In this paper, we prepared composite fibers via electrospinning from either W/O or O/W emulsion. SEM images demonstrate the beads-in-string structures in these fibers and proved this technique to be an effective method for microencapsulation. As a practical application, Ca-alginate microspheres, which serve as reservoirs for hydrophilic drugs, were prepared in a reverse emulsion and then incorporated into poly (l-lactic acid) (PLLA) fibers by electrospinning. With the bovine serum albumin (BSA) loaded into the microspheres, the beads-in-string structure thus entrapped hydrophilic proteins in hydrophobic polymeric matrix. In the in vitro release test, BSA, which was released from composite fibers, achieved prolonged release profiles and lower burst release rates than those from naked Ca-alginate microspheres. In comparison with other well-established techniques to prepare microcapsules, such as solvent evaporation and spray-drying techniques, emulsion electrospinning features partly competing, partly complementary characteristics. Extension to other emulsion systems will be able to fabricate new types of functional structures.

The biomedical applications of aniline oligomers and their derivatives have attracted increasing interest due to their electroactive and biodegradable properties. However, no reports have systematically examined the toxicity of these electroactive materials, which has severely hindered their biomedical applications. In this work, the cellular responses of aniline oligomers including aniline dimer, trimer and tetramer to mouse embryo fibroblast (NIH-3T3) cells and adenocarcinomic human alveolar basal epithelial (A549) cells were determined and compared for the first time. Our results demonstrated that the aniline trimer showed the highest cytotoxicity to both types of cells. Compared with the NIH-3T3 cells, aniline oligomers exhibited the least cytotoxicity to A549 cells. Taken together, we demonstrate that both the properties of aniline oligomers and cell types could influence the cellular responses of aniline oligomers. As the first report focused on the cytotoxicity of aniline oligomers, this work provides some fundamental and important information about the cytotoxicity of aniline oligomers, which should be valuable for their biomedical applications. † Electronic supplementary information (ESI) available: Detailed information about the MS spectra of aniline trimer and tetramer, cell morphology observation of aniline oligomers to NIH-3T3 and A549 cells for 24 and 48 h were provided in supplementary information. See

Bone marrow mesenchymal stem cells (MSCs) have demonstrated their pluripotency to differentiate into different cell lineages and may be an alternative cell source for vascular tissue engineering. The objective of this study is to create small diameter vessels by seeding and culture of genetically modified MSCs onto a synthetic polymer scaffold produced by an electrospinning technique. A tubular scaffold (2 mm in diameter) with a microstructure of nonwoven fibers was produced by electrospinning of poly (propylene carbonate) (PPC). Rat MSCs obtained from bone marrow were expanded in culture and modified with vasculoprotective gene endothelial nitric oxide synthase (eNOS) or marker gene green fluorescent protein (GFP). These MSCs were seeded onto the electrospun fibrous grafts (internal diameter = 2 mm), and cultured in 5% CO(2) at 37 degrees C. The growth of MSCs in the scaffold was analyzed with scanning electron microscopy (SEM) and hematoxylin and eosin (H&E) staining. The gene transfer and transgenic gene expression were examined with fluorescence-activated cell sorting (FACS), immunochemical staining, reverse transcriptase-polymerase chain reaction (RT-PCR), and western blot. The production of nitric oxide (NO) by the engineered vessels was measured with an NO detection kit. Our data showed that the seeded cells integrated with the microfibers of the scaffold to form a three-dimensional cellular network, indicating a favorable interaction between this synthetic PPC scaffold with MSCs. High transduction efficiency was obtained with the use of concentrated retrovirus in the gene transfection of MSCs. The eNOS gene transcripts and protein were detected in the grafts seeded with eNOS-modified MSCs by RT-PCR and immunochemical staining. The amount of NO produced by grafts seeded with eNOS-modified MSCs was comparable to that produced by native blood vessels, and it was significantly higher than that in the grafts seeded with nonmodified MSCs. In summary, the vascular graft produced by culture of eNOS gene-modified MSCs onto the electrospun tubular scaffolds shows promising results in terms of function. The use of MSCs and therapeutic genes in tissue engineering of blood vessels could be helpful in improving vessel regeneration and patency.

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The objective of this study was to fabricate biomatrix/polymer hybrid heart valve leaflet scaffolds using an electrospinning technique and seeded by mesenchymal stem cells. Mesenchymal stem cells were obtained from rats. Porcine aortic heart valve leaflets were decellularized, coated with basic fibroblast growth factor/chitosan/poly-4-hydroxybutyrate using an electrospinning technique, reseeded, and cultured over a time period of 14 days. Controls were reseeded and cultured over an equivalent time period. Specimens were examined biochemically, histologically, and mechanically. Recellularization of the hybrid heart valve leaflet scaffolds was significantly improved compared to controls. Biochemical and mechanical analysis revealed a significant increase of cell mass, 4-hydroxyproline, collagen, and strength in the hybrid heart valve leaflets compared to controls. This is the first attempt in tissue-engineered heart valves to fabricate hybrid heart valve leaflets using mesenchymal stem cells combined with a slow release technique and an electrospinning technique.

The delivery of local chemotherapy using polymeric implants is a promising anti-glioma strategy, but a high drug loading rate can lead to a problematic initial burst of drug and subsequent neurotoxicity. In this study, we designed and fabricated a biodegradable implant for the local delivery of combined paclitaxel and temozolomide (TMZ) with low drug loading rates. Paclitaxel-loaded Ca-alginate microparticles were formed using an emulsifying-solvent evaporation process. Polypropylene carbonate and different weights of TMZ were then added to the emulsion. An electrospinning process was used to form fibers that consisted of a beads-in-string structure. Using this approach, we achieved with the TMZ + paclitaxel fibers a paclitaxel loading rate of 2.1%, with a reduced initial burst of drug and prolonged release time compared to the paclitaxel-loaded microparticles alone. The TMZ loading rates of fibers with TMZ:paclitaxel ratios of 1:2, 1:1, or 2:1 (by manufacturing weight) were 1.2, 2.3, and 4.1%, respectively. A cytotoxicity assay suggested that glioma C6 cells were more sensitive to the TMZ + paclitaxel fibers compared to either agent alone. Cytotoxicity assay also showed that optimal synergistic effect was achieved when the weight ratio of the two drugs was 1:1.

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