Nonwoven Polyethylene Terephthalate Research Articles

Gene Expression Analysis Using a High‐Resolution DNA Microarray of Peripheral Whole Blood Immediately Before and After Leukocytapheresis for Rheumatoid Arthritis

Leukocytapheresis (LCAP) is a safe, unique therapy pertaining to intractable rheumatoid arthritis (RA) even in cases of drug allergy or infectious states. To investigate how to represent LCAP efficacy, we have conducted gene expression analyses from the peripheral blood of RA patients treated with non-woven polyethylene terephthalate filters. Peripheral blood samples were collected immediately before and after treatment from eight RA patients who received LCAP. Among these patients, all of them achieved 20% improvement in the core set of the American College of Rheumatology (ACR20), and thus, they were confirmed as LCAP responders. Gene expression analysis was done with a high-resolution DNA microarray. The results of each of the two groups' gene expression values (immediately before and after LCAP) were calculated using Welch's t-test. Calculations were performed with a statistical software R.basic package: if the P-value was less than 0.05, this was seen as a significant change. In a comparison of 25,370 gene expressions, the number of genes showing a P-value < 0.05 in the upregulating group was 2110, and in the downregulating group it was 1864. The results of pathway analysis using the MetaCore program indicate that gene groups work for cytoskeletal remodeling are upregulated, and genes related to immune responses, such as antigens presenting via major histocompatibility complex class I and II, are downregulated just after LCAP. These findings may relate to LCAP efficacy for RA patients, but this needs further investigation.

Evaporation-induced, close-packed silica nanoparticle-embedded nonwoven composite separator membranes for high-voltage/high-rate lithium-ion batteries: Advantageous effect of highly percolated, electrolyte-philic microporous architecture

Abstract Evaporation-induced, close-packed silica (SiO 2 ) nanoparticle-embedded polyethylene terephthalate (PET) nonwoven composite separator membranes (hereinafter, referred to as “NW-separators”) are fabricated for application in high-voltage/high-rate lithium-ion batteries. The heat-resistant PET nonwoven is employed as a physical support to suppress thermal shrinkage of the NW-separator. A distinctive characteristic of the NW-separator is the well-connected interstitial voids formed between compactly packed SiO 2 nanoparticles adhered by polyvinylidene fluoride–hexafluoropropylene (PVdF–HFP) binders. This allows for the evolution of highly percolated, electrolyte-philic microporous architecture in the NW-separator. In comparison to a commercialized polyethylene (PE) separator, the NW-separator featuring the aforementioned structural uniqueness exhibits substantial improvements in porosity, air permeability, and electrolyte wettability, which contribute to the facile ionic transport and retarded growth of cell impedance during cycling. As a result, superior cell performance is obtained in the NW-separator. Notably, this advantageous effect of the NW-separator on cell performance becomes more pronounced at challenging charge/discharge conditions of high voltages (herein, 4.4 V) and high current densities.

Composition ratio-dependent structural evolution of SiO2/poly(vinylidene fluoride-hexafluoropropylene)-coated poly(ethylene terephthalate) nonwoven composite separators for lithium-ion batteries

We demonstrate a facile approach for the fabrication of new silica (SiO2) nanoparticles/polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP)-coated polyethylene terephthalate (PET) nonwoven composite separators for use in lithium-ion batteries. By varying the SiO2/PVdF-HFP composition ratio, we can fine-tune the porous structure of the composite separators. At a low SiO2/PVdF-HFP ratio, a nonporous structure featuring the PVdF-HFP matrix and SiO2 domains is obtained. By contrast, an unusual porous structure (i.e., highly-percolated interstitial voids formed between close-packed SiO2 nanoparticles) is developed at a high SiO2/PVdF-HFP ratio, where PVdF-HFP serves as a binder to interconnect SiO2 powders. This drastic change in the morphology of the composite separators is further confirmed by observing their air permeability and ionic conductivity. Meanwhile, a PET nonwoven is employed as a mechanical substrate to suppress thermal shrinkage of the composite separators. On the basis of morphological characterization, the effects of the composition ratio-dependent structural evolution of the composite separators on the electrochemical performance of cells are investigated. Notably, the composite separator fabricated from a composition ratio of SiO2/PVdF-HFP=90/10 (wt%/wt%) provides superior cell performance owing to a well-tailored microporous structure, as compared to a commercialized polyethylene (PE) separator.

