Enhancing Diabetic Wound Healing Through Improved Angiogenesis: The Role of Emulsion-Based Core-Shell Micro/Nanofibrous Scaffold with Sustained CuO Nanoparticle Delivery.

Attempts are made to design a system for sustaining the delivery of copper ions into diabetic wounds and induce angiogenesis with minimal dose-dependent cytotoxicity. Here, a dual drug-delivery micro/nanofibrous core-shell system is engineered using polycaprolactone/sodium sulfated alginate-polyvinyl alcohol (PCL/SSA-PVA), as core/shell parts, by emulsion electrospinning technique to optimize sustained delivery of copper oxide nanoparticles (CuO NP). Herein, different concentrations of CuO NP (0.2, 0.4, 0.8, and 1.6%w/w) are loaded into the core part of the core-shell system. The morphological, biomechanical, and biocompatibility properties of the scaffolds are fully determined in vitro and in vivo. The 0.8%w/w CuO NP scaffold reveals the highest level of tube formation in HUVEC cells and also upregulates the pro-angiogenesis genes (VEGFA and bFGF) expression with no cytotoxicity effects. The presence of SSA and its interaction with CuO NP, and also core-shell structure sustain the release of the nanoparticles and provide a non-toxic microenvironment for cell adhesion and tube formation, with no sign of adverse immune response in vivo. The optimized scaffold significantly accelerates diabetic wound healing in a rat model. This study strongly suggests the 0.8%w/w CuO NP-loaded PCL/SSA-PVA as an excellent diabetic wound dressing with significantly improved angiogenesis and wound healing.

Bioengineering of fibroblast-conditioned polycaprolactone/gelatin electrospun scaffold for skin tissue engineering.

BACKGROUND: Synthetic tissue engineering scaffolds has poor biocompatiblity with very low angiogenic properties. Conditioning the scaffolds with functional groups, coating with biological components, especially extracellular matrix (ECM), is an excellent strategy for improving their biomechanical and biological properties. METHODS: In the current study, a composite of polycaprolactone and gelatin (PCL/Gel) was electrospun in the ratio of 70/30 and surface modified with 1% gelatin-coating (G-PCL/Gel) or plasma treatment (P-PCL/Gel). The surface modification was determined by SEM and ATR-FTIR spectroscopy, respectively. The scaffolds were cultured with fibroblast 3T3, then decellularized during freeze-thawing process to fabricate a fibroblast ECM-conditioned PCL/Gel scaffold (FC-PCL/Gel). The swelling and degaradtion as well as in vitro and in vivo biocompatibility and angiogenic properties of the scaffolds were evaluated. RESULTS: The structure of the surface-modified G-PCL/Gel and P-PCL/Gel were unique and not changed compared with the PCL/Gel scaffolds. ATR-FTIR analysis admitted the formation of oxygen-containing groups, hydroxyl and carboxyl, on the surface of the P-PCL/Gel scaffold. The SEM micrographs and DAPI staining confirmed the cell attachment and the ECM deposition on the platform and successful removal of the cells after decellularization. P-PCL/Gel showed better cell attachment, ECM secretion and deposition after decellularization compared with G-PCL/Gel. The FC-PCL/Gel was considered as an optimized scaffold for further assays in this study. The FC-PCL/Gel showed increased hydrophilic behavior and cytobiocompatibility compared with P-PCL/Gel. The ECM on the FC-PCL/Gel scaffold showed a gradual degradation during 30 days of degradation time, as a small amount of ECM remained over the FC-PCL/Gel scaffold at day 30. The FC-PCL/Gel showed significant biocompatibility and improved angiogenic property compared with P-PCL/Gel when subcutaneously implanted in a mouse animal model for 7 and 28 days. CONCLUSIONS: Our findings suggest FC-PCL/Gel as an excellent biomimetic construct with high angiogenic properties. This bioengineered construct can serve as a possible application in our future pre-clinical and clinical studies for skin regeneration.

Human amniotic membrane extracellular matrix scaffold for dental pulp regeneration in vitro and in vivo.

AIM: In order to obtain a 3-dimentional scaffold with predictable clinical results for pulp regeneration, this study aims to fabricate and characterize a porous decellularized human amniotic membrane (HAM) extracellular matrix (ECM) scaffold, and evaluate its potential to promote pulp regeneration in vitro and in vivo. METHODOLOGY: The HAM was decellularized, and its histology and DNA content were analysed to confirm decellularization. The scaffolds were synthesized with 15, 22.5 and 30 mg/ml concentrations. The porosity, pore size, phosphate-buffered saline (PBS) absorption and degradation rate of the scaffolds were assessed. In vitro experiments were performed on human dental pulp stem cells (hDPSCs) to assess their viability, proliferation, adhesion and migration on the scaffolds. The optimal group was selected for in vivo immunogenicity assessment and was also used as the cell-free or cell-loaded scaffold in root segment models to evaluate pulp regeneration. All nonparametric data were analysed with the Kruskal-Wallis test followed by Dunn's post hoc test, whilst quantitative data were analysed with one-way anova. RESULTS: Decellularization of HAM was confirmed (p < .05). The porosity of all scaffolds was more than 95%, and the pore size decreased with an increase in ECM concentration (p < .01). PBS absorption was not significantly different amongst the groups, whilst 30 mg/ml ECM scaffold had the highest degradation rate (p < .01). The hDPSCs adhered to the scaffold, whilst their proliferation rate increased over time in all groups (p < .001). Cell migration was higher in 30 mg/ml ECM scaffold (p < .05). In vivo investigation with 30 mg/ml ECM scaffold revealed mild to moderate inflammatory response. In root segments, both cell-free and cell-loaded 30 mg/ml scaffolds were replaced with newly formed, pulp-like tissue with no significant difference between groups. Immunohistochemical assessments revealed high revascularization and collagen content with no significant difference amongst the groups. CONCLUSION: The 30 mg/ml HAM ECM scaffold had optimal physical properties and better supported hDPSC migration. The HAM ECM scaffold did not interfere with formation of pulp-like tissue and revascularization within the root canal when employed as both cell-free and cell-loaded scaffold. These results highlight the potential of HAM ECM membrane for further investigations in regenerative endodontics.

Sulfated polysaccharide as biomimetic biopolymers for tissue engineering scaffolds fabrication: Challenges and opportunities.

Sulfated polysaccharides play important roles in tissue engineering applications because of their high growth factor preservation ability and their native-like biological features. There are different sulfated polysaccharides based on different repeating units in the carbohydrate backbone, the position of the sulfate group, and the sulfation degree of the polysaccharide. These led to various sulfated polymers with different negative charge densities and resultant structure-property relationships. Since numerous reports are presented related to sulfated polysaccharide applications in tissue engineering, it is crucial to review the role of effective physicochemical and biological parameters in their usage; as well as their structure-property relationships. Within this review, we focused on the effect of naturally occurring and synthetic sulfated polysaccharides in tissue engineering applications reported in the last years, highlighting the challenges of the scaffold fabrication process, the position, and the degree of sulfate on biomedical activity. Additionally, we discussed their use in numerous in vitro and in vivo model systems.

Alginate hydrogel-PCL/gelatin nanofibers composite scaffold containing mesenchymal stem cells-derived exosomes sustain release for regeneration of tympanic membrane perforation.

Exosomes are among the most effective therapeutic tools for tissue engineering. This study demonstrates that a 3D composite scaffold containing exosomes can promote regeneration in rat tympanic membrane perforation (TMP). The scaffolds were characterized using scanning electron microscopy (SEM), degradation, PBS adsorption, swelling, porosity, and mechanical properties. To confirm the isolation of exosomes from human adipose-derived mesenchymal stem cells (hAMSCs), western blot, SEM, and dynamic light scattering (DLS) were performed. The Western blot test confirmed the presence of exosomal surface markers CD9, CD81, and CD63. The SEM test revealed that the isolated exosomes had a spherical shape, while the DLS test indicated an average diameter of 82.5 nm for these spherical particles. MTT assays were conducted to optimize the concentration of hAMSCs-exosomes in the hydrogel layer of the composite. Exosomes were extracted on days 3 and 7 from an alginate hydrogel containing 100 and 200 µg/mL of exosomes, with 100 µg/mL identified as the optimal value. The optimized composite scaffold demonstrated improved growth and migration of fibroblast cells. Animal studies showed complete tympanic membrane regeneration (TM) after five days. These results illustrate that a scaffold containing hAMSC-exosomes can serve as an appropriate tissue-engineered scaffold for enhancing TM regeneration.

