Promotion of Osteogenic Cell Response Using Quasicovalent Immobilized Fibronectin on Titanium Surfaces: Introduction of a Novel Biomimetic Layer System

Protein absorption on titanium surfaces treated with a high-power laser: A systematic review

STATEMENT OF PROBLEM

The surface of titanium dental implants treated with a high-power laser has been reported to favor osseointegration, mainly by altering protein uptake. Despite the large number of articles that address the topic, the heterogeneity of methodologies and results makes an understanding of the treatment's benefits difficult, and a systematic review is needed.

PURPOSE

The purpose of this systematic review was to further the knowledge on protein uptake on titanium surfaces that have undergone treatment with a high-power laser.

MATERIAL AND METHODS

This review followed the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines and was registered with the Open Science Framework (OSF) (osf.io/gcbna). Searches were performed in PubMed, Scopus, Web of Science, Embase, and Google Scholar databases. The articles were selected in 2 steps by 2 independent reviewers according to the previously selected eligibility criteria. The risk of bias was analyzed by using the Joanna Briggs Institute (JBI)-adapted quasi-experimental study evaluation tool.

RESULTS

The studies addressed have shown that applying a high-power laser to the implant surface, depending on its settings, generates topographical changes that can optimize the protein absorption process and thus accelerate the other biological processes.

CONCLUSIONS

The studies identified in this systematic review showed that surface treatment with a high-power laser represents a promising technique with a positive influence on protein uptake and osseointegration.

Innervation of an Ultrasound-Mediated PVDF-TrFE Scaffold for Skin-Tissue Engineering

In this work, electrospun polyvinylidene-trifluoroethylene (PVDF-TrFE) was utilized for its biocompatibility, mechanics, and piezoelectric properties to promote Schwann cell (SC) elongation and sensory neuron (SN) extension. PVDF-TrFE electrospun scaffolds were characterized over a variety of electrospinning parameters (1, 2, and 3 h aligned and unaligned electrospun fibers) to determine ideal thickness, porosity, and tensile strength for use as an engineered skin tissue. PVDF-TrFE was electrically activated through mechanical deformation using low-intensity pulsed ultrasound (LIPUS) waves as a non-invasive means to trigger piezoelectric properties of the scaffold and deliver electric potential to cells. Using this therapeutic modality, neurite integration in tissue-engineered skin substitutes (TESSs) was quantified including neurite alignment, elongation, and vertical perforation into PVDF-TrFE scaffolds. Results show LIPUS stimulation promoted cell alignment on aligned scaffolds. Further, stimulation significantly increased SC elongation and SN extension separately and in coculture on aligned scaffolds but significantly decreased elongation and extension on unaligned scaffolds. This was also seen in cell perforation depth analysis into scaffolds which indicated LIPUS enhanced perforation of SCs, SNs, and cocultures on scaffolds. Taken together, this work demonstrates the immense potential for non-invasive electric stimulation of an in vitro tissue-engineered-skin model.

Post-treatments of polydopamine coatings influence cellular response

Polydopamine (PDA) is the final oxidation product of dopamine or other catecholamines. Since the first reports of PDA coatings starting around 2007, these coatings have been widely studied as a versatile and inexpensive one-step coating option for biomaterial functionalization. The coating attach to a wide range of materials and can subsequently be modified with biomolecules or nanoparticles. However, as a strong candidate for biomaterial research and even clinical use, it is important to unravel the changes in physico-chemical properties and the cell-PDA interaction as a function of heat sterilization procedures and shelf storage periods. Four groups were examined in this study: titanium (Ti), PDA-coated Ti samples and PDA-coated Ti samples either stored for up to two weeks at room temperature or heated at 121 °C for 24 h, respectively. We used X-ray Photoelectron Spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and Water contact angle (WCA) to characterize chemical composition and surface properties of the groups. Cell adhesion and proliferation was examined by three different cell types: human primary dermal fibroblasts (hDF), human epidermal keratinocytes (HaCaTs) and a murine preosteoblastic cell line (MC3T3-E1), respectively. Cells were cultured on PDA coated samples for 4 h, 3 days and 5 days. Both thermal treatment of PDA at 121℃ for 24 h and storage of the samples for 2 weeks increased the amount of quinone groups at the surface and decreased the amount of primary amine groups as detected by XPS and ToF-SIMS. Even though these surface reactions increased the WCA of the PDA coating, we found that the post-treatments increased cell proliferation for both hDFs, HaCaTs and MC3T3-E1 s as compared to pristine PDA. This emphasizes the importance of post-treatment and shelf-time for PDA coatings.

