Mechanism of silk fibroin scaffolds with oriented multichannels and its cytocompatibility

As a biomaterial, besides excellent biocompatibility and biodegradability, suitable macropores and pores structure should be provided to guide cell extension and migration. In present study, the silk fibroin (SF) scaffold with uniaxial channels was prepared by directional temperature field freezing technique. The average pore diameter, pore density and porosity of the scaffold with oriented channels are ～128.7 µm, ～158 mm^?2 and ～91.4 %, respectively. By controlling of the temperature gradient direction, the oriented multichannels of the scaffolds were formed in longitudinal easily. In process of the scaffolds fabrication, the directional growth of ice crystal could shear and draft to the silk fibroin molecule segments, which resulted in the new crystal nucleus formation in new zone and increase of β-sheet components in the scaffolds. In vitro, L929 cells were seeded on the scaffolds with oriented channels to evaluate the effect on cell behavior. Cell viability, adhesion and morphology were determined by methyl thiazolyl tetrazolium, confocal microscope and scanning electron microscope. The results showed that the cells anchored on the oriented channels, spread along the direction of the channels and hold a higher viability on the scaffolds with oriented channels. These new oriented multichannel scaffold could guide the adhesion and proliferation of L929 cells, which hold a potential in tissue engineering.     

Fabrication of silk fibroin based three dimensional scaffolds for tissue engineering

Herein we report successful synthesis of silk fibroin (SF) three dimensional scaffolds (SF 3D-scaffold) from SF sponge and SF nanofibers. Both the nanofibers and sponge were prepared from Bombyx mori fibroin. The SF 3D-scaffold was prepared by electrospinning the fibroin nanofibers over the sponge. Surface morphology was determined by scanning electron microscopy (SEM), while nanofiber diameter and pore size were measured using imageJ software. Effect of spinning time on the pore size and cell adhesion was determined. Average diameter of the SF nanofibers was measured to be 320 nm and pore size was found to reduce with increasing spinning time, such that, for 1 h spinning time pore size was 231 µm and the same for 3.5 h was 4.1 µm. However, the number of pores increased with spinning time. The results confirmed adhesion of MC3T3-E1 cells on the SF sponge, SF nanofibers and SF three dimensional scaffolds. Higher cell adhesion was found on the three dimensional scaffold in comparison to the nanofibers and sponge, possibly due to highly porous structure with very small and numerous pores in the resultant composite; hence more cell adhesion sites. The cell adhesion result confirmed biocompatibility of the SF 3D-scaffold and hence its suitability for applications in tissue engineering.     

Chondrogenic differentiation of rat mesenchymal stem cells on silk fibroin/chondroitin sulfate/hyaluronic acid ternary scaffolds

Cartilage repair is a challenge in bone tissue reconstruction. In this study, silk fibroin (SF), chondroitin sulfate (CS) and hyaluronic acid (HA) were employed to fabricate scaffolds for tissue engineered cartilage by freeze drying technique. The secondary pores were formed in the main pores of SF/CS/HA scaffold which improved the pore connectivity and equilibrium swelling of the scaffold. Furthermore, rat bone marrow mesenchymal stem cells were seeded on the scaffolds to evaluate the cell adhesion and proliferation. Results of hematoxylin/eosin staining and cell counting kit-8 assay showed that the cells migration and differentiation of SF/CS/HA (80/15/5) scaffold were better than that of SF/CS/HA scaffolds with different ratios after 7 days culture. Moreover, immunohistochemistry and scanning electron microscope demonstrated that large amounts of collagen II and proteoglycans of the cells were expressed in the SF/CS/HA 3D scaffold, while the expression of collagen I was barely visible by immunohistochemistry. Abound of extracellular matrix was formed to morphologically round and distributed uniformly throughout the scaffolds. The 3D ternary scaffold could promote the cells chondrogenic differentiation without using any inductive agent and offer potential for cartilage tissue regeneration.     