Electrospun nanofibrous membranes for high flux microfiltration

Highly porous electrospun nanofibrous membranes have gained considerable interest in water filtration applications. To understand the effects of electrospun nanofibrous structures on the filtration performance, a series of nanofibrous membranes with different fiber diameters, diameter distributions and membrane thicknesses were prepared and studied. The results indicate a strong correlation between the physical parameters of the membrane and the filtration performance. For example, a thicker membrane with a smaller average fiber diameter greatly favors the formation of a smaller pore size and narrower pore size distribution, although the influence of the membrane thickness is relatively limited. Based on successful control of the total composite structure (electrospun polyacrylonitrile (PAN)/non-woven polyethylene terephthalate (PET)) containing the electrospun layer thickness of 200 ± 10 μm and a mean fiber diameter of 100 ± 20 nm, a high flux microfiltration (MF) membrane with a maximum pore size of 0.62 ± 0.03 μm and a mean pore size of 0.22 ± 0.01 μm was obtained. The PAN/PET nanofibrous MF membranes performed significantly better than the commercial MF membrane of the same mean pore size (0.22 μm), with two to three times higher flux (∼1.5 L/m 2 h). The nanofibrous MF filter could maintain a very high rejection ratio of micro-particle and bacteria (LRV = 6). The results suggest that electrospun nanofibrous membranes are excellent materials for high-flux MF applications.

Adsorption of surfactin produced from Bacillus subtilis using nonwoven PET (polyethylene terephthalate) fibrous membranes functionalized with chitosan

This article deals with an alternative method for bio-separation of surfactin produced by Bacillus subtilis using sorption method on nonwoven PET (polyethylene terephthalate) fibrous membranes functionalized with chitosan. In the first part of the study, surface functionalization of the PET nonwoven fibrous membranes is carried out with aqueous 65% deacetylated chitosan solution with or without a prior surface activation using air-atmospheric plasma treatment. Very small modification of the PET fibrous nonwoven air-permeability confirms the functionalization of PET fibre surface with little reduction of membrane porosity. The functionalized membranes are then characterized by physico-chemical methods: X-ray Photoelectron Spectroscopy (XPS), Wettability and zeta potential. Chitosan increases drastically the zeta potential of PET at all pH values though a prior plasma treatment of the PET membrane reduces slightly the increase in zeta potential values. Sorption of surfactin quantified by HPLC shows that the extent of surfactin sorption on PET nonwovens depends on the surface functionalization method. Surface functionalization with chitosan results in immediate sorption of the entire quantity of surfactin. A prior surface activation by air atmospheric plasma treatment of the PET membranes before chitosan application retards the sorption of entire surfactin which takes place after 1.5 h, only. Increased zeta potential and increased hydrophobic behavior in the presence of chitosan without plasma activation would explain the interesting surfactin sorption results.

Particle size-dependent, tunable porous structure of a SiO2/poly(vinylidene fluoride-hexafluoropropylene)-coated poly(ethylene terephthalate) nonwoven composite separator for a lithium-ion battery

We demonstrate a new silica (SiO2) nanoparticle/polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP)-coated polyethylene terephthalate (PET) nonwoven composite separator for a lithium-ion battery as a promising alternative to a commercialized polyethylene (PE) separator. A distinctive feature of the nonwoven composite separator is its porous structure, i.e. well-connected interstitial voids formed between close-packed SiO2 nanoparticles interconnected by PVdF-HFP binders. More notably, this unusual porous structure of the nonwoven composite separator can be tuned by controlling the SiO2 particle size (herein, 40 nm and 530 nm SiO2 powders are exploited). Such morphological variation of the nonwoven composite separator has a crucial influence on separator properties such as porosity, electrolyte wettability, and ionic conductivity. The PET nonwoven is employed as a physical support to prevent thermal shrinkage of the nonwoven composite separator. Based on this understanding of the separator characteristics, the effects of the SiO2 particle size-dependent, tunable porous structure of nonwoven composite separators on the electrochemical performance of cells are investigated. In comparison to a nonwoven composite separator containing 530 nm SiO2 particles as well as the conventional PE separator, the nonwoven composite separator incorporating 40 nm SiO2 particles provides superior cell performance owing to facile ion transport and retarded growth of cell impedance during cycling.

