs. Half of the TiO2 plates were photofunctionalized to be compared with the non-PhF ones. Rat's bone marrow stem cells were seeded into the plates and then CCK8 assay, cell viability assay, immunofluorescence, and Scanning electron microscopy (SEM) were done after 24 hours. Gene expression analysis was done using real time quantitative PCR (qPCR) one week later to check for the mRNA expression of Collagen-1, Osteopontin and Osteocalcin. Alkaline phosphatase (ALP) activity was assessed after 2 weeks of cell seeding.

RESULTS

Our new topography has shown remarkable osteogenic potential. The new surface was the most biocompatible, and the 10 nm GNPs did not show any cytotoxicity. There was a significant increase in bioactivity, enhanced gene expressions and ALP activity.

CONCLUSIONS

GNPs enhances osteogenic differentiation of stem cells and Photofunctionalizing GNPs highly increases this. We have further created a novel highly efficient topography which highly enhances the speed and extent of osseointegration. This may have great potential for improving treatment outcomes for implant, maxillofacial as well as orthopedic patients.

Osseointegration of Sandblasted or Anodised Hydrothermally-Treated Titanium Implants: Mechanical, Histomorphometric and Bone Hardness Measurements

The improvement of the implant-bone interface is still an open problem in the long-term mechanical stability of cementless fixed implants. Mechanical, histomorphometric and bone hardness measurements were performed in sheep femoral cortical bone implants at 8 and 12 weeks from surgery to compare in vivo the osseointegration of titanium screws (Ø 3.5 mm × 7 mm length) with two different surface treatments: sandblasting with 70–100 μm HA followed by acid etching with HNO3 (Group A) and Ca-P anodization followed by a hydrothermal treatment (Group B). No significant differences were found for maximum push-out force and interfacial strength between groups at both experimental times. No significant difference was observed for Bone Ingrowth between groups at both experimental times, while the Affinity Index of Group B was significantly higher (7.5%, p<0.05) and lower (10.2%, p<0.05) than that of Group A at 8 and 12 weeks, respectively. Finally, a significant increase in bone microhardness measured within 200 μm from the interface and inside the thread depth of Group A was observed between the two experimental times (p<0.05). In conclusion, present findings show that osseointegration may be accelerated by adequate surface roughness and bioactive ceramic coating such as current tested treatments which enhance bone interlocking and mineralization.

Biomaterials in Orthopedic Surgery: Effects of a Nickel-Reduced Stainless Steel on in Vitro Proliferation and Activation of Human Osteoblasts

A new austenitic stainless steel compound, P558, has been widely recognized to have good mechanical properties, excellent potential for corrosion resistance and negligible nickel ion release, making it a promising substitute for more expensive metallic prostheses with limited machinable features. The effect of P558 was studied in vitro and human osteoblast- like cells (MG63) were cultured directly on P558, Ti6Al4V alloy (Ti), and polystyrene (Control) for 72 hours. Osteoblast functions were evaluated by assaying cell proliferation and synthetic activity after 1.25(OH)2D3 stimulation. Results demonstrated that growth of MG63 on P558 was not negatively affected when compared to the Ti and Control groups and showed no alteration in the production of ALP, NO and PICP. Moreover, IL-6 was lower, whereas OC and TGFbeta1 were significantly higher. SEM images revealed that cells proliferated and differentiated on P558 without any alteration in their morphology. The current findings have demonstrated that P558 promotes osteoblast proliferation, activation and differentiation without negative effects and, thus, its good biocompatibility when used for orthopedic application.

Bone Response to Two Dental Implants with Different Sandblasted/Acid-Etched Implant Surfaces: A Histological and Histomorphometrical Study in Rabbits

Background

Scientific evidence in the field of implant dentistry of the past 20 years established that titanium rough surfaces have shown improved osseointegration rates. In a majority of dental implants, the surface microroughness was obtained by grit blasting and/or acid etching. The aim of the study was to evaluate in vivo two different highly hydrophilic surfaces at different experimental times.

Methods

Calcium-modified (CA) and SLActive surfaces were evaluated and a total of 18 implants for each type of surface were positioned into the rabbit articular femoral knee-joint in a split model experiment, and they were evaluated histologically and histomorphometrically at 15, 30, and 60 days of healing.

Results

Bone-implant contact (BIC) at the two-implant surfaces was significantly different in favor of the CA surface at 15 days (p = 0.027), while SLActive displayed not significantly higher values at 30 (p = 0.51) and 60 days (p = 0.061).

