Comparison of neurite growth in three dimensional natural and synthetic hydrogels

Extracellular matrix incorporated within a scaffold plays an important role in assisting cell behavior in neural tissue engineering. In this study, we investigated how the concentration of fibronectin (FN) affected neurite growth when incorporated within a synthetic polymer gel made of poly(ethylene glycol) (PEG) or a natural polymer gel of collagen I. Mechanical and chemical properties of the scaffold were varied by using a range of concentrations of gels and FN. Rheology was used to determine the mechanical stiffness of hydrogels and neurite length and viability were measured to evaluate cell response. In both types of gels, increasing the concentration of the base scaffold (PEG or collagen) increased the mechanical stiffness as denoted by G^?. Neurite lengths in PEG gels increased with increasing FN concentration and decreased with increasing G^?. In collagen gels, FN reduced neurite extension for the lowest concentrations of collagen (0.4–0.6?mg/mL) while FN increased neurite extension for mid and high collagen concentrations (1.0–2.0?mg/mL). The results from these two different scaffolds indicate that both stiffness and FN concentration impact the growth of the neurite and that the addition of small amounts of FN (100?μg/ml) permits PEG gels to perform on par with similar stiffness collagen gels.     

Mesenchymal stem cell interaction with a non‐woven hyaluronan‐based scaffold suitable for tissue repair

The fabrication of biodegradable 3‐D scaffolds enriched with multipotent stem cells seems to be a promising strategy for the repair of irreversibly injured tissues. The fine mechanisms of the interaction of rat mesenchymal stem cells (rMSCs) with a hyaluronan‐based scaffold, i.e. HYAFF®11, were investigated to evaluate the potential clinical application of this kind of engineered construct. rMSCs were seeded (2 × 10⁶ cells cm^?2) on the scaffold, cultured up to 21 days and analysed using appropriate techniques. Light (LM), scanning (SEM) and transmission (TEM) electron microscopy of untreated scaffold samples showed that scaffolds have a highly porous structure and are composed of 15‐µm‐thick microfibres having a rough surface. As detected by trypan blue stain, cell adhesion was high at day 1. rMSCs were viable up to 14 days as shown by CFDA assay and proliferated steadily on the scaffold as revealed by MTT assay. LM showed rMSCs in the innermost portions of the scaffold at day 3. SEM revealed a subconfluent cell monolayer covering 40 ± 10% of the scaffold surface at day 21. TEM of early culture showed rMSCs wrapping individual fibres with regularly spaced focal contacts, whereas confocal microscopy showed polarized expression of CD44 hyaluronan receptor; TEM of 14‐day cultures evidenced fibronexus formation. Immunohistochemistry of 21‐day cultures showed that fibronectin was the main matrix protein secreted in the extracellular space; decorin and versican were seen in the cell cytoplasm only and type IV collagen was minimally expressed. The expression of CD90, a marker of mesenchymal stemness, was found unaffected at the end of cell culture. Our results show that HYAFF®11 scaffolds support the adhesion, migration and proliferation of rMSCs, as well as the synthesis and delivery of extracellular matrix components under static culture conditions without any chemical induction. The high retention rate and viability of the seeded cells as well as their fine modality of interaction with the substrate suggest that such scaffolds could be potentially useful when wide tissue defects are to be repaired as in the case of cartilage repair, wound healing and large vessel replacement.     

Physicomechanical properties of sintered scaffolds formed from porous and protein-loaded poly(DL-lactic-co-glycolic acid) microspheres for potential use in bone tissue engineering

An injectable poly(DL-lactic-co-glycolic acid) (PLGA) system comprising both porous and protein-loaded microspheres capable of forming porous scaffolds at body temperature was developed for tissue regeneration purposes. Porous and non-porous (lysozyme loaded) PLGA microspheres were formulated to represent ‘low molecular weight’ 22–34 kDa, ‘intermediate molecular weight’ (IMW) 53 kDa and ‘high molecular weight’ 84–109 kDa PLGA microspheres. The respective average size of the microspheres was directly related to the polymer molecular weight. An initial burst release of lysozyme was observed from both microspheres and scaffolds on day 1. In the case of the lysozyme-loaded microspheres, this burst release was inversely related to the polymer molecular weight. Similarly, scaffolds loaded with 1 mg lysozyme/g of scaffold exhibited an inverse release relationship with polymer molecular weight. The burst release was highest amongst IMW scaffolds loaded with 2 and 3 mg/g. Sustained lysozyme release was observed after day 1 over 50 days (microspheres) and 30 days (scaffolds). The compressive strengths of the scaffolds were found to be inversely proportional to PLGA molecular weight at each lysozyme loading. Surface analysis indicated that some of the loaded lysozyme was distributed on the surfaces of the microspheres and thus responsible for the burst release observed. Overall the data demonstrates the potential of the scaffolds for use in tissue regeneration.     