Preparation and characterization of blended <Emphasis Type="Italic">Bombyx mori</Emphasis> silk fibroin scaffolds

The aim of this study was to compare physical, mechanical and biological properties of 3-dimensional scaffolds prepared from Bombyx mori silk fibroin (SF), fibroin blended with collagen (SF/C), and fibroin blended with gelatin (SF/G) using a freeze-drying technique. The prepared scaffolds were sponge-like structure that exhibited homogeneous porosity with highly interconnected pores. Average pore size of these scaffolds ranged from 65–147 μm. All biodegradable scaffolds were capable of water absorption of 90 %. The degradation behavior of these scaffolds could be controlled by varying the amount of blended polymer. The SF/C and SF/G scaffolds showed higher compressive modulus than that of SF scaffolds which could be attributed to the thicker pore wall observed in the blended constructs. The less crystalline SF structure was observed in SF/G scaffolds as compared to SF/C scaffolds. Thus, the highest compressive modulus was observed on SF/C matrix. To investigate the feasibility of the scaffolds for cartilage tissue engineering application, rat articular chondrocytes were seeded onto the scaffolds. The MTT assay demonstrated that blending collagen or gelatin into SF sponge facilitated cell attachment and proliferation better than SF scaffolds. The blended SF scaffolds possessed superior physical, mechanical and biological properties in comparison to SF scaffolds and showed high potential for application in cartilage tissue engineering.     

Chitosan-Alginate Biocomposite Containing Fucoidan for Bone Tissue Engineering

Over the last few years, significant research has been conducted in the construction of artificial bone scaffolds. In the present study, different types of polymer scaffolds, such as chitosan-alginate (Chi-Alg) and chitosan-alginate with fucoidan (Chi-Alg-fucoidan), were developed by a freeze-drying method, and each was characterized as a bone graft substitute. The porosity, water uptake and retention ability of the prepared scaffolds showed similar efficacy. The pore size of the Chi-Alg and Chi-Alg-fucoidan scaffolds were measured from scanning electron microscopy and found to be 62–490 and 56–437 µm, respectively. In vitro studies using the MG-63 cell line revealed profound cytocompatibility, increased cell proliferation and enhanced alkaline phosphatase secretion in the Chi-Alg-fucoidan scaffold compared to the Chi-Alg scaffold. Further, protein adsorption and mineralization were about two times greater in the Chi-Alg-fucoidan scaffold than the Chi-Alg scaffold. Hence, we suggest that Chi-Alg-fucoidan will be a promising biomaterial for bone tissue regeneration.     

Conductive 3D structure nanofibrous scaffolds for spinal cord regeneration

The complex nature of spinal cord injuries has provided much inspiration for the design of novel biomaterials and scaffolds which are capable of stimulating neural tissue repair strategies. Recently, conductive polymers have gained much attention for improving the nerve regeneration. In our previous study, a three-dimensional (3D) structure with reliable performance was achieved for electrospun scaffolds. The main purpose in the current study is formation of electrical excitable 3D scaffolds by appending polyaniline (PANI) to biocompatible polymers. In this paper, an attempt was made to develop conductive nanofibrous scaffolds, which can simultaneously present both electrical and topographical cues to cells. By using a proper 3D structure, two kinds of conductive scaffolds are compared with a non-conductive scaffold. The 3D nanofibrous core-sheath scaffolds, which are conductive, were prepared with nanorough sheath and aligned core. Two different sheath polymers, including poly(lactic-co-glycolic acid) PLGA and PLGA/PANI, with identical PCL/PANI cores were fabricated. Nanofibers of PCL and PLGA blends with PANI have fiber diameters of 234±60.8 nm and 770±166.6 nm, and conductivity of 3.17×10^-5 S/cm and 4.29×10^-5 S/cm, respectively. The cell proliferation evaluation of nerve cells on these two conductive scaffolds and previous non-conductive scaffolds (PLGA) indicate that the first conductive scaffold (PCL/ PANI-PLGA) could be more effective for nerve tissue regeneration. Locomotor scores of grafted animals by developed scaffolds showed significant performance of non-conductive 3D scaffolds. Moreover, the animal studies indicated the ability of two new types of conductive scaffolds as spinal cord regeneration candidates.     