Conclusion

Both implant surfaces show an intimate interaction with newly formed bone.

Bioactive Coating with Two-Layer Hierarchy of Relief Obtained by Sol-Gel Method with Shock Drying and Osteoblast Response of Its Structure

In this work, we analyze the efficiency of the modification of the implant surface. This modification was reached by the formation of a two-level relief hierarchy by means of a sol-gel approach that included dip coating with subsequent shock drying. Using this method, we fabricated a nanoporous layer with micron-sized defects on the nanotitanium surface. The present work continues an earlier study by our group, wherein the effect of osteoblast-like cell adhesion acceleration was found. In the present paper, we give the results of more detailed evaluation of coating efficiency. Specifically, cytological analysis was performed that included the study of the marker levels of osteoblast-like cell differentiation. We found a significant increase in the activity of alkaline phosphatase at the initial incubation stage. This is very important for implantation, since such an effect assists the decrease in the induction time of implant engraftment. Moreover, osteopontin expression remains high for long expositions. This indicates a prolonged osteogenic effect in the coating. The results suggest the acceleration of the pre-implant area mineralization and, correspondingly, the potential use of the developed coatings for bone implantation.

Effects of glucose concentration on osteogenic differentiation of type II diabetes mellitus rat bone marrow-derived mesenchymal stromal cells on a nano-scale modified titanium

BACKGROUND AND OBJECTIVE

Diabetes mellitus (DM) is a common disease worldwide. Patients with DM have an increased risk of losing their teeth compared with other individuals. Dental implants are a standard of care for treating partial or full edentulism, and various implant surface treatments have recently been developed to increase dental implant stability. However, some studies have reported that DM reduces osseointegration and the success rate of dental implants. The purpose of this study was to determine the effects of high glucose levels for hard tissue formation on a nano-scale modified titanium surface.

MATERIAL AND METHODS

Titanium disks were heated at 600°C for 1 h after treatment with or without 10 m NaOH solution. All disks were incubated with type II DM rat bone marrow-derived mesenchymal stromal cells before exposure to one of four concentrations of glucose (5.5, 8.0, 12.0 or 24.0 mm). The effect of different glucose concentrations on bone marrow-derived mesenchymal stromal cell osteogenesis and inflammatory cytokines on the nano-scale modified titanium surface was evaluated.

RESULTS

Alkaline phosphatase activity decreased with increasing glucose concentration. In contrast, osteocalcin production and calcium deposition were significantly decreased at 8.0 mm glucose, but increased with glucose concentrations over 8.0 mm. Differences in calcium/phosphate ratio associated with the various glucose concentrations were similar to osteocalcin production and calcium deposition. Inflammatory cytokines were expressed at high glucose concentrations, but the nano-scale modified titanium surface inhibited the effect of high glucose concentrations.

CONCLUSION

High glucose concentration increased hard tissue formation, but the quality of the mineralized tissue decreased. Furthermore, the nano-scale modified titanium surface increased mineralized tissue formation and anti-inflammation, but the quality of hard tissue was dependent on glucose concentration.

Implant Surface Design Regulates Mesenchymal Stem Cell Differentiation and Maturation

Changes in dental implant materials, structural design, and surface properties can all affect biological response. While bulk properties are important for mechanical stability of the implant, surface design ultimately contributes to osseointegration. This article reviews the surface parameters of dental implant materials that contribute to improved cell response and osseointegration. In particular, we focus on how surface design affects mesenchymal cell response and differentiation into the osteoblast lineage. Surface roughness has been largely studied at the microscale, but recent studies have highlighted the importance of hierarchical micron/submicron/nanosurface roughness, as well as surface roughness in combination with surface wettability. Integrins are transmembrane receptors that recognize changes in the surface and mediate downstream signaling pathways. Specifically, the noncanonical Wnt5a pathway has been implicated in osteoblastic differentiation of cells on titanium implant surfaces. However, much remains to be elucidated. Only recently have studies been conducted on the differences in biological response to implants based on sex, age, and clinical factors; these all point toward differences that advocate for patient-specific implant design. Finally, challenges in implant surface characterization must be addressed to optimize and compare data across studies. An understanding of both the science and the biology of the materials is crucial for developing novel dental implant materials and surface modifications for improved osseointegration.

