Potential Tissue Engineering Scaffold Research Articles

Effect of Silver Content and T4 Treatment on the In Vitro Degradation Behavior of Gasar Porous Mg–Ag Alloy

Mg–Ag alloy has potential as a material for bone tissue repair, but the faster degradation rate in vivo limits its use in medical applications. In this study, pure Mg and Mg99.5Ag0.5 alloy with a porous structure are prepared using the metal/gas eutectic unidirectional solidification method (Gasar process). The influence of introducing Ag on the degradation behavior of porous Mg99.5Ag0.5 and pure Mg is investigated. The addition of Ag increases the compressive strength and elastic modulus of the material. The corrosion resistance of as‐cast Mg99.5Ag0.5 alloy decreases due to localized aggregation of Ag in the alloys. Therefore, the T4 (solution treatment) is chosen for the Mg99.5Ag0.5 alloy. After T4 treatment, due to the uniform distribution of Ag atoms in the alloy, the corrosion behavior on the alloy surface is more uniform, and a denser Mg(OH)2 passivation layer is formed on the surface, which reduces the degradation rate of Mg99.5Ag0.5. Importantly, insoluble Ca–P compounds in the form of hydroxyapatite (HA) phases gradually grown on passivated layers of porous T4 Mg99.5Ag0.5 contribute to bone growth. This indicates the feasibility of using the T4 Gasar porous Mg99.5Ag0.5 alloy as a potential tissue engineering scaffold.

Chitosan Poly(vinyl alcohol) Methacrylate Hydrogels for Tissue Engineering Scaffolds.

A major challenge in tissue engineering scaffolds is controlling scaffold degradation rates during healing while maintaining mechanical properties to support tissue formation. Hydrogels are three-dimensional matrices that are widely applied as tissue scaffolds based on their unique properties that can mimic the extracellular matrix. In this study, we develop a hybrid natural/synthetic hydrogel platform to tune the properties for tissue engineering scaffold applications. We modified chitosan and poly(vinyl alcohol) (PVA) with photo-cross-linkable methacrylate functional groups and then synthesized a library of chitosan PVA methacrylate hydrogels (ChiPVAMA) with two different photoinitiators, Irgacure 2959 (I2959) and lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP). ChiPVAMA hydrogels showed tunability in degradation rates and mechanical properties based on both the polymer content and photoinitiator type. This tunability could enable their application in a range of tissue scaffold applications. In a 2D scratch wound healing assay, all hydrogel samples induced faster wound closure compared to a gauze clinical wound dressing control. NIH/3T3 cells encapsulated in hydrogels showed a high viability (∼92%) over 14 days, demonstrating the capacity of this system as a supportive cell scaffold. In addition, hydrogels containing a higher chitosan content demonstrated a high antibacterial capacity. Overall, ChiPVAMA hydrogels provide a potential tissue engineering scaffold that is tunable, degradable, and suitable for cell growth.

3D-Printed Chitosan-Based Hydrogels Loaded with Levofloxacin for Tissue Engineering Applications.

Herein, we demonstrate the feasibility of a three-dimensional printed chitosan (CS)-poly(vinyl alcohol) (PVA)-gelatin (Gel) hydrogel incorporating the antimicrobial drug levofloxacin (LEV) as a potential tissue engineering scaffold. Hydrogels were prepared by physically cross-linking the polymers, and the printability of the prepared hydrogels was determined. The hydrogel with 3% w/v of CS, 3% w/v of PVA, and 2% w/v of Gel presented the best printability, producing smooth and uniform scaffolds. The integrity of 3D-printed scaffolds was improved via a neutralization process since after testing three different neutralized agents, i.e., NH3 vapors, EtOH/NaOH, and KOH solutions. It was proved that the CS/PVA/Gel hydrogel was formed by hydrogen bonds and remained amorphous in the 3D-printed structures. Drug loading studies confirmed the successful incorporation of LEV, and its in vitro release continued for 48 h. The cytotoxicity/cytocompatibility tests showed that all prepared scaffolds were cytocompatible.