Enhanced selective cellular proliferation by multi-biofunctionalization of medical implant surfaces with heterodimeric BMP-2/6, fibronectin, and FGF-2

Increasing cell adhesion on implant surfaces is an issue of high biomedical importance. Early colonization with endogenous cells reduces the risk of bacterial contamination and enhances the integration of an implant into the diverse cellular tissues surrounding it. In vivo integration of implants is controlled by a complex spatial and temporal interplay of cytokines and adhesive molecules. The concept of a multi-biofunctionalized TiO₂ surface for stimulating bone and soft tissue growth is presented here. All supramolecular architectures were built with a biotin-streptavidin coupling system. Biofunctionalization of TiO₂ with immobilized FGF-2 and heparin could be shown to selectively increase the proliferation of fibroblasts while immobilized BMP-2 only stimulated the growth of osteoblasts. Furthermore, TiO₂ surfaces biofunctionalized with either the BMP-2 or BMP-2/6 growth factor and the cell adhesion-enhancing protein fibronectin showed higher osteoblast adhesion than a TiO₂ surface functionalized with only one of these proteins. In conclusion, the presented immobilization strategy is applicable in vivo for a selective surface coating of implants in both hard and connective tissue. The combined immobilization of different extracellular proteins on implants has the potential to further influence cell-specific reactions. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2910-2922, 2018.

Kaempferol-immobilized titanium dioxide promotes formation of new bone: effects of loading methods on bone marrow stromal cell differentiation in vivo and in vitro

Background

Surface modification of titanium dioxide (TiO₂) implants promotes bone formation and shortens the osseointegration period. Kaempferol is a flavonoid that has the capacity to promote osteogenic differentiation in bone marrow stromal cells. The aim of this study was to promote bone formation around kaempferol immobilized on TiO₂ implants.

Methods

There were four experimental groups. Alkali-treated TiO₂ samples (implants and discs) were used as a control and immersed in Dulbecco's phosphate-buffered saline (DPBS) (Al-Ti). For the coprecipitation sample (Al-cK), the control samples were immersed in DPBS containing 50 µg kaempferol/100% ethanol. For the adsorption sample (Al-aK), 50 µg kaempferol/100% ethanol was dropped onto control samples. The surface topography of the TiO₂ implants was observed by scanning electron microscopy with energy-dispersive X-ray spectroscopy, and a release assay was performed. For in vitro experiments, rat bone marrow stromal cells (rBMSCs) were cultured on each of the TiO₂ samples to analyze cell proliferation, alkaline phosphatase activity, calcium deposition, and osteogenic differentiation. For in vivo experiments, TiO₂ implants placed on rat femur bones were analyzed for bone-implant contact by histological methods.

Results

Kaempferol was detected on the surface of Al-cK and Al-aK. The results of the in vitro study showed that rBMSCs cultured on Al-cK and Al-aK promoted alkaline phosphatase activity, calcium deposition, and osteogenic differentiation. The in vivo histological analysis revealed that Al-cK and Al-aK stimulated new bone formation around implants.

Conclusion

TiO₂ implant-immobilized kaempferol may be an effective tool for bone regeneration around dental implants.

Multifunctional biomaterial coatings: synthetic challenges and biological activity

A controlled interaction of materials with their surrounding biological environment is of great interest in many fields. Multifunctional coatings aim to provide simultaneous modulation of several biological signals. They can consist of various combinations of bioactive, and bioinert components as well as of reporter molecules to improve cell-material contacts, prevent infections or to analyze biochemical events on the surface. However, specific immobilization and particular assembly of various active molecules are challenging. Herein, an overview of multifunctional coatings for biomaterials is given, focusing on synthetic strategies and the biological benefits by displaying several motifs.

Protein adsorption on a laser-modified titanium implant surface

PURPOSE

The aim of this study was to investigate the earlier phase of the osseointegration of a laser-treated implant surface in terms of human protein adsorption.

