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J. Funct. Biomater., Volume 9, Issue 4 (December 2018)

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Cover Story (view full-size image) The objective of the present study is to characterize the result of the application of sandblasted [...] Read more.
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Open AccessFeature PaperArticle Effects of a New Bioceramic Material on Human Apical Papilla Cells
J. Funct. Biomater. 2018, 9(4), 74; https://doi.org/10.3390/jfb9040074
Received: 22 November 2018 / Revised: 12 December 2018 / Accepted: 13 December 2018 / Published: 16 December 2018
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Abstract
Background: The development of materials with bioregenerative properties is critically important for vital pulp therapies and regenerative endodontic procedures. The aim of this study was to evaluate the cytocompatibility and cytotoxicity of a new endodontic biomaterial, PulpGuard, in comparison with two other biomaterials [...] Read more.
Background: The development of materials with bioregenerative properties is critically important for vital pulp therapies and regenerative endodontic procedures. The aim of this study was to evaluate the cytocompatibility and cytotoxicity of a new endodontic biomaterial, PulpGuard, in comparison with two other biomaterials widely used in endodontic procedures, ProRoot Mineral Trioxide Aggregate (MTA) and Biodentine. Methods: Apical papilla cells (APCs) were isolated from third molars with incomplete rhizogenesis from patients with orthodontic indication for dental extraction. Cultured APCs were incubated for 24, 48, or 72 h with different dilutions of eluates prepared from the three materials. Cellular viability, mobility, and proliferation were assessed in vitro using the Alamar Blue assay and a wound-healing test. The cells were also cultured in direct contact with the surface of each material. These were then analyzed via Scanning Electron Microscopy (SEM), and the surface chemical composition was determined by Energy-Dispersive Spectroscopy (EDS). Results: Cells incubated in the presence of eluates extracted from ProRoot MTA and PulpGuard presented rates of viability comparable to those of control cells; in contrast, undiluted Biodentine eluates induced a significant reduction of cellular viability. The wound-healing assay revealed that eluates from ProRoot MTA and PulpGuard allowed for unhindered cellular migration and proliferation. Cellular adhesion was observed on the surface of all materials tested. Consistent with their disclosed composition, EDS analysis found high relative abundance of calcium in Biodentine and ProRoot MTA and high abundance of silicon in PulpGuard. Significant amounts of zinc and calcium were also present in PulpGuard discs. Concerning solubility, Biodentine and ProRoot MTA presented mild weight loss after eluate extraction, while PulpGuard discs showed significant water uptake. Conclusions: PulpGuard displayed a good in vitro cytocompatibility profile and did not significantly affect the proliferation and migration rates of APCs. Cells cultured in the presence of PulpGuard eluates displayed a similar profile to those cultured with eluates from the widely used endodontic cement ProRoot MTA. Full article
(This article belongs to the Special Issue Endodontic Biomaterials)
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Open AccessArticle The Plasma Bioavailability of Coenzyme Q10 Absorbed from the Gut and the Oral Mucosa
J. Funct. Biomater. 2018, 9(4), 73; https://doi.org/10.3390/jfb9040073
Received: 30 August 2018 / Revised: 30 November 2018 / Accepted: 13 December 2018 / Published: 15 December 2018
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Abstract
Coenzyme Q10 (CoQ10) has a central role in the generation of cellular bioenergy and its regulation. The hydrophobicity exhibited by the CoQ10 molecule leads to reports of poor absorption profiles, therefore, the optimization of formulations and modes of delivery [...] Read more.
Coenzyme Q10 (CoQ10) has a central role in the generation of cellular bioenergy and its regulation. The hydrophobicity exhibited by the CoQ10 molecule leads to reports of poor absorption profiles, therefore, the optimization of formulations and modes of delivery is an ever-evolving therapeutic goal. The aim of this study was to investigate different CoQ10 formulations. The article summarizes the findings from an Australian comparative study involving adults administered CoQ10 through different oral delivery platforms. A total of 11 participants (six males and five females) voluntarily participated in a comparative clinical study of three different CoQ10 formulations across a six-week period, completing 198 person-hours of cumulative contribution equivalent to n = 33 participation. All of the eligible participants (n = 11) administered the three formulations blinded from who the commercial supplier of the formulation was and from what the chemical form of the CoQ10 was that was being administered. The dosing between the CoQ10 preparations were dispensed sequentially and were administered following three-week washouts. Three commercial preparations were tested, which included the following: formulations with capsules each containing ubiquinol and ubiquinone (150 mg/capsule), and a liposome ubiquinone formulation (40 mg/mL at 2 actuations of the pump). A significant inter-subject variation in the plasma level of CoQ10 at baseline that was observed to increase with an increase in age. This trend persisted in the post administration of the different formulations. Furthermore, it was observed that the intestinal absorption and bioavailability of CoQ10 varied significantly in the plasma between subjects, irrespective of whether the ubiquinol or ubiquinone forms were administered. The administration of CoQ10 as a liposome for preparation showed the poorest response in bioavailability. Although the ubiquinol capsule form of CoQ10 was observed to have increased in the plasma versus the ubiquinone capsules and the ubiquinol liposome at the two-hour interval, the inter-subject variation was such that the difference was not significant (p > 0.05). All of the CoQ10 formulations showed no further increases in their plasma levels over the remaining study period (i.e., four hours). This study further concluded that the intestinal absorption of CoQ10 is highly variable and is independent of the molecular form administered. Furthermore, it also concludes that liposomes are not an effective vehicle for the oral administration of CoQ10, and as such, did not improve the oral mucosal/sublingual absorption and bioavailability of the molecule. Of interest was the observation that with the increasing subject age, there was an observed increase in the baseline plasma CoQ10 levels in the participants prior to dosing. It was posited that the increase in the baseline plasma levels of CoQ10 with an increase in age could be due to the loss of skeletal muscle mass, a result that still needs to be verified. Full article
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Open AccessArticle A Three-Dimensional Dense Collagen Hydrogel to Model Cancer Cell/Osteoblast Interactions
J. Funct. Biomater. 2018, 9(4), 72; https://doi.org/10.3390/jfb9040072
Received: 31 October 2018 / Revised: 26 November 2018 / Accepted: 3 December 2018 / Published: 12 December 2018
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Abstract
No curative treatment options exist once breast cancer metastasizes to bone. This is due, in part, to an incomplete understanding of how osteolytic cancers interact with bone. Presented here is a novel approach to study the interactions between triple negative breast cancer cells [...] Read more.