Neuroregeneration of Induced Pluripotent Stem Cells in Polyacrylamide-Chitosan Inverted Colloidal Crystal Scaffolds with Poly(lactide-co-glycolide) Nanoparticles and Transactivator of Transcription von Hippel-Lindau Peptide

Polyacrylamide (PAAM) and chitosan were fabricated by inverted colloidal crystal (ICC) method for scaffolds comprising regular pores. The hybrid PAAM-chitosan ICC scaffolds were grafted with poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) for a rougher pore surface and grafted with transactivator of transcription von Hippel-Lindau (TATVHL) peptide for a better differentiation of induced pluripotent stem (iPS) cells toward neural lineage. By scanning electron microscopy, we found that iPS cells cultured in PAAM-chitosan ICC scaffolds with PLGA NPs at 1.0 mg/mL and TATVHL peptide at 15 μg/mL elongated the axonal length to 15 μm. A combination of PLGA NPs and TATVHL peptide favored the adhesion of iPS cells, reduced the embryonic phenotype after cultivation, and guided the production of βIII tubulin-positive cells in PAAM-chitosan ICC scaffolds. In addition to the differentiation toward neurite-like cells, an increase in the content of TATVHL peptide in PAAM-chitosan ICC scaffolds inhibited the differentiation of iPS cells toward astrocytes. ICC scaffolds composed of PAAM, chitosan, PLGA NPs, and TATVHL peptide can be an efficacious matrix to differentiate iPS cells toward neurons and retard the glial formation for nerve regeneration.

Effect of surface modification of zirconia on cell adhesion, metabolic activity and proliferation of human osteoblasts

Titanium dental implants with sandblasted and/or acid-etched surfaces have shown clinical superiority in comparison to their smooth, machined counterparts, and are now state of the art. Sandblasting of finished, sintered zirconia implants, however, will damage the surface structure and affect the mechanical properties. To improve osseointegration of zirconia dental implants without impairing the original mechanical strength by crack initiation and partial phase transformation from tetragonal to monoclinic, roughening of the zirconia surface by sandblasting before the final sintering step was employed. Impact of the treatments on cellular reactions of SAOS-2 human osteoblast-like cells was investigated. Sandblasting of Yttrium-stabilized zirconia (Y-TZP) with 120 μm and 250 μm Al

Proliferation, behavior, and differentiation of osteoblasts on surfaces of different microroughness

OBJECTIVES

Titanium surface roughness is recognized as an important parameter influencing osseointegration. However, studies concerning the effect of well-defined surface topographies of titanium surfaces on osteoblasts have been limited in scope. In the present study we have investigated how Ti surfaces of different micrometer-scale roughness influence proliferation, migration, and differentiation of osteoblasts in-vitro.

METHODS

Titanium replicas with surface roughnesses (Ra) of approximately 0, 1, 2, and 4μm were produced and MG-63 osteoblasts were cultured on these surfaces for up to 5 days. The effect of surface micrometer-scale roughness on proliferation, migration in time-lapse microscopy experiments, as well as the expression of alkaline phosphatase, osteocalcin, vascular-endothelial growth factor (VEGF), osteoprotegerin (OPG), and receptor activator of nuclear factor kappa-B ligand (RANKL) were investigated.

RESULTS

Proliferation of MG-63 cells was found to decrease gradually with increasing surface roughness. However, the highest expression of alkaline phosphatase, osteocalcin and VEGF was observed on surfaces with Ra values of approximately 1 and 2μm. Further increase in surface roughness resulted in decreased expression of all investigated parameters. The cell migration speed measured in time-lapse microscopy experiments was significantly lower on surfaces with a Ra value of about 4μm, compared to those with lower roughness. No significant effect of surface roughness on the expression of OPG and RANKL was observed.

SIGNIFICANCE

Thus, surfaces with intermediate Ra roughness values of 1-2μm seem to be optimal for osteoblast differentiation. Neither proliferation nor differentiation of osteoblasts appears to be supported by surfaces with higher or lower Ra values.