In vitro chondrocyte behavior on porous biodegradable poly (e-caprolactone)/polyglycolic acid scaffolds for articular chondrocyte adhesion and proliferation

In this study, poly(e-caprolactone)/polyglycolic acid (PCL/PGA) scaffolds for repairing articular cartilage were fabricated via solid-state cryomilling along with compression molding and porogen leaching. Four distinct scaffolds were fabricated using this approach by four independent cryomilling times. These scaffolds were assessed for their suitability to promote articular cartilage regeneration with in vitro chondrocyte cell culture studies. The scaffolds were characterized for pore size, porosity, swelling ratio, compressive, and thermal properties. Cryomilling time proved to significantly affect the physical, mechanical, and morphological properties of the scaffolds. In vitro bovine chondrocyte culture was performed dynamically for 1, 7, 14, 28, and 35 days. Chondrocyte viability and adhesion were tested using MTT assay and scanning electron microscopy micrographs. Glycosaminoglycan (GAG) and DNA assays were performed to investigate the extracellular matrix (ECM) formation and cell proliferation, respectively. PCL/PGA scaffolds demonstrated high porosity for all scaffold types. Morphological analysis and poly(ethylene oxide) continuity demonstrated the existence of a co-continuous network of interconnected pores with pore sizes appropriate for tissue engineering and chondrocyte ingrowth. While mean pore size decreased, water uptake and compressive properties increased with increasing cryomilling times. Compressive modulus of 12, 30, and 60 min scaffolds matched the compressive modulus of human articular cartilage. Viable cells increased besides increase in cell proliferation and ECM formation with progress in culture period. Chondrocytes exhibited spherical morphology on all scaffold types. The pore size of the scaffold affected chondrocyte adhesion, proliferation, and GAG secretion. The results indicated that the 12 min scaffolds delivered promising results for applications in articular cartilage repair.     

Antibacterial nanohydroxyapatite/polyurethane composite scaffolds with silver phosphate particles for bone regeneration

Solving the issue of infection associated with implanted bone substitutes is one of the modern challenges of the biomedical engineering field. The purpose of this study was to develop a novel porous scaffold with sufficient antibacterial activity for bone repair or regeneration. Porous nanohydroxyapatite/polyurethane (n-HA/PU) composite scaffolds containing different amounts of silver phosphate particles were prepared through the in situ foaming method. Subsequently, their physicochemical properties, antibacterial abilities, and preliminary cytocompatibilities were evaluated. The results indicated that the porosity and mechanical properties of the n-HA/PU scaffolds incorporated with Ag₃PO₄ did not change significantly compared to n-HA/PU scaffold without Ag₃PO₄. The release of Ag⁺ was time and concentration dependent, increasing with the immersion time and Ag₃PO₄ percentage in the scaffolds. A continuous Ag⁺ release can last more than 3 weeks. The antibacterial tests and cytocompatibility evaluation revealed that n-HA/PU scaffolds with 3 wt% Ag₃PO₄ (n-HA/PU3) exhibit stronger antimicrobial effects as well as satisfactory cytocompatibility. The n-HA/PU3 scaffolds may hold great potential for application in the field of bone regeneration, especially for infection-associated bone defect repair.     

Effects of Stephania dinklagei (Engl.) Diels methanol root extract on alloxan-induced diabetic Wistar rats

The natives of Orba in Udenu, Enugu State, Nigeria use the roots of Stephania dinklagei to treat folkloric “sugar disease.” The methanol root extract of S. dinklagei was investigated for antidiabetic activity in alloxan-induced diabetic Wistar rats and also evaluated for in vitro and in vivo antioxidant potentials. Extraction was by cold maceration in 80 % methanol for 48 h. Diabetes was induced with alloxan monohydrate at 160 mg/?kg, intraperitoneally. Treatment was done orally using the extract at doses of 100, 200, and 400 mg/?kg with glibenclamide (2 mg/?kg) as the standard reference drug for 14 days. Fasting blood sugar levels were measured at days 0, 7, and 14 using an autoanalyzer (Accu-Chek Advantage^®) glucose kit. Total cholesterol and malondialdehyde were evaluated on day 14. The extract and the glibenclamide caused a time-dependent decrease in the fasting blood glucose levels of the diabetic rats when compared to the negative control group at various levels of significance (p?<?0.05–0.0001). The extract at the dose of 100 mg/?kg reduced the fasting blood glucose level by 60.5 % on day 14. S. dinklagei extract also caused a significant reduction in total cholesterol and malondialdehyde when compared with the negative control (p?<?0.05–0.0001). The highest activity was observed at the dose of 100 mg/?kg of the extract. There was a concentration-dependent increase in percentage total antioxidant activity from 10 to 400 μg/?ml. The results suggest that S. dinklagei has significant antidiabetic and antioxidant potentials in type 2-induced diabetic Wistar rats.     

Adsorbed fibrinogen leads to improved bone regeneration and correlates with differences in the systemic immune response

Designing new biomaterials that can modulate the inflammatory response instead of attempting just to reduce it constitutes a paradigm change in regenerative medicine. This work aimed to investigate the capacity of an immunomodulatory biomaterial to enhance bone regeneration. For that purpose we incorporated a molecule with well-established pro-inflammatory and pro-healing roles, fibrinogen, in chitosan scaffolds. Two different incorporation strategies were tested, leading to concentrations of 0.54 ± 0.10 mg fibrinogen g^?1 scaffold immediately upon adsorption (Fg-Sol), and 0.34 ± 0.04 mg fibrinogen g^?1 scaffold after washing (Fg-Ads). These materials were implanted in a critical size bone defect in rats. At two months post-implantation the extent of bone regeneration was examined by histology and the systemic immune response triggered was evaluated by determining the percentages of myeloid cells, T and B lymphocytes in the draining lymph nodes. The results obtained indicate that the fibrinogen incorporation strategy conditioned the osteogenic capacity of biomaterials. Fg-Ads scaffolds led to more bone formation, and the presence of Fg stimulated angiogenesis. Furthermore, animals implanted with Fg-Ads scaffolds showed significant increases in the percentages of B lymphocytes and myeloid cells in the draining lymph nodes, while levels of T lymphocytes were not significantly different. Finally, a significant increase in TGF-β1 was detected in the plasma of animals implanted with Fg-Ads. Taken together the results presented suggest a potential correlation between the elicited immune response and biomaterial osteogenic performance.     

Preparation of carboxylated Ag nanoparticles as a coating material for medical devices and control of antibacterial activity

Carboxyl group-donated silver (Ag) nanoparticles for coating on medical devices were prepared by a two-phase reduction system in situ. AgNO₃ was the Ag ion source, tetraoctylammonium bromide [N(C₈H₁₇)₄Br] the phase-transfer agent, sodium tetrahydroborate (NaBH₄) the reducing agent and 10-carboxy-1-decanthiol (C₁₁H₂₂O₂S, CDT) the capping agent. The characterizations of the Ag nanoparticles were conducted by diffuse reflectance Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric differential thermal analysis (TG/DTA) and transmission electron microscope. With CDT capped on Ag nanoparticles, we found that the band around 3,100 cm^?1 was attributed to COO-H stretching vibration, two adsorptions at 2,928 and 2,856 cm^?1 to C–H symmetric/anti-symmetric stretching vibration, and at 1,718 cm^?1 to C=O stretching vibration in the FT-IR spectra. The organic components of the carboxylated Ag nanoparticles were 5.8–25.9 wt%, determined by TG/DTA. The particle sizes of the carboxylated Ag nanoparticles were well controlled by the addition of the capping agent, CDT, into the reaction system. The antimicrobial activity of the Ag nanoparticles covered with different contents of CDT against E. coli was evaluated. Smaller-size Ag nanoparticles showed higher antibacterial activity, which depended on a surface area that attached easily to a microorganism cell membrane.     

Oral pre‐treatment with rosuvastatin protects porcine myocardium from ischaemia/reperfusion injury via a mechanism related to nitric oxide but not to serum cholesterol level

Aims: The aim of this study was to test whether oral pre‐treatment with rosuvastatin at a dosage giving clinically relevant plasma concentrations protects the myocardium against ischaemia/reperfusion injury and to investigate the involvement of nitric oxide (NO) and neutrophil infiltration. Methods: Pigs were given placebo (n = 7), rosuvastatin (80 mg day^?1, n =7), rosuvastatin (160 mg day^?1, n = 7) or pravastatin (160 mg day^?1, n = 7) orally for 5 days before being subjected to coronary artery ligation and reperfusion. An additional group was given rosuvastatin 160 mg day^?1 and a nitric oxide synthase (NOS) inhibitor. Results: Rosuvastatin 80 and 160 mg day^?1 resulted in plasma concentrations of 2.6 ± 0.7 and 5.6 ± 1.0 ng mL^?1, respectively. Serum cholesterol was not affected. Rosuvastatin 160 mg day^?1 and pravastatin limited the infarct size from 82 ± 3% of the area at risk in the placebo group to 61 ± 3% (P < 0.05), and to 61 ± 2% (P < 0.05) respectively. Rosuvastatin 80 mg day^?1 limited the infarct size to 69 ± 2%, however, this effect was not statistically significant. Rosuvastatin 160 mg day^?1 attenuated neutrophil infiltration in the ischaemic/reperfused myocardium. The protective effect of rosuvastatin 160 mg day^?1 was abolished by NOS inhibition. The expression of NOS2 and NOS3 in the myocardium did not differ between the groups. Conclusions: Oral pre‐treatment with rosuvastatin limited infarct size following ischaemia/reperfusion without affecting cholesterol levels. The cardioprotective effect is suggested to be dependent on maintained bioactivity of NO, without influencing NOS expression.     

Selected biochemical parameters in plasma of blood and semen of Persian sturgeon,Acipenser persicus

The investigation of blood and seminal plasma biochemical parameters is essential for fish stock conservation and development of artificial propagation methods via extender improvement. In this research, comparison of blood and seminal plasma compounds and their relationship in Persian sturgeon, Acipenser persicus, were studied. Seminal plasma contained 59.53?±?2.56 mEq/l sodium (Na⁺), 4.72?±?0.31 mEq/l potassium (K⁺), 1.45?±?0.075 mEq/l chloride (Cl^?), 9.1?±?1.42 mEq/l calcium (Ca²⁺), 0.7?±?0.072 mEq/l magnesium (Mg²⁺), 0.11?±?0.021 g/dl total protein, 6.67?±?1.04 mg/dl cholesterol, 15.2?±?0.65 mg/dl triacylglycerol, and 18.22?±?4.16 mg/dl glucose. Also, blood biochemical values were determined (mean?±?SEM) for Na⁺ (123.2?±?1.31 mEq/l), K⁺ (2.77?±?0.088 mEq/l), Cl^? (97.18?±?1.23 mEq/l), Ca²⁺ (6.67?±?0.24 mEq/l), Mg²⁺ (1.29?±?0.074 mEq/l), glucose (198.49?±?18.03 mg/dl), triacylglycerol (214.22?±?13.38 mg/dl), total protein (3.62?±?0.23 g/dl), and cholesterol (127.11?±?6.94 mg/dl). The mean blood and seminal osmolality values were 244.62?±?3.66 and 86.9?±?4.22 mOsm/kg, respectively. Results of the comparison between biochemical parameters of seminal and blood plasma indicated that the concentrations of all parameters of blood plasma were significantly (P?++ and Na⁺ of the seminal plasma (P?P?相似文献   

Surface modification of electrospun poly(methyl methacrylate) (PMMA) nanofibers for the development of in vitro respiratory epithelium model

Scaffold design is an important aspect of in vitro model development. In this study, nanoscaffold surface modification, namely UV radiation and genipin cross-linking to immobilize collagen on the surface of electrospun poly (methyl methacrylate) (PMMA) nanofiber sheet was investigated. Samples were divided into four groups; PMMA nanofibers (PMMA), collagen-coated PMMA nanofibers (PMMACOL), genipin cross-linked collagen-coated PMMA nanofibers (PMMAGEN), and UV-irradiated collagen-coated PMMA nanofibers (PMMAUV). 6 h of UV radiation significantly reduced the hydrophobicity of PMMA nanofibers from (131.88° ± 1.33°) to (110.04° ± 0.27°) (p < 0.05). The amount of collagen immobilized was significantly higher in PMMAGEN group (239.36 ± 16.63 μg collagen/mg nanofibers) (p < 0.05) compared to the other groups. RECs on all scaffold expressed epithelial cell-specific markers (CK18 and CK14), mucin-producing cell marker (MUC5Ac) and were actively proliferating, based on the positive expression of Ki67. Total number of attached cells was significantly the highest in PMMAUV group on day 9 (6.44 × 10⁴ ± 2.77 × 10⁴ cells/cm²) and it has the highest proliferation rate from day 4 to 9 (0.005 ± 0.003 h^?1) compared to the other groups. Even though PMMAGEN group showed the highest collagen adsorption, in terms of cells attachment and proliferation, PMMAUV group showed a better outcome compared to the other groups. Thus, PMMAUV scaffold is more suitable to be used in the construction of in vitro respiratory epithelial model.     