Three-dimensional biomimetic reinforced chitosan/gelatin composite scaffolds containing PLA nano/microfibers for soft tissue engineering application.

In the current study, we successfully prepared chitosan/gelatin composite scaffolds reinforced by centrifugally spun polylactic acid (PLA) chopped nano/microfibers (PLA-CFs). Herein, different amounts of PLA-CFs (0 %, 1 %, 2 %, 3 %, and 4 % w/v) dispersed in chitosan/gelatin solution were used. Morphological characterization of prepared scaffolds revealed that at the initial stage of adding PLA-CFs, the chopped fibers were localized at the wall of the pores; however, as the fiber load increased, aggregations of chopped-fibers could be seen. Also, mechanical evaluation of scaffolds in terms of compression and tensile mode showed that samples reinforced with 2 % PLA-CFs had enhanced mechanical properties. Indeed, its tensile strength increased from 123.8 to 247.2 kPa for dry and 18.9 to 48.6 kPa for wet conditions. Furthermore, the tensile modulus associated with both conditions increased from 2.99 MPa and 44.5 kPa to 6.43 MPa and 158.4 kPa, respectively. The results of cell culture studies also confirmed that the prepared composite scaffold exhibited appropriate biocompatibility, cell proliferation and migration. The cell infiltration study of the samples revealed that scaffolds reinforced with 2 % PLA-CFs had significantly better cell penetration and distribution compared with the control ones on both days (7 and 14).

Hybrid gelatin-sulfated alginate scaffolds as dermal substitutes can dramatically accelerate healing of full-thickness diabetic wounds.

Diabetic foot ulcers (DFUs) are defined as chronic and non-healing wounds that cause skin disorders. Here, we introduce a novel biodegradable gelatin/sulfated alginate hybrid scaffold as a dermal substitute to accelerate the healing of full-thickness diabetic ulcers in a diabetic mouse model. The hybrid scaffold possessing different weight ratios of sulfated alginate, from 10 % up to 50 %, were prepared through chemical crosslinking by carbodiimide chemistry and further freeze-drying. Based on the in vitro cytotoxicity experiments, the hybrid scaffolds not only showed no cytotoxicity, but the cell growth also dramatically increased by increasing the sulfated alginate content. Finally, the pathology of hybrid scaffolds as the dermal substitutes for healing of full-thickness diabetic wounds showed the more appropriate formation of epidermal layer, more homogeneous distribution of collagenous tissue and lower penetration of immune cells for the hybrid scaffolds-treated wounds.

Alginate sulfate/ECM composite hydrogel containing electrospun nanofiber with encapsulated human adipose-derived stem cells for cartilage tissue engineering.

Stem cell therapy is a promising strategy for cartilage tissue engineering, and cell transplantation using polymeric scaffolds has recently gained attention. Herein, we encapsulated human adipose-derived stem cells (hASCs) within the alginate sulfate hydrogel and then added them to polycaprolactone/gelatin electrospun nanofibers and extracellular matrix (ECM) powders to mimic the cartilage structure and characteristic. The composite hydrogel scaffolds were developed to evaluate the relevant factors and conditions in mechanical properties, cell proliferation, and differentiation to enhance cartilage regeneration. For this purpose, different concentrations (1-5 % w/v) of ECM powder were initially loaded within an alginate sulfate solution to optimize the best composition for encapsulated hASCs viability. Adding 4 % w/v of ECM resulted in optimal mechanical and rheological properties and better cell viability. In the next step, electrospun nanofibrous layers were added to the alginate sulfate/ECM composite to prepare different layered hydrogel-nanofiber (2, 3, and 5-layer) structures with the ability to mimic the cartilage structure and function. The 3-layer structure was selected as the optimum layered composite scaffold, considering cell viability, mechanical properties, swelling, and biodegradation behavior; moreover, the chondrogenesis potential was assessed, and the results showed promising features for cartilage tissue engineering application.

Fabrication and optimization of multilayered composite scaffold made of sulfated alginate-based nanofiber/decellularized Wharton's jelly ECM for tympanic membrane tissue engineering.