In vitro Cytotoxicity Evaluation of Flowable Hyaluronic Acid-Acellular Stromal Vascular Fraction (HA-aSVF) Mixture for Tissue Engineering Applications.

The stromal vascular fraction (SVF) is an aqueous fraction isolated from the adipose tissue that constitutes different kinds of cells and extracellular matrix components. Hyaluronic acid (HA) is a linear polysaccharide in vertebrate tissues and is considered a potential tissue engineering scaffold due to its biocompatible nature. In this study, we have evaluated the cytotoxicity of xenofree HA in combination with an acellular component of adipose SVF (HA-aSVF) to propose it as a candidate biomaterial for future applications. 3-(4,5-dimethyl thiazolyl-2)-2,5-diphenyltetrazolium bromide assay of L-929 cells treated with HA-aSVF was used in our study. Data were normalized to cell control (untreated) and extracts of copper and ultra-high molecular weight polyethylene were used as positive (PC) and negative controls (NC). Fibroblast cells retained the morphology after 24 h of treatment with HA-aSVF mixture and exhibited a similar percentage of cell activity compared to NC. PC showed a positive cytotoxic response as expected. The cells incubated with HA-aSVF showed a linear increase in cell activity indicating proliferation. The mixture of HA and acellular SVF in its flowable form is non-cytotoxic and showed improved cell proliferation. Hence the mixture can be proposed as a biomaterial and can be further explored for specific tissue engineering applications.

Placenta Powder-Infused Thiol-Ene PEG Hydrogels as Potential Tissue Engineering Scaffolds.

Human placenta is a source of extracellular matrix for tissue engineering. In this study, placenta powder (PP), made from decellularized human placenta, was physically incorporated into synthetic poly(ethylene glycol) (PEG)-based hydrogels via UV-initiated thiol-ene coupling (TEC). The PP-incorporated PEG hydrogels (MoDPEG+) showed tunable storage moduli ranging from 1080 ± 290 to 51,400 ± 200 Pa. The addition of PP (1, 4, or 8 wt %) within the PEG hydrogels increased the storage moduli, with the 8 wt % PP hydrogels showing the highest storage moduli. PP reduced the swelling ratios compared with the pristine hydrogels (MoDPEG). All hydrogels showed good biocompatibility in vitro toward human skin cells and murine macrophages, with cell viability above 91%. Importantly, cells could adhere and proliferate on MoDPEG+ hydrogels due to the bioactive PP, while MoDPEG hydrogels were bio-inert as cells moved away from the hydrogel or were distributed in a large cluster on the hydrogel surface. To showcase their potential use in application-driven research, the MoDPEG+ hydrogels were straightforwardly (i) 3D printed using the SLA technique and (ii) produced via high-energy visible light (HEV-TEC) to populate damaged soft-tissue or bone cavities. Taking advantage of the bioactivity of PP and the tunable physicochemical properties of the synthetic PEG hydrogels, the presented MoDPEG+ hydrogels show great promise for tissue regeneration.

Production of Polycaprolactone / Gelatin / Polydimethylsiloxane Hybrid Nanofibers with Different Morphologies as Potential Scaffolds for Tissue Engineering

Production of Polycaprolactone / Gelatin / Polydimethylsiloxane Hybrid Nanofibers with Different Morphologies as Potential Scaffolds for Tissue Engineering

3D Biocomposites Comprising Marine Collagen and Silica-Based Materials Inspired on the Composition of Marine Sponge Skeletons Envisaging Bone Tissue Regeneration.