High-throughput 3-D cell-based proliferation and cytotoxicity assays for drug screening and bioprocess development

We have designed, built and tested a three-dimensional (3-D) cell culture system on modified microplates for high-throughput, real-time, proliferation and cytotoxicity assays. In this 3-D culture system, cells expressing the enhanced green fluorescent protein (EGFP) were cultured in nonwoven polyethylene terephthalate (PET) fibrous scaffolds. Compared to 2-D cultures in conventional microplates, 3-D cultures gave more than 10-fold higher fluorescence signals with significantly increased signal-to-noise ratio (SNR), thus extending the application of conventional fluorescence microplate readers for online monitoring of culture fluorescence. The 3-D system was successfully used to demonstrate the effects of fetal bovine serum, fibronectin coating of PET fibers, and cytotoxicity of dexamethasone on recombinant murine embryonic stem D3 cells. The dosage effects of 5-fluorouracil and gemcitabine on high-density colon cancer HT-29 cells were also tested. These studies demonstrated that the 3-D culture microplate system with EGFP expressing cells can be used as a high-throughput system in drug discovery and bioprocess development.

Effect of Sterilization on Non‐woven Polyethylene Terephthalate Fiber Structures for Vascular Grafts

Non-woven polyethylene terephthalate (PET) fibers produced via melt blowing and compounded into a 6 mm diameter 3D tubular scaffold were developed with artery matching mechanical properties. This work compares the effects of ethylene oxide (EtO) and low temperature plasma (LTP) sterilization on PET surface chemistry and biocompatibility. As seen through X-ray photoelectron spectroscopy (XPS) analysis, LTP sterilization led to an increase in overall oxygen content and the creation of new hydroxyl groups. EtO sterilization induced alkylation of the PET polymer. The in vitro cytotoxicity showed similar fibroblastic viability on LTP- and EtO-treated PET fibers. However, TNF-α release levels, indicative of macrophage activation, were significantly higher when macrophages were incubated on EtO-treated PET fibers. Subcutaneous mice implantation revealed an inflammatory response with foreign body reaction to PET grafts independent of the sterilization procedure.

Modeling Tissue Growth Within Nonwoven Scaffolds Pores

In this study we present a novel approach for predicting tissue growth within the pores of fibrous tissue engineering scaffolds. Thin nonwoven polyethylene terephthalate scaffolds were prepared to characterize tissue growth within scaffold pores, by mouse NR6 fibroblast cells. On the basis of measurements of tissue lengths at fiber crossovers and along fiber segments, mathematical models were determined during the proliferative phase of cell growth. Tissue growth at fiber crossovers decreased with increasing interfiber angle, with exponential relationships determined on day 6 and 10 of culture. Analysis of tissue growth along fiber segments determined two growth profiles, one with enhanced growth as a result of increased tissue lengths near the fiber crossover, achieved in the latter stage of culture. Derived mathematical models were used in the development of a software program to visualize predicted tissue growth within a pore. This study identifies key pore parameters that contribute toward tissue growth, and suggests models for predicting this growth, based on fibroblast cells. Such models may be used in aiding scaffold design, for optimum pore infiltration during the tissue engineering process.

Preparation and characterization of NaOH treated micro-fibrous polyethylene terephthalate nonwovens for biomedical application

Recently, micro-fibrous polyethylene terephthalate nonwovens have been investigated and applied in many biotechnological and biomedical applications. NaOH treatment has been used as a simple and cost effective method to alter surface properties, in order to overcome their surface inertness. However, the effects of this treatment on the matrices mechanical and physical properties; particularly, those composed of fibers with small diameter (<20 μm); have been poorly investigated. This study investigates the variations, imposed by the NaOH treatment, in the physical and tensile properties of micro-fibrous polyethylene terephthalate mats. Polyethylene terephthalate webs with two different average fiber diameters of 6±2.5 and 10±4 μm were produced by melt blowing process. A number of these webs were consolidated to prepare fibrous matrices using a thermal treatment. The matrices were treated using NaOH 1 N at 65 °C for various durations (ranging from 20 min to 24 h). In addition to their physical properties such as weight loss, thickness, porosity, shrinkage and surface density; their morphology and tensile properties were also evaluated using scanning electron microscopy and micromechanical tester, respectively. In general, by increasing treatment duration, weight loss, porosity, and shrinkage increased, while thickness and density decreased. As a result of treatment duration, pores appeared on the surface of individual fibers, and tensile stress and Young’s modulus decreased while tensile strain increased. Mats with different fiber diameters showed different physical and mechanical properties. These findings suggested that the structure of the matrices and the properties required for its end use, for biomedical applications including scaffolding materials for tissue engineering, should be considered in selecting NaOH treatment condition.

A novel poly(vinylidene fluoride-hexafluoropropylene)/poly(ethylene terephthalate) composite nonwoven separator with phase inversion-controlled microporous structure for a lithium-ion battery

We demonstrate a novel and facile approach to fabrication of a new composite nonwoven separator for a lithium-ion battery, which comprises a phase inversion-controlled, microporous polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) gel polymer electrolyte and a polyethylene terephthalate (PET) nonwoