Showing papers in "Journal of Biomedical Materials Research Part A in 2018"
TL;DR: The results suggest that FDM technology is a fast and reproducible technique that can be used to fabricate tridimensional custom-made scaffolds for tissue engineering.
Abstract: Autografts remain the gold standard for orthopedic transplantations. However, to overcome its limitations, bone tissue engineering proposes new strategies. This includes the development of new biomaterials such as synthetic polymers, to serve as scaffold for tissue production. The objective of this present study was to produce poly(lactic) acid (PLA) scaffolds of different pore size using fused deposition modeling (FDM) technique and to evaluate their physicochemical and biological properties. Structural, chemical, mechanical, and biological characterizations were performed. We successfully fabricated scaffolds of three different pore sizes. However, the pore dimensions were slightly smaller than expected. We found that the 3D printing process induced decreases in both, PLA molecular weight and degradation temperatures, but did not change the semicrystalline structure of the polymer. We did not observe any effect of pore size on the mechanical properties of produced scaffolds. After the sterilization by γ irradiation, scaffolds did not exhibit any cytotoxicity towards human bone marrow stromal cells (HBMSC). Finally, after three and seven days of culture, HBMSC showed high viability and homogenous distribution irrespective of pore size. Thus, these results suggest that FDM technology is a fast and reproducible technique that can be used to fabricate tridimensional custom-made scaffolds for tissue engineering. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 887-894, 2018.
211 citations
TL;DR: A shear-thinning and self-healing hydrogel crosslinked through dynamic covalent chemistry for 3D bioprinting is presented, introducing a simple approach to both fabricate and modify 3D printed scaffolds.
Abstract: The fabrication of three-dimensional (3D) scaffolds is indispensable to tissue engineering and 3D printing is emerging as an important approach towards this. Hydrogels are often used as inks in extrusion-based 3D printing, including with encapsulated cells; however, numerous challenging requirements exist, including appropriate viscosity, the ability to stabilize after extrusion, and cytocompatibility. Here, we present a shear-thinning and self-healing hydrogel crosslinked through dynamic covalent chemistry for 3D bioprinting. Specifically, hyaluronic acid was modified with either hydrazide or aldehyde groups and mixed to form hydrogels containing a dynamic hydrazone bond. Due to their shear-thinning and self-healing properties, the hydrogels could be extruded for 3D printing of structures with high shape fidelity, stability to relaxation, and cytocompatibility with encapsulated fibroblasts (>80% viability). Forces for extrusion and filament sizes were dependent on parameters such as material concentration and needle gauge. To increase scaffold functionality, a second photocrosslinkable interpenetrating network was included that was used for orthogonal photostiffening and photopatterning through a thiol-ene reaction. Photostiffening increased the scaffold's modulus (∼300%) while significantly decreasing erosion (∼70%), whereas photopatterning allowed for spatial modification of scaffolds with dyes. Overall, this work introduces a simple approach to both fabricate and modify 3D printed scaffolds. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 865-875, 2018.
188 citations
TL;DR: Fibrinogen (Fg) adsorption is identified as the single most important event determining the biocompatibility of implants in soft tissue and in blood.
Abstract: Fibrinogen (Fg) adsorption is an important mechanism underlying cell adhesion to biomaterials and was the major focus of the author's research career. This article summarizes our work on Fg adsorption, with citations of related work as appropriate. The molecular properties of Fg that promote adsorption and cell adhesion will be described. In addition, the adsorption behavior of Fg from buffer, binary solutions with other proteins, and blood plasma will be discussed, including the Vroman effect. Studies of platelet adhesion to surfaces preadsorbed with blood plasmas selectively deficient in Fg, vitronectin (Vn), fibronectin (Fn), or von Willebrand's factor (vWf) will be reviewed. These studies clearly showed a major role for Fg in platelet adhesion under static conditions and both Fg and vWf for adhesion from flowing suspensions, but no significant role for Vn or Fn. However, it was also shown that platelet adhesion was poorly correlated with the total amount of adsorbed Fg, but very well correlated with the binding of antibodies specific to the cell binding domains of Fg. A brief overview of nonfouling surfaces for prevention of Fg adsorption will be given. A more extensive discussion of structural changes in Fg after its adsorption is included, including changes detected with both physicochemical and biological methods. A short discussion of the state of the art of structural determination of adsorbed proteins with computational methods is also given. A final section identifies Fg adsorption as the single most important event determining the biocompatibility of implants in soft tissue and in blood. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2777-2788, 2018.
108 citations
TL;DR: The data suggest that GelMA hydrogels prepared with 5% polymer concentration has promoted homogeneous extracellular matrix calcification and it is a great candidate for BTE applications.