Controlling the extrudate swell in melt extrusion additive manufacturing of 3D scaffolds: a designed experiment

Tissue engineering using three-dimensional porous scaffolds has shown promise for the restoration of normal function in injured and diseased tissues and organs. Rigorous control over scaffold architecture in melt extrusion additive manufacturing is highly restricted mainly due to pronounced variations in the deposited strand diameter upon any variations in process conditions and polymer viscoelasticity. We have designed an I-optimal, split-plot experiment to study the extrudate swell in melt extrusion additive manufacturing and to control the scaffold architecture. The designed experiment was used to generate data to relate three responses (swell, density, and modulus) to a set of controllable factors (plotting needle diameter, temperature, pressure, and the dispensing speed). The fitted regression relationships were used to optimize the three responses simultaneously. The swell response was constrained to be close to 1 while maximizing the modulus and minimizing the density. Constraining the extrudate swell to 1 generates design-driven scaffolds, with strand diameters equal to the plotting needle diameter, and allows a greater control over scaffold pore size. Hence, the modulus of the scaffolds can be fully controlled by adjusting the in-plane distance between the deposited strands. To the extent of the model’s validity, we can eliminate the effect of extrudate swell in designing these scaffolds, while targeting a range of porosity and modulus appropriate for bone tissue engineering. The result of this optimization was a predicted modulus of 14 MPa and a predicted density of 0.29 g/cm³ (porosity ≈ 75%) using polycaprolactone as scaffold material. These predicted responses corresponded to factor levels of 0.6 μm for the plotting needle diameter, plotting pressure of 2.5 bar, melt temperature of 113.5 °C, and dispensing speed of 2 mm/s. The validation scaffold enabled us to quantify the percentage difference for the predictions, which was 9.5% for the extrudate swell, 19% for the density, and 29% for the modulus.     

Influence of ionic crosslinkers (Ca2+/Ba2+/Zn2+) on the mechanical and biological properties of 3D Bioplotted Hydrogel Scaffolds

Three dimensional (3D) bioplotting requires appropriate crosslinkers to crosslink the hydrogel precursor while simultaneously maintaining the viability of embedded cells. However, the evaluation and comparison of various types of crosslinkers in bioplotting remains underexplored to date. This paper presents our study of the influence of three ionic crosslinkers—calcium chloride (CaCl₂), barium chloride (BaCl₂), and zinc chloride (ZnCl₂)—on the mechanical and biological properties of 3D bioplotted alginate scaffolds. The scaffold mechanical properties characterized included the elastic modulus, swelling, and degradation while the biological properties considered included Schwann cell viability and surface morphology. The mechanical and biological properties of the bioplotted scaffolds were both dependent on the crosslinkers used for fabrication; specifically, crosslinking ions resulted in the elastic modulus of the hydrogels decreasing in the order BaCl₂>CaCl₂>ZnCl₂ over 42 days while Schwann cell viability decreased in the order CaCl₂>BaCl₂>ZnCl₂ over 7 days. Taken together, these results offer insights that are effective in terms of manipulating the 3D bioplotting process so as to tune and optimize the mechanical and biological performance of the plotted scaffolds for tissue engineering applications.     

