Enhanced wound regeneration by PGS/PLA fiber dressing containing platelet-rich plasma: an in vitro study.

Novel wound dressings with therapeutic effects are being continually designed to improve the wound healing process. In this study, the structural, chemical, physical, and biological properties of an electrospun poly glycerol sebacate/poly lactide acid/platelet-rich plasma (PGS/PLA-PRP) nanofibers were evaluated to determine its impacts on in vitro wound healing. Results revealed desirable cell viability in the Fibroblast (L929) and macrophage (RAW-264.7) cell lines as well as human umbilical vein endothelial cells (HUVEC). Cell migration was evident in the scratch assay (L929 cell line) so that it promoted scratch contraction to accelerate in vitro wound healing. Moreover, addition of PRP to the fiber structure led to enhanced collagen deposition (~ 2 times) in comparison with PGS/PLA scaffolds. While by addition PRP to PGS/PLA fibers not only decreased the expression levels of pro-inflammatory cytokines (IL-6 and TNF-α) in RAW-264.7 cells but also led to significantly increased levels of cytokine (IL-10) and the growth factor (TGF-ß), which are related to the anti-inflammatory phase (M2 phenotype). Finally, PGS/PLA-PRP was found to induce a significant level of angiogenesis by forming branching points, loops, and tubes. Based on the results obtained, the PGS/PLA-PRP dressing developed might be a promising evolution in skin tissue engineering ensuring improved wound healing and tissue regeneration.

Harnessing IL-10 induced anti-inflammatory response in maturing macrophages in presence of electrospun dexamethasone-loaded PLLA scaffold.

The ultimate goal of tissue engineering is to repair and regenerate damaged tissue or organ. Achieving this goal requires blood vessel networks to supply oxygen and nutrients to new forming tissues. Macrophages are part of the immune system whose behavior plays a significant role in angiogenesis and blood vessel formation. On the other hand, macrophages are versatile cells that change their behavior in response to environmental stimuli. Given that implantation of a biomaterial is followed by inflammation; therefore, we reasoned that this inflammatory condition in tissue spaces modulates the final phenotype of macrophages. Also, we hypothesized that anti-inflammatory glucocorticoid dexamethasone improves modulating macrophages behavior. To check these concepts, we investigated the macrophages that had matured in an inflammatory media. Furthermore, we examined macrophages' behavior after maturation on a dexamethasone-containing scaffold and analyzed how the behavioral change of maturing macrophages stimulates other macrophages in the same environment. In this study, the expression of pro-inflammatory markers TNFa and NFκB1 along with pro-healing markers IL-10 and CD163 were investigated to study the behavior of macrophages. Our results showed that macrophages that were matured in the inflammatory media in vitro increase expression of IL-10, which in turn decreased the expression of pro-inflammatory markers TNFa and NFκB in maturing macrophages. Also, macrophages that were matured on dexamethasone-containing scaffolds decreased the expression of IL-10, TNFa, and NFκB and increase the expression of CD163 compared to the control group. Moreover, the modulation of anti-inflammatory response in maturing macrophages on dexamethasone-containing scaffold resulted in increased expression of TNFa and CD163 by other macrophages in the same media. The results obtained in this study, proposing strategies to improve healing through controlling the behavior of maturing macrophages and present a promising perspective for inflammation control using tissue engineering scaffolds.

Coaxial electrospun PGS/PCL and PGS/PGS-PCL nanofibrous membrane containing platelet-rich plasma for skin tissue engineering.

Wound healing will be enhanced using structures with therapeutic effects. This study fabricated a novel nanofibrous scaffold for skin tissue regeneration using a coaxial structure polyglycerol sebacate (PGS)/platelet-rich plasma (PRP) was embedded in the core and two different compositions were selected for the shell; in one group, polycaprolactone (PCL), and in the other group, PGS/PCL blend was used. The physical, mechanical behavior, drug delivery patterns, and cell response of scaffolds were evaluated. Results revealed that by adding PRP to the core and PGS to the shell, fiber diameters decreased to 260.8 ± 31.3 nm. It also decreased the water contact angle from 66° to 32°, that is ideal candidate for cell attachment. The drug release showed a burst release pattern in the first 30 min, followed by a continuous and slow release during the first day. Adding PGS to the shell decreased the elastic modulus, and its value reached about 500 kPa, which is near the skin elastic modulus and will lead to greater mechanical compatibility for cell proliferation. Particularly, the addition of PRP to the fiber structure enhanced the cell viability and cell adhesion with a suitable morphology. Based on the results, nanofibrous PGS-PRP/PGS-PCL dressing can enhance skin tissue regeneration.