Silk fibroin/hyaluronic acid porous scaffold for dermal wound healing

The use of silk protein as a biomaterial has been studied for decades. In this study, silk fibroin (SF)/hyaluronic acid (HA) blend scaffolds were prepared by freeze-drying technique. The structure and properties of the blend scaffolds were examined and analyzed. The results demonstrated that the secondary structures of the SF/HA scaffolds were mainly amorphous and β-sheet structures. The pore radius and porosity of the scaffolds decreased with a decrease in the freezing temperature decrease and an increase in the HA ratio. The pore radius and porosity were regulated from 32.22 μm to 290.76 μm and from 74.1 % to 91.15 %, respectively. In vitro, the SF/HA scaffolds could support the fibroblast cell adhesion and proliferation and showed good cytocompatibility. In vivo, the SF/HA scaffolds were implanted into the dorsum of Sprague Dawley rats to evaluate their bioactivity for dermal tissue reconstruction. The vascular-like structures appeared more rapidly in SF/HA scaffolds than that in the PVA group, and a new dermal layer was formed, as determined by histological analysis. The SF/HA porous scaffolds have promise as a dermal substitute.     

Fabrication of Silk Scaffold Containing Simvastatin-Loaded Silk Fibroin Nanoparticles for Regenerating Bone Defects

Background:In the present study, a tissue engineered SF scaffold containing simvastatin-loaded SFNPs were used to stimulate the regeneration of the defected bone.Methods:At first, the porous SF scaffold was prepared using freeze-drying. Then simvastatin-loaded SFNPs were made by dissolvation method and embedded in the SF scaffold. Afterwards, the scaffold and the NPs were characterized in terms of physicochemical properties and the ability to release the simvastatin small molecule.Results:The results exhibited that the SF scaffold had a porous structure suitable for releasing the small molecule and inducing the proliferation and attachment of osteoblast cells. SFNPs containing simvastatin had spherical morphology and were 174 ± 4 nm in size with -24.5 zeta potential. Simvastatin was also successfully encapsulated within the SFNPs with 68% encapsulation efficiency. Moreover, the small molecule revealed a sustained release profile from the NPs during 35 days. The results obtained from the in vitro cell-based studies indicated that simvastatin-loaded SFNPs embedded in the scaffold had acceptable capacity to promote the proliferation and ALP production of osteoblast cells while inducing osteogenic matrix precipitation. Conclusion:The SF scaffold containing simvastatin-loaded SFNPs could have a good potential to be used as a bone tissue-engineered construct.     

Increased Osteogenic Potential of Pre-Osteoblasts on Three-Dimensional Printed Scaffolds Compared to Porous Scaffolds for Bone Regeneration

Background:One of the main challenges with conventional scaffold fabrication methods is the inability to control scaffold architecture. Recently, scaffolds with controlled shape and architecture have been fabricated using 3D-printing. Herein, we aimed to determine whether the much tighter control of microstructure of 3DP PLGA/β-TCP scaffolds is more effective in promoting osteogenesis than porous scaffolds produced by solvent casting/porogen leaching. Methods:Physical and mechanical properties of porous and 3DP scaffolds were studied. The response of pre-osteoblasts to the scaffolds was analyzed after 14 days. Results:The 3DP scaffolds had a smoother surface (R_a: 22 ± 3 µm) relative to the highly rough surface of porous scaffolds (R_a: 110 ± 15 µm). Water contact angle was 112 ± 4° on porous and 76 ± 6° on 3DP scaffolds. Porous and 3DP scaffolds had the pore size of 408 ± 90 and 315 ± 17 µm and porosity of 85 ± 5% and 39 ± 7%, respectively. Compressive strength of 3DP scaffolds (4.0 ± 0.3 MPa) was higher than porous scaffolds (1.7 ± 0.2 MPa). Collagenous matrix deposition was similar on both scaffolds. Cells proliferated from day 1 to day 14 by fourfold in porous and by 3.8-fold in 3DP scaffolds. ALP activity was 21-fold higher in 3DP scaffolds than porous scaffolds. Conclusion:The 3DP scaffolds show enhanced mechanical properties and ALP activity compared to porous scaffolds in vitro, suggesting that 3DP PLGA/β-TCP scaffolds are possibly more favorable for bone formation. Key Words: Alkaline phosphatase, β-tricalcium phosphate, Poly(lactic-co-glycolic) acid copolymer     