No curative treatment options exist once breast cancer metastasizes to bone. This is due, in part, to an incomplete understanding of how osteolytic cancers interact with bone. Presented here is a novel approach to study the interactions between triple negative breast cancer cells and osteoblasts within a 3D collagenous environment. More specifically, a dense collagen hydrogel was employed to model interactions between MDA-MB-231 breast cancer cells and MC3T3-E1 pre-osteoblasts. Co-cultures with these two cell types, or MDA-MB-231-derived conditioned medium applied to MC3T3-E1 cells, were established in the context of plastically compressed dense collagen gel matrices. Importantly, breast cancer-derived conditioned medium or the establishment of breast cancer/osteoblast co-cultures did not negatively influence MC3T3-E1 cell viability. The inclusion of either conditioned medium or the presence of MDA-MB-231 cells resulted in impaired MC3T3-E1 differentiation into osteoblasts, which coincided with reduced osteoblast-mediated mineralization. The results presented here demonstrate that dense collagen gels provide a model environment to examine the effect of osteolytic breast cancer cells on osteoblast differentiation and subsequent mineralization of the collagen scaffold. Full article
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Open AccessArticle Superficial Characteristics of Titanium after Treatment of Chorreated Surface, Passive Acid, and Decontamination with Argon Plasma
J. Funct. Biomater. 2018, 9(4), 71; https://doi.org/10.3390/jfb9040071
Received: 16 October 2018 / Revised: 5 December 2018 / Accepted: 8 December 2018 / Published: 11 December 2018
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Abstract
(1) Background. Titanium is characterized by its biocompatibility, resistance to maximum stress, and fatigue and non-toxicity. The composition, surface structure, and roughness of titanium have a key and direct influence on the osseointegration processes when it is used in the form of dental [...] Read more.
(1) Background. Titanium is characterized by its biocompatibility, resistance to maximum stress, and fatigue and non-toxicity. The composition, surface structure, and roughness of titanium have a key and direct influence on the osseointegration processes when it is used in the form of dental implants. The objective of the present study is to characterize, at chemical, superficial, and biological levels, the result of the application of the sandblasted with large-grit and acid-etched (SLA) treatment consisting of coarse-grained and double-passivated acid blasting with subsequent decontamination with argon plasma on the surface of titanium implants type IV. (2) Methods. Four Oxtein® dental implants (Zaragoza, Spain) were investigated with the following coding: Code L63713T (titanium grade IV, 3.75 mm in diameter, and 13 mm in length). The surface of the implants was SLA type obtained from coarse-grained, double passivated acid, and decontaminated with argon plasma. The samples were in their sealed packages and were opened in our laboratory. The X-ray photoelectron spectroscopy (XPS) technique was used to characterize the chemical composition of the surface, and the scanning electronic microscope (SEM) technique was used to perform topographic surface evaluation. Cell cultures were also performed on both surfaces. (3) Results. The superficial chemical analysis of the studied samples presented the following components, approximately, expressed in atomic percentage: O: 39%; Ti: 18%; C: 39%; N: 2%; and Si: 1%. In the same way, the topographic analysis values were obtained in the evaluated roughness parameters: Ra: 1.5 μm ± 0.02%; Rq: 1.31 μm ± 0.33; Rz: 8.98 μm ± 0.73; Rp: 5.12 μm ± 0.48; Rv: 3.76 μm ± 0.51; and Rc: 4.92 μm ± 0.24. At a biological level, the expression of osteocalcin was higher (p < 0.05) on the micro-rough surface compared to that machined at 48 and 96 h of culture. (4) Conclusions. The data obtained in our study indicate that the total carbon content, the relative concentration of titanium, and the roughness of the treatment performed on the implants are in agreement with those found in the literature. Further, the roughness of the treatment performed on the implants throws a spongy, three-dimensional surface suitable for bone growth on it. The biological results found are compatible with the clinical use of the surface tested. Full article
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Open AccessArticle Microfluidic Deformability Study of an Innovative Blood Analogue Fluid Based on Giant Unilamellar Vesicles
J. Funct. Biomater. 2018, 9(4), 70; https://doi.org/10.3390/jfb9040070
Received: 13 October 2018 / Revised: 12 November 2018 / Accepted: 27 November 2018 / Published: 4 December 2018
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Abstract
Blood analogues have long been a topic of interest in biofluid mechanics due to the safety and ethical issues involved in the collection and handling of blood samples. Although the current blood analogue fluids can adequately mimic the rheological properties of blood from [...] Read more.