Preclinical in vivo assessment of a cell-free multi-layered scaffold prepared by 3D printing and electrospinning for small-diameter blood vessel tissue engineering in a canine model.

Tissue-engineered vascular grafts (TEVGs) are promising alternatives to existing prosthetic grafts. The objective of this study is to evaluate the clinical feasibility of a novel multi-layered small-diameter vascular graft that has a hierarchical structure. Vascular grafts with elaborately designed composition and architecture were prepared by 3D printing and electrospinning and were implanted into the femoral artery of 5 dogs. The patency of the grafts was assessed using Doppler ultrasonography. After 6 months, the grafts were retrieved and histological and SEM examinations were conducted. During implantation, the grafts exhibited resistance to kinking and no blood seepage thanks to the helical structure of the innermost and outermost layers. The grafts showed a high patency rate and remodelling ability. At 6 months post-implantation, the lumen was endothelialized and middle layers were regenerated by infiltration of smooth muscle cells (SMCs) and deposition of extracellular matrix (ECM). These results suggest that the multi-layered vascular graft may be a promising candidate for small-diameter blood vessel tissue engineering in clinical practice.

Cellulosic textile/clove nanocomposite as an antimicrobial wound dressing: In vitro and in vivo study.

Clove (Syzygium aromaticum) is one of the useful herbal medicine to prevent the bacteria infection. This herbal medicine plant shows high antimicrobial, antioxidant, and anti-inflammation activities because the essential oil and extract of this herb contains a rich source of phenolic compounds. The important phenolic compound of the herb is eugenol. In this study, we endeavored to develop the flexible cellulosic textile nanocomposite by dipping the cellulosic textile in a nano emulsion containing clove herbal medicine (32%wt). This nanocomposite was subjected to detail analyzes using Fourier Transform Infrared Spectroscopy (FTIR), field-emission scanning electron microscope (FESEM) and gas chromatography-mass spectrometry (GC-MS). The mean size of this nano emulsion as measured by electron microscopy is between 100 and 300 nm. The presence of eugenol in this nano emulsion has been confirmed by GC-MS. The wound dressing shows high antimicrobial activity against E. coli (3 ± 0.11 mm), P. aeruginosa (2.8 ± 0.06 mm), S. epidemidis (2.9 ± 0.09 mm), and S. aureus (2.6 ± 0.07 mm). This nano composite showed significant improvement in in vivo wound healing and in vitro cellular compatibility. Nearly 85% of the operation wound was healed during14 days. Accordingly, cellulosic textile/clove wound dressing can be a potential candidate for biomedical application and pre-clinical surveys.

Blood compatibility and cell response improvement of poly glycerol sebacate/poly lactic acid scaffold for vascular graft applications.

Plasma surface modification is one of the new methods for improving the surface properties of the scaffold and accelerating tissue regeneration. The aim of this study was to create poly glycerol sebacate/poly lactic acid (PGS/PLA) composite scaffold by electrospun method and modified the scaffold by oxygen plasma for use as a vascular graft. Plasma surface modified PGS/PLA scaffold morphology study showed relatively uniform fibers with an average diameter of 637 ± 149.4 nm and porosity of 82%. The mechanical evaluation of the PGS/PLA scaffold showed properties close to the natural vessels. Atomic force microscopy images exhibited an increase in the roughness of the scaffold after plasma surface modification; however, hemocompatibility studies revealed that it had no adverse effect on blood compatibility. Wettability studies revealed the superhydrophilic property of the modified scaffold (contact angle near to zero). Besides, the human umbilical vein endothelial cells proliferation and adhesion were improved significantly. Obtaining mechanical properties near to the natural vessels due to the suitable composition and significant improvement in blood compatibility and cell growth make the modified PGS/PLA composite a suitable candidate for vascular tissue regeneration.

In vitro study of a novel multi-substituted hydroxyapatite nanopowder synthesized by an ultra-fast, efficient and green microwave-assisted method.

