Aligned Poly Research Articles

Directional Growth of cm-Long PLGA Nanofibers by a Simple and Fast Wet-Processing Method.

The development of aligned nanofibers as useful scaffolds for tissue engineering is an actively sought-for research objective. Here, we propose a novel improvement of an existing self-assembly-based nanofabrication technique (ASB-SANS). This improvement, which we termed Directional ASB-SANS, allows one to produce cm2-large domains of highly aligned poly(lactic-co-glycolic acid) (PLGA) nanofibers in a rapid, inexpensive, and easy way. The so-grown aligned PLGA nanofibers exhibited remarkable adhesion to different substrates (glass, polyimide, and Si/SiOx), even when immersed in PBS solution and kept at physiological temperature (37 °C) for up to two weeks. Finally, the Directional ASB-SANS technique allowed us to grow PLGA fibers also on highly heterogeneous substrates such as polyimide-based, gold-coated flexible electrodes. These results suggest the viability of Directional ASB-SANS method for realizing biocompatible/bioresorbable, nanostructured coatings, potentially suitable for neural interface systems.

Lysine-doped polydopamine coating enhances antithrombogenicity and endothelialization of an electrospun aligned fibrous vascular graft

Accelerating in situ endothelialization while inhibiting thrombosis is critical for the success of small-caliber tissue-engineered vascular grafts (TEVGs). In this study, a lysine (Lys) doped polydopamine (PDA) coating strategy was exploited to functionalize the TEVGs for vascular tissue regeneration. Using electrospun aligned poly(L-lactide-co-caprolactone) (PLCL) fiber arrays as the demonstrating biomaterial, introduction of Lys to the dopamine polymerization process was found to promote the formation of PDA-Lys composite coating layer atop the fiber surface via Schiff base and Michael addition reactions. Such a surface functionalization remarkably improved the coating layer uniformity, wettability, and protein adsorption capacity. In vitro assessment showed that the PDA-Lys coating layer was anti-thrombogenic and anti-inflammatory, and accelerated the formation of confluent endothelial monolayer by promoting cell-fiber and cell-cell interactions. Upon implantation in a rabbit carotid artery replacement model for 3 months, the constructed TEVGs (2 mm inner diameter), with oriented fiber architecture parallel to the longitudinal axis of grafts, were confirmed to significantly suppress thrombosis and accelerate regeneration of endothelium and tunica media layer, thereby exhibiting a positive vascular remodeling and integration capability in revascularization. This study demonstrated that the lysine-doped PDA coating provided a facile and effective platform for the improvement of antithrombogenicity and endothelialization of TEVGs.

The role of PGS/PCL scaffolds in promoting differentiation of human embryonic stem cells into retinal ganglion cells

The stem cell-based retinal ganglion cells (RGCs) replacement therapy offers a potential to restore vision in progressive optic neuropathies including glaucoma by replacing degenerated RGCs and by simulating axonal regeneration. Injured optic nerve axons do not regenerate owing to the limited intrinsic capacity of the neurons and the inhibitory environment at the injury site. Polymeric tissue scaffolds are able to modulate the physical environment while providing structural support for transplanted cells, however, their application specific to the RGC generation has been far from conclusive. The successful generation of clinically safe and functional RGCs that can appropriately integrate into the hosts’ retinas still remain largely unresolved.Our study reports on a process that enables generation of RGCs from human embryonic stem cells (hESCs) that is simple, straightforward and repeatable and, investigates the influence of the aligned poly(glycerol sebacate) (PGS)/poly(ε-caprolactone) (PCL) scaffold on this differentiation process. Our findings demonstrate that PGS/PCL scaffold promotes differentiation of hESCs into RGC-like cells possibly by the simulation of cell active environmental signalling and, facilitates the growth of RGCs neurites along their lengths. Statement of significanceGlaucoma can lead to the degeneration of retinal ganglion cells (RGCs), with consequential vision loss. RGCs are incapable of self-renewal, replacement of diseased RGCs with healthy cells has been a goal to restore vision in glaucoma patients. In this regard, stem cell RGC replacement therapy has been shown to improve vision in animal models of glaucoma, which could be facilitated by using tissue-engineered polymeric scaffolds.In this study, we generated homogenous stem cell-derived RGCs via a straightforward differentiation protocol and evaluated the effects of PGS/PCL scaffold on RGCs differentiation and growth of RGCs neurites. Our study contributes to the knowledge on how biomaterial scaffolds are able to support the regeneration of RGC neurites (i.e., axons or dendrites) as a part of a possible future clinical therapy for the treatment of glaucoma.

A Hierarchical Janus Nanofibrous Membrane Combining Direct Osteogenesis and Osteoimmunomodulatory Functions for Advanced Bone Regeneration

AbstractAn ideal guided bone regeneration membrane (GBRM) is expected not only to perform barrier function, but also to enhance osteogenesis and resist bacteria infection. However, currently available membranes have limited bioactivities. To address this challenge, a Janus GBRM (JGM) is designed and fabricated by sequential fractional electrospinning here. The random gelatin fibers loaded with hydroxyapatite (HAP) are designed as the inner face to promote the osteoblasts’ adhesion, proliferation, and osteogenic differentiation, meanwhile the aligned poly(caprolactone) (PCL) nanofibers loaded with poly(methacryloxyethyltrimethyl ammonium chloride‐co‐2‐Aminoethyl 2‐methylacrylate hydrochloride) (P(DMC‐AMA)) are designed as the outer layer to resist epithelia invasion and bacterial infection. In vitro assays reveal that the inner face displays enhanced osteogenic effects, meanwhile the outer surface can regulate the epithelia to spread along the aligned direction and kill the contacted bacteria. Interestingly, the outer face can induce macrophages to polarize toward the M2 phenotype, thus manipulating a favorable osteoimmune environment. These results suggest that the JGM simultaneously meets the critical requirements of barrier, osteogenic, antibacterial, and osteoimmunomodulatory functions. Consequently, the JGM shows better in vivo bone tissue regeneration performance than the commercial Bio‐Gide membrane. This work provides a novel platform to design multi‐functional membranes/scaffolds, displaying great potential applications in tissue engineering.

The Treatment of Muscle Atrophy after Rotator Cuff Tears Using Electroconductive Nanofibrous Matrices.

Rotator cuff tears (RCTs) are a common cause of disability and pain in the adult population. Despite the successful repair of the torn tendon, the delay between the time of injury and time of repair can cause muscle atrophy. The goal of the study was to engineer an electroconductive nanofibrous matrix with an aligned orientation to enhance muscle regeneration after rotator cuff (RC) repair. The electroconductive nanofibrous matrix was fabricated by coating Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) nanoparticles onto the aligned poly(ε-caprolactone) (PCL) electrospun nanofibers. The regenerative potential of the matrix was evaluated using two repair models of RCTs include acute and sub-acute. Sprague-Dawley rats (n=39) were randomly assigned to 1 of 8 groups. For the acute model, the matrix was implanted on supraspinatus muscle immediately after the injury. The repair surgery for the sub-acute model was conducted 6 weeks after injury. The supraspinatus muscle was harvested for histological analysis two and six weeks after repair. The results demonstrated the efficacy of electrical and topographical cues on the treatment of muscle atrophy in vivo. In both acute and sub-acute models, the stimulus effects of topographical and electrical cues reduced the gap area between muscle fibers. This study showed that muscle atrophy can be alleviated by successful surgical repair using an electroconductive nanofibrous matrix in a rat RC model.

Roles of Pgs/Pcl Scaffold in Promoting Differentiation of Human Embryonic Stem Cells into Retinal Ganglion Cells

Stem cell-based therapeutic approaches have opened promising avenues to restoring vision in progressive optic neuropathies, including glaucomatous, and as such, the stem cell-based retinal ganglion cells (RGCs) replacement therapy offers a potential to replace degenerated RGCs and promote RGC axon regeneration. However, challenges associated with the successful generation of clinically safe and functional RGCs, which can appropriately integrate into the hosts’ retinas still remain unresolved. The use of polymeric tissue-supporting scaffolds is a known and tested solution to enhance the efficiency of cell delivery and differentiation process due to providing an appropriate physical environment and structural support, however, for RGC generation their application has been far from conclusive. Our study aims, firstly, to reveal a process that enables generation of RGCs from human embryonic stem cells (hESCs) that is simple, straightforward and repeatable and, secondly, to show the influence of the aligned poly(glycerol sebacate) (PGS)/poly(e-caprolactone) (PCL) scaffold on this differentiation process. Our findings demonstrate that PGS/PCL scaffold promotes differentiation of hESCs into RGCs, possibly, by simulating cells active environmental signalling, as well as, by supporting the growth of RGCs neurites along their lengths.

A bioactive multi-functional heparin-grafted aligned poly(lactide-co-glycolide)/curcumin nanofiber membrane to accelerate diabetic wound healing

Curcumin is reported to possess excellent efficacy to treat wounds that exhibit impaired healing. Heparin shows high affinity for many growth factors that are key biological mediators during the wound healing process. In this study, we aimed to prepare wound dressing membranes, for sustained release of an exogenous factor curcumin as well as sequestering endogenous growth factors at the wound site, to promote wound healing in diabetic rats. Toward this end, we prepared aligned curcumin-loaded poly(lactide-co-glycolide) (PLGA) nanofiber membranes (PC NFMs), followed by high density surface grafting of heparin to fabricate PLGA/curcumin (PCH) NFMs. Both PC and PCH NFMs show high tensile strength, low cytotoxicity and suitable water vapor transmission rate for application as wound dressings. Nonetheless, the PCH NFM shows higher curcumin release rate than PC due to enhanced hydrophilicity, which leads to higher cell migration rate and induced oxidative stress protection of HS68 fibroblast cells in vitro. In vivo study indicated the PCH exhibits the fastest wound closure rate among all membranes with accelerated re-epithelization rate, higher angiogenesis rate and more collagen deposition at the wound site. The accelerated and better skin tissue regeneration could be suggested to correlate with the multi-functionality of nanofibers, where grafted heparin attracting and stabilizing the growth factors important for wound healing in situ, together with relieving the high oxidative stress and the inflammatory cascade from released curcumin during diabetic wound healing.

Axonal extension from dorsal root ganglia on fibrillar and highly aligned poly(lactic acid)-polypyrrole substrates obtained by two different techniques: Electrospun nanofibres and extruded microfibres

The biological behaviour of Schwann cells (SCs) and dorsal root ganglia (DRG) on fibrillar, highly aligned and electroconductive substrates obtained by two different techniques is studied. Mats formed by nanometer-sized fibres of poly(lactic acid) (PLA) are obtained by the electrospinning technique, while bundles formed by micrometer-sized extruded PLA fibres are obtained by grouping microfibres together. Both types of substrates are coated with the electrically conductive polymer polypyrrole (PPy) and their morphological, physical and electrical characterization is carried out. SCs on micrometer-sized substrates show a higher motility and cell-cell interaction, while a higher cell-material interaction with a lower cell motility is observed for nanometer-sized substrates. This higher motility and cell-cell interaction of SCs on the micrometer-sized substrates entails a higher axonal growth from DRG, since the migration of SCs from the DRG body is accelerated and, therefore, the SCs tapestry needed for the axonal growth is formed earlier on the substrate. A higher length and area of the axons is observed for these micrometer-sized substrates, as well as a higher level of axonal sprouting when compared with the nanometer-sized ones. These substrates offer the possibility of being electrically stimulated in different tissue engineering applications of the nervous system.

Aligned PCL Fiber Conduits Immobilized with Nerve Growth Factor Gradients Enhance and Direct Sciatic Nerve Regeneration

AbstractTopographical guidance and chemotaxis are crucial factors for peripheral nerve regeneration. This study describes the preparation of highly aligned poly(ε‐caprolactone) (PCL) fiber conduits coated with a concentration gradient of nerve growth factor (NGF) (A/G‐PCL) using a newly designed electrospinning receiving device. The A/G‐PCL conduits are confirmed in vitro to enhance and attract the neurite longitudinal growth of dorsal root ganglion (DRG) neurons toward their high‐concentration gradient side. In vivo, the A/G‐PCL conduits are observed to direct a longitudinal stronger attraction of axons and migration of Schwann cells in 15 mm rat sciatic nerve defects. At 12 weeks, rats transplanted with A/G‐PCL conduits show satisfactory morphological and functional improvements in g‐ratio, total number, and area of myelinated nerve fibers as well as the sciatic function index, compound muscle action potentials, and muscle wet weight ratio as compared to aligned PCL fibers conduits with uniform NGF (A/U‐PCL). The performance of A/G‐PCL is similar to that of autografts. Moreover, mRNA‐seq and RT‐PCR results reveal that Rap1, MAPK, and cell adhesion molecules signaling pathways are closely associated with axon chemotactic response and attraction. Altogether, by combining structural guidance with axon chemotaxis, the NGF‐gradient/aligned PCL fiber conduits represent a promising approach for peripheral nerve defect repair.

Beneficial effects of biodelivery of brain-derived neurotrophic factor and gold nanoparticles from functionalized electrospun PLGA scaffold for nerve tissue engineering

Despite of the pivotal role of Schwann cells (SCs) in peripheral nerve regeneration, lack of an available source has prompted researches for Schwann-like cells transdifferentiation. This study suggests an effective method for tuning the surface of aligned poly (lactic-co-glycolic acid) (PLGA) nanofibers to enhance attachment and proliferation of h-ADSCs on the scaffold through coating of laminin. Following the characterization of biofunctionalized PLGA, brain-derived neurotropic factor (BDNF) and gold nanoparticles (AuNPs) were encapsulated in chitosan nanoparticles (CSNPs), added into laminin solution, and coated on the surface of aligned PLGA scaffold. The release behavior of BDNF and AuNPs from scaffold was evaluated by Bradford assay and inductive coupled plasma optical emission spectrometry (ICP-OES) technique, respectively. Afterwards, experimental groups were investigated for potential of Schwann cell differentiation using immunocytochemical staining and real-time RT-PCR technique. Results of MTT assay showed the significantly higher proliferation of h-ADSCs on laminin-functionalized scaffold compared to PLGA scaffold (p < 0.05). Additionally, the presence of BDNF and AuNPs on scaffold significantly improved the expression of SCs markers as compared to the control group (p < 0.05). Therefore, use of biofunctionalized PLGA nanofibers can be a promising strategy for inducing the differentiation of h-ADSCs into SCs for nerve tissue engineering.

Biodegradation and cellular evaluation of aligned and random poly (3-hydroxybutyrate)/chitosan electrospun scaffold for nerve tissue engineering applications

ABSTRACTThe aim of this study is to gain the best structure of Poly (3-hydroxybutyrate) (PHB)/chitosan electrospun aligned and random fibrous scaffold for nerve tissue engineering applications using electrospinning method, morphologically and biologically. The results illustrated that by addition of chitosan, surface porosity percentages have increased while the water contact angle has decreased, for both structures. Results of biodegradation rate noted that aligned PHB/chitosan fibrous scaffolds had a slower degradation rate than random PHB/chitosan fibrous scaffolds. Finally, cultivation results of rat neuronal-like cells (B65 cell line) on electrospun-aligned and random fibrous scaffolds were compared. Results of MTT assay demonstrated better improvement for the proliferation of B65 cells on electrospun-aligned PHB/chitosan scaffolds. Also, SEM images indicated that the bi-polar neurite extensions and the orientation of nerve cells were aligned in the direction of the fibre alignment.

Enhanced performance of piezoelectric nanogenerator based on aligned nanofibers and three-dimensional interdigital electrodes

Piezoelectric nanogenerators (PENGs) based on highly aligned poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE)] nanofibers and micropatterned three-dimensional (3D) interdigital electrodes with good flexibility and highly output performance are constructed. The optimal PENG with 3D interdigital electrodes could charge the commercial capacitor of 100 nF to 3.2 V under the pressure of 2 kPa at a frequency of 1.5 Hz, which is nearly 10-fold higher than that of PENG with flat interdigital electrodes. The enhanced performance is mainly attributed to micropatterned 3D interdigital electrodes that could simultaneously optimize output voltages and currents of PENGs. And maximum power density of the optimal PENG could reach as high as 8.75 μW/cm2, which is superior to some PENGs based on PVDF and its copolymers. In addition, the optimal PENG generates a voltage as high as 150 V during fingers pressure/release cycles, the outputs could light up 32 light-emitting diodes after direct-current rectification. The flexible PENG can also be used to harvest the biomechanical energy of human movements, such as fingers tapping, walking, and jumping. The designed 3D interdigital electrodes represent a novel strategy to improve the performance of PENGs based on aligned nanofibers. This kind of PENG shows potential as an energy harvester and effective self-powered nanogenerator to drive wearable devices.

Fabrication of carboxylic graphene oxide-composited polypyrrole film for neurite growth under electrical stimulation

An aligned composite film was fabricated via the deposition of carboxylic graphene oxide (C-GO) and polypyrrole (PPy) nanoparticles on aligned poly(L-lactic acid) (PLLA) fiber-films (named as C-GO/PPy/PLLA), which has the core (PLLA)-sheath (C-GO/PPy) structure, and the composition of C-GO (∼4.8 wt.% of PPy sheath) significantly enhanced the tensile strength and the conductivity of the PPy/PLLA film. Especially, after 4 weeks of immersion in the PBS solution, the conductivity and the tensile strength of C-GO/PPy/PLLA films still remained ∼6.10 S/cm and 28.9 MPa, respectively, which could meet the need of the sustained electrical stimulation (ES) therapy for nerve repair. Moreover, the neurite length and the neurite alignment were significantly increased through exerting ES on C-GO/PPy/PLLA films due to their sustained conductivity in the fluid of cell culture. These results indicated that C-GO/PPy/PLLA with sustained conductivity and mechanical property possessed great potential of nerve repair by exerting lasting-ES.

Peptide nanostructures on nanofibers for peripheral nerve regeneration.

Self-assembled peptide nanofibrous scaffolds with designer sequences, similar to neurite growth promoting molecules enhance the differentiation of neural stem cells. However, self-assembled peptide nanofibrous scaffolds lack the required mechanical strength to suffice to bridge long critical-sized peripheral nerve defects. Hence, there is a demand for a potential neural substrate, which could be biomimetic coupled with bioactive nanostructures to regrow the denuded axons towards the distal end. In the present study, we developed designer self-assembling peptide-based aligned poly(lactic-co-glycolic acid) (PLGA) nanofibrous scaffolds by simple surface coating of peptides or coelectrospinning. Retention of secondary structures of peptides in peptide-coated and cospun fibers was confirmed by circular dichroism spectroscopy. The rod-like peptide nanostructures enhance the typical bipolar morphology of Schwann cells. Although the peptide-coated PLGA scaffolds exhibited significant increase in Schwann cell proliferation than pristine PLGA and PLGA-peptide cospun scaffolds (p<.05), peptide cospun scaffolds demonstrated better cellular infiltration and significantly higher gene expression of neural cell adhesion molecule, glial fibrillary acidic protein, and peripheral myelin protein22 compared to the pristine PLGA and PLGA-peptide-coated scaffolds. Our results demonstrate the positive effects of aligned peptide coelectrospun scaffolds with biomimetic cell recognition motifs towards functional proliferation of Schwann cells. These scaffolds could subsequently repair peripheral nerve defects by augmenting axonal regeneration and functional nerve recovery.

Preparation of aligned poly(glycerol sebacate) fibrous membranes for anisotropic tissue engineering

The use of fibrous scaffolds for tissue repair or regeneration is advantageous for its microstructure similar to that of the native ECM. Aligned fibrous scaffold, in particular, can be used to manipulate cell alignment and hence the microstructure of the resultant tissue. In our previous study, nanofibers consisting of solely poly(glycerol sebacate) (PGS) have been successfully fabricated using core-shell coaxial electrospinning followed by curing and subsequent shell removal. When we tried to fabricate aligned PGS fibrous membranes by collecting the electrospun fibers on a rapidly rotating drum, however, loss of fibrous structure was observed upon curing. This might be due to the broken fibers that were collected under tension; the core PGS prepolymer that melts at high temperature could leak from the broken ends during curing. In this study, attempts were made to reduce the possibility of the fiber breakage. At each stage of preparation, fiber morphology was examined by SEM and fiber compositions were verified by Fourier transform infrared spectroscopy and differential scanning calorimetry. Mechanical properties of the aligned PGS fibrous membrane were evaluated by uniaxial tensile testing both in parallel and perpendicular to the principal fiber direction. SEM images showed that fibrous morphology was better preserved upon the adjustment of the shell composition and the rotational speed of the collector drum. The final PGS fibers remained to be aligned although the alignment was less strong than that of as-spun core-shell fibers. The aligned PGS fibrous membrane exhibited anisotropic mechanical properties with Young's modulus in parallel and perpendicular to the principal fiber direction being 0.98 ± 0.04 MPa and 0.52 ± 0.02 MPa, respectively. The aligned PGS fibrous membrane was capable of guiding the orientation of cultured cells and therefore has the potential to be used to fabricate structurally anisotropic tissue-engineered constructs.