Pre-treatment of titanium alloy with platelet-rich plasma enhances human osteoblast responses

Osseointegration, the histological direct bone-to-implant contact, is the ultimate goal of implant healing and the first prerequisite for long-term success of endosseous implants. It is well-known that metal implants with rough surfaces achieve better osseointegration than those with smooth surfaces in vivo. The implantation of metal materials into bone is always accompanied by bleeding. The implant surface is initially coated with blood and these initial events could determine subsequent osseointegration. However, there is little concordance between in vitro results and in vivo findings regarding the effect of surface roughness on osseointegration. Here, we show that the osteoblast response to metal surfaces pre-treated with platelets and plasma proteins elucidates the superior osseointegration of rough surfaced implants in vivo. We found that osteoblast attachment, proliferation, and osteoblastic differentiation were significantly higher on a rough titanium surface pre-treated with platelet-rich plasma (PRP) than on the same surface without pretreatment. Furthermore, we found that the three-dimensional fibrillar network formed on the rough surface of the titanium by PRP pre-treatment might enhance osteoblast responses. Our results demonstrate why osseointegration is found to be most active on metal implants with a rough surface in vivo. We anticipate that our assay would be a useful tool for mimicking the in vivo model of osseointegration. Because cellular responses to the titanium implant that are pre-treated with platelet and plasma proteins on their surfaces after the biomimetic process in vitro, may be more similar to the events that occur in vivo.

Relevant aspects in the surface properties in titanium dental implants for the cellular viability

Roughness and topographical features are the most relevant of the surface properties for a dental implant for its osseointegration. For that reason, we studied the four surfaces more used in titanium dental implants: machined, sandblasted, acid etching and sandblasted plus acid etching. The roughness and wettability (contact angle and surface free energy) was studied by means 3D-interferometric microscope and sessile drop method. Normal human gingival fibroblasts (HGF) were obtained from small oral mucosa biopsies and were used for cell cultures. To analyze cell integrity, we first quantified the total amount of DNA and LDH released from dead cells to the culture medium. Then, LIVE/DEAD assay was used as a combined method assessing cell integrity and metabolism. All experiments were carried out on each cell type cultured on each Ti material for 24h, 48h and 72h. To evaluate the in vivo cell adhesion capability of each Ti surface, the four types of discs were grafted subcutaneously in 5 Wistar rats. Sandblasted surfaces were significantly rougher than acid etching and machined. Wettability and surface free energy decrease when the roughness increases in sand blasted samples. This fact favors the protein adsorption. The DNA released by cells cultured on the four Ti surfaces did not differ from that of positive control cells (p>0.05). The number of cells per area was significantly lower (p<0.05) in the sand-blasted surface than in the machined and surface for both cell types (7±2 cells for HGF and 10±5 cells for SAOS-2). The surface of the machined-type discs grafted in vivo had a very small area occupied by cells and/or connective tissue (3.5%), whereas 36.6% of the sandblasted plus acid etching surface, 75.9% of sandblasted discs and 59.6% of acid etching discs was covered with cells and connective tissue. Cells cultured on rougher surfaces tended to exhibit attributes of more differentiated osteoblasts than cells cultured on smoother surfaces. These surface properties justify that the sandblasted implants is able to significantly increase bone contact and bone growth with very good osseointegration results in vivo.

Effects of Line and Pillar Array Microengineered SiO2 Thin Films on the Osteogenic Differentiation of Human Bone Marrow-Derived Mesenchymal Stem Cells

A primary goal in bone tissue engineering is the design of implants that induce controlled, guided, and rapid healing. The events that normally lead to the integration of an implant into bone and determine the performance of the device occur mainly at the tissue-implant interface. Topographical surface modification of a biomaterial might be an efficient tool for inducing stem cell osteogenic differentiation and replace the use of biochemical stimuli. The main goal of this work was to develop micropatterned bioactive silica thin films to induce the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hMSCs) only through topographical stimuli. Line and pillar micropatterns were developed by a combination of sol-gel/soft lithography and characterized by scanning electron microscopy, atomic force microscopy, and contact angle measurements. hMSCs were cultured onto the microfabricated thin films and flat control for up to 21 days under basal conditions. The micropatterned groups induced levels of osteogenic differentiation and expression of osteoblast-associated markers higher than those of the flat controls. Via comparison of the micropatterns, the pillars caused a stronger response of the osteogenic differentiation of hMSCs with a higher level of expression of osteoblast-associated markers, ALP activity, and extracellular matrix mineralization after the cells had been cultured for 21 days. These findings suggest that specific microtopographic cues can direct hMSCs toward osteogenic differentiation.