Blood analogues have long been a topic of interest in biofluid mechanics due to the safety and ethical issues involved in the collection and handling of blood samples. Although the current blood analogue fluids can adequately mimic the rheological properties of blood from a macroscopic point of view, at the microscopic level blood analogues need further development and improvement. In this work, an innovative blood analogue containing giant unilamellar vesicles (GUVs) was developed to mimic the flow behavior of red blood cells (RBCs). A natural lipid mixture, soybean lecithin, was used for the GUVs preparation, and three different lipid concentrations were tested (1 × 10−3 M, 2 × 10−3 M and 4 × 10−3 M). GUV solutions were prepared by thin film hydration with a buffer, followed by extrusion. It was found that GUVs present diameters between 5 and 7 µm which are close to the size of human RBCs. Experimental flow studies of three different GUV solutions were performed in a hyperbolic-shaped microchannel in order to measure the GUVs deformability when subjected to a homogeneous extensional flow. The result of the deformation index (DI) of the GUVs was about 0.5, which is in good agreement with the human RBC’s DI. Hence, the GUVs developed in this study are a promising way to mimic the mechanical properties of the RBCs and to further develop particulate blood analogues with flow properties closer to those of real blood. Full article
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Open AccessArticle Development of Phosphatized Calcium Carbonate Biominerals as Bioactive Bone Graft Substitute Materials, Part I: Incorporation of Magnesium and Strontium Ions
J. Funct. Biomater. 2018, 9(4), 69; https://doi.org/10.3390/jfb9040069
Received: 25 October 2018 / Revised: 19 November 2018 / Accepted: 27 November 2018 / Published: 2 December 2018
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Abstract
Synthetic materials based on calcium phosphate (CaP) are frequently used as bone graft substitutes when natural bone grafts are not available or not suitable. Chemical similarity to bone guarantees the biocompatibility of synthetic CaP materials, whereas macroporosity enables their integration into the natural [...] Read more.
Synthetic materials based on calcium phosphate (CaP) are frequently used as bone graft substitutes when natural bone grafts are not available or not suitable. Chemical similarity to bone guarantees the biocompatibility of synthetic CaP materials, whereas macroporosity enables their integration into the natural bone tissue. To restore optimum mechanical performance after the grafting procedure, gradual resorption of CaP implants and simultaneous replacement by natural bone is desirable. Mg and Sr ions released from implants support osteointegration by stimulating bone formation. Furthermore, Sr ions counteract osteoporotic bone loss and reduce the probability of related fractures. The present study aimed at developing porous Ca carbonate biominerals into novel CaP-based, bioactive bone implant materials. Macroporous Ca carbonate biominerals, specifically skeletons of corals (aragonite) and sea urchins (Mg-substituted calcite), were hydrothermally converted into pseudomorphic CaP materials with their natural porosity preserved. Sr ions were introduced to the mineral replacement reactions by temporarily stabilizing them in the hydrothermal phosphate solutions as Sr-EDTA complexes. In this reaction system, Na, Mg, and Sr ions favored the formation of correspondingly substituted β-tricalcium phosphate over hydroxyapatite. Upon dissolution, the incorporated functional ions became released, endowing these CaP materials with bioactive and potentially osteoporotic properties. Full article
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Open AccessFeature PaperArticle Fibrin as a Tissue Adhesive and Scaffold with an Angiogenic Agent (FGF-1) to Enhance Burn Graft Healing In Vivo and Clinically
J. Funct. Biomater. 2018, 9(4), 68; https://doi.org/10.3390/jfb9040068
Received: 21 September 2018 / Revised: 2 November 2018 / Accepted: 12 November 2018 / Published: 26 November 2018
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Abstract
There is a need for a strategy to reduce scarring in meshed skin graft healing leading to a better cosmetic result without a significant increase in cost. The strategy in this paper is to increase the closure rate of a meshed skin graft [...] Read more.
There is a need for a strategy to reduce scarring in meshed skin graft healing leading to a better cosmetic result without a significant increase in cost. The strategy in this paper is to increase the closure rate of a meshed skin graft to reduce scarring, which should also decrease the infection rate. Specifically, we used fibrin glue to attach all parts of the graft to the wound bed and added in an angiogenic growth factor and made the fibrin porous to further help the growth of blood vessels from the wound bed into the graft. There was a 10-day animal study and a one-month clinical study. Neither making the fibrin porous or adding an angiogenic agent (i.e., fibroblast growth factor-1 (FGF-1)) seemed to make a significant improvement in vivo or clinically. The use of fibrin on a meshed skin graft appears to speed up the regenerative healing rate leading to less scarring in the holes in the mesh. It appears to shorten the healing time by five days and keep the tissue stiffness close to normal levels vs. the doubling of the stiffness by the controls. A larger clinical study, however, is needed to definitively prove this benefit as well as the mechanism for this improvement. Full article
(This article belongs to the Special Issue Biomaterial Enhanced Regeneration)
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Open AccessArticle Development of Phosphatized Calcium Carbonate Biominerals as Bioactive Bone Graft Substitute Materials, Part II: Functionalization with Antibacterial Silver Ions
J. Funct. Biomater. 2018, 9(4), 67; https://doi.org/10.3390/jfb9040067
Received: 25 October 2018 / Revised: 15 November 2018 / Accepted: 20 November 2018 / Published: 23 November 2018
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Abstract
Porous calcium phosphate (CaP) materials as bone graft substitutes can be prepared from Ca carbonate biomineral structures by hydrothermal conversion into pseudomorphic CaP scaffolds. The present study aims at furnishing such phosphatized Ca carbonate biomineral (PCCB) materials with antibacterial Ag ions in order [...] Read more.
Porous calcium phosphate (CaP) materials as bone graft substitutes can be prepared from Ca carbonate biomineral structures by hydrothermal conversion into pseudomorphic CaP scaffolds. The present study aims at furnishing such phosphatized Ca carbonate biomineral (PCCB) materials with antibacterial Ag ions in order to avoid perisurgical wound infections. Prior to this study, PCCB materials with Mg and/or Sr ions incorporated for stimulating bone formation were prepared from coral skeletons and sea urchin spines as starting materials. The porous PCCB materials were treated with aqueous solutions of Ag nitrate with concentrations of 10 or 100 mmol/L, resulting in the formation of Ag phosphate nanoparticles on the sample surfaces through a replacement reaction. The materials were characterized using scanning electron microscopy (SEM) energy-dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). In contact with Ringer`s solution, the Ag phosphate nanoparticles dissolved and released Ag ions with concentrations up to 0.51 mg/L, as shown by atomic absorption spectroscopy (AAS) analyses. In tests against Pseudomonas aeruginosa and Staphylococcus aureus on agar plates, antibacterial properties were similar for both types of Ag-modified PCCB materials. Concerning the antibacterial performance, the treatment with AgNO3 solutions with 10 mmol/L was almost as effective as with 100 mmol/L. Full article
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Open AccessArticle The Feasibility of Using Pulsatile Electromagnetic Fields (PEMFs) to Enhance the Regenerative Ability of Dermal Biomaterial Scaffolds
J. Funct. Biomater. 2018, 9(4), 66; https://doi.org/10.3390/jfb9040066
Received: 6 August 2018 / Revised: 28 October 2018 / Accepted: 28 October 2018 / Published: 19 November 2018
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Abstract
Degradable regenerative scaffolds usually require adjunctive treatment to meet the clinical healing performance requirements. This study was designed to look at pulsatile electromagnetic fields (PEMF) as an adjunctive therapy for these scaffolds in skin wounds; however, no scaffold was used in this study [...] Read more.
Degradable regenerative scaffolds usually require adjunctive treatment to meet the clinical healing performance requirements. This study was designed to look at pulsatile electromagnetic fields (PEMF) as an adjunctive therapy for these scaffolds in skin wounds; however, no scaffold was used in this study in order to isolate the effects of PEMF alone. In this study, New Zealand rabbits received four full-thickness defects with a size of 3 cm × 3 cm on the dorsolateral aspect. The rabbits in the treatment group were placed in a chamber and subjected to a PEMF at six different predetermined frequency and intensity combinations for 2 h a day for a 2-week period. At the end of the 2-week period, the animals were sacrificed and tissue samples were taken. Half of each tissue sample was used for histomorphometric analysis and the other half was for tensile testing. The study showed an increased healing response by all the PEMF treatments compared to that in the control, although different combinations led to increases in different aspects of the healing response. This suggests that although some treatments are better for the critical clinical parameter—healing rate, it might be beneficial to use treatments in the early stages to increase angiogenesis before the treatment is switched to the one best for the healing rate to get an even better haling rate. Full article
(This article belongs to the Special Issue Biomaterial Enhanced Regeneration)
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Open AccessArticle Mesenchymal Stem Cells and Transforming Growth Factor-β3 (TGF-β3) to Enhance the Regenerative Ability of an Albumin Scaffold in Full Thickness Wound Healing
J. Funct. Biomater. 2018, 9(4), 65; https://doi.org/10.3390/jfb9040065
Received: 27 September 2018 / Revised: 25 October 2018 / Accepted: 1 November 2018 / Published: 14 November 2018
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Abstract
Pressure ulcers are one of the most common forms of skin injury, particularly in the spinal cord injured (SCI). Pressure ulcers are difficult to heal in this population requiring at least six months of bed rest. Surgical treatment (grafting) is the fastest recovery [...] Read more.
Pressure ulcers are one of the most common forms of skin injury, particularly in the spinal cord injured (SCI). Pressure ulcers are difficult to heal in this population requiring at least six months of bed rest. Surgical treatment (grafting) is the fastest recovery time, but it still requires six weeks of bed rest plus significant additional costs and a high recurrence rate. A significant clinical benefit would be obtained by speeding the healing rate of a non-surgical treatment to close to that of surgical treatment (approximately doubling of healing rate). Current non-surgical treatment is mostly inactive wound coverings. The goal of this project was to look at the feasibility of doubling the healing rate of a full-thickness defect using combinations of three treatments, for the first time, each shown to increase healing rate: application of transforming growth factor-β3 (TGF-β3), an albumin based scaffold, and mesenchymal stem cells (MSCs). At one week following surgery, the combined treatment showed the greatest increase in healing rate, particularly for the epithelialization rate. Although the target level of a 100% increase in healing rate over the control was not quite achieved, it is anticipated that the goal would be met with further optimization of the treatment. Full article
(This article belongs to the Special Issue Biomaterial Enhanced Regeneration)
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Open AccessArticle Transcatheter Decellularized Tissue-Engineered Heart Valve (dTEHV) Grown on Polyglycolic Acid (PGA) Scaffold Coated with P4HB Shows Improved Functionality over 52 Weeks due to Polyether-Ether-Ketone (PEEK) Insert
J. Funct. Biomater. 2018, 9(4), 64; https://doi.org/10.3390/jfb9040064
Received: 31 July 2018 / Revised: 26 August 2018 / Accepted: 10 September 2018 / Published: 13 November 2018
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Abstract
Many congenital heart defects and degenerative valve diseases require replacement of heart valves in children and young adults. Transcatheter xenografts degenerate over time. Tissue engineering might help to overcome this limitation by providing valves with ability for self-repair. A transcatheter decellularized tissue-engineered heart [...] Read more.
Many congenital heart defects and degenerative valve diseases require replacement of heart valves in children and young adults. Transcatheter xenografts degenerate over time. Tissue engineering might help to overcome this limitation by providing valves with ability for self-repair. A transcatheter decellularized tissue-engineered heart valve (dTEHV) was developed using a polyglycolic acid (PGA) scaffold. A first prototype showed progressive regurgitation after 6 months in-vivo due to a suboptimal design and misguided remodeling process. A new geometry was developed accordingly with computational fluid dynamics (CFD) simulations and implemented by adding a polyether-ether-ketone (PEEK) insert to the bioreactor during cultivation. This lead to more belly-shaped leaflets with higher coaptation areas for this second generation dTEHV. Valve functionality assessed via angiography, intracardiac echocardiography, and MRI proved to be much better when compared the first generation dTEHV, with preserved functionality up to 52 weeks after implantation. Macroscopic findings showed no thrombi or signs of acute inflammation. For the second generation dTEHV, belly-shaped leaflets with soft and agile tissue-formation were seen after explantation. No excessive leaflet shortening occurred in the second generation dTEHV. Histological analysis showed complete engraftment of the dTEHV, with endothelialization of the leaflets and the graft wall. Leaflets consisted of collagenous tissue and some elastic fibers. Adaptive leaflet remodeling was visible in all implanted second generation dTEHV, and most importantly no fusion between leaflet and wall was found. Very few remnants of the PGA scaffold were detected even 52 weeks after implantation, with no influence on functionality. By adding a polyether-ether-ketone (PEEK) insert to the bioreactor construct, a new geometry of PGA-scaffold based dTEHV could be implemented. This resulted in very good valve function of the implanted dTEHV over a period of 52 weeks. Full article
(This article belongs to the Special Issue Biomaterial Enhanced Regeneration)
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Open AccessArticle Development and Application of an Additively Manufactured Calcium Chloride Nebulizer for Alginate 3D-Bioprinting Purposes
J. Funct. Biomater. 2018, 9(4), 63; https://doi.org/10.3390/jfb9040063
Received: 24 August 2018 / Revised: 24 October 2018 / Accepted: 5 November 2018 / Published: 9 November 2018
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Abstract
Three-dimensional (3D)-bioprinting enables scientists to mimic in vivo micro-environments and to perform in vitro cell experiments under more physiological conditions than is possible with conventional two-dimensional (2D) cell culture. Cell-laden biomaterials (bioinks) are precisely processed to bioengineer tissue three-dimensionally. One primarily used matrix [...] Read more.
Three-dimensional (3D)-bioprinting enables scientists to mimic in vivo micro-environments and to perform in vitro cell experiments under more physiological conditions than is possible with conventional two-dimensional (2D) cell culture. Cell-laden biomaterials (bioinks) are precisely processed to bioengineer tissue three-dimensionally. One primarily used matrix material is sodium alginate. This natural biopolymer provides both fine mechanical properties when gelated and high biocompatibility. Commonly, alginate is 3D bioprinted using extrusion based devices. The gelation reaction is hereby induced by a CaCl2 solution in the building chamber after material extrusion. This established technique has two main disadvantages: (1) CaCl2 can have toxic effects on the cell-laden hydrogels by oxygen diffusion limitation and (2) good printing resolution in the CaCl2 solution is hard to achieve, since the solution needs to be removed afterwards and substituted by cell culture media. Here, we show an innovative approach of alginate bioprinting based on a CaCl2 nebulizer. The device provides CaCl2 mist to the building platform inducing the gelation. The necessary amount of CaCl2 could be decreased as compared to previous gelation strategies and limitation of oxygen transfer during bioprinting can be reduced. The device was manufactured using the MJP-3D printing technique. Subsequently, its digital blueprint (CAD file) can be modified and additive manufactured easily and mounted in various extrusion bioprinters. With our approach, a concept for a more gentle 3D Bioprinting method could be shown. We demonstrated that the concept of an ultrasound-based nebulizer for CaCl2 mist generation can be used for 3D bioprinting and that the mist-induced polymerization of alginate hydrogels of different concentrations is feasible. Furthermore, different cell-laden alginate concentrations could be used: Cell spheroids (mesenchymal stem cells) and single cells (mouse fibroblasts) were successfully 3D printed yielding viable cells and stable hydrogels after 24 h cultivation. We suggest our work to show a different and novel approach on alginate bioprinting, which could be useful in generating cell-laden hydrogel constructs for e.g., drug screening or (soft) tissue engineering applications. Full article
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Open AccessFeature PaperArticle Three-Dimensional Bone Substitutes for Oral and Maxillofacial Surgery: Biological and Structural Characterization
J. Funct. Biomater. 2018, 9(4), 62; https://doi.org/10.3390/jfb9040062
Received: 27 September 2018 / Revised: 29 October 2018 / Accepted: 2 November 2018 / Published: 8 November 2018
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Abstract
Background: Bone substitutes, either from human (autografts and allografts) or animal (xenografts) sources, suffer from inherent drawbacks including limited availability or potential infectivity to name a few. In the last decade, synthetic biomaterials have emerged as a valid alternative for biomedical applications in [...] Read more.
Background: Bone substitutes, either from human (autografts and allografts) or animal (xenografts) sources, suffer from inherent drawbacks including limited availability or potential infectivity to name a few. In the last decade, synthetic biomaterials have emerged as a valid alternative for biomedical applications in the field of orthopedic and maxillofacial surgery. In particular, phosphate-based bone substitution materials have exhibited a high biocompatibility due to their chemical similitude with natural hydroxyapatite. Besides the nature of the biomaterial, its porous and interconnected architecture is essential for a correct osseointegration. This performance could be predicted with an extensive characterization of the biomaterial in vitro. Methods: In this study, we compared the biological, chemical, and structural features of four different commercially available bone substitutes derived from an animal or a synthetic source. To this end, µ-CT and SEM were used to describe the biomaterials structure. Both FTIR and EDS analyses were carried out to provide a chemical characterization. The results obtained by these techniques were correlated with cell adhesion and proliferation of the osteosarcoma MG-63 human cell line cultured in vitro. Results: The findings reported in this paper indicate a significant influence of both the nature and the structure of the biomaterials in cell adhesion and proliferation, which ultimately could affect the clinical performance of the biomaterials. Conclusions: The four commercially available bone substitutes investigated in this work significantly differed in terms of structural features, which ultimately influenced in vitro cell proliferation and may so affect the clinical performance of the biomaterials. Full article
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Open AccessFeature PaperCommunication Organo-Clay Nanomaterials Based on Halloysite and Cyclodextrin as Carriers for Polyphenolic Compounds
J. Funct. Biomater. 2018, 9(4), 61; https://doi.org/10.3390/jfb9040061
Received: 1 October 2018 / Revised: 31 October 2018 / Accepted: 1 November 2018 / Published: 3 November 2018
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Hybrid material based on halloysite covalently linked to a hyper-reticulated cyclodextrin network was investigated as a potential carrier for polyphenolic compounds. The absorption ability of the hybrid system was studied in different pH conditions as well as the kinetic release of curcumin, chosen [...] Read more.
Hybrid material based on halloysite covalently linked to a hyper-reticulated cyclodextrin network was investigated as a potential carrier for polyphenolic compounds. The absorption ability of the hybrid system was studied in different pH conditions as well as the kinetic release of curcumin, chosen as a drug model. A preliminary study was performed to assess the antioxidant capacity of the obtained carrier. The obtained results highlighted that the curcumin molecule can have sustained release from the carrier over the time, retaining its antioxidant properties due to the combination of two different host systems that give rise to an hyper-reticulated structure, allowing an increase in the drug loading and stabilization. Therefore, this work puts forward an efficient strategy to prepare organic-inorganic hybrids with three different cavities that could encapsulate two or more drug molecules with different physico-chemical properties. Full article
(This article belongs to the Special Issue Clay-Based Biomaterials: From Synthesis to Applications)
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Open AccessCommunication Filling of Mater-Bi with Nanoclays to Enhance the Biofilm Rigidity
J. Funct. Biomater. 2018, 9(4), 60; https://doi.org/10.3390/jfb9040060
Received: 26 September 2018 / Revised: 17 October 2018 / Accepted: 18 October 2018 / Published: 21 October 2018
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Abstract
We investigated the efficacy of several nanoclays (halloysite, sepiolite and laponite) as nanofillers for Mater-Bi, which is a commercial bioplastic extensively used within food packaging applications. The preparation of Mater-Bi/nanoclay nanocomposite films was easily achieved by means of the solvent casting method from [...] Read more.
We investigated the efficacy of several nanoclays (halloysite, sepiolite and laponite) as nanofillers for Mater-Bi, which is a commercial bioplastic extensively used within food packaging applications. The preparation of Mater-Bi/nanoclay nanocomposite films was easily achieved by means of the solvent casting method from dichloroethane. The prepared bio-nanocomposites were characterized by dynamic mechanical analysis (DMA) in order to explore the effect of the addition of the nanoclays on the mechanical behavior of the Mater-Bi-based films. Tensile tests found that filling Mater-Bi with halloysite induced the most significant improvement of the mechanical performances under traction force, while DMA measurements under the oscillatory regime showed that the polymer glass transition was not affected by the addition of the nanoclay. The tensile properties of the Mater-Bi/halloysite nanotube (HNT) films were competitive compared to those of traditional petroleum plastics in terms of the elastic modulus and stress at the breaking point. Both the mechanical response to the temperature and the tensile properties make the bio-nanocomposites appropriate for food packaging and smart coating purposes. Here, we report a preliminary study of the development of sustainable hybrid materials that could be employed in numerous industrial and technological applications within materials science and pharmaceutics. Full article
(This article belongs to the Special Issue Clay-Based Biomaterials: From Synthesis to Applications)
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Open AccessArticle Direct-Contact Cytotoxicity Evaluation of CoCrFeNi-Based Multi-Principal Element Alloys
J. Funct. Biomater. 2018, 9(4), 59; https://doi.org/10.3390/jfb9040059
Received: 26 September 2018 / Revised: 8 October 2018 / Accepted: 16 October 2018 / Published: 19 October 2018
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Abstract
Transition metal multi-principal element alloys (MPEAs) are novel alloys that may offer enhanced surface and mechanical properties compared with commercial metallic alloys. However, their biocompatibility has not been investigated. In this study, three CoCrFeNi-based MPEAs were fabricated, and the in vitro cytotoxicity was [...] Read more.