In this study, we fabricated a novel multilayer polyvinyl alcohol (PVA)/alginate sulfate (ALG-S) nanofiber/decellularized Wharton's Jelly ECM (d-ECM) composite for tympanic membrane perforations (TMPs) tissue engineering (TE). Initially, electrospun PVA/ALG-S scaffolds with different blend ratios were fabricated. The influence of ALG-S ratio on surface morphology, mechanical, physical and biological properties of the nanofibers was studied. Secondly, 3-layer composites were developed as a combination of PVA/ALG-S nanofibers and d-ECM to take synergic advantages of electrospun mats and d-ECM. As part of the evaluation of the effects of d-ECM incorporation, the composite's mechanical properties, in vitro degradation, swelling ratio, and biological activities were assessed. The MTT assay showed that PVA/ALG-S nanofibers with 50:50 ratio provided a more desirable environment to support cell growth. A composite containing 25 mg/cm2 d-ECM was determined as the optimal composite through MTT assay, and this composite was used for animal studies inducing TMP regeneration. According to the in vivo studies, the optimal composite not only stimulated the healing of TMPs but also shortened the healing period. These results suggest that a multilayer nanofiber/hydrogel composite could be a potential platform for regenerating TMPs.

An aorta ECM extracted hydrogel as a biomaterial in vascular tissue engineering application.

Biological scaffolds have been undergoing significant growth in tissue engineering applications over the last years. Biopolymers extracted from ECM with various protein factors and other biological agents have been active in restoring damaged tissue. In the present study, bioactive scaffold is prepared from bovine aorta extracted natural polymeric hydrogel with advantages of availability and cost-effectiveness. The biological scaffolds were prepared through freeze-drying method to make a 3D sponge with appropriate structure, well-defined architecture and interconnected pores for vascular tissue engineering, and studied the effect of aorta hydrogel concentrations (1, 2, 3, and 4% w/v) on the scaffolds. The prepared biological scaffolds were analyzed by mechanical tests, FTIR, SEM, porosity and PBS absorption. Moreover, the morphology and proliferation of human umbilical vein cord cells on the 3D sponges were investigated. Histological analysis including, Masson trichrome (MT), hematoxylin and eosin (H&E), Verhoeff/Van Gieson (VVG) and alcian blue (AB) revealed that during this process the main components of aorta extracellular matrix containing collagen, elastin, and glycosaminoglycan were well preserved. The obtained results revealed that the scaffolds porosity were more than 90%. The Aorta-ECM4% enabled HUVECs to survive, proliferate and migrate better than 2% and 3% aorta-ECM.

Fabrication and In Vitro Evaluation of A Chondroitin Sulphate-Polycaprolactone Composite Nanofibrous Scaffold for Potential Use in Dermal Tissue Engineering.

OBJECTIVE: Poly(ε-caprolactone) (PCL) has considerable mechanical and biological properties that make it a good candidate for tissue engineering applications. PCL alongside proteins and polysaccharides, like gelatin (GEL) and chondroitin sulphate (CS), can be used to fabricate composite scaffolds that provide mechanical and biological requirements for skin tissue engineering scaffolds. The aim of this study was fabricating novel composite nanofibrous scaffold containing various ratios of GEL/CS and PCL using co-electrospinning process. MATERIALS AND METHODS: In this experimental study, PCL mixed with a GEL/CS blend has limitations in miscibility and the lack of a common solvent. Here, we electrospun PCL and GEL/CS coincide separately on the same drum by using different nozzles to create composite nanofibrous scaffolds with different ratios (2:1, 1:1 and 1:2) of GEL to CSPCL, and we mixed them at the micro/nanoscale. Morphology, porosity, phosphate-buffered saline (PBS) absorption, chemical structure, mechanical property and in vitro bioactivity of the prepared composite scaffolds were analysed. RESULTS: Scanning electron microscopy (SEM) images showed beadless nanofibres at all ratios of GEL to CS-PCL. The composite scaffolds (2:1, 1:1 and 1:2) had increased porosity compared to the PCL nanofibrous scaffolds, in addition to a significant increase in PBS absorption. The mechanical properties of the composite scaffolds were investigated under different conditions. The results demonstrated that all of the composite specimens had better strength when compared with the GEL/CS nanofibres. The increase in PCL ratio led to an increase in tensile strength of the nanofibres. Human dermal fibroblasts (HDF) were cultured on the fabricated composite scaffolds and evaluated by 3-(4,5-dimethylthiazol- 2-yl)-5-(3 carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) analysis and SEM. The results showed the bioactivity of these nanofibres and the potential for these scaffolds to be used for skin tissue engineering applications. CONCLUSION: The fabricated co-electrospun composite scaffolds had higher porosity and PBS absorption in comparison with the PCL nanofibrous scaffolds, in addition to significant improvements in mechanical properties under wet and dry conditions compared to the GEL/CS scaffold.