Preparation, structure, and in vitro degradation behavior of the electrospun poly(lactide-co-glycolide) ultrafine fibrous vascular scaffold

The PLGA ultrafine fibrous scaffold was successfully fabricated by electrospinning. The morphology and properties of the PLGA vascular scaffolds were examined. In particular, the in vitro degradation behavior of the electrospun PLGA vascular scaffolds was investigated by means of morphology, microstructure, mass loss, M_w, and breaking strength characterization. The results showed that electrospun scaffold possessed ultrafine fibrous and porous structure, and had adequate mechanical properties to be developed as a substitute for native blood vessels. In vitro degradation study showed that the PLGA ultrafine fibrous scaffold could biodegrade in the PBS solution, and the mass loss, M_w, and breaking strength studies indicated that degradation rate of the electrospun PLGA nanofibers was greater in the first 2 weeks. After the degradation of 2 weeks, the degradation slowed down. Furthermore, with the extension of the degradation time, the thermal decomposition temperature of the PLGA scaffold decreased gradually. The results indicated that the electrospun PLGA vascular scaffold could be considered as an ideal candidate for tissue-engineered blood vessel.     

Effects of PLGA nanofibrous scaffolds structure on nerve cell directional proliferation and morphology

Electrospinning has been recognized as an efficient technique for the fabrication of neural tissue engineering scaffolds. Many approaches have been developed on material optimization, electrospinning techniques, and physical properties of scaffolds to produce a suitable scaffold for tissue engineering aspects. In this study, structural properties of scaffolds were promoted by controlling the speed of fiber collection without any post-processing. PLGA scaffolds, in two significantly different solution concentrations, were fabricated by the electrospinning process to produce scaffolds with the optimum nerve cell growth in a desired direction. The minimum, intermediate and maximum rate of fiber collection (0.4, 2.4, 4.8 m/s) formed Random, Aligned and Drown-aligned fibers, with various porosities and hydrophilicities. The scaffolds were characterized by fiber diameter, porosity, water contact angle and morphology. Human nerve cells were cultured on fiber substrates for seven days to study the effects of different scaffold structures on cell morphology and proliferation, simultaneously. The results of MTT assay, the morphology of cells and scaffold characterization recommend that the best structure to promote cell direction, morphology and proliferation is accessible in an optimized hydrophilicity and porosity of scaffolds, which was obtained at the collector linear speed of 2.4 m/s.     

Effects of Nanofiber Scaffolds Coated with Nanoparticulate and Microparticulate Freeze Dried Bone Allograft on the Morphology,Adhesion, and Proliferation of Human Mesenchymal Stem Cells