MATERIALS AND METHODS

Titanium surfaces were divided into machined (M), sandblasted (SB), and laser-treated (LT). The LT surfaces were created with an Nd diode-pumped laser in Q-switching, whereas the SB were treated with Al2O3. An x-ray photoelectron spectroscopy (XPS) analysis of titanium surface was performed. Titanium discs were used for albumin and fibronectin adsorption evaluation through fluorescence intensity. Fibronectin evaluation was also made with Western Blot analysis on experimental implants.

RESULTS

LT discs appeared to trigger a higher albumin and fibronectin adsorption with a regular pattern. The mean count of albumin adsorption was 0.29 and 3.8 for SB and LT, respectively (P = 0.016), whereas fibronectin values were 0.67 and 4.9 for (SB) and (LT) titanium (P = 0.02). XPS analysis showed that titanium, oxygen, carbon, and nitrogen were found on all 3 surfaces.

CONCLUSION

Laser-engineered porous titanium surface seems to promote, in vitro, the adsorption of albumin and fibronectin more than sandblasted (SB) or machined (M) implants.

Comparison of growth & function of endothelial progenitor cells cultured on deproteinized bovine bone modified with covalently bound fibronectin and bound vascular endothelial growth factor

OBJECTIVES

The objective of this study was to assess and compare the growth and function of Endothelial Progenitor Cells (EPCs) cultured on covalently bonded Vascular Endothelial Growth Factor (VEGF) and covalently bonded Fibronectin (FN) coating on deproteinized bovine bone (DBB) (test samples), compared to non-modified DBB blocks (control sample).

MATERIALS AND METHODS

The test samples were prepared by plasma polymerization of allylamine onto DBB blocks. Group1 of test samples were prepared with VEGF coating (VEGF-DBB) where as the Group2 test samples were coated with FN (FN-DBB). Non-modified DBB blocks served as a Control. EPCs were isolated and cultivated from buffy coats of peripheral blood of healthy volunteers and cultivated in the different samples and examined at time intervals of 24 h, 3 days, and 7 days. Evaluation of growth by cell count and cell morphology was done using Confocal Laser Scanning Electron Microscopy; vitality and function of cells was assessed using MTT assay and RT-PCR and ELISA for eNOS and iNOS respectively.

RESULTS

The results of the study show that both VEGF and FN could be successfully immobilized by plasma polymerization onto a complex, porous, three-dimensional structure of DBB. When comparing vital cell coverage, proliferation and function of EPCs, FN-DBB provided more positive values followed by VEGF-DBB as compared to DBB samples. eNOS level were significant higher in VEGF-DBB and FN-DBB when compared to DBB (P = 0.019 and P = 0.002). The difference between VEGF-DBB and FN-DBB was not significant.

CONCLUSIONS

Biomimetic coatings of Fibronectin may clinically relate to faster angiogenesis and earlier healing potential.

A new application of cell-free bone regeneration: immobilizing stem cells from human exfoliated deciduous teeth-conditioned medium onto titanium implants using atmospheric pressure plasma treatment

Introduction

Surface modification of titanium (Ti) implants promotes bone formation and shortens the osseointegration period. The aim of this study was to promote bone regeneration and stability around implants using atmospheric pressure plasma (APP) pretreatment. This was followed by immobilization of stem cells from human exfoliated deciduous teeth-conditioned medium (SHED-CM) on the Ti implant surface.

Methods

Ti samples (implants, discs, powder) were treated with APP for 30 seconds. Subsequently, these were immobilized on the treated Ti surface, soaked and agitated in phosphate-buffered saline or SHED-CM for 24 hours at 37 °C. The surface topography of the Ti implants was observed using scanning electron microscopy with energy dispersive X-ray spectroscopy. In vivo experiments using Ti implants placed on canine femur bone were then conducted to permit histological analysis at the bone-implant boundary. For the in vitro experiments, protein assays (SDS-PAGE, Bradford assay, liquid chromatography-ion trap mass spectrometry) and canine bone marrow stromal cell (cBMSC) attachment assays were performed using Ti discs or powder.