In order to improve the biological activity of hydroxyapatite (HA), a multi-substituted HA (SHA) nanopowder with the chemical composition of Ca9.5Mg0.25Sr0.25(PO4)5.5(SiO4)0.5(OH)1.2F0.8 was synthesized using the microwave-assisted method. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) revealed that all ions were substituted in the HA crystal lattice. The HA and SHA nanoparticles had a semi-spherical morphology with the average size of 90 and 80 nm, respectively. In-vitro bioactivity assessments showed that after the 28-day immersion of the samples in the simulated body fluid, the morphology of the precipitated apatites on the surface of the HA sample still consisted of spherical particles with a cauliflower-like structure. However, in the SHA sample, the morphology of the precipitated apatites was changed to a nanorod-like one similar to the bone-like apatite, which may be attributed the presence of Sr in the precipitated apatites. The results showed that the release of the substituted ions not only had no adverse effect on the cell viability and cell attachment, but also enhanced the alkaline phosphatase activity of MG63 osteoblast like cells in the SHA group, as compared to the HA and control groups. The results indicated that the simultaneous substitution of Si, Mg, Sr, and F in HA nanoparticles could effectively promote bioactivity, cell proliferation and differentiation. This novel HA composition could be, therefore, well used for implant coating, bone tissue engineering and other orthopedic applications.

In-vivo evaluation of a partially resorbable poly l-lactic acid/ braided bioactive glass fibers reinforced composite for load bearing fracture fixation.

Our previous studies have been focused on the design, optimization and manufacture of a partially resorbable composite bone plate consisting of a poly l-lactic acid matrix reinforced with braided fabrics bioactive glass fibers (PLLA/BG). In the present study, the response of the composite samples, the degradation rate, the inflammatory response, fibrous capsule formation and tissue-implant bonding to the in-vivo environment were assessed via implantation in the rabbit subcutaneous tissue. Despite the presence of both enzymatic degradation and hydrolysis processes within the body, the rate of the molecular weight loss as an indicator of degradation did not show a significant difference with the in-vitro conditions. It was predicted that strength loss would show the same trend since it was a consequence of molecular chain disruption and the loss of molecular weight. Inexistence of chronic inflammation, as confirmed by our previous results on the controlled degradation rate, also showed the maintenance of the physiological pH in the peripheral environment of the implant. Moreover, lack of the fibrous capsule tissue around the implant indicated that the implant was bioactive. In addition, given the composition of the bioactive glass fibers, that could be bonded to soft and hard tissues, tissue bonding with the PLLA/BG composite samples was also observed, thereby confirming the bioactivity and biocompatibility of the proposed bone plate.

Promoting neural cell proliferation and differentiation by incorporating lignin into electrospun poly(vinyl alcohol) and poly(glycerol sebacate) fibers.

Electrospinning of natural and synthetic polymers open a new practical approach to tissue engineering by producing fibers. In this study, aligned electrospun poly(vinyl alcohol) (PVA)-poly(glycerol sebacate) (PGS) fibers with various percentages of lignin (0, 1, 3, and 5%wt) fabricated for nerve tissue engineering. The effect of the different amount of lignin on the morphology and diameter of the fibers was investigated by scanning electron microscopy (SEM). The physicochemical properties of fibers were studied using FTIR, tensile strain, contact angle, water uptake, and degradation test. MTT assay and SEM were employed to evaluate PC12 cell proliferation and adhesion, respectively. Immunocytochemistry and gene expression were utilized to study how the lignin affected on cell differentiation. The results revealed the smooth with a uniform diameter of the fabricated fibers, and the increased amount of lignin reduced the fiber diameter from 530 to 370 nm. The modulus of elasticity increased from 0.1 to 0.4 MPa by increasing the lignin percentage. The PC12 cell culture indicated that the lignin enhanced cell proliferation. The mRNA expression level for Gfap, ß-Tub III, and Map2 and immunocytochemistry (Map2) revealed the positive effect of lignin on neural cell differentiation. Finally, the results suggest PVA-PGS/5% lignin as a promising material for nerve tissue engineering.

Fabrication and evaluation of a nerve guidance conduit capable of Ca2+ ion release to accelerate axon extension in peripheral nerve regeneration.