Ocean resources are a priceless repository of unique species and bioactive compounds with denouement properties that can be used in the fabrication of advanced biomaterials as new templates for supporting the cell culture envisaging tissue engineering approaches. The collagen of marine origin can be sustainably isolated from the underrated fish processing industry by-products, while silica and related materials can be found in the spicules of marine sponges and diatoms frustules. Aiming to address the potential of biomaterials composed from marine collagen and silica-based materials in the context of bone regeneration, four different 3D porous structure formulations (COL, COL:BG, COL:D.E, and COL:BS) were fabricated by freeze-drying. The skins of Atlantic cod (Gadus morhua) were used as raw materials for the collagen (COL) isolation, which was successfully characterized by SDS-PAGE, FTIR, CD, and amino acid analyses, and identified as a type I collagen, produced with a 1.5% yield and a preserved characteristic triple helix conformation. Bioactive glass 45S5 bioglass® (BG), diatomaceous earth (D.E.) powder, and biosilica (BS) isolated from the Axinella infundibuliformis sponge were chosen as silica-based materials, which were obtained as microparticles and characterized by distinct morphological features. The biomaterials revealed microporous structures, showing a porosity higher than 85%, a mean pore size range of 138-315 μm depending on their composition, with 70% interconnectivity which can be favorable for cell migration and ensure the needed nutrient supply. In vitro, biological assays were conducted by culturing L929 fibroblast-like cells, which confirmed not only the non-toxic nature of the developed biomaterials but also their capability to support cell adhesion and proliferation, particularly the COL:BS biomaterials, as observed by calcein-AM staining upon seven days of culture. Moreover, phalloidin and DAPI staining revealed well-spread cells, populating the entire construct. This study established marine collagen/silica biocomposites as potential scaffolds for tissue engineering, setting the basis for future studies, particularly envisaging the regeneration of non-load-bearing bone tissues.

In vitro characterization of a biocompatible composite based on poly(3-hydroxybutyrate)/hydroxyapatite nanoparticles as a potential scaffold for tissue engineering

The use of regeneration scaffolds has been a promising strategy in the bone tissue engineering area. Among the materials available for this purpose the poly(3-hydroxybutyrate) - PHB stands out for its adequate biocompatibility and osteoinduction capacity. Hydroxyapatite, in turn, has as its main characteristics its ability to increase bioactivity and cell proliferation. Thus, the objective of the present study was to obtain PHB composites with nanohydroxyapatite (Hap) (0.05%, 0.20%, and 0.50%) and evaluate the microstructure, thermal and mechanical properties and molecular dynamics. Besides that, in vitro biological properties such as wettability, cell viability and adhesion of L929 fibroblasts cells, enzymatic degradation and radiographic contrast were evaluated. The results indicate a weak interaction between Hap and PHB, however, the dispersion states of the nanoparticles can influence crystallization and thermal stability. Through the evaluation of the mechanical behavior was verified a harder behavior with the Hap addition. The wettability of the systems showed a tendency to increase with the addition of nanoparticles. All systems presented high values of viability and cell adhesion, the latter being more pronounced for systems containing Hap. The nanoparticles acted as a barrier slowing the rate of enzymatic degradation and contributed to the increase in radiographic contrast. The results obtained indicate that the systems are promising for application in tissue engineering.

Mechanical properties and in vitro biodegradation behavior of GASAR porous Mg-Ag alloy

In this thesis, porous pure Mg and Mg-3 wt%Ag alloys with oriented regular pore structures were prepared by the metal/gas eutectic unidirectional solidification method (GASAR process). The effects of the Ag content on the mechanical properties and early in vitro biodegradation behavior of porous Mg-Ag alloys were investigated. The results of compression experiments showed that Ag addition significantly enhanced the compressive strength and elastic modulus of the porous Mg-Ag alloy. Immersion experiments in SBF at 37℃ showed that although the Mg-3 wt%Ag alloy exhibited a faster corrosion reaction, the addition of Ag facilitated the precipitation of calcium and phosphorus salts, resulting in better osteoinductivity of the samples, which indicates its feasibility as a potential tissue engineering scaffold.