Results

In the in vitro study, treatment of Ti implant surfaces with SHED-CM led to calcium phosphate and extracellular matrix protein immobilization. APP pretreatment increased the amount of SHED-CM immobilized on Ti powder, and contributed to increased cBMSC attachment on Ti discs. In the in vivo study, histological analysis revealed that the Ti implants treated with APP and SHED-CM stimulated new bone formation around implants.

Conclusions

Implant device APP pretreatment followed by SHED-CM immobilization may be an effective application to facilitate bone regeneration around dental implants.

Osseoconductivity of a Specific Streptavidin-Biotin-Fibronectin Surface Coating of Biotinylated Titanium Implants - A Rabbit Animal Study

BACKGROUND

Biofunctionalized implant surfaces may accelerate bony integration and increase long-term stability.

PURPOSE

The aim of the study was to evaluate the osseous reaction toward biomimetic titanium implants surfaces coated with quasicovalent immobilized fibronectin in an in vivo animal model.

MATERIALS AND METHODS

A total of 84 implants (uncoated [control 1, n = 36], streptavidin-biotin coated [test 1, n = 24], streptavidin-biotin-fibronectin coated [test 2, n = 24]) were inserted 1 mm supracortically in the proximal tibia of 12 rabbits. The samples were examined after 3 and 6 weeks. Total bone-implant contact (tBIC; %), bone-implant contact in the cortical (cBIC; %) and in the spongious bone (sBIC; %) as well as the percentage of linear bone fill (PLF; %) were evaluated.

RESULTS

After 3 weeks, streptavidin-biotin-fibronectin implants had a significant higher sBIC (p = .043) and PLF (p = .007) compared with the uncoated samples. After 6 weeks, this difference was significant for tBIC (p = .016) and cBIC (p < .001). Additionally, uncoated screws showed a significant higher sBIC when compared with the fibronectin coating (p < .001). Streptavidin-biotin-coated implants showed less bone growth at both time points of all examined parameters when compared with their counterparts (all p < .001).

CONCLUSIONS

Quasicovalent immobilization of biotinylated fibronectin with the streptavidin-biotin-fibronectin system on smooth surface titanium shows a beneficial faster osseous healing in vivo. Besides, an antifouling effect of the streptavidin-biotin coating was proven.

Fibronectin immobilization on to robotic-dispensed nanobioactive glass/polycaprolactone scaffolds for bone tissue engineering

Bioactive nanocomposite scaffolds with cell-adhesive surface have excellent bone regeneration capacities. Fibronectin (FN)-immobilized nanobioactive glass (nBG)/polycaprolactone (PCL) (FN-nBG/PCL) scaffolds with an open pore architecture were generated by a robotic-dispensing technique. The surface immobilization level of FN was significantly higher on the nBG/PCL scaffolds than on the PCL scaffolds, mainly due to the incorporated nBG that provided hydrophilic chemical-linking sites. FN-nBG/PCL scaffolds significantly improved cell responses, including initial anchorage and subsequent cell proliferation. Although further in-depth studies on cell differentiation and the in vivo animal responses are required, bioactive nanocomposite scaffolds with cell-favoring surface are considered to provide promising three-dimensional substrate for bone regeneration.

Layer-by-layer assembly of a streptavidin-fibronectin multilayer on biotinylated TiO(X)

The biomodification of surfaces, especially titanium, is an important issue in current biomedical research. Regarding titanium, it is also important to ensure a specific protein modification of its surface because here protein binding that is too random can be observed. Specific nanoscale architectures can be applied to overcome this problem. As recently shown, streptavidin can be used as a coupling agent to immobilize biotinylated fibronectin (bFn) on a TiO(X) surface. Because of the conformation of adsorbed biotinylated fibronectin on a streptavidin monolayer, it is possible to adsorb more streptavidin and biotinylated fibronectin layers. On this basis, an alternating protein multilayer can be built up. In contrast to common layer-by-layer technology, in this procedure the mechanism of layer adsorption is very specific because of the interaction of biotin and streptavidin. In addition, we showed that the assembly of this multilayer system and its stability are dependent on the degree of labeling of biotinylated fibronectin. Hence we conclude that it is possible to build up well-defined nanoscale protein architectures by varying the degree of labeling of biotinylated fibronectin.