Abstract: Gelatin methacrylate (GelMA) is an inexpensive, photocrosslinkable, cell-responsive hydrogel which has drawn attention for a wide range of tissue engineering applications. The potential of GelMA scaffolds was demonstrated to be tunable for different tissue engineering (TE) applications through modifying the polymer concentration, methacrylation degree, or UV light intensity. Despite the promising results of GelMA hydrogels in tissue engineering, the influence of polymer concentration for bone tissue engineering (BTE) scaffolds was not established yet. Thus, in this study, we have demonstrated the effect of polymer concentration in GelMA scaffolds on osteogenic differentiation. We prepared GelMA scaffolds with 5 and 10% polymer concentrations and characterized the scaffolds in terms of porosity, pore size, swelling characteristics, and mechanical properties. Subsequent to the scaffolds characterization, the scaffolds were seeded with bone marrow derived rat mesenchymal stem cells and cultured in osteogenic media to evaluate the possible osteogenic differentiation effect exerted by the polymer concentration. After 7, 14, 21, and 28 days, DNA content, calcium deposition, and alkaline phosphatase (ALP) activity of scaffolds were evaluated quantitatively by colorimetric bioassays. Furthermore, the distribution of the calcium deposition within the scaffolds was attained qualitatively and quantitatively by microcomputer tomography (µCT). Our data suggest that GelMA hydrogels prepared with 5% polymer concentration has promoted homogeneous extracellular matrix calcification and it is a great candidate for BTE applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 201-209, 2018.
108 citations
TL;DR: Results showed that addition of GT to SF increased nanofiber's diameter, bulk hydrophilicity, surface wettability, mass loss percentage, but decreased Young's modulus, tensile strength, and porosity of the SF/GT mats.
Abstract: In this study, a nanofibrous electrospun substrate based on the silk fibroin (SF) and gelatin (GT) polymers were prepared and evaluated. The SF/GT blended solutions were prepared with various ratios of GT in formic acid and electrospun to obtain bead-free fibers. Results showed that addition of GT to SF increased nanofiber's diameter, bulk hydrophilicity, surface wettability, mass loss percentage, but decreased Young's modulus, tensile strength, and porosity of the SF/GT mats. According to the obtained results, the mat containing 10% of GT was selected as the optimized mat for further studies and loaded with thyme essential oil (TEO) and doxycycline monohydrate (DCMH) as the antibacterial agents. Release studies showed a burst release of TEO from the mat within the first 3 h, while the DCMH had a sustained release during 48 h. In comparison to the TEO-loaded mat, the DCMH-loaded one showed larger inhibition zones against Staphylococcus aureus and Klebsiella pneumoniae bacteria. Meanwhile, cellular studies using mouse fibroblast L929 cells showed excellent cell-compatibility of TEO- and DCMH-loaded mats. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1092-1103, 2018.
106 citations
TL;DR: Bacteria were able to synthesize selenium nanoparticles through the use of different functional structures within the organisms, mainly enzymes such as selenite reductases, which represent a viable approach to reduce bacteria growth without antibiotics overcoming the drawbacks of synthetic methods that employ toxic chemicals.
Abstract: Antimicrobial resistance is a global concern that affects more than two million people each year. Therefore, new approaches to kill bacteria are needed. One of the most promising methodologies may come from metallic nanoparticles, since bacteria may not develop a resistance to these nanostructures as they do for antibiotics. While metallic nanoparticle synthesis methods have been well studied, they are often accompanied by significant drawbacks such as cost, extreme processing conditions, and toxic waste production since they use harsh chemicals such as corrosive agents (hydrazine) or strong acids (hydrochloride acid). In this work, we explored the environmentally safe synthesis of selenium nanoparticles, which have shown promise in killing bacteria. Using Escherichia coli, Pseudomonas aeruginosa, Methicillin-resistance Staphylococcus aureus, and S. aureus, 90-150 nm average diameter selenium nanoparticles were synthesized using an environmentally safe approach. Nanoparticles were characterized using transmission electron microscopy, energy dispersive X-ray spectroscopy to determine the chemical composition, and inductively coupled plasma mass spectrometry to validate chemistry. Nanoparticles were also characterized and tested for their ability to inhibit bacterial growth. A decay in bacterial growth after 24 h was achieved against both S. aureus and E. coli at biogenic selenium nanoparticle concentrations from 25 to 250 µg/mL and showed no significant cytotoxicity effect against human dermal fibroblasts for 24 h. Bacteria were able to synthesize selenium nanoparticles through the use of different functional structures within the organisms, mainly enzymes such as selenite reductases. Therefore, biogenic selenium nanoparticles made by bacteria represent a viable approach to reduce bacteria growth without antibiotics overcoming the drawbacks of synthetic methods that employ toxic chemicals. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1400-1412, 2018.
90 citations
TL;DR: The organoid Trojan horse system is a possible approach for delivering drugs to inflamed areas due to their ability to adsorb small nanoparticle inside the lumen and attach to the damaged area.
Abstract: Inflammatory bowel disease (IBD) causes inflammation to the gastrointestinal tract. Local administration of anti-inflammatory drugs such as 5-aminosalicylic acid (5-ASA) can alleviate the symptoms of IBD. The application of nanoparticles for IBD treatment in direct rectal administration showed high drug availability and treatment efficacy. However, relying on size-dependent adsorption of smaller particles is not sufficient for making the formulation capable of targeting. Intestinal organoids can improve the functionality of the nanoparticles due to their ability to adsorb small nanoparticle inside the lumen and attach to the damaged area. In this study, intestinal organoids were used as carriers of 5-ASA-loaded poly(lactic-co-glycolic acid) nanoparticles. The nanoparticle sizes, confirmed by scanning electron microscopy, were 200-300 nm and the zeta potential were negative. The nanoparticles did not have any noticeable pernicious effect on organoid growth and viability. After mixing the nanoparticles with Matrigel and organoids, Rhodamine B loaded inside the nanoparticles was highly detected inside the organoid's lumen after 3 days by confocal fluorescent microscopy and no longer detected in the lumen after day 4. It may be attributed to the ability of the lumen to digest particles. Thus, the organoid Trojan horse system is a possible approach for delivering drugs to inflamed areas. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 876-886, 2018.
83 citations
TL;DR: PEO coatings incorporated with bioactive glasses can provide environment-friendly antimicrobial surfaces with exceptional bioactivity, biocompatibility, and osseointegration.
Abstract: Plasma electrolytic oxidation (PEO) is an advance technique to develop porous oxidation layer on light metals, primarily to enhance corrosion and wear resistance. The oxidation layer can also offer a wide variety of mechanical, biomedical, tribological, and antibacterial properties through the incorporation of several ions and particles. Due to the increasing need of antimicrobial surfaces for biomedical implants, antibacterial PEO coatings have been developed through the incorporation of antibacterial agents. Metallic nanoparticles that have been employed most widely as antibacterial agents are reported to demonstrate serious health and environmental threats. To overcome the current limitations of these coatings, there is a significant need to develop antibacterial surfaces that are not harmful for patient's health and environment. Attention of the readers has been directed to utilize bioactive glasses as antibacterial agents for PEO coatings. Bioactive glasses are well known for their excellent bioactivity, biocompatibility, and antibacterial character. PEO coatings incorporated with bioactive glasses can provide environment-friendly antimicrobial surfaces with exceptional bioactivity, biocompatibility, and osseointegration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 590-605, 2018.
68 citations
TL;DR: Alginate/gelatin-based porous scaffolds are proposed as a viable ECM substitute for applications in cardiac tissue engineering and showed superior mechanical properties for the desired application and supported better adhesion, growth, and differentiation of myoblasts under static conditions.
Abstract: Tissue engineering has emerged as a viable approach to treat disease or repair damage in tissues and organs. One of the key elements for the success of tissue engineering is the use of a scaffold serving as artificial extracellular matrix (ECM). The ECM hosts the cells and improves their survival, proliferation, and differentiation, enabling the formation of new tissue. Here, we propose the development of a class of protein/polysaccharide-based porous scaffolds for use as ECM substitutes in cardiac tissue engineering. Scaffolds based on blends of a protein component, collagen or gelatin, with a polysaccharide component, alginate, were produced by freeze-drying and subsequent ionic and chemical crosslinking. Their morphological, physicochemical, and mechanical properties were determined and compared with those of natural porcine myocardium. We demonstrated that our scaffolds possessed highly porous and interconnected structures, and the chemical homogeneity of the natural ECM was well reproduced in both types of scaffolds. Furthermore, the alginate/gelatin (AG) scaffolds better mimicked the native tissue in terms of interactions between components and protein secondary structure, and in terms of swelling behavior. The AG scaffolds also showed superior mechanical properties for the desired application and supported better adhesion, growth, and differentiation of myoblasts under static conditions. The AG scaffolds were subsequently used for culturing neonatal rat cardiomyocytes, where high viability of the resulting cardiac constructs was observed under dynamic flow culture in a microfluidic bioreactor. We therefore propose our protein/polysaccharide scaffolds as a viable ECM substitute for applications in cardiac tissue engineering. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 769-781, 2018.
67 citations
TL;DR: It was found that the thin films prepared from inks without an additive or any thin film post-treatment provide limited conductivity and stability for use in biomedical applications, and these properties were greatly improved by using ethylene glycol and thermal annealing.
Abstract: Biocompatibility tests and a study of the electrical properties of thin films prepared from six electroactive polymer ink formulations based on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) were performed The aim was to find a suitable formulation of PEDOT:PSS and conditions for preparing thin films in order to construct printed bioelectronic devices for biomedical applications The stability and electrical properties of such films were tested on organic electrochemical transistor (OECT)-based sensor platforms and their biocompatibility was evaluated in assays with 3T3 fibroblasts and murine cardiomyocytes It was found that the thin films prepared from inks without an additive or any thin film post-treatment provide limited conductivity and stability for use in biomedical applications These properties were greatly improved by using ethylene glycol and thermal annealing Addition or post-treatment by ethylene glycol in combination with thermal annealing provided thin films with electrical resistance and a stability sufficient to be used in sensing of animal cell physiology These films coated with collagen IV showed good biocompatibility in the assay with 3T3 fibroblasts when compared to standard cell culture plastics Selected films were then used in assays with murine cardiomyocytes We observed that these cells were able to attach to the PEDOT:PSS films and form an active sensor element Spontaneously beating clusters were formed, indicating a good physiological status for the cardiomyocyte cells These results open the door to construction of cheap printed electronic devices for biointerfacing in biomedical applications © 2018 Wiley Periodicals, Inc J Biomed Mater Res Part A: 106A: 1121-1128, 2018
65 citations
TL;DR: This review discusses the application of polymer-based scaffolds, with an emphasis on hydrogels in cartilage tissue engineering, and highlights injectable hydrogel with various micro- and nanoparticles, as they constitute a novel and attractive type of scaffolds.
Abstract: Cartilage loss due to age-related degeneration and mechanical trauma is a significant and challenging problem in the field of surgical medicine. Unfortunately, cartilage tissue can be characterized by the lack of regenerative ability. Limitations of conventional treatment strategies, such as auto-, allo-, and xenografts or implants stimulate an increasing interest in the tissue engineering approach to cartilage repair. This review discusses the application of polymer-based scaffolds, with an emphasis on hydrogels in cartilage tissue engineering. We highlight injectable hydrogels with various micro- and nanoparticles, as they constitute a novel and attractive type of scaffolds. We discuss advantages, limitations, and future perspectives of injectable nanocomposite hydrogels for cartilage tissue regeneration. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2762-2776, 2018.
TL;DR: Three-dimensional nanofibrous graphene and poly(caprolactone) (PCL + G) composite scaffold for cardiac tissue engineering has been explored for the first time and graphene especially affected Ca2+ handling properties of mES-CM compared to that of cardiomyocytes cultured in 2D culture, highlighting the potential of PCL + G for in vitro cardiac tissueengineering.
Abstract: Contractile behavior of cardiomyocytes relies on directed signal propagation through the electroconductive networks that exist within the native myocardium. Due to their unique electrical properties, electroactive materials, such as graphene, have recently emerged as promising candidate materials for cardiac tissue engineering applications. In this work, the potential of three-dimensional (3D) nanofibrous graphene and poly(caprolactone) (PCL + G) composite scaffold for cardiac tissue engineering has been explored for the first time. The addition of graphene into PCL led to an increased volume conductivity of scaffolds with an even distribution of graphene particles throughout the matrix. Graphene particles provided local conductive sites within the PCL matrix, which enabled application of external electrical stimulation throughout the scaffold using a custom point stimulation device. When mouse embryonic stem cell derived cardiomyocytes (mES-CM) were seeded on PCL + G scaffolds, cells adhered well, contracted spontaneously, and exhibited classical cardiomyocyte phenotype confirming the biocompatibility of electroactive PCL + G scaffolds. Further functional characterization demonstrated that graphene especially affected Ca2+ handling properties of mES-CM compared to that of cardiomyocytes cultured in 2D culture, highlighting the potential of PCL + G for in vitro cardiac tissue engineering. © 2018 Wiley Periodicals, Inc. J. Biomed. Mater. Res. Part A: 106A: 2923-2933, 2018.
TL;DR: A robust in vivo model to enhance the applicability of drug delivery systems in wound healing applications is presented and it is shown that the nanoscaffolds induced faster wound healing activity in dorsal wounds compared to the control.
Abstract: Diabetic wounds are susceptible to microbial infection. The treatment of these wounds requires a higher payload of growth factors. With this in mind, the strategy for this study was to utilize a novel payload comprising of Eudragit RL/RS 100 nanofibers carrying the bacterial inhibitor gentamicin sulfate (GS) in concert with recombinant human epidermal growth factor (rhEGF); an accelerator of wound healing. GS containing Eudragit was electrospun to yield nanofiber scaffolds, which were further modified by covalent immobilization of rhEGF to their surface. This novel fabricated nanoscaffold was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The thermal behavior of the nanoscaffold was determined using thermogravimetric analysis and differential scanning calorimetry. In the in vitro antibacterial assays, the nanoscaffolds exhibited comparable antibacterial activity to pure gentemicin powder. In vivo work using female C57/BL6 mice, the nanoscaffolds induced faster wound healing activity in dorsal wounds compared to the control. The paradigm in this study presents a robust in vivo model to enhance the applicability of drug delivery systems in wound healing applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 641-651, 2018.
TL;DR: A systematic search of MEDLINE database was conducted for in vitro studies on the use of graphene and its derivatives for bone tissue engineering from January 2000 to February 2018, and it was discovered that graphene with lateral size less than 5 µm, along with GO and RGO with lateral dimension less than 1 µm decrease cell viability.
Abstract: Graphene and its derivatives have been well-known as influential factors in differentiating stem/progenitor cells toward the osteoblastic lineage. However, there have been many controversies in the literature regarding the parameters effect on bone regeneration, including graphene concentration, size, type, dimension, hydrophilicity, functionalization, and composition. This study attempts to produce a comprehensive review regarding the given parameters and their effects on stimulating cell behaviors such as proliferation, viability, attachment and osteogenic differentiation. In this study, a systematic search of MEDLINE database was conducted for in vitro studies on the use of graphene and its derivatives for bone tissue engineering from January 2000 to February 2018, organized according to the PRISMA statement. According to reviewed articles, different graphene derivative, including graphene, graphene oxide (GO) and reduced graphene oxide (RGO) with mass ratio ≤1.5 wt % for all and concentration up to 50 μg/mL for graphene and GO, and 60 μg/mL for RGO, are considered to be safe for most cell types. However, these concentrations highly depend on the types of cells. It was discovered that graphene with lateral size less than 5 µm, along with GO and RGO with lateral dimension less than 1 µm decrease cell viability. In addition, the three-dimensional structure of graphene can promote cell-cell interaction, migration and proliferation. When graphene and its derivatives are incorporated with metals, polymers, and minerals, they frequently show promoted mechanical properties and bioactivity. Last, graphene and its derivatives have been found to increase the surface roughness and porosity, which can highly enhance cell adhesion and differentiation. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2284-2343, 2018.
TL;DR: The presence of gel/fiber architecture along with electrical conductivity may lead the scaffold to be very promising for bone regeneration, according to the results of assessments on pristine hydrogel and hydrogels.
Abstract: Hydrogel/fiber composites have emerged as compelling scaffolds for regeneration purposes. Any bio-related modification or feature may endow more regenerative functionality to these composites. In the present study, a hydrogel/fiber scaffold possessing electrical conductivity in both phases, hydrogel and fiber, has been prepared and evaluated. Fiber component possessed electrical conductivity due to the presence of polyaniline (PANi) and hydrogel fraction thanks to the presence of graphene nanoparticles. PANi based fibers were processed via electrospinning and transformed into a three-dimensional structure through ultrasonication. The hydrogel precursor solution composed of oxidized polysaccharides, gelatin and graphene with predesigned ratio was added to fibers and left to gel. The results of assessments on pristine hydrogel and hydrogel/fiber denoted that inclusion of conducting fibers into hydrogel increased elastic modulus, roughness and electrical conductivity, whereas decreased hydrophilicity. Moreover, the results showed that hydrogel/fiber composite better supported human osteoblast-like cell adhesion, proliferation and morphology comparing hydrogel alone. In a nutshell, the presence of gel/fiber architecture along with electrical conductivity may lead the scaffold to be very promising for bone regeneration. This article is protected by copyright. All rights reserved.
TL;DR: In vitro cytotoxicity and hemolysis test analysis indicated that OBC0.05/3 scaffold is cellular and blood compatible, demonstrating its potential application as a good candidate for peripheral nerve repair and improving the biodegradability of OBC scaffolds.
Abstract: Peripheral nerve injury is a serious medical problem and severely affects normal life of patient. Bacterial cellulose (BC) is considered as a novel promising biomaterial for tissue engineering, but the poor biodegradability limits its application. In this study, biodegradable bacterial cellulose scaffolds were prepared with different oxidation degrees (O.Ds.) using sodium periodate, evaluating their potential application in peripheral nerve repair. The chemical structure and surface morphology of the oxidized bacterial cellulose (OBC) scaffolds were characterized using Fourier transform infrared spectroscopy, Wide angle X-ray diffraction, and Scanning electron microscope. The porosity, mechanical properties, and degradation behavior of the OBC series scaffolds were extensively examined. Cellular viability and blood compatibility of OBC scaffolds were studied by MTT assay and hemolytic test using Schwann cells (SCs) and red blood cells (RBCs), respectively. The results demonstrated that the biodegradability of OBC scaffolds was improved significantly. OBC scaffolds with lower O.Ds. displayed high porosity with interconnected pores, suitable mechanical property, and biodegradability for peripheral nerve repair. In vitro cytotoxicity and hemolysis test analysis indicated that OBC0.05/3 scaffold is cellular and blood compatible, demonstrating its potential application as a good candidate for peripheral nerve repair. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1288-1298, 2018.
TL;DR: The F-Gly-MTX NPs have a very remarkable anticancer effect, for breast cancer cell line, and as prepared MNPs are biocompatible.
Abstract: In this study, magnetic nanoparticles (MNPs) coated with glycine (F-Gly NPs) and conjugated with methotrexate (MTX) (F-Gly-MTX NPs) were synthesized through a coprecipitation method followed by amidation reaction between the carboxylic acid end groups on MTX and the amine groups on the MNPs surface and studied its cytotoxic effect in vitro. The successful conjugating of MTX onto the nanoparticles (NPs) was confirmed by X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, vibrating sample magnetometer, and transmission electron microscopy techniques. The results showed that the average size was 46.82 ± 5.03 nm. This target drug delivery system is dependent on the release of the MTX within the lysosomal compartment. Hemolysis assay and cytotoxicity study results on HFF-2 and HEK-293 cell lines show that as prepared MNPs are biocompatible. The cytotoxicity of void of the MTX and F-Gly-MTX NPs were compared to each other by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay of the treated MCF-7 cell line. Enzymatic release studies exhibited the release of the MTX via peptide bond cleavage in the presence of proteinase K. These studies specify that the F-Gly-MTX NPs have a very remarkable anticancer effect, for breast cancer cell line. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1646-1654, 2018.
TL;DR: In conclusion, this study has developed and characterized injectable HA-PH-RGD based hydrogel, which represents a suitable material for further combinatorial therapies in neural tissue engineering.
Abstract: Hydrogel scaffolds which bridge the lesion, together with stem cell therapy represent a promising approach for spinal cord injury (SCI) repair. In this study, a hydroxyphenyl derivative of hyaluronic acid (HA-PH) was modified with the integrin-binding peptide arginine-glycine-aspartic acid (RGD), and enzymatically crosslinked to obtain a soft injectable hydrogel. Moreover, addition of fibrinogen was used to enhance proliferation of human Wharton's jelly-derived mesenchymal stem cells (hWJ-MSCs) on HA-PH-RGD hydrogel. The neuroregenerative potential of HA-PH-RGD hydrogel was evaluated in vivo in acute and subacute models of SCI. Both HA-PH-RGD hydrogel injection and implantation into the acute spinal cord hemisection cavity resulted in the same axonal and blood vessel density in the lesion area after 2 and 8 weeks. HA-PH-RGD hydrogel alone or combined with fibrinogen (HA-PH-RGD/F) and seeded with hWJ-MSCs was then injected into subacute SCI and evaluated after 8 weeks using behavioural, histological and gene expression analysis. A subacute injection of both HA-PH-RGD and HA-PH-RGD/F hydrogels similarly promoted axonal ingrowth into the lesion and this effect was further enhanced when the HA-PH-RGD/F was combined with hWJ-MSCs. On the other hand, no effect was found on locomotor recovery or the blood vessel ingrowth and density of glial scar around the lesion. In conclusion, we have developed and characterized injectable HA-PH-RGD based hydrogel, which represents a suitable material for further combinatorial therapies in neural tissue engineering. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1129-1140, 2018.
TL;DR: The possibility to tailor spongy-like hydrogels properties by including calcium as a crosslinker and by varying the amount of HAp will further contribute to understand how these features influence bone cells performance in vitro and bone formation in vivo.
Abstract: Portuguese Foundation for Science and Technology (FCT); contract grant numbers: SFRH/BD/78025/2011 (LdS), SFRH/BD/81356/2011 (DBP), IF/01285/2015 (JMO), IF/01214/2014 (VMC), and NORTE2020 for NORTE-010145-FEDER-000021 (MTC) Contract grant sponsor: project OsteoCart; contract grant number: PTDC/CTM-BPC/115977/2009
TL;DR: Fibrin and collagen are revealed to be most suitable for bioprinting of ECs, because these hydrogels showed acceptable swelling/degradation characteristics, supported vasculogenesis-related EC parameters and showed good printability.
Abstract: In tissue engineering applications, vascularization can be accomplished by coimplantation of tissue forming cells and endothelial cells (ECs), whereby the latter are able to form functional blood vessels. The use of three-dimensional (3D) bioprinting technologies has the potential to improve the classical tissue engineering approach because these will allow the generation of scaffolds with high spatial control of endothelial cell allocation. This study focuses on a side by side comparison of popular commercially available bioprinting hydrogels (Matrigel, fibrin, collagen, gelatin, agarose, Pluronic F-127, alginate, and alginate/gelatin) in the context of their physicochemical parameters, their swelling/degradation characteristics, their biological effects on vasculogenesis-related EC parameters and their printability. The aim of this study was to identify the most suitable hydrogel or hydrogel combination for inkjet printing of ECs to build prevascularized tissue constructs. Most tested hydrogels displayed physicochemical characteristics suitable for inkjet printing. However, Pluronic F-127 and the alginate/gelatin blend were rapidly degraded when incubated in cell culture medium. Agarose, Pluronic F-127, alginate and alginate/gelatin hydrogels turned out to be unsuitable for bioprinting of ECs because of their non-adherent properties and/or their incapability to support EC proliferation. Gelatin was able to support EC proliferation and viability but was unable to support endothelial cell sprouting. Our experiments revealed fibrin and collagen to be most suitable for bioprinting of ECs, because these hydrogels showed acceptable swelling/degradation characteristics, supported vasculogenesis-related EC parameters and showed good printability. Moreover, ECs in constructs of preformed spheroids survived the printing process and formed capillary-like cords. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 935-947, 2018.
TL;DR: The obtained results confirm that the 3-componemnt fibrous scaffold of PVA/nHAp/CNF has promising potential in hard TE.
Abstract: The article is focused on the role of nanohydroxy apatite (nHAp) and cellulose nanofibers (CNFs) as fillers in the electrospun poly (vinyl alcohol) (ES-PVA) nanofibers for bone tissue engineering (TE). Fibrous scaffolds of PVA, PVA/nHAp (10 wt.%), and PVA/nHAp(10 wt.%)/CNF(3 wt.%) were successfully fabricated and characterized. Tensile test on electrospun PVA/nHAp10 and PVA/nHAp10/CNF3 revealed a three-fold and seven-fold increase in modulus compared with pure ES-PVA (45.45 ± 4.77). Although, nanofiller loading slightly reduced the porosity percentage, all scaffolds had porosity higher than 70%. In addition, contact angle test proved the great hydrophilicity of scaffolds. The presence of fillers reduced in vitro biodegradation rate in PBS while accelerates biomineralization in simulated body fluid (SBF). Furthermore, cell viability, cell attachment, and functional activity of osteoblast MG-63 cells were studied on scaffolds showing higher cellular activity for scaffolds with nanofillers. Generally, the obtained results confirm that the 3-componemnt fibrous scaffold of PVA/nHAp/CNF has promising potential in hard TE. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1111-1120, 2018.
TL;DR: The inhibition of reactive oxygen species production by composite materials predicted potential anti-inflammatory properties of scaffolds thus confirming their biocompatibility and suggest good potential application of this scaffold as filler to repair bone defects.
Abstract: This study reports on the development of a scaffold with a gradient of bioactive solid signal embedded in the biodegradable polymer matrix by combining a sol-gel approach and freeze-drying technology. The chemical approach based on the sol-gel transition of calcium phosphates ensures the particles dispersion into the gelatin matrix and a direct control of interaction among COOHgelatin /Ca2+ ions. Morphological analysis demonstrated that on the basis of the amount of inorganic component and by using specific process conditions, it is possible to control the spatial distribution of nanoparticles around the gelatin helix. In fact, methodology and formulations were able to discriminate between the different hydroxyapatite concentrations and their respective morphology. The good biological response represented by good cell attachment, proliferation and increased levels of alkaline phosphatase as an indicator of osteoblastic differentiation of human mesenchymal stem cells toward the osteogenic lineage, demonstrating the effect of bioactive solid signals on cellular behavior. Furthermore, the inhibition of reactive oxygen species production by composite materials predicted potential anti-inflammatory properties of scaffolds thus confirming their biocompatibility. Indeed, these interesting biological results suggest good potential application of this scaffold as filler to repair bone defects. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2007-2019, 2018.