Evaluation of PVA/Chitosan Cryogels as Potential Tissue Engineering Scaffolds; Synthesis, cytotoxicity and genotoxicity investigations

Cryogelation has become an advantageous method to obtain macro-porous materials with well-defined, interconnected pores for tissue engineering applications. Herein, polyvinyl alcohol and chitosan polymers (PVA-CHI) were used to produce cryogel scaffolds via cryogelation. Glutaraldehyde was used as a crosslinking agent and the effect of crosslinking amount on the properties of scaffolds investigated. Glutaraldehyde amount was divided into 5, 10, and 15% total amount of polymer concentration. The optimized pore morphology was obtained as a scaffold containing 5% glutaraldehyde amount. In addition to the FTIR, SEM, swelling, and degradation analyses, mechanical tests were performed to present the characterization properties of the cryogels. Direct and indirect cytotoxicity test and genotoxicity experiments were performed with Mouse Embryonic Fibroblasts (MEF). In addition, cell morphologies on scaffolds were analyzed with SEM. The results showed that PVA-CHI based cryogels had no genotoxic and cytotoxic effects on MEF cells and have a potential for tissue engineering applications.

Evaluation of PVA/Chitosan Cryogels as Potential Tissue Engineering Scaffolds; Synthesis, cytotoxicity and genotoxicity investigations

Evaluation of PVA/Chitosan Cryogels as Potential Tissue Engineering Scaffolds; Synthesis, cytotoxicity and genotoxicity investigations

Fabrication and Characterization of Fe(III) Metal-organic Frameworks Incorporating Polycaprolactone Nanofibers: Potential Scaffolds for Tissue Engineering

Fabrication of nanofibrous scaffolds of biodegradable polymers provides a great premise for several biological applications. In this study, nanofibrous polycaprolactone (PCL) mats incorporating Fe-MOF (PCL/x%Fe-MOF, x=5, 10, 20) were fabricated by electrospinning technique. The Fe-MOFs were separately synthesized by the hydrothermal method and then were added to PCL solution for preparation of nanofibrous composites. The presence of Fe-MOF in the fibers was demonstrated by various methods including FT-IR (Fourier-transform infrared), PXRD (powder X-ray diffraction), EDS (energy dispersive X-ray spectroscopy) mapping, SEM (scanning electron microscope), and TEM (transmission electron microscope). In the FT-IR spectra of the nanocomposites, the characteristic bands for the pure PCL and Fe-MOF showed no significant change in their positions, suggesting a weak chemical interaction with each other, although they physically mixed uniformly. Nanofibrous structure of the as-prepared nanocomposites was confirmed by SEM and TEM images. The diameter of PCL nanofibers was measured to be 369 nm. Biological investigations indicated that the experimented scaffolds including PCL/5%Fe-MOF and PCL/10%Fe-MOF nanofibrous scaffolds provided appropriate surface and mechanical properties such as cellular biocompatibility, high porosity, chemical stability, and optimum fiber diameter for cell adhesion, viability, and proliferation compared with PCL and PCL/20%Fe-MOF nanocomposites. Indeed, our results demonstrated that percent of Fe-MOF in the composites played a significant role in cell attachment and viability. Also, according to the implantation studies, up to at least 4 weeks, none of the animals showed any inflammatory response. Totally, we can be claimed that the modified electrospun scaffolds have been developed for tissue engineering applications.

Synthesis and characterization of L-tyrosine-conjugated quaternary ammonium salt chitosan and their cytocompatibility as a potential tissue engineering scaffold

A novel amino acid-modified biomacromolecule was designed and synthesized as the quaternary ammonium salt chitosan grafted-tyrosine (CA-g-Tyr) suitable for biomedical applications. L-tyrosine was grafted onto the quaternary ammonium salt chitosan (CA) by N-(3-dimethylaminopropy)-N-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). The chemical structure of CA-g-Tyr was confirmed by Fourier transform infrared (FTIR) spectroscopy and 13C-NMR. The change in the crystalline structure after the graft was characterized by differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). The surface wettability and moisturizing performance of the CA-g-Tyr were also characterized. The CA-g-Tyr film possessed good hydrophilicity, and the mechanical tensile experiments showed that the introduction of tyrosine gave CA mechanical properties more suitable for blood vessel. Cell experiments showed that the endothelial cells can adhere and proliferate better on the surface of a CA-g-Tyr film than CA. The results confirm the favorable properties and biocompatibility of CA–g-Tyr with potential applications as scaffolds for tissue engineering.

Electrospun cellulose acetate butyrate/polyethylene glycol (CAB/PEG) composite nanofibers: A potential scaffold for tissue engineering

Electrospinning is a common method to prepare nanofiber scaffolds for tissue engineering. One of the common cellulose esters, cellulose acetate butyrate (CAB), has been electrospun into nanofibers and studied. However, the intrinsic hydrophobicity of CAB limits its application in tissue engineering as it retards cell adhesion. In this study, the properties of CAB nanofibers were improved by fabricating the composite nanofibers made of CAB and hydrophilic polyethylene glycol (PEG). Different ratios of CAB to PEG were tested and only the ratio of 2:1 resulted in smooth and bead-free nanofibers. The tensile test results show that CAB/PEG composite nanofibers have 2-fold higher tensile strength than pure CAB nanofibers. The hydrophobicity of the composite nanofibers was also reduced based on the water contact angle analysis. As the hydrophilicity increases, the swelling ability of the composite nanofiber increases by 2-fold with more rapid biodegradation. The biocompatibility of the nanofibers was tested with normal human dermal fibroblasts (NHDF). The cell viability assay results revealed that the nanofibers are non-toxic. In addition to that, CAB/PEG nanofibers have better cell attachment compared to pure CAB nanofibers. Based on this study, CAB/PEG composite nanofibers could potentially be used as a nanofiber scaffold for applications in tissue engineering.

Novel Bionanocellulose/κ-Carrageenan Composites for Tissue Engineering

In this work, novel bacterial cellulose/κ-carrageenan (BNC/κ-Car) composites, being potential scaffolds for tissue engineering (TE), and outperforming the two polymers when used as scaffolds separately, were for the first time obtained using an in situ method, based on the stationary culture of bacteria Komagateibacter xylinus E25. The composites were compared with native BNC in terms of the morphology of fibers, chemical composition, crystallinity, tensile and compression strength, water holding capacity, water retention ratio and swelling properties. Murine chondrogenic ATDC5 cells were applied to assess the utility of the BNC/κ-Car composites as potential scaffolds. The impact of the composites on the cells viability, chondrogenic differentiation, and expression patterns of Col1α1, Col2α1, Runx2, and Sox9, which are indicative of ATDC5 chondrogenic differentiation, was determined. None of the composites obtained in this study caused the chondrocyte hypertrophy. All of them supported the differentiation of ATDC5 cells to more chondrogenic phenotype.

Evaluation of tofu as a potential tissue engineering scaffold.

Tofu not only is a delicious vegetarian food, but also shows potential biomedical applications for its high protein content and typical porous scaffold structure. Herein, two kinds of porous soybean scaffolds were developed, the first based on the traditional tofu manufacturing processes, the second modified via covalent crosslinking. The morphology, physicochemical properties and biocompatibility in vitro and in vivo were systematically investigated. A similar porous micromorphology was observed in both the tofu scaffolds and crosslinked soybean protein scaffolds. Both scaffolds exhibited good cell proliferation and cellular adherence. No obvious inflammatory response was observed after subcutaneous implantation tests for either material. These results demonstrated that the tofu scaffolds or soybean protein scaffolds fabricated by tofu processing have potential as new food-source biomaterials in tissue engineering applications.

Mechanical enhancement and in vitro biocompatibility of nanofibrous collagen-chitosan scaffolds for tissue engineering

The collagen–chitosan complex with a three-dimensional nanofiber structure was fabricated to mimic native ECM for tissue repair and biomedical applications. Though the three-dimensional hierarchical fibrous structures of collagen–chitosan composites could provide more adequate stimulus to facilitate cell adhesion, migrate and proliferation, and thus have the potential as tissue engineering scaffolding, there are still limitations in their applications due to the insufficient mechanical properties of natural materials. Because poly (vinyl alcohol) (PVA) and thermoplastic polyurethane (TPU) as biocompatible synthetic polymers can offer excellent mechanical properties, they were introduced into the collagen–chitosan composites to fabricate the mixed collagen/chitosan/PVA fibers and a sandwich structure (collagen/chitosan-TPU-collagen/chitosan) of nanofiber in order to enhance the mechanical properties of the nanofibrous collagen–chitosan scaffold. The results showed that the tensile behavior of materials was enhanced to different degrees with the difference of collagen content in the fibers. Besides the Young’s modulus had no obvious changes, both the break strength and the break elongation of materials were heightened after reinforced by PVA. For the collagen–chitosan nanofiber reinforced by TPU, both the break strength and the Young’s modulus of materials were heightened in different degrees with the variety of collagen content in the fibers despite the decrease of the break elongation of materials to some extent. In vitro cell test demonstrated that the materials could provide adequate environment for cell adhesion and proliferation. All these indicated that the reinforced collagen–chitosan nanofiber could be as potential scaffold for tissue engineering according to the different mechanical requirements in clinic.

PLA-Based Hybrid and Composite Electrospun Fibrous Scaffolds as Potential Materials for Tissue Engineering

The aim of the study was to manufacture poly(lactic acid)- (PLA-) based nanofibrous nonwovens that were modified using two types of modifiers, namely, gelatin- (GEL-) based nanofibres and carbon nanotubes (CNT). Hybrid nonwovens consisting of PLA and GEL nanofibres (PLA/GEL), as well as CNT-modified PLA nanofibres with GEL nanofibres (PLA + CNT/GEL), in the form of mats, were manufactured using concurrent-electrospinning technique (co-ES). The ability of such hybrid structures as potential scaffolds for tissue engineering was studied. Both types of hybrid samples and one-component PLA and CNTs-modified PLA mats were investigated using scanning electron microscopy (SEM), water contact angle measurements, and biological and mechanical tests. The morphology, microstructure, and selected properties of the materials were analyzed. Biocompatibility and bioactivity in contact with normal human osteoblasts (NHOst) were studied. The coelectrospun PLA and GEL nanofibres retained their structures in hybrid samples. Both types of hybrid nonwovens were not cytotoxic and showed better osteoinductivity in comparison to scaffolds made from pure PLA. These samples also showed significantly reduced hydrophobicity compared to one-component PLA nonwovens. The CNT-contained PLA nanofibres improved mechanical properties of hybrid samples and such a 3D system appears to be interesting for potential application as a tissue engineering scaffold.

Photopolymerized Injectable Water-soluble Maleilated Chitosan/ Poly(ethylene glycol) Diacrylate Hydrogels as Potential Tissue Engineering Scaffolds

Photopolymerized Injectable Water-soluble Maleilated Chitosan/ Poly(ethylene glycol) Diacrylate Hydrogels as Potential Tissue Engineering Scaffolds

Antheraea pernyi silk sericin mediating biomimetic nucleation and growth of hydroxylapatite crystals promoting bone matrix formation.

Bone biomineralization is well-regulated processes mediated by extracellular matrix proteins. The materials that can direct nucleation of hydroxylapatite (HAp) crystals and assembly of well-structured material-minerals complex are the key to mimicking the natural mineralization. This study used sericin from Antheraea pernyi (A.pernyi), non-mulberry silkworm cocoon as template to mediate nucleation of HAp crystals. Here we find out that AS (Antheraea pernyi sericin) can nucleate the formation HAp crystals in simulated body fluid verified by XRD and FTIR observations. The HAp crystals are organized into nano-rods oriented with c-axis preferentially parallel to the long axis of AS due to hydrogen bonds and electrostatic interaction and finally aggregated into HAp globule. The cell culture of human bone marrow-derived mesenchymal stem cells (BMSCs) showed that the HAp crystals mediated by AS not only stimulate cell adhesion and proliferation but also promote 0f osteogenic differentiation, suggesting that the resultant mineralized AS biomaterial has potential in promoting bone formation. Thus our work will provide significant implication on biomineralization of A. pernyi silk sericin as a potential scaffold for tissue engineering.