In this study, biodegradable nanocomposites consisting of poly (glycerol sebacate) (PGS) elastomeric matrix and the reinforcing phase of calcium titanate (CaTiO3 ) nanoparticles were fabricated as a nerve guidance conduit (NGC) for peripheral nerve regeneration. CaTiO3 nanoparticles were synthesized via the sol-gel method and calcined at 800°C for 60 min. PGS elastomer was synthesized via the polycondensation reaction of glycerol and sebacate (1:1) and 2.5 and 5 wt. percentages of the synthesized CaTiO3 nanoparticles were added to the PGS prepolymer solution. The composites obtained were heated in order to make crosslinks in the pre-polymer. CaTiO3 nanoparticles, PGS elastomer, and the composites fabricated were characterized in terms of their structural, chemical, physical, mechanical, and cell response properties to evaluate the feasibility of using the nanocomposite for NGC applications. The results indicated that CaTiO3 nanoparticles were 50 nm in size. When the nanoparticles were added to the PGS, the elastic modulus and tensile strength of the nanocomposite reached values of about 1 and 0.5 MPa, respectively that are near those of natural nerves. The degradation behavior and swelling of the nanocomposites, as compared with those of the PGS elastomer, were controlled by introducing CaTiO3 into the PGS, which swelling limitation could prevent nerve compression. It was observed that Ca2+ ions established chemical bonds with PGS, which led to high crosslink densities that, in turn, contribute to improved mechanical properties of the composite. The Ca2+ ions released from the nanocomposite samples were in the nontoxic range. The PC12 cell line on the surface of the nanocomposite specimens showed good cell adhesion and proliferation with improved axon outgrowth and extension. Based on the results obtained the fabricated PGS/CaTiO3 nanocomposite may be recommended as a suitable NGC with desirable effects on peripheral nerve regeneration. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2181-2189, 2018.

Designing an Optimized Novel Femoral Stem.

BACKGROUND: After total hip arthroplasty, there would be some problems for the patients. Implant loosening is one of the significant problems which results in thigh pain and even revision surgery. Difference between Young's modulus of bone-metal is the cause of stress shielding, atrophy, and subsequent implant loosening. MATERIALS AND METHODS: In this paper, femoral stem stiffness is reduced by novel biomechanical and biomaterial design which includes using proper design parameters, coating it with porous surface, and modeling the sketch by the software. Parametric design of femoral stem is done on the basis of clinical reports. RESULTS: Optimized model for femoral stem is proposed. Curved tapered stem with trapezoidal cross-section and particular neck and offset is designed. Fully porous surface is suggested. Moreover, Designed femoral stem analysis showed the Ti6Al4V stem which is covered with layer of 1.5 mm in thickness and 50% of porosity is as stiff as 77 GPa that is 30% less than the stem without any porosity. Porous surface of designed stem makes it fix biologically; thus, prosthesis loosening probability decreases. CONCLUSION: By optimizing femoral stem geometry (size and shape) and also making a porous surface, which had an intermediate stiffness of bone and implant, a more efficient hip joint prosthesis with more durability fixation was achieved due to better stress transmission from implant to the bone.

In vitro hemocompatibility and cytocompatibility of a three-layered vascular scaffold fabricated by sequential electrospinning of PCL, collagen, and PLLA nanofibers.

Aiming to mimic a blood vessel structurally, morphologically, and mechanically, a sequential electrospinning technique using a small diameter mandrel collector was performed and a three-layered tubular scaffold composed of nanofibers of polycaprolactone, collagen, and poly(l-lactic acid) as inner, intermediate, and outer layers, respectively, was developed. Biological performances of the scaffold in terms of compatibility with blood and endothelial cells were assessed to get some insights into its potential use as a tissue engineered small-diameter vascular replacement compared to an expanded polytetrafluoroethylene vascular graft. Due to direct contact of the blood and endothelial cells with inner surface of the scaffold, polycaprolactone fibers were characterized using SEM, water contact angle measurement, and ATR-FTIR. Despite similar surface wettability of the electrospun scaffold and the expanded polytetrafluoroethylene graft, the three-layered scaffold significantly reduced platelet adhesion and hemolysis ratio compared to expanded polytetrafluoroethylene graft while comparable blood clotting profiles were observed for both electrospun scaffold and expanded polytetrafluoroethylene graft. However, inflammatory response to nanofibrous surface of the scaffold was reduced compared to expanded polytetrafluoroethylene graft. The electrospun scaffold also presented a significantly more supportive substrate for endothelialization than the expanded polytetrafluoroethylene graft. The results described herein suggested that the three-layered scaffold has superior biological properties compared to an expanded polytetrafluoroethylene graft for vascular tissue engineering.