Design and fabrication of poly (glycerol sebacate)‐based fibers for neural tissue engineering: Synthesis, electrospinning, and characterization

Poly (glycerol sebacate) (PGS) is a thermoset biodegradable elastomer considered as a promising candidate material for nerve applications. However, PGS synthesis is very time and energy consuming. In this study, the PGS pre‐polymer (pPGS) was synthesized using three synthesis times of 3, 5, and 7 hours at 170°C. Fourier transform infrared (FTIR), nuclear magnetic resonance spectroscopy, X‐ray diffraction analysis, and differential scanning calorimetry thermogram were utilized to study the pPGS behavior. Poly (vinyl alcohol) was used as a carrier to fabricate aligned poly (vinyl alcohol)‐poly (glycerol sebacate) (PVA‐PGS) fibers with various ratios (60:40, 50:50, and 40:60) using electrospinning and crosslinked through the thermal crosslinking method. Morphology of the fibers was studied before and after crosslinking using scanning electron microscopy (SEM). FTIR, mechanical properties in the dry and wet state, water contact angle, in vitro degradation, and water uptake behavior of crosslinked scaffolds were also investigated. 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay, SEM analysis, and 4′, 6‐diamidino‐2‐phenylindole (DAPI) staining were utilized to determine the biocompatibility of scaffolds. The results show the synthesized pPGS in 3 hours at 170°C is the optimized sample in the terms of chemical reaction. All scaffolds have bead‐free and a uniform fiber diameter. The Young's modulus of crosslinked PVA‐PGS (50:50 and 40:60) fibers is shown to be in the expected range for nerve applications. The cell culture studies reveal PVA‐PGS (50:50 and 40:60) fibers could lead to better cell adhesion and proliferation. The results suggest that PVA‐PGS (50:50 and 40:60) is a suitable and promising biodegradable material in the fabrication of scaffolds for nerve regeneration.

RGD-Functionalized Nanofibers Increase Early GFAP Expression during Neural Differentiation of Mouse Embryonic Stem Cells.

Stem cell differentiation toward a specific lineage is controlled by its microenvironment. Polymer scaffolds have long been investigated to provide microenvironment cues; however, synthetic polymers lack the specific signaling motifs necessary to direct cellular responses on their own. In this study, we fabricated random and aligned poly(ε-caprolactone) nanofiber substrates, surface-functionalized with RGD viastrain-promoted azide-alkyne cycloaddition, that were used to investigate the role of a covalently tethered bioactive peptide (RGD) and nanofiber orientation on neural differentiation of mouse embryonic stem cells. Gene and protein expression showed neural differentiation progression over 14 days, with similar expression on RGD random and aligned nanofibers for neurons and glia over time. The high levels of glial fibrillary acidic protein expression at early time points were indicative of neural progenitors, and occurred earlier than on controls or in previous reports. These results highlight the influence of RGD binding versus topography in differentiation.

