[Show abstract][Hide abstract] ABSTRACT: In the vascular prosthetic field, the prevailing thought is that for clinical, long-term success, especially
bioresorbable grafts, cellular migration and penetration into the prosthetic structure is required to promote
neointima formation and vascular wall development. In this study, we fabricated poly (l-lactic
acid-co-�-caprolactone) P(LLA-CL)/silk fibroin (SF) vascular scaffolds through electrospinning using both
perforated mandrel subjected to various intraluminal air pressures (0–300 kPa), and solid mandrel. The
scaffolds were evaluated the cellular infiltration in vitro and mechanical properties. Vascular scaffolds
were seeded with smooth muscle cells (SMCs) to evaluate cellular infiltration at 1, 7, and 14 days. The
results revealed that air-impedance scaffolds allowed significantly more cell infiltration as compared
to the scaffolds fabricated with solid mandrel. Meanwhile, results showed that both mandrel model and
applied air pressure determined the interfiber distance and the alignment of fibers in the enhanced porosity
regions of the structure which influenced cell infiltration. Uniaxial tensile testing indicated that the
air-impedance scaffolds have sufficient ultimate strength, suture retention strength, and burst pressure
as well as compliance approximating a native artery. In conclusion, the air-impedance scaffolds improved
cellular infiltration without compromising overall biomechanical properties. These results support the
scaffold’s potential for vascular grafting and in situ regeneration.
[Show abstract][Hide abstract] ABSTRACT: Capping techniques have been used as a treatment modality for the prevention of neuroma formation and the management of neuropathic pain. However, the results are inconsistent and unpredictable. We hypothesize that this situation may be attributable, in part, to the disparities in the type of materials used to manufacturing of the conduits.
[Show abstract][Hide abstract] ABSTRACT: An electrospun-aligned nanoyarn-reinforced nanofibrous scaffold (NRS) was developed for tendon tissue engineering to improve mechanical strength and cell infiltration. The novel scaffold composed of aligned nanoyarns and random nanofibers was fabricated via electrospinning using a two-collector system. The aim of the present study was to investigate three different types of electrospun scaffolds (random nanofibrous scaffold, aligned nanofibrous scaffold and NRS) based on silk fibroin (SF) and poly(l-lactide-co-caprolactone) blends. Morphological analysis demonstrated that the NRS composed of aligned nanoyarns and randomly distributed nanofibers formed a 3D microstructure with relatively large pore sizes and high porosity. Biocompatibility analysis revealed that bone marrow-derived mesenchymal stem cells exhibited a higher proliferation rate when cultured on the NRS compared with the other scaffolds. The mechanical testing results indicated that the tensile properties of the NRS were reinforced in the direction parallel to the nanoyarns and satisfied the mechanical requirements for tendon repair. In addition, cell infiltration was significantly enhanced on the NRS. In conclusion, with its improved porosity and appropriate mechanical properties, the developed NRS shows promise for tendon tissue engineering applications.
[Show abstract][Hide abstract] ABSTRACT: This paper presents a facile method for the fabrication of uniform hollow mesoporous silica nanoparticles (HMSNs) with tunable shell thickness and pore size. In this method, a series of amphiphilic block copolymers of polystyrene-b-poly (acrylic acid) (PS-b-PAA) with different hydrophobic block (PS) lengths were first synthesized via atom transfer radical polymerization (ATRP). The as-synthesized PS-b-PAA and cetyltrimethylammonium bromide (CTAB) were subsequently used as co-templates to fabricate HMSNs. This approach allows the control of shell thickness and pore size distribution of the synthesized HMSNs simply by changing the amounts of PS-b-PAA and CTAB, respectively. In vitro cytotoxicity and hemolysis assays demonstrated that the synthesized HMSNs had a low and shell thickness-dependent cytotoxicity and hemolytic activity. Therefore, these HMSNs have great potential for biomedical applications due to their good biocompatibility and ease of synthesis.