Multilayered 3-D nanofibrous scaffold with chondroitin sulfate sustained release as dermal substitute.

Electrospun nanofibers for skin tissue engineering applications face two main challenges. The low thickness of electrospun mats is the main reason for their weak load-bearing performance at clinical applications and limited cell penetration due to their small pore sizes. We have developed multi-layered nanofibrous 3D (M3DN) scaffolds comprising gelatin, polyvinyl alcohol, and chondroitin sulfate (CS) by an electrospinning method and attaching three electrospun layers via ethanol to cause interface fibers to come in contact with each other. Prepared M3DN scaffolds revealed a sustained CS release profile. The improved mechanical performance, stable release of CS, and penetration capability of the cells and blood vessels through the spaces between layers in the prepared multi-layered nanofibrous scaffolds demonstrate their potential applications in response to the increasing demand for replacement of damaged dermis. The results of animal studies on the dorsal skin of Rat with full-thickness wounds have shown that the reconstruction of full-thickness skin lesions is significantly higher for M3DN scaffolds than a control group (treated with sterile gauze). The amount of epithelization, collagen arrangement, and inflammatory cells (acute and chronic) has been investigated, and their associated results demonstrated that M3DN scaffolds have great potential for full-thickness wound restoration.

An additive manufacturing-based 3D printed poly ɛ-caprolactone/alginate sulfate/extracellular matrix construct for nasal cartilage regeneration.

Various composite scaffolds with different fabrication techniques have been applied in cartilage tissue engineering. In this study, poly ɛ-caprolactone (PCL) was printed by fused deposition modeling method, and the prepared scaffold was filled with Alginate (Alg): Alginate-Sulfate (Alg-Sul) hydrogel to provide a better biomimetic environment and emulate the structure of glycosaminoglycans properly. Furthermore, to enhance chondrogenesis, different concentrations of decellularized extracellular matrix (dECM) were added to the hydrogel. For cellular analyses, the adipose-derived mesenchymal stem cells were seeded on the hydrogel and the results of MTT assay, live/dead staining, and SEM images revealed that the scaffold with 1% dECM had better viscosity, cell viability, and proliferation. The study was conducted on the optimized scaffold (1% dECM) to determine mechanical characteristics, chondrogenic differentiation, and results demonstrated that the scaffold showed mechanical similarity to the native nasal cartilage tissue along with possessing appropriate biochemical features, which makes this new formulation based on PCL/dECM/Alg:Alg-Sul a promising candidate for further in-vivo studies.

Alginate-magnetic short nanofibers 3D composite hydrogel enhances the encapsulated human olfactory mucosa stem cells bioactivity for potential nerve regeneration application.

The design of 3D hydrogel constructs to elicit highly controlled cell response is a major field of interest in developing tissue engineering. The bioactivity of encapsulated cells inside pure alginate hydrogel is limited by its relatively inertness. Combining short nanofibers within a hydrogel serves as a promising method to develop a cell friendly environment mimicking the extracellular matrix. In this paper, we fabricated alginate hydrogels incorporating different magnetic short nanofibers (M.SNFs) content for olfactory ecto-mesenchymal stem cells (OE-MSCs) encapsulation. Wet-electrospun gelatin and superparamagnetic iron oxide nanoparticles (SPIONs) nanocomposite nanofibers were chopped using sonication under optimized conditions and subsequently embedded in alginate hydrogels. The storage modulus of hydrogel without M.SNFs as well as with 1 and 5 mg/mL of M.SNFs were in the range of nerve tissue. For cell encapsulation, OE-MSCs were used as a new hope for neuronal regeneration due to their neural crest origin. Resazurin analyses and LIVE/DEAD staining confirmed that the composite hydrogels containing M.SNFs can preserve the cell viability after 7 days. Moreover, the proliferation rate was enhanced in M.SNF/hydrogels compared to alginate hydrogel. The presence of SPIONs in the short nanofibers can accelerate neural-like differentiation of OE-MSCs rather than the sample without SPIONs.