Efficacy of Kelamidium® in the prevention and treatment of Trypanosoma brucei brucei infection in albino rats

The efficacy of Kelamidium® in the prevention and treatment of experimental Trypanosoma brucei brucei infection of albino rats was studied. Adult albino rats (55) weighing between 147 and 240 g were used for the study. The rats were kept in metal cages in a fly-proof house and were adequately fed and given water ad libitum. Two experiments were carried out. In experiment I (chemotherapy), 30 adult albino rats were divided into six groups of five rats each, whereas in experiment II (chemoprophylaxis), 25 adult albino rats were divided into five groups of five rats each. In both experiments, groups I and II were uninfected control and infected untreated control, respectively. In experiment I, rats in groups III and V were each infected with 5.0?×?10⁵ trypanosomes and were later treated with 0.5 mg/kg of Kelamidium® (low-dose treatment), and rats in groups IV and VI were infected with 5.0?×?10⁵ trypanosomes and treated with 1.0 mg/kg of Kelamidium® (high-dose treatment). Treatment was given to rats in groups III and IV at day 7 postinfection (PI; early treatment), whereas groups V and VI were treated at day 10 PI (late treatment). In experiment II, rats in groups III, IV, and V were each treated with 2.0 mg/kg of Kelamidium® at day 0 and were later infected at days 14, 28, and 42 PI, respectively, with 5.0?×?10⁵ trypanosomes. Parasites were detectable in the blood of the infected rats in all the infected groups in experiment I and in group II in experiment II, 4–7 days PI. Parasitemia, however, was not recorded in the remaining groups in experiment II. The drug cleared the parasites from the blood of the infected rats in experiment I, 2–7 days posttreatment (PT). Relapse of infection, however, occurred in all the infected treated groups. It was thus concluded that Kelamidium® may be more useful as a prophylactic agent than as a chemotherapeutic agent in the management of animal trypanosomosis.     

Novel fiber-based pure chitosan scaffold for tendon augmentation: biomechanical and cell biological evaluation

One possibility to improve the mechanical properties after tendon ruptures is augmentation with a scaffold. Based on wet spinning technology, chitosan fibres were processed to a novel pure high-grade multifilament yarn with reproducible quality. The fibres were braided to obtain a 3D tendon scaffold. The CS fibres and scaffolds were evaluated biomechanically and compared to human supraspinatus (SSP) tendons. For the cytobiological characterization, in vitro cell culture experiments with human mesenchymal stem cells (hMSC) were performed. Three types of 3D circular braided scaffolds were fabricated. Significantly, higher ultimate stress values were measured for scaffold with larger filament yarn, compared to scaffold with smaller filament yarn. During cultivation over 28 days, the cells showed in dependence of isolation method and/or donor a doubling or tripling of the cell number or even a six-fold increase on the CS scaffold, which was comparable to the control (polystyrene) or in the case of cells obtained from human biceps tendon even higher proliferation rates. After 14 days, the scaffold surface was covered homogeneously with a cell layer. In summary, the present work demonstrates that braided chitosan scaffolds constitute a straightforward approach for designing tendon analogues, maintaining important flexibility in scaffold design and providing favourable mechanical properties of the resulting construct.     

Semi-interpenetrating network (sIPN) gelatin nanofiber scaffolds for oral mucosal drug delivery

The oral mucosa is a promising absorption site for drug administration because it is permeable, highly vascularized and allows for ease of administration. Nanofiber scaffolds for local or systemic drug delivery through the oral mucosa, however, have not been fully explored. In this work, we fabricated electrospun gelatin nanofiber scaffolds for oral mucosal drug delivery. To improve structural stability of the electrospun gelatin scaffolds and allow non-invasive incorporation of therapeutics into the scaffold, we employed photo-reactive polyethylene glycol diacrylate (PEG-DA575, 575 gmol^?1) as a cross-linker to stabilize the scaffold by forming semi-interpenetrating network gelatin nanofiber scaffolds (sIPN NSs), during which cross-linker concentration was varied (1×, 2×, 4× and 8×). The results showed that electrospun gelatin nanofiber scaffolds after being cross-linked with PEG-DA575 (i.e. sIPN NS1×, 2×, 4× and 8×) retained fiber morphology and possessed improved structural stability. A series of structural parameters and properties of the cross-linked electrospun gelatin scaffolds were systematically characterized in terms of morphology, fiber diameter, mechanical properties, porosity, swelling and degradation. Mucin absorption onto sIPN NS4× was also confirmed, indicating this scaffold possessed greatest mucoadhesion properties among those tested. Slow release of nystatin, an anti-fungal reagent, from the sIPN gelatin nanofiber scaffold was demonstrated.     