TL;DR: N,N'-methylenebis(acrylamide) (MBA)-crosslinked poly(acrylic acid) (PAA) particles with low degree of cross-linking were synthesized using distillation precipitation polymerization and results showed that microspheres had a narrow size dispersity.
Abstract: N,N'-methylenebis(acrylamide) (MBA)-crosslinked poly(acrylic acid) (PAA) particles with low degree of cross-linking were synthesized using distillation precipitation polymerization. Size and size distribution of particles were obtained using dynamic light scattering and field emission scanning electron microscopy( and results showed that microspheres had a narrow size dispersity. Proton nuclear magnetic resonance results indicated that amount of cross-linker in structure of particles is a little more than the molar percentage of feeded MBA because of greater activity ratio of MBA than AA. pH-responsive behavior of samples was investigated using UV-vis. absorption at 480 nm where each sample showed a sudden deplete in UV absorbance at a peculiar pH. Synthesized particles were used as carriers of anti-cancer drug doxorubicin using two different approaches including physically loading of drug and drug conjugation via an acid-labile hydrazone linkage. Release results showed that in the first case, amount of released drug has an inverse relationship with the amount of cross-linker in the structure and also, by adding an acid-labile linkage, the amount of burst release decreased drastically. Also, the amount of released drug for conjugated systems was much lesser than particles with physically loaded drug. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 342-348, 2018.
TL;DR: In this paper, the authors developed collagen (COL) and collagen/β tricalcium phosphate (COL/β-TCP) scaffolds by freeze-drying, which had a much higher compressive modulus (970 ± 1.20 KPa) than pure COL (0.8 ± 0.82 KPa).
Abstract: We developed collagen (COL) and collagen/beta tricalcium phosphate (COL/β-TCP) scaffolds with a β-TCP/collagen weight ratio of 4 by freeze-drying. Mouse bone marrow-derived mesenchymal stem cells (BMMSCs) were cultured on these scaffolds for 14 days. Samples were characterized by physicochemical analyses and their biological properties such as cell viability and alkaline phosphatase (ALP) activity was, also, examined. Additionally, the vascularization potential of the prepared scaffolds was tested subcutaneously in Wistar rats. We observed a microporous structure with large porosity (∼95-98%) and appropriate pore size (120-200 µm). The COL/β-TCP scaffolds had a much higher compressive modulus (970 ± 1.20 KPa) than pure COL (0.8 ± 1.82 KPa). In vitro model of apatite formation was established by immersing the composite scaffold in simulated body fluid for 7 days. An ALP assay revealed that porous COL/β-TCP can effectively activate the differentiation of BMMSCs into osteoblasts. The composite scaffolds also promoted vascularization with good integration with the surrounding tissue. Thus, introduction of β-TCP powder into the porous collagen matrix effectively improved the mechanical and biological properties of the collagen scaffolds, making them potential bone substitutes for enhanced bone regeneration in orthopedic and dental applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 73-85, 2018.
TL;DR: By applying an electrical stimulus to the percolated PLA/TrGO, the antibacterial behavior can be dramatically increased and the addition of GO and TrGO into a PLA matrix allows the development of multifunctional composites for potential applications in biomedicine.
Abstract: Poly(lactic acid) (PLA) is a biodegradable and biocompatible polyester widely used in biomedical applications. Unfortunately, this biomaterial suffers from some shortcomings related with the absence of both bioactivity and antibacterial capacity. In this work, composites of PLA with either graphene oxide (GO) or thermally reduced graphene oxide (TrGO) were prepared by melt mixing to overcome these limitations. PLA composites with both GO and TrGO inhibited the attachment and proliferation of Escherichia coli and Staphylococcus aureus bacteria depending on the kind and amount of filler. Noteworthy, it is shown that by applying an electrical stimulus to the percolated PLA/TrGO, the antibacterial behavior can be dramatically increased. MTT analysis showed that while all the PLA/GO composites were more cytocompatible to osteoblast-like cells (SaOS-2) than pure PLA, only low content of TrGO was able to increase this property. These tendencies were related with changes in the surface properties of the resulting polymer composites, such as polarity and roughness. In this way, the addition of GO and TrGO into a PLA matrix allows the development of multifunctional composites for potential applications in biomedicine. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1051-1060, 2018.
TL;DR: Current approaches for fabricating antibacterial Ti and its limitations and countermeasures are reviewed, and direction for further studies of biofunctionalization of Ti with antibacterial properties is provided.
Abstract: Titanium (Ti) and its alloys are widely applied as orthopedic implants for hip and knee prosthesis, fixation, and dental implants. However, Ti and its alloys are bioinert and susceptible to bacteria and biofilm formation. Strategies for improving the antibacterial properties of Ti can be divided into two approaches, namely, passive coating and active coating on the Ti surface. Passive coating on Ti mainly kills the bacteria in contact but does not kill plankton or bacteria dwell in the bone tissue around the Ti implant. Active coating mainly involves the release of antibacterial agents to kill the bacteria, but this may result in the development of bacterial resistance. Both strategies include advantages and disadvantages. This article reviews the current and potential future approaches for improving antibacterial activity on Ti. We mainly focus on current approaches for fabricating antibacterial Ti and its limitations and countermeasures, and provide direction for further studies of biofunctionalization of Ti with antibacterial properties. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A:2531-2539, 2018.
TL;DR: The developed nanogels can be employe as an excellent candidate to overcome the inefficiency of 5-Fu in anticancer treatments and possibly can employe for further evaluation as a chemotherapical agent in applications beyond cancer.