Fish cartilage: A promising source of biomaterial for biological scaffold fabrication in cartilage tissue engineering.

Here, engineered cartilage-like scaffold using an extracellular matrix (ECM) from sturgeon fish cartilage provided a chondroinductive environment to stimulate cartilaginous matrix synthesis in human adipose stem cells (hASCs). Three dimensional porous and degradable fish cartilage ECM-derived scaffold (FCS) was produced using a protocol containing chemical decellularization, enzymatic solubilization, freeze-drying and EDC-crosslinking treatments and the effect of different ECM concentrations (10, 20, 30, and 40 mg/ml) on prepared scaffolds was investigated through physical, mechanical and biological analysis. The histological and scanning electron microscopy analysis revealed the elimination of the cell fragments and a 3-D interconnected porous structure, respectively. Cell viability assay displayed no cytotoxic effects. The prepared porous constructs of fish cartilage ECM were seeded with hASCs for 21 days and compared to collagen (Col) and collagen-10% hyaluronic acid (Col-HA) scaffolds. Cell culture results evidenced that the fabricated scaffolds could provide a proper 3-D structure to support the adhesion, proliferation and chondrogenic differentiation of hASCs considering the synthesis of specific proteins of cartilage, collagen type II (Col II) and aggrecan (ACAN). Based on the results of the present study, it can be concluded that the porous scaffold derived from fish cartilage ECM possesses an excellent potential for cartilage tissue engineering.

Alginate sulfate-based hydrogel/nanofiber composite scaffold with controlled Kartogenin delivery for tissue engineering.

In this study, we fabricated two different arrangements of laminated composite scaffolds based on Alginate:Alginate sulfate hydrogel, PCL:Gelatin electrospun mat, and Kartogenin-PLGA nanoparticles (KGN-NPs). The optimized composite scaffold revealed a range of advantages such as improved mechanical features as well as less potential of damage (less dissipated energy), interconnected pores of hydrogel and fiber with adequate pore size, excellent swelling ratio, and controlled biodegradability. Furthermore, the synthesized KGN-NPs with spherical morphology were incorporated into the composite scaffold and exhibited a linear and sustained release of KGN within 30 days with desirable initial burst reduction (12% vs. 20%). Additionally, the cytotoxicity impact of the composite was evaluated. Resazurin assay and Live/Dead staining revealed that the optimized composite scaffold has no cytotoxic effect and could improve cell growth. Overall, according to the enhanced mechanical features, suitable environment for cellular growth, and sustained drug release, the optimized scaffold would be a good candidate for tissue regeneration.

Cardiac ECM/chitosan/alginate ternary scaffolds for cardiac tissue engineering application.

Since cardiovascular diseases are the number one cause of death in worldwide, and the traditional treatments have limitations, the emergence of cardiac tissue engineering (CTE) can be a promising approach. In this study, scaffold fabrication from the solubilized cardiac extracellular matrix (ECM) accompanied with alginate and chitosan for CTE was carried out. The influence of blending ratios on chemical and physical properties of the scaffolds including FTIR spectroscopy, porosity, pore size, and their mechanical properties were investigated. The porosity of scaffolds was more than 96% with very high swelling rate while maintaining their stability in PBS solution. Blending ECM with chitosan and alginate significantly improve the tensile strength of ECM. FTIR spectrum of scaffolds demonstrated interaction of solubilized ECM with two opposite-charged polysaccharides. The proliferation of human mesenchymal stem cells (hMSCs) on the ternary scaffolds using MTS assay, revealed that blending ECM with polysaccharides at ratio of 75: 25 (E75/P25) led to improve the proliferation of hMSCs on scaffolds. Scanning electron microscope (SEM) revealed the porous structure and the presence of hMSCs cells inside the pores. In addition, histological analysis confirmed that cardiomyocyte penetration inside scaffolds after 7 days of culture. The immunofluorescence staining revealed that higher expression of cardiac marker (cTnT) in ternary scaffold in comparison with ECM.