Background:Freeze dried bone allograft nanoparticles on a nanofiber membrane may serve as an ideal scaffold for bone regeneration. This study aimed to assess the biological behavior of human MSCs in terms of proliferation and adhesion to nanoparticulate and microparticulate FDBA scaffolds on PLLA nanofiber membrane. Methods:In this experimental study, PLLA nanofiber scaffolds were synthesized by the electrospinning method. The FDBA nanoparticles were synthesized mechanically. The FDBA nanoparticles and microparticles were loaded on the surface of PLLA nanofiber membrane. A total of 64 scaffold samples in four groups of n-FDBA/PLLA, FDBA/PLLA, PLLA and control were placed in 24-well polystyrene tissue culture plates; 16 wells were allocated to each group. Data were analyzed using one-way ANOVA and Bonferroni test. Results:The proliferation rate of MSCs was significantly higher in the nanoparticulate group compared to the microparticulate group at five days (p = 0.034). Assessment of cell morphology at 24 hours revealed spindle-shaped cells with a higher number of appendages in the nanoparticulate group compared to other groups. Conclusion:MSCs on n-FDBA/PLLA scaffold were morphologically more active and flatter with a higher number of cellular appendages, as compared to FDBA/PLLA. It seems that the nanoparticulate scaffold is superior to the microparticulate scaffold in terms of proliferation, attachment, and morphology of MSCs in vitro.Key Words: Allografts, Bone regeneration, Mesenchymal stem cells, Nanofibers     

Antimicrobial electrospun silk fibroin mats with silver nanoparticles for wound dressing application

In this report, silk fibroin (SF) mats coated with silver nanoparticles (AgNPs) were manufactured as a prototypic wound dressing and evaluated for antimicrobial properties. SF was extracted from cocoons of Thai silkworms Bombyx mori (variant Nangnoi Si Sa Ket) and fabricated into nonwoven mats by electrospinning. In a one-step synthesis method, colloidal AgNPs were prepared from silver nitrate by gamma irradiation and inspected by transmission electron microscopy. Using the in vitro disc diffusion and growth-inhibition assays, AgNP-coated SF mats effectively inhibited the growth of Staphyllococus aureus and Pseudomonas aeruginosa when the coating solution containing colloidal AgNPs was 4 mM, or equivalent to 50.4 ng/cm² of adsorbed AgNPs. Based on these results, the AgNP-coated SF mats can potentially be used as antimicrobial wound dressings.     

Binding of κ-Conotoxin-PVIIA to Open and Closed Shaker K-Channels Are Differentially Affected by the Ionic Strength

κ-Conotoxin-PVIIA (κ-PVIIA) is a potassium-channel blocking peptide from the venom of the fish-hunting snail, Conus purpurascens, which is essential for quick prey’s excitotoxic immobilization. Binding of one κ-PVIIA to Shaker K-channels occludes the K⁺-conduction pore without additional conformational effects. Because this 27-residue toxin is +4-charged at neutral pH, we asked if electrostatic interactions play a role in binding. With Voltage-Clamp electrophysiology, we tested how ionic strength (IS) affects κ-PVIIA blockade to Shaker. When IS varied from ~0.06 to ~0.16 M, the dissociation constant for open and closed channels increased by ~5- and ~16-fold, respectively. While the association rates decreased equally, by ~4-fold, in open and closed channels, the dissociation rates increased 4–5-fold in closed channels but was IS-insensitive in open channels. To explain this differential IS-dependency, we propose that the bound κ-PVIIA wobbles, so that in open channels the intracellular environment, via ion-conduction pore, buffers the imposed IS-changes in the toxin-channel interface. A Brønsted-Bjerrum analysis on the rates predicts that if, instead of fish, the snail preyed on organisms with seawater-like lymph ionic composition, a severely harmless toxin, with >100-fold diminished affinity, would result. Thus, considerations of the native ionic environment are essential for conotoxins evaluation as pharmacological leads.     

Effect of Dioxane and N-Methyl-2-pyrrolidone as a Solvent on Biocompatibility and Degradation Performance of PLGA/nHA Scaffolds