Dalton transactions (Cambridge, England : 2003). 06/2014;
[Show abstract][Hide abstract] ABSTRACT: Electrospinning has been widely used in fabrication of tissue engineering scaffolds. Currently, most of the electrospun nanofibers performed like a conventional two-dimensional (2D) membrane, which hindered their further applications. Moreover, the low production rate of the traditional needle-electrospinning (NE) also limited the commercialization. In this article, disc-electrospinning (DE) was utilized to fabricate a three-dimensional (3D) scaffold consisting of porous macro/nanoscale fibers. The morphology of the porous structure was investigated by scanning electron microscopy images, which showed irregular pores of nanoscale spreading on the surface of DE polycaprolactone (PCL) fibers. Protein adsorption assessment illustrated the porous structure could significantly enhance proteins pickup, which was 55% higher than that of solid fiber scaffolds. Fibroblasts were cultured on the scaffold. The results demonstrated that DE fiber scaffold could enhance initial cell attachment. In the 7 days of culture, fibroblasts grew faster on DE fiber scaffold in comparison with solid fiber, solvent cast (SC) film and TCP. Fibroblasts on DE fibers showed a stretched shape and integrated with the porous surface tightly. Cells were also found to migrate into the DE scaffold up to 800μm. Results supported the use of DE PCL fibers as a 3D tissue engineering scaffold in soft tissue regeneration.
Colloids and surfaces B: Biointerfaces 06/2014; · 4.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Poly(l-lactic acid-co-ε-caprolactone) (P(LLA-CL)) is a kind of copolymer polymerized from lactic acid and ε-caprolactone. Electrospun P(LLA-CL) nanofibers have good biocompatibility, biodegradability, and mechanical property. However, this type of nanofibers will produce acid groups during the degradation, so that, the pH value of the environment will decrease and result in tissue inflammation. On the other hand, Magnesium (Mg) alloy tissue engineering scaffolds will show alkaline during the degradation because of the electrochemical corrosion. Based on the principle of acid-based neutralization, combination of these two kinds of materials through electrospinning could keep the pH of the degradation environment neutral. In this paper, fabrication and characterization of Mg/P(LLA-CL)-blended nanofiber scaffolds with different ratios will be studied by scanning electron microscopy and universal materials testing machines to observe the morphology and mechanical properties of nanofibers, respectively. Furthermore, PIECs were cultured and seeded on the scaffolds for different time to evaluate the proliferation behavior on the scaffolds by MTT assay. The degradation tests of the samples lasted for three months in phosphate-buffered saline to evaluate the pH values of degradation solutions and the weight loss of nanofibers during degradation. The results showed that the mechanical property and biocompatibility of Mg/P(LLA-CL)-blended nanofibers were worse than that of pure P(LLA-CL). Moreover, the addition of Mg in the nanofibers accelerated the weight loss of the Mg/P(LLA-CL) blending fibers and increased the pH values of the environment during degradation of Mg/P(LLA-CL)-blended nanofibers.
[Show abstract][Hide abstract] ABSTRACT: In the vascular prosthetic field, the prevailing thought is that for clinical, long-term success, especially bioresorbable grafts, cellular migration and penetration into the prosthetic structure is required to promote neointima formation and vascular wall development. In this study, we fabricated poly (l-lactic acid-co-ɛ-caprolactone) P(LLA-CL)/silk fibroin (SF) vascular scaffolds through electrospinning using both perforated mandrel subjected to various intraluminal air pressures (0-300kPa), and solid mandrel. The scaffolds were evaluated the cellular infiltration in vitro and mechanical properties. Vascular scaffolds were seeded with smooth muscle cells (SMCs) to evaluate cellular infiltration at 1, 7, and 14 days. The results revealed that air-impedance scaffolds allowed significantly more cell infiltration as compared to the scaffolds fabricated with solid mandrel. Meanwhile, results showed that both mandrel model and applied air pressure determined the interfiber distance and the alignment of fibers in the enhanced porosity regions of the structure which influenced cell infiltration. Uniaxial tensile testing indicated that the air-impedance scaffolds have sufficient ultimate strength, suture retention strength, and burst pressure as well as compliance approximating a native artery. In conclusion, the air-impedance scaffolds improved cellular infiltration without compromising overall biomechanical properties. These results support the scaffold's potential for vascular grafting and in situ regeneration.