Transition metal multi-principal element alloys (MPEAs) are novel alloys that may offer enhanced surface and mechanical properties compared with commercial metallic alloys. However, their biocompatibility has not been investigated. In this study, three CoCrFeNi-based MPEAs were fabricated, and the in vitro cytotoxicity was evaluated in direct contact with fibroblasts for 168 h. The cell viability and cell number were assessed at 24, 96, and 168 h using LIVE/DEAD assay and alamarBlue assay, respectively. All MPEA sample wells had a high percentage of viable cells at each time point. The two quaternary MPEAs demonstrated a similar cell response to stainless steel control with the alamarBlue assay, while the quinary MPEA with Mn had a lower cell number after 168 h. Fibroblasts cultured with the MPEA samples demonstrated a consistent elongated morphology, while those cultured with the Ni control samples demonstrated changes in cell morphology after 24 h. No significant surface corrosion was observed on the MPEAs or stainless steel samples following the cell culture, while the Ni control samples had extensive corrosion. The cell growth and viability results demonstrate the cytocompatibility of the MPEAs. The biocompatibility of MPEAs should be investigated further to determine if MPEAs may be utilized in orthopedic implants and other biomedical applications. Full article
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Open AccessFeature PaperReview The Use of Some Clay Minerals as Natural Resources for Drug Carrier Applications
J. Funct. Biomater. 2018, 9(4), 58; https://doi.org/10.3390/jfb9040058
Received: 20 September 2018 / Revised: 16 October 2018 / Accepted: 17 October 2018 / Published: 19 October 2018
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Abstract
The goal of modern research is to use environmentally preferable materials. In this context, clay minerals are emerging candidates for their bio- and ecocompatibility, low cost and natural availability. Clay minerals present different morphologies according to their layer arrangements. The use of clay [...] Read more.
The goal of modern research is to use environmentally preferable materials. In this context, clay minerals are emerging candidates for their bio- and ecocompatibility, low cost and natural availability. Clay minerals present different morphologies according to their layer arrangements. The use of clay minerals, especially in biomedical applications is known from ancient times and they are regaining attention in recent years. The most representative clay minerals are kaolinit, montmorillonite, sepiolites and halloysite. This review summarizes some clay minerals and their derivatives for application as nanocontainer for biologically active species. Full article
(This article belongs to the Special Issue Clay-Based Biomaterials: From Synthesis to Applications)
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Open AccessTechnical Note The 3D Printing of Calcium Phosphate with K-Carrageenan under Conditions Permitting the Incorporation of Biological Components—A Method
J. Funct. Biomater. 2018, 9(4), 57; https://doi.org/10.3390/jfb9040057
Received: 13 June 2018 / Revised: 6 September 2018 / Accepted: 11 October 2018 / Published: 17 October 2018
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Abstract
Critical-size bone defects are a common clinical problem. The golden standard to treat these defects is autologous bone grafting. Besides the limitations of availability and co-morbidity, autografts have to be manually adapted to fit in the defect, which might result in a sub-optimal [...] Read more.
Critical-size bone defects are a common clinical problem. The golden standard to treat these defects is autologous bone grafting. Besides the limitations of availability and co-morbidity, autografts have to be manually adapted to fit in the defect, which might result in a sub-optimal fit and impaired healing. Scaffolds with precise dimensions can be created using 3-dimensional (3D) printing, enabling the production of patient-specific, ‘tailor-made’ bone substitutes with an exact fit. Calcium phosphate (CaP) is a popular material for bone tissue engineering due to its biocompatibility, osteoconductivity, and biodegradable properties. To enhance bone formation, a bioactive 3D-printed CaP scaffold can be created by combining the printed CaP scaffold with biological components such as growth factors and cytokines, e.g., vascular endothelial growth factor (VEGF), bone morphogenetic protein-2 (BMP-2), and interleukin-6 (IL-6). However, the 3D-printing of CaP with a biological component is challenging since production techniques often use high temperatures or aggressive chemicals, which hinders/inactivates the bioactivity of the incorporated biological components. Therefore, in our laboratory, we routinely perform extrusion-based 3D-printing with a biological binder at room temperature to create porous scaffolds for bone healing. In this method paper, we describe in detail a 3D-printing procedure for CaP paste with K-carrageenan as a biological binder. Full article
(This article belongs to the Special Issue 3D Printing of Biomaterials)
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Open AccessArticle Development and Evaluation of an Injectable Chitosan/β-Glycerophosphate Paste as a Local Antibiotic Delivery System for Trauma Care
J. Funct. Biomater. 2018, 9(4), 56; https://doi.org/10.3390/jfb9040056
Received: 29 August 2018 / Revised: 23 September 2018 / Accepted: 9 October 2018 / Published: 12 October 2018
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Abstract
Complex open musculoskeletal wounds are a leading cause of morbidity worldwide, partially due to a high risk of bacterial contamination. Local delivery systems may be used as adjunctive therapies to prevent infection, but they may be nondegradable, possess inadequate wound coverage, or migrate [...] Read more.