Background:Solvent casting/particulate leaching is one of the most conventional methods for fabricating polymer/ceramic composite scaffolds. In this method, the solvent generally affects resulting scaffold properties, including porosity and degradation rate. Methods:Herein, composite scaffolds of PLGA/nHA with different percentages of nHA (25, 35, and 45 wt. %) were prepared by the solvent casting/particle leaching combined with freeze drying. The effects of two different solvents, DIO and NMP, on morphology, porosity, bioactivity, degradation rate, and biocompatibility of the resulting scaffolds were investigated. Results:The results revealed that increasing the nHA percentages had no significant effect on the porosity and interconectivity of scaffolds (p > 0.05), whereas altering the solvent from DIO into NMP decreased the porosity from about 87% into 71%, respectively. Moreover, scaffolds of DIO illustrated the high results of cell proliferation compared to those of NMP; the cell viability of GD25 decreased from 85% to 65% for GN25. The findings also indicated that scaffolds prepared by NMP had a higher rate of losing weight in comparison to DIO. Adding nHA to PLGA had a significant effect on the bioactivity of scaffolds (p < 0.05), composite scaffolds with 45 wt % nHA had at least 30% more weight gain compared to the neat polymer scaffolds. Conclusion:The DIO scaffolds have higher rates of porosity, interconnectivity, bioactivity, and biocompatibility than NMP scaffolds due to its high evaporation rate. Key Words: Freeze drying, Porosity, Solvents     

Structural and physical properties ofAntheraea pernyi silk fibroin fiber treated with I2-KI aqueous solution

Silk fibroin (SF) fiber from theAntheraea pernyi silkworm was treated with a 1.23 N iodine-potassium iodide (I₂-KI) aqueous solution, and the structure and physical properties were investigated to clarify the effects of the iodine treatment. The noticeably high weight gain value of SF fiber, about 25 wt% was attributed to the absorption of polyiodide ions in the form of I₃ ^? and I₅ ^?. Fourier transform infrared spectroscopy and X-ray diffraction measurements suggested that polyiodide ions mainly entered the amorphous region. In addition, a new sharp reflection on the meridional direction, corresponding to a period of 7.0 Å, was observed and indicated the possibility of the formation of mesophase structure ofβ-conformation chains. Dynamic viscoelastic measurements showed that the damping tanδ peak at 270°C gradually shifted to lower temperature in the iodinated SF fibers, suggesting an enhancement of the molecular motion of the fibroin chains induced by the presence of polyiodide ions. With heating above 254 °C, the iodine component introduced intermolecular cross-linking of SF, and the melt flow of the sample was inhibited. The thermal decomposition stability of fibroin molecules was greatly enhanced by iodine treatment.     

Functionalizing cellulose scaffold prepared by ionic liquid with bovine serum albumin for biomedical application

The present study reports the preparation of a cellulose scaffold for tissue engineering directly from cellulose fiber using ionic liquid (IL) by the NaCl leaching method with bovine serum albumin (BSA), which is well known protein utilized for biomedical applications like degradation of polymer, cell attachment and proliferation on scaffold. The 1-n-allyl-3-methylimidazolium chloride (AmimCl) IL was used as a solvent for cellulose. The morphology of the scaffold was studied by scanning electron microscopy (SEM) and the images showed that the pore sizes of the scaffolds were about 200 µm. In addition, the water uptake (WU) and degree of degradation of the cellulose scaffold were measured. Meanwhile, the biocompatibility and bioactivity of the scaffold were determined via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenytetrazolium bromide (MTT) assay and the Live/Dead viability test. The various results demonstrated the ability of the Mesenchymal stem cells (MSC) to attach to the surface of the scaffolds amplified as percentage of BSA increased in cellulose scaffold.     

Ultrasound-mediated preparation and evaluation of a collagen/PVP-PCL micro- and nanofiber scaffold electrospun from chloroform/ethanol mixture