The effects of pulsed electromagnetic field (PEMF) on osteoblast-like cells cultured on titanium and titanium-zirconium surfaces

BACKGROUND

Commercially pure Ti, together with Ti Ni, Ti-6Al-4V, and Ti-6Al-7Nb alloys, are among the materials currently being used for this purpose. Titanium-zirconium (TiZr) has been developed that allows SLActive surface modification and that has comparable or better mechanical strength and improved biocompatibility compared with existing Ti alloys. Furthermore, approaches have targeted making the implant surface more hydrophilic, as with the Straumann SLActive surface, a modification of the SLA surface.

PURPOSE

The aim of this study is to evaluate the effects of pulsed electromagnetic field (PEMF) to the behavior of neonatal rat calvarial osteoblast-like cells cultured on commercially pure titanium (cpTi) and titanium-zirconium alloy (TiZr) discs with hydrophilic surface properties.

MATERIALS AND METHODS

Osteoblast cells were cultured on titanium and TiZr discs, and PEMF was applied. Cell proliferation rates, cell numbers, cell viability rates, alkaline phosphatase, and midkine (MK) levels were measured at 24 and 72 hours.

RESULTS

At 24 hours, the number of cells was significantly higher in the TiZr group. At 72 hours, TiZr had a significantly higher number of cells when compared to SLActive, SLActive + PEMF, and machine surface + PEMF groups. At 24 hours, cell proliferation was significantly higher in the TiZr group than SLActive and TiZr + PEMF group. At 72 hours, TiZr group had higher proliferation rate than machine surface and TiZr + PEMF. Cell proliferation in the machine surface group was lower than both SLActive + PEMF and machine surface + PEMF. MK levels of PEMF-treated groups were lower than untreated groups for 72 hours.

CONCLUSIONS

Our findings conclude that TiZr surfaces are similar to cpTi surfaces in terms of biocompatibility. However, PEMF application has a higher stimulative effect on cells cultured on cpTi surfaces when compared to TiZr.

Engineering nanoscale stem cell niche: direct stem cell behavior at cell-matrix interface

Biophysical cues on the extracellular matrix (ECM) have proven to be significant regulators of stem cell behavior and evolution. Understanding the interplay of these cells and their extracellular microenvironment is critical to future tissue engineering and regenerative medicine, both of which require a means of controlled differentiation. Research suggests that nanotopography, which mimics the local, nanoscale, topographic cues within the stem cell niche, could be a way to achieve large-scale proliferation and control of stem cells in vitro. This Progress Report reviews the history and contemporary advancements of this technology, and pays special attention to nanotopographic fabrication methods and the effect of different nanoscale patterns on stem cell response. Finally, it outlines potential intracellular mechanisms behind this response.

A Key Role of Autophagy in Osteoblast Differentiation on Titanium-Based Dental Implants

Autophagy plays an important role in embryogenesis, for the maintenance of tissue homeostasis and the elimination of damaged subcellular structures. Furthermore, autophagy could be a mode of physiological cell death and also be implicated in cell differentiation. Thus, we hypothesized that autophagy may have an impact on the differentiation of osteoblast cells influenced by various titanium-based surfaces. Interactions between smooth, commercially available pure titanium (Ti cp), rough Ticer, acid-etched Ti cp (SS) and M1-M3 (comprised of the monoclinic phase of sodium-titanium oxides and rutile; M2 contains amorphous calcium phosphates) and human osteoblast cells were investigated. Immunofluorescent staining was used for detecting autophagy, cell cluster formation and collagen type I (Col-1) expression. Flow cytometry was employed to identify autophagy, the production of endogenous nitric oxide (NO) and the size and granularity of the cells. Rough surfaces caused osteoblast differentiation via the autophagic-dependent PI3/Akt signalling pathway. These surfaces induced the formation of discrete populations of large, granular cells, i.e. mature osteoblasts. In addition, M1-M3 provoked the development of a third population of small, granular cells, responsible for cell cluster formation, which are important for the formation of bone noduli and mineralisation. The same surfaces induced faster osteoblast maturation and enhanced NO production, a hallmark of the already mentioned processes. Neither the mature osteoblasts nor the small cells appeared after the inhibition of autophagy. Inhibition of autophagy also prevented cell cluster formation. We demonstrate that autophagy plays an essential role in the osteoblast differentiation on titanium-based surfaces with rough topography.