Complex open musculoskeletal wounds are a leading cause of morbidity worldwide, partially due to a high risk of bacterial contamination. Local delivery systems may be used as adjunctive therapies to prevent infection, but they may be nondegradable, possess inadequate wound coverage, or migrate from the wound site. To address this issue, a thermo-responsive, injectable chitosan paste was fabricated by incorporating beta-glycerophosphate. The efficacy of thermo-paste as an adjunctive infection prevention tool was evaluated in terms of cytocompatibility, degradation, antibacterial, injectability, and inflammation properties. In vitro studies demonstrated thermo-paste may be loaded with amikacin and vancomycin and release inhibitory levels for at least 3 days. Further, approximately 60% of thermo-paste was enzymatically degraded within 7 days in vitro. The viability of cells exposed to thermo-paste exceeded ISO 10993-5 standards with approximately 73% relative viability of a control chitosan sponge. The ejection force of thermo-paste, approximately 20 N, was lower than previously studied paste formulations and within relevant clinical ejection force ranges. An in vivo murine biocompatibility study demonstrated that thermo-paste induced minimal inflammation after implantation for 7 days, similar to previously developed chitosan pastes. Results from these preliminary preclinical studies indicate that thermo-paste shows promise for further development as an antibiotic delivery system for infection prevention. Full article
(This article belongs to the Special Issue Chitosan and Chitosan-Based Biomaterials)
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Open AccessArticle Evaluation of Antibiotic-Releasing Triphasic Bone Void Filler In-Vitro
J. Funct. Biomater. 2018, 9(4), 55; https://doi.org/10.3390/jfb9040055
Received: 31 July 2018 / Revised: 31 August 2018 / Accepted: 17 September 2018 / Published: 21 September 2018
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Abstract
Bone void fillers (BVFs) containing calcium sulfate, tricalcium phosphate (TCP), and hydroxyapatite can be loaded with antibiotics for infection treatment or prevention under surgeon-directed use. The aim of this study was to characterize the handling and elution properties of a triphasic BVF loaded [...] Read more.
Bone void fillers (BVFs) containing calcium sulfate, tricalcium phosphate (TCP), and hydroxyapatite can be loaded with antibiotics for infection treatment or prevention under surgeon-directed use. The aim of this study was to characterize the handling and elution properties of a triphasic BVF loaded with common antibiotics. BVF was mixed with vancomycin and/or tobramycin to form pellets, and the set time was recorded. A partial refreshment elution study was conducted with time points at 4, 8, and 24 h, as well as 2, 7, 14, 28, and 42 days. Effects on dissolution were evaluated in a 14-day dissolution study. Set time increased to over 1 h for groups containing tobramycin, although vancomycin had a minimal effect. Pellets continued to elute antibiotics throughout the 42-day elution study, suggesting efficacy for the treatment or prevention of orthopedic infections. BVF containing vancomycin or tobramycin showed similar dissolution at 14 days compared to BVF without antibiotics; however, BVF containing both antibiotics showed significantly more dissolution. Full article
(This article belongs to the Special Issue Biomaterial Enhanced Regeneration)
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Open AccessArticle An In Vitro Model for Assessing Corneal Keratocyte Spreading and Migration on Aligned Fibrillar Collagen
J. Funct. Biomater. 2018, 9(4), 54; https://doi.org/10.3390/jfb9040054
Received: 5 September 2018 / Revised: 16 September 2018 / Accepted: 18 September 2018 / Published: 21 September 2018
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Abstract
Background: Corneal stromal cells (keratocytes) are responsible for developing and maintaining normal corneal structure and transparency, and for repairing the tissue after injury. Corneal keratocytes reside between highly aligned collagen lamellae in vivo. In addition to growth factors and other soluble biochemical factors, [...] Read more.
Background: Corneal stromal cells (keratocytes) are responsible for developing and maintaining normal corneal structure and transparency, and for repairing the tissue after injury. Corneal keratocytes reside between highly aligned collagen lamellae in vivo. In addition to growth factors and other soluble biochemical factors, feedback from the extracellular matrix (ECM) itself has been shown to modulate corneal keratocyte behavior. Methods: In this study, we fabricate aligned collagen substrates using a microfluidics approach and assess their impact on corneal keratocyte morphology, cytoskeletal organization, and patterning after stimulation with platelet derived growth factor (PDGF) or transforming growth factor beta 1 (TGFβ). We also use time-lapse imaging to visualize the dynamic interactions between cells and fibrillar collagen during wound repopulation following an in vitro freeze injury. Results: Significant co-alignment between keratocytes and aligned collagen fibrils was detected, and the degree of cell/ECM co-alignment further increased in the presence of PDGF or TGFβ. Freeze injury produced an area of cell death without disrupting the collagen. High magnification, time-lapse differential interference contrast (DIC) imaging allowed cell movement and subcellular interactions with the underlying collagen fibrils to be directly visualized. Conclusions: With continued development, this experimental model could be an important tool for accessing how the integration of multiple biophysical and biochemical signals regulate corneal keratocyte differentiation. Full article
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