[Show abstract][Hide abstract] ABSTRACT: A novel electrospun nanoyarn scaffold, aimed to improve cell infiltration and vascularization, as well as guide cell behaviors by its biomimetic structure, was fabricated for tissue engineering. Electrospun nanofibers were deposited and twisted into yarns in a water vortex before collecting on a rotating mandrel to form a nanoyarn scaffold. Field emission-scanning electronic microscope (FE-SEM) images revealed that the scaffold, composed of aligned nanoyarns (24 micro m) which were composed of a bundle of nanofibers, created a porous structure which may be conducive to cellular infiltration. Thus, we hypothesized that the biomimetic nanoyarn will have a positive influence on cell proliferation and morphology. Pig iliac endothelial cells (PIECs) and MC3T3-E1 pre-osteoblastic cells cultured on the nanoyarn scaffolds showed significantly higher proliferation rates than that on traditional electrospun nanofiber scaffolds. Histological analysis demonstrated that cells infiltrate throughout the nanoyarn scaffolds over a 10-day period, however, no cell infiltration was observed on the nanofiber scaffolds. Moreover, confocal microscopy images indicated that both PIECs and MC3T3-E1 pre-osteoblastic cells cultured on the nanoyarn scaffolds exhibit an extremely elongated morphology compared to the flattened morphology when cells were cultured on electrospun nanofiber scaffolds or tissue culture plates. Furthermore, complex capillary-like structures were observed when PIECs cultured on the nanoyarn scaffold for 7 days, indicating that the nanoyarns provide templates and topographical cues for the assembly of PIECs and the promotion of a capillary network in vitro. In conclusion, the positive cellular interactions on the nanoyarn scaffold demonstrate potential application for use in tissue engineering.
Journal of Biomedical Nanotechnology 04/2014; 10(4):603-14. · 7.58 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Osteochondral defects affect both the articular cartilage and the underlying subchondral bone, but poor osteochondral regeneration is still a daunting challenge. Although the tissue engineering technology provides a promising approach for osteochondral repair, an ideal biphasic scaffold is in high demand with regards to proper biomechanical strength. In this study, an oriented poly( L -lacticacid)- co -poly( ε -caprolactone) P(LLA-CL)/collagen type I(Col-I) nanofiber yarn mesh, fabricated by dynamic liquid electrospinning served as a skeleton for a freeze-dried Col-I/ Hhyaluronate (HA) chondral phase(SPONGE) to enhance the mechanical strength of the scaffold. In vitro results show that the Yarn Col-I/HA hybrid scaffold (Yarn-CH) can allow the cell infiltration like sponge scaffolds. Using porous beta-tricalcium phosphate (TCP) as the osseous phase, the Yarn-CH/TCP biphasic scaffold was then assembled by freeze drying. After combination of BMSCs, the biphasic complex was successfully used to repair the osteochondral defects in a rabbit model with greatly improved repairing scores and compressive modulus.
Journal of Biomedical Materials Research Part A 04/2014; · 2.83 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mechanical stimulation plays an important role in the development and remodeling of tendons. Tendon-derived stem cells (TDSCs) are an attractive cell source for tendon injury and tendon tissue engineering. However, these cells have not yet been fully explored for tendon tissue engineering application, and there is also lack of understanding to the effect of mechanical stimulation on the maturation of TDSCs-scaffold construct for tendon tissue engineering. In this study, we assessed the efficacy of TDSCs in a poly(L-lactide-co-ε-caprolactone)/collagen (P(LLA-CL)/Col) scaffold under mechanical stimulation for tendon tissue engineering both in vitro and in vivo, and evaluated the utility of the transplanted TDSCs-scaffold construct to promote rabbit patellar tendon defect regeneration. TDSCs displayed good proliferation and positive expressed tendon-related extracellular matrix (ECM) genes and proteins under mechanical stimulation in vitro. After implanting into the nude mice, the fluorescence imaging indicated that TDSCs had long-term survival, and the macroscopic evaluation, histology and immunohistochemistry examinations showed high-quality neo-tendon formation under mechanical stimulation in vivo. Furthermore, the histology, immunohistochemistry, collagen content assay and biomechanical testing data indicated that dynamically cultured TDSCs-scaffold construct could significantly contributed to tendon regeneration in a rabbit patellar tendon window defect model. TDSCs have significant potential to be used as seeded cells in the development of tissue-engineered tendons, which can be successfully fabricated through seeding of TDSCs in a P(LLA-CL)/Col scaffold followed by mechanical stimulation.