In this study, to improve the cellular biocompatibility of PVP-PCL micro- and nanofiber scaffold, a novel electrospun collagen/PVP-PCL micro- and nanofiber scaffold was sucessfully prepared assisted by ultrasonic irradiation using chloroform/ethanol mixtures as solvent. The micro- and nanofibers of the electrospun PCL-PVP scaffolds still presented compact inter-fiber entanglement and three-dimensional netlike network with some certain range of pore space after introducing collagen. The incorporated collagen phase was dispersed as inclusions within the electrospun fibers, and then could be easily released by immersing the scaffold in Hanks simulated body fluid. Meanwhile, the integral triple helix structure of collagen could be maintained after blending with the PVP-PCL mixture due to the weak intermolecular interactions. Furthermore, the suitable mechanical and degradation properties of the PVP-PCL scaffold were still reserved after introducing collagen, and the introduction of collagen could further promote the thermostability of the PVP-PCL scaffold. Above all, the collagen/PVP-PCL scaffold showed no cytotoxicity, better cell proliferation, and improved viability of primary fibroblasts than the PVP-PCL scaffold. In conclusion, blending collagen with the PVP-PCL mixture in this study has potential for promoting the biocompatibility of PVP-PCL micro- and nanofiber scaffolds for tissue engineering.     

Mesenchymal Stem Cells as an Alternative for Schwann Cells in Rat Spinal Cord Injury

Background: Spinal cord has a limited capacity to repair; therefore, medical interventions are necessary for treatment of injuries. Transplantation of Schwann cells has shown a great promising result for spinal cord injury (SCI). However, harvesting Schwann cell has been limited due to donor morbidity and limited expansion capacity. Furthermore, accessible sources such as bone marrow stem cells have drawn attentions to themselves. Therefore, this study was designed to evaluate the effect of bone marrow-derived Schwann cell on functional recovery in adult rats after injury. Methods: Mesenchymal stem cells were cultured from adult rats’ bone marrow and induced into Schwann cells in vitro. Differentiation was confirmed by immunocytochemistry and RT-PCR. Next, Schwann cells were seeded into collagen scaffolds and engrafted in 3 mm lateral hemisection defects. For 8 weeks, motor and sensory improvements were assessed by open field locomotor scale, narrow beam, and tail flick tests. Afterwards, lesioned spinal cord was evaluated by conventional histology and immunohistochemistry. Results: In vitro observations showed that differentiated cells had Schwann cell morphology and markers. In this study, we had four groups (n = 10 each): laminectomy, control, scaffold and scaffold + Schwann cells. Locomotor and sensory scores of cell grafted group were significantly better than control and scaffold groups. In histology, axonal regeneration and remyelination were better than control and scaffold groups. Conclusion: This study demonstrates that bone marrow-derived Schwann cells can be considered as a cell source for Schwann cells in SCI treatment. Key Words: Rats, Spinal cord injuries (SCI), Bone marrow, Schwann cells, Cell transdifferentiation     

Highly porous three-dimensional poly(lactide-co-glycolide) (PLGA) microfibrous scaffold prepared by electrospinning method: A comparison study with other PLGA type scaffolds on its biological evaluation

In this study, a three-dimensional (3D) poly(lactide-co-glycolide) (PLGA) microfibrous scaffold with high porosity (ca. 90 % porosity) was developed for evaluating its performance in tissue engineering application. A dope solution of PLGA/polyethylene oxide (PEO) blend was electrospun into a methanol coagulation bath for fabricating highly porous 3D PLGA scaffold and a salt leaching method was used for making interconnected pores of 100?C200 ??m size inside the scaffold. The morphological structure, pore size and porosity of the microfibrous scaffold were determined, and compared with twodimensional (2D) mat-type and 3D sponge-type of PLGA scaffold. Also, swelling ratio, water uptake and compressive strength were compared in order to elucidate the structure-property relationships of different types of the scaffolds, especially in a wet condition. As a result of scanning electron microscopy (SEM) observation, normal human dermal fibroblasts (nHDF) were migrated, attached, and proliferated well inside the 3D scaffold. MTT assay confirmed that the highly porous 3D PLGA microfibrous scaffold had superior cell adhesion and proliferation abilities due to fibrous structure of large specific surface area, and interconnected pore structure. Therefore, this high performance 3D PLGA scaffold can have a high potentiality for application in tissue engineering in comparison with conventional PLGA scaffolds.