Enhanced differentiation of human osteoblasts on Ti surfaces pre-treated with human whole blood

Early and effective integration of a metal implant into bone tissue is of crucial importance for its long-term stability. While different material properties including surface roughness and wettability but also initial blood-implant surface interaction are known to influence this osseointegration, implications of the latter process are still poorly understood. In this study, early interaction between blood and the implant surface and how this affects the mechanism of osseointegration were investigated. For this, blood coagulation on a micro-roughened hydrophobic titanium (Ti) surface (SLA-H(phob)) and on a hydrophilic micro-roughened Ti surface with nanostructures (SLActive-H(phil)NS), as well as the effects of whole human blood pre-incubation of these two surfaces on the differentiation potential of primary human bone cells (HBC) was assessed. Interestingly, pre-incubation with blood resulted in a dense fibrin network over the entire surface on SLActive-H(phil)NS but only in single patches of fibrin and small isolated fibre complexes on SLA-H(phob). On SLActive-H(phil)NS, the number of HBCs attaching to the fibrin network was greatly increased and the cells displayed enhanced cell contact to the fibrin network. Notably, HBCs displayed increased expression of the osteogenic marker proteins alkaline phosphatase and collagen-I when cultivated on both surfaces upon blood pre-incubation. Additionally, blood pre-treatment promoted an earlier and enhanced mineralization of HBCs cultivated on SLActive-H(phil)NS compared to SLA-H(phob). The results presented in this study therefore suggest that blood pre-incubation of implant surfaces mimics a more physiological situation, eventually providing a more predictive in vitro model for the evaluation of novel bone implant surfaces.

Regulation of Osteoblast Differentiation by Acid-Etched and/or Grit-Blasted Titanium Substrate Topography Is Enhanced by 1,25(OH)2D3 in a Sex-Dependent Manner

This study assessed contributions of micron-scale topography on clinically relevant titanium (Ti) to differentiation of osteoprogenitor cells and osteoblasts; the interaction of this effect with 1α,25-dihydroxyvitamin D₃ (1α,25(OH)₂D₃); and if the effects are sex-dependent. Male and female rat bone marrow cells (BMCs) were cultured on acid-etched (A, R_a = 0.87 μm), grit-blasted (GB, R_a = 3.90 μm), or grit-blasted/acid-etched (SLA, R_a = 3.22 μm) Ti. BMCs were sensitive to surface topography and underwent osteoblast differentiation. This was greatest on SLA; acid etching and grit blasting contributed additively. Primary osteoblasts were also sensitive to SLA, with less effect from individual structural components, demonstrated by enhanced local factor production. Sex-dependent responses of BMCs to topography varied with parameter whereas male and female osteoblasts responded similarly to surface treatment. 1α,25(OH)₂D₃ enhanced cell responses on all surfaces similarly. Effects were sex-dependent and male cells grown on a complex microstructured surface were much more sensitive than female cells. These results indicate that effects of the complex SLA topography are greater than acid etching or grit blasting alone on multipotent BMCs and committed osteoblasts and that individual parameters are sex-specific. The effect of 1α,25(OH)₂D₃ was sex dependent. The results also suggest that levels of 1α,25(OH)₂D₃ in the patient may be important in osseointegration.

Behavior of osteoblasts on TI surface with two different coating designed for orthodontic devices

In the present study we coated Ti surfaces with polytetrafluorethylene (PTFE) and titanium nitride (TiN) and investigated in vitro the behavior of osteoblasts on these surfaces. MG-63 osteoblasts were cultured on titanium discs with different surface treatment: uncoated Ti6Al4V, TiN-coated, PTFE-coated. Cell viability/proliferation was detected by MTT assay. Gene-expression levels of alkaline phosphatase (ALP), osteocalcin (OC), type I collagen, receptor activator of nuclear factor-kappa-B ligand (RANKL), and osteoprotegerin (OPG) were determined by qPCR. Cell behavior on different surfaces was observed by time-lapse microscopy. Cells grown on PTFE-coated Ti surface exhibited delayed surface attachment and decreased proliferation after 48 h. However, after 168 h of culture cells grown on PTFE-coated surface exhibited higher viability/proliferation, higher expression levels of ALP and OC, and higher OPG/RANKL ratio compared to uncoated surface. No effect of TiN-coating on any investigated parameter was found. Our results shows that PTFE coating exhibits no toxic effect on MG-63 cells and slightly stimulates expression of several genes associated with osteogenesis. We propose that PTFE coating could be considered as a possible choice for a surface treatment of temporary skeletal anchorage devices in orthodontics.