[Show abstract][Hide abstract] ABSTRACT: The metallic stents covered with heparin loaded poly(l-lactide-co-caprolactone) nanofibers via emulsion electrospinning have been fabricated as a novel covered stent. The morphology and inner-structure of core–shell nanofibers were respectively ion observed by scanning electron microscopy and transmission electron microscopy. The distribution of heparin aqueous solution and chemical component in nanofibers was separately determined by fluorescence microscopy and Fourier transform infrared spectrum. The results showed that the nanofibrous matrix successfully encapsulated with heparin would not rupture with the expansion of metallic stent, which could effectively separate the aneurysm dome with bloodstream in the rabbit model. The aneurysm was immediately obliterated after the stenting and angiogram at 14 days follow-up showed that the aneurysm was still obliterated. No obvious stenosis and intima hyperplasia in parent artery were found. Therefore, this work provides a promising approach to fabricate covered stent for aneurysm treatment.
[Show abstract][Hide abstract] ABSTRACT: Silk fibroin (SF) from Bombyx mori has many established excellent properties and has found various applications in the biomedical field. However, some abilities or capacities of SF still need improving to meet the need for using practically. Indeed, diverse SF-based composite biomaterials have been developed. Here we report the feasibility of fabricating pantothenic acid (vitamin B5, VB5)-reinforcing SF nanofibrous matrices for biomedical applications through green electrospinning. Results demonstrated the successful loading of d-pantothenic acid hemicalcium salt (VB5-hs) into resulting composite nanofibers. The introduction of VB5-hs did not alter the smooth ribbon-like morphology and the silk I structure of SF, but significantly decreased the mean width of SF fibers. SF conformation transformed into β-sheet from random coil when composite nanofibrous matrices were exposed to 75% (v/v) ethanol vapor. Furthermore, nanofibers still remained good morphology after being soaked in water environment for five days. Interestingly, as-prepared composite nanofibrous matrices supported a higher level of cell viability, especially in a long culture period and significantly assisted skin cells to survive under oxidative stress compared with pure SF nanofibrous matrices. These findings provide a basis for further extending the application of SF in the biomedical field, especially in the personal skin-care field.
[Show abstract][Hide abstract] ABSTRACT: Surface functionalization of mesoporous silica nanoparticles (MSNs) has been proposed as an efficient approach to enhance the biocompatibility and efficiency of MSN-based carrier systems. Herein, polyelectrolyte multilayers (PEMs) composed of poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) were coated onto the MSN surface via a layer-by-layer (LbL) technique, and doxorubicin hydrochloride (DOX) was loaded into the prepared PEM-MSNs, thus constructing potential pH-responsive carrier systems. Extensive studies were performed to evaluate their biocompatibility and efficiency, emphasizing the influences of the layer numbers on the release profiles, cytotoxicity and hemocompatibility. It is demonstrated that PEM layer thickness has an exponential relationship with the number of coated layers, and release profiles of nanoparticles were both pH- and layer thickness-dependent. PEM-MSNs exhibited a very low and layer thickness-dependent cytotoxicity against macrophage cells. They did not induce obvious hemolysis or cause significant platelet aggregation, but also did not activate any coagulation pathways. The cellular uptake of DOX-loaded PEM-MSNs in HeLa cells was remarkably larger than that in L929 cells, thus resulting in a desirable growth-inhibiting effect on cancer cells. DOX-loaded PEM-MSNs exhibited a slower and prolonged DOX accumulation in the nucleus than free DOX. In vivo biodistribution indicated that they induced a sustained drug concentration in blood plasma but lower drug accumulation in the major organs, especially in the heart, compared to free DOX. The histological results also revealed that DOX-loaded PEM-MSNs had lower systemic toxicity than free DOX. Therefore, LbL functionalization of MSNs provides the practical possibility for creating MSN-based carrier systems with low systemic toxicity and high efficiency.