Abstract: 5-Fluorouracil (5-Fu) commonly use in the treatment of different kinds of cancer, but limited cellular uptake and death is still a problem Herein, we report a simple process for the synthesis of pressure-sensitive nanogels that indicate to be appropriate in the delivery of 5-Fu The hydrogels (Al-CD) prepare by crosslinking of alginate (Al) with modified beta Cyclodextrin (β-CD) as Crosslinker Next, nanoparticles obtaine by an emulsification method 5-Fu as model drug loades into the Al-CD nanogels easily by mixing it in aqueous solution with the nanoparticles The results revealed that the Al-CD nanogels are cytocompatible They have also a noticeable drug encapsulation (821 ±57%) while they can release (in vitro controlled) 5-Fu in conditions that imitate the intravascular pressure conditions These nanogels can rapidly be taken up by HT-29 cells (a colon cell line) In addition, a higher 5-Fu intracellular accumulation and a significant cell death extension by apoptosis mechanism is notice when compare with free 5-Fu Accordingly, the developed nanogels can be employe as an excellent candidate to overcome the inefficiency of 5-Fu in anticancer treatments and possibly can employe for further evaluation as a chemotherapical agent in applications beyond cancer © 2017 Wiley Periodicals, Inc J Biomed Mater Res Part A: 106A: 349-359, 2018
TL;DR: This review highlights the progress in the application of biomaterials, stem cells and tissue engineering in promoting nonunion bone fracture healing.
Abstract: Depending on the duration of healing process, 5-10% of bone fractures may result in either nonunion or delayed union. Because nonunions remain a clinically important problem, there is interest in the utilization of tissue engineering strategies to augment bone fracture repair. Three basic biologic elements that are required for bone regeneration include cells, extracellular matrix scaffolds and biological adjuvants for growth, differentiation and angiogenesis. Mesenchymal stem cells (MSCs) are capable to differentiate into various types of the cells including chondrocytes, myoblasts, osteoblasts, and adipocytes. Due to their potential for multilineage differentiation, MSCs are considered important contributors in bone tissue engineering research. In this review we highlight the progress in the application of biomaterials, stem cells and tissue engineering in promoting nonunion bone fracture healing. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A:2551-2561, 2018.
TL;DR: The scaffold, providing a trophic support for MSCs, may promote GMSCs differentiation toward a neuronal phenotype and survival, confirming the neurogenic commitment of these cells.
Abstract: The combined approach of mesenchymal stem cells (MSCs) and scaffolds has been proposed as a potential therapeutic tool for the treatment of neurodegenerative diseases. Indeed, even if MSCs can promote neuronal regeneration, replacing lost neurons or secreting neurotrophic factors, many limitations still exist for their application in regenerative medicine, including the low survival and differentiation rate. The scaffolds, by mimicking the endogenous microenvironment, have shown to promote cell survival, proliferation, and differentiation. In this work, gingival mesenchymal stem cells (GMSCs), isolated from healthy donors, were expanded in vitro, by culturing them adherent in plastic dishes (CTR-GMSCs) or on a poly(lactic acid) scaffold (SC-GMSCs). In order to evaluate the survival and the neurogenic differentiation potential, we performed a comparative transcriptomic analysis between CTR-GMSCs and SC-GMSCs by next generation sequencing. We found that SC-GMSCs showed an increased expression of neurogenic and prosurvival genes. In particular, genes involved in neurotrophin signaling and PI3K/Akt pathways were upregulated. On the contrary, proapoptotic and negative regulator of neuronal growth genes were downregulated. Moreover, nestin and GAP-43 protein levels increased in SC-GMSCs, confirming the neurogenic commitment of these cells. In conclusion, the scaffold, providing a trophic support for MSCs, may promote GMSCs differentiation toward a neuronal phenotype and survival. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 126-137, 2018.
TL;DR: A decellularized ECM-based composite hydrogel was formulated by using modified GAGs that covalently bind tissue particles that demonstrated tunable gelation kinetics and mechanical properties, offering the possibility of numerous in vivo and in vitro applications with different property requirements.
Abstract: Tissue extracellular matrix (ECM) is a complex material made up of fibrous proteins and ground substance (glycosaminoglycans, GAGs) that are secreted by cells. ECM contains important biological cues that modulate cell behaviors, and it also serves as a structural scaffold to which cells can adhere. For clinical applications, where immune rejection is a constraint, ECM can be processed using decellularization methods intended to remove cells and donor antigens from tissue or organs, while preserving native biological cues essential for cell growth and differentiation. In this study, a decellularized ECM-based composite hydrogel was formulated by using modified GAGs that covalently bind tissue particles. These GAG-ECM composite hydrogels combine the advantages of solid decellularized ECM scaffolds and pepsin-digested ECM hydrogels by facilitating ECM hydrogel formation without a disruptive enzymatic digestion process. Additionally, engineered hydrogels can contain more than one type of ECM (from bone, fat, liver, lung, spleen, cartilage, or brain), at various concentrations. These hydrogels demonstrated tunable gelation kinetics and mechanical properties, offering the possibility of numerous in vivo and in vitro applications with different property requirements. Retained bioactivity of ECM particles crosslinked into this hydrogel platform was confirmed by the variable response of stem cells to different types of ECM particles with respect to osteogenic differentiation in vitro, and bone regeneration in vivo. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 147-159, 2018.