Polyvinyl alcohol/sulfated alginate nanofibers induced the neuronal differentiation of human bone marrow stem cells.

Scaffolds that are used for neural tissue engineering are fabricated to mimic the extracellular matrix. In this paper, we have fabricated polyvinyl alcohol/sulfated alginate (PVA/SA) nanofibers with different concentrations (10, 20 and 30 wt%) of sulfated alginate by electrospinning technique. The average fibers diameters of 169-488 nm were achieved by electrospinning of polymers blend (PVA/SA). The results of the MTT assay and scanning electron microscopy showed that PVA/sulfated alginate nanofibrous scaffold with 30 wt% SA provided more desirable surface attachment of C6, Schwann cells (SCs) and human bone marrow mesenchymal stem cells (hBMSCs). RT-PCR and immunocytochemistry for MAP-2 marker were conducted to confirm the neural-differentiation of hBMSCs. The expression of MAP-2 confirmed neural differentiation for up to 14 days. Our results showed that PVA/SA nanofibrous scaffold with 30 wt% SA is a suitable substrate for mesenchymal stem cells growth and is capable of inducing neuronal differentiation.

Preparation and characterization of polylactic-co-glycolic acid/insulin nanoparticles encapsulated in methacrylate coated gelatin with sustained release for specific medical applications.

This study aimed to examine the possibility of using insulin orally with gelatin encapsulation to enhance the usefulness of the drug and increase the lifespan of insulin in the body using polylactic-co-glycolic acid (PLGA) nanoparticles alongside gelatin encapsulation. In this regard, PLGA was synthesized via ring opening polymerization, and PLGA/insulin nanoparticles were prepared by a modified emulsification-diffusion process. The resulting nanoparticles with various amounts of insulin were fully characterized using FTIR, DSC, DLS, zeta potential, SEM, and glucose uptake methods, with results indicating the interaction between the insulin and PLGA. The process efficiency of encapsulation was higher than 92%, while the encapsulation efficiency of nanoparticles, based on an insulin content of 20 to 40%, was optimized at 93%. According to the thermal studies, the PLGA encapsulation increases the thermal stability of the insulin. The morphological studies showed the fine dispersion of insulin in the PLGA matrix, which we further confirmed by the Kjeldahl method. According to the release studies and kinetics, in-vitro degradation, and particle size analysis, the sample loaded with 30% insulin showed optimum overall properties, and thus it was encapsulated with gelatin followed by coating with aqueous methacrylate coating. Release studies at pH values of 3 and 7.4, alongside the Kjeldahl method and standard dissolution test at pH 5.5, and glucose uptake assay tests clearly showed the capsules featured 3-4 h biodegradation resistance at a lower pH along with the sustained release, making these gelatin-encapsulated nanoparticles promising alternatives for oral applications.[Figure: see text].

Tough, hybrid chondroitin sulfate nanofibers as a promising scaffold for skin tissue engineering.

Fabrication of gelatin/polyvinyl alcohol/chondroitin sulfate (GEL/PVA/CS) hybrid nanofibrous scaffolds using acetic acid and water as an environmentally friendly solvent system via electrospinning for skin tissue engineering was investigated. Modeling and optimization of the nanofibers were performed using response surface methodology (RSM). The influence of CS ratio on mechanical, physical and biological properties of the nanofibers was studied. PVA was used as a carrier and enhancer of mechanical properties. The mechanical properties of hybrid nanofibers were investigated in dry and wet states. The results showed that in the cross-linked dry state the tensile strength was up to 4 MPa. In the wet state, nanofibers exhibited 200% elongation at break, indicating a toughness behavior which enhances the flexibility for clinical applications. Scanning electron microscope (SEM) confirmed the stability of nanofibrous morphology during degradation up to 21 days. Human dermal fibroblast-green fluorescent protein-positive (HDF-GFP+) cells were cultured on the scaffolds and results showed the appropriate biocompatibility. 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay was employed to study cell proliferation, and the results confirmed the positive effect of CS ratio on HDF cells attachment as well as proliferation on the nanofibers. Considering the results of in vitro assay, nanofibers containing 15% CS ratio suggested as an optimum CS ratio.