Nanotopographical Surfaces for Stem Cell Fate Control: Engineering Mechanobiology from the Bottom

During embryogenesis and tissue maintenance and repair in an adult organism, a myriad of stem cells are regulated by their surrounding extracellular matrix (ECM) enriched with tissue/organ-specific nanoscale topographical cues to adopt different fates and functions. Attributed to their capability of self-renewal and differentiation into most types of somatic cells, stem cells also hold tremendous promise for regenerative medicine and drug screening. However, a major challenge remains as to achieve fate control of stem cells in vitro with high specificity and yield. Recent exciting advances in nanotechnology and materials science have enabled versatile, robust, and large-scale stem cell engineering in vitro through developments of synthetic nanotopographical surfaces mimicking topological features of stem cell niches. In addition to generating new insights for stem cell biology and embryonic development, this effort opens up unlimited opportunities for innovations in stem cell-based applications. This review is therefore to provide a summary of recent progress along this research direction, with perspectives focusing on emerging methods for generating nanotopographical surfaces and their applications in stem cell research. Furthermore, we provide a review of classical as well as emerging cellular mechano-sensing and -transduction mechanisms underlying stem cell nanotopography sensitivity and also give some hypotheses in regard to how a multitude of signaling events in cellular mechanotransduction may converge and be integrated into core pathways controlling stem cell fate in response to extracellular nanotopography.

Effects of vanadium (V) and magnesium (Mg) on rat bone tissue: mineral status and micromorphology. Consequences of V-Mg interactions

The extent to which the 12 week separate and combined administration of vanadium (as sodium metavanadate--SMV, 0.125 mg V per ml) and magnesium (as magnesium sulphate--MS, 0.06 mg Mg per ml) affects bone mineral status and micromorphology as well as the alkaline phosphatase (ALP) activity in femoral diaphysis (FD) was examined in male rats. The bone chemical composition of SMV-exposed rats was also investigated. SMV alone or in combination with MS (as SMV-MS) reduced the levels of MgFD (by 21% and 20%) and PFD (by 12% and 9%), lowered the CaFD content (by 7% and 10%), and caused a rise of the FeFD concentration (by 22.5% and 17%), compared with the control; SMV alone also reduced and enhanced the KFD and ZnFD concentrations (by 19% and 15%, respectively) but remained without significant effect on the femoral bone surface roughness (FBSR), whereas MS alone lowered the VFD, PFD, and CuFD levels (by 42%, 10%, and 20.6%), reduced FBSR, and created the regular femoral bone surface shape. The SMV-MS combination also induced a decline and rise in the levels of CuFD (by 30%) and NaFD (by 15%), respectively, compared with the control and the MS-supplemented rats; elevated ALPFD activity (by 24%, 35%, and 40%), compared with the control, SMV-exposed, and MS-supplemented animals; and increased FBSR. Relationships between the root mean square roughness (Sq) and skewness (Ssk): Sq [MS < SMV < Control < SMV-MS] ⇔ Ssk [SMV-MS > Control > SMV > MS], ALPFD and Sq: ALPFD⇔ Sq [SMV-MS > Control > SMV > MS], and between other variables were demonstrated. A partial limitation of the drop in the PFD and KFD levels and normalization of the ZnFD concentration were a consequence of the V-Mg antagonistic interaction whereas a consequence of the V-Mg synergistic interaction was the increase in the NaFD level, ALPFD activity, and FBSR. Ca10(PO4)5(SiO4)(OH) was part of the inorganic component of the bone of the SMV-exposed rats.

Nanotopographic Biomaterials for Isolation of Circulating Tumor Cells

Circulating tumor cells (CTCs) shed from the primary tumor mass and circulating in the bloodstream of patients are believed to be vital to understand of cancer metastasis and progression. Capture and release of CTCs for further enumeration and molecular characterization holds the key for early cancer diagnosis, prognosis and therapy evaluation. However, detection of CTCs is challenging due to their rarity, heterogeneity and the increasing demand of viable CTCs for downstream biological analysis. Nanotopographic biomaterial-based microfluidic systems are emerging as promising tools for CTC capture with improved capture efficiency, purity, throughput and retrieval of viable CTCs. This review offers a brief overview of the recent advances in this field, including CTC detection technologies based on nanotopographic biomaterials and relevant nanofabrication methods. Additionally, the possible intracellular mechanisms of the intrinsic nanotopography sensitive responses that lead to the enhanced CTC capture are explored.