Effect of poly (l-lactic acid) scaffolds seeded with aligned diaphragmatic myoblasts overexpressing connexin-43 on infarct size and ventricular function in sheep with acute coronary occlusion

Diaphragmatic myoblasts (DM) are stem cells of the diaphragm, a muscle displaying high resistance to stress and exhaustion. We hypothesized that DM modified to overexpress connexin-43 (cx43), seeded on aligned poly (l-lactic acid) (PLLA) sheets would decrease infarct size and improve ventricular function in sheep with acute myocardial infarction (AMI). Sheep with AMI received PLLA sheets without DM (PLLA group), sheets with DM (PLLA-DM group), sheets with DM overexpressing cx43 (PLLA-DMcx43) or no treatment (control group, n = 6 per group). Infarct size (cardiac magnetic resonance) decreased ∼25% in PLLA-DMcx43 [from 8.2 ± 0.6 ml (day 2) to 6.5 ± 0.7 ml (day 45), p < .01, ANOVA-Bonferroni] but not in the other groups. Ejection fraction (EF%) (echocardiography) at 3 days post-AMI fell significantly in all groups. At 45 days, PLLA-DM y PLLA-DMcx43 recovered their EF% to pre-AMI values (PLLA-DM: 61.1 ± 0.5% vs. 58.9 ± 3.3%, p = NS; PLLA-DMcx43: 64.6 ± 2.9% vs. 56.9 ± 2.4%, p = NS), but not in control (56.8 ± 2.0% vs. 43.8 ± 1.1%, p < .01) and PLLA (65.7 ± 2.1% vs. 56.6 ± 4.8%, p < .01). Capillary density was higher (p < .05) in PLLA-DMcx43 group than in the remaining groups. In conclusion, PLLA-DMcx43 reduces infarct size in sheep with AMI. PLLA-DMcx43 and PLLA-DM improve ventricular function similarly. Given its safety and feasibility, this novel approach may prove beneficial in the clinic.

Human Amniotic Membrane with Aligned Electrospun Fiber as Scaffold for Aligned Tissue Regeneration.

Fabrication of composite scaffolds is one of the strategies proposed to enhance the functionality of tissue-engineered scaffolds for improved tissue regeneration. By combining multiple elements together, unique biomimetic scaffolds with desirable physical and mechanical properties can be tailored for tissue-specific applications. Despite having a highly porous structure, the utility of electrospun fibers (EF) as scaffold is usually hampered by their insufficient mechanical strength. In this study, we attempted to produce a mechanically competent scaffold with cell-guiding ability by fabricating aligned poly lactic-co-glycolic acid (PLGA) fibers on decellularized human amniotic membrane (HAM), known to possess favorable tensile and wound healing properties. Decellularization of HAM in 18.75 μg/mL of thermolysin followed by a brief treatment in 0.25 M sodium hydroxide efficiently removed the amniotic epithelium and preserved the ultrastructure of the underlying extracellular matrix. The electrospinning of 20% (w/v) PLGA 50:50 polymer on HAM yielded beadless fibers with straight morphology. Subsequent physical characterization revealed that EF-HAM scaffold with a 3-min fabrication had the most aligned fibers with the lowest fiber diameter in comparison with EF-HAM 5- and 7-min scaffolds. Hydrated EF-HAM scaffolds with 3-min deposition had a greater tensile strength than the other scaffolds despite having thinner fibers. Nevertheless, wet HAM and EF-HAMs regardless of the fiber thicknesses had a significantly lower Young's modulus, and hence, a higher elasticity compared with dry HAM and EF-HAMs. Biocompatibility analysis showed that the viability and migration rate of skeletal muscle cells on EF-HAMs were similar to control and HAM alone. Skeletal muscle cells seeded on HAM were shown to display random orientation, whereas cells on EF-HAM scaffolds were oriented along the alignment of the electrospun PLGA fibers. In summary, besides having good mechanical strength and elasticity, EF-HAM scaffold design decorated with aligned fiber topography holds a promising potential for use in the development of aligned tissue constructs.

Using aligned poly(3-hexylthiophene)/poly(methyl methacrylate) blend fibers to detect volatile organic compounds

In this study, we developed a novel sensing material fabricated using a poly(3-hexylthiophene) (P3HT)/poly(methyl methacrylate) (PMMA) blend fiber on a glass substrate. The sensing materials can easily be used for sensing toluene vapor detected from extinction spectral changes. The extinction spectra variation is noted from the absorption of volatile organic compounds in a highly specific surface area of fibrous coating. An electrospinning technique is applied to generate a nonwoven structure and uniaxial orientation by fibrous coating. The response of the uniaxially orientated fibrous film is even improved at several toluene vapor concentrations. The best detection limit of this well-aligned fibrous film is up to 200 ppm for toluene vapor.