Beneficial effect of aligned nanofiber scaffolds with electrical conductivity for the directional guide of cells

Abstract

Conducting polymer-based scaffolds receive biological and electrical signals from the extracellular matrix (ECM) or peripheral cells, thereby promoting cell growth and differentiation. Chitin, a natural polymer, is widely used as a scaffold because it is biocompatible, biodegradable, and nontoxic. In this study, we used an electrospinning technique to fabricate conductive scaffolds from aligned chitin/polyaniline (Chi/PANi) nanofibers for the directional guidance of cells. Pure chitin and random and aligned Chi/PANi nanofiber scaffolds were characterized using field emission scanning electron microscope (FE-SEM) and by assessing wettability, mechanical properties, and electrical conductivity. The diameters of aligned Chi/PANi nanofibers were confirmed to be smaller than those of pure chitin and random nanofibers owing to electrostatic forces and stretching produced by rotational forces of the drum collector. The electrical conductivity of aligned Chi/PANi nanofiber scaffolds was ~91% higher than that of random nanofibers. We also studied the viability of human dermal fibroblasts (HDFs) cultured on Chi/PANi nanofiber scaffolds in vitro using a CCK-8 assay, and found that cell viability on the aligned Chi/PANi nanofiber scaffolds was ~2.1-fold higher than that on random Chi/PANi nanofiber scaffolds after 7 days of culture. Moreover, cells on aligned nanofiber scaffolds spread in the direction of the aligned nanofibers (bipolar), whereas cells on the random nanofibers showed no spreading (6 h of culture) or multipolar patterns (7 days of culture). These results suggest that aligned Chi/PANi nanofiber scaffolds with conductivity exert effects that could improve survival and proliferation of cells with directionality.     

Exploration of the wound healing effect of topical administration of nicotine in combination with collagen scaffold in a rabbit model

Nicotine has been reported to prolong the wound healing; however, we showed that the topical application of 10^?4 M nicotine promoted murine wound healing. The objective of this study was to explore the wound healing effects of nicotine in combination with collagen scaffold using skin defects in rabbit. Three full-thickness skin defects 8 mm in diameter were made on the rabbit auricle. Artificial dermis was applied to the defects, and 10 μl of nicotine solution (10^?5, 10^?4, and10^?3 M), bFGF solution (0.5 μg/10 μl), and both bFGF and 10^?4 M nicotine solutions were injected into the artificial dermis once daily for 7 days. Rabbits were sacrificed on day 10, 15, or 20, and the wound healing process was evaluated. bFGF was superior in the formation of the dermis-like tissue and capillaries. In nicotine groups, the epithelial length and the dermis-like tissue formations in the 10^?4 M group were superior, in contrast, those were inhibited in the 10^?3 M group. The synergistic effect of bFGF and 10^?4 M nicotine was not confirmed. This study suggests that the topical application of 10^?4 M nicotine promoted wound healing in rabbit, but the effect was not apparent compared with murine models.     

Porous polycaprolactone scaffold for cardiac tissue engineering fabricated by selective laser sintering

An advanced manufacturing technique, selective laser sintering (SLS), was utilized to fabricate a porous polycaprolactone (PCL) scaffold designed with an automated algorithm in a parametric library system named the “computer-aided system for tissue scaffolds” (CASTS). Tensile stiffness of the sintered PCL strut was in the range of 0.43 ± 0.15 MPa when a laser power of 3 W and scanning speed of 150 in s^?1 was used. A series of compressive mechanical characterizations was performed on the parametric scaffold design and an empirical formula was presented to predict the compressive stiffness of the scaffold as a function of total porosity. In this work, the porosity of the scaffold was selected to be 85%, with micropores (40–100 μm) throughout the scaffold. The compressive stiffness of the scaffold was 345 kPa. The feasibility of using the scaffold for cardiac tissue engineering was investigated by culturing C2C12 myoblast cells in vitro for 21 days. Fluorescence images showed cells were located throughout the scaffold. High density of cells at 1.2 × 10⁶ cells ml^?1 was recorded after 4 days of culture. Fusion and differentiation of C2C12 were observed as early as 6 days in vitro and was confirmed with myosin heavy chain immunostaining after 11 days of cell culture. A steady population of cells was then maintained throughout 21 days of culturing. This work demonstrated the feasibility of tailoring the mechanical property of the scaffold for soft tissue engineering using CASTS and SLS. The macroarchitecture of the scaffold can be modified efficiently to fabricate scaffolds with different macropore sizes or changing the elemental cell design in CASTS. Further process and design optimization could be carried out in the future to fabricate scaffolds that match the tensile strength of native myocardium, which is of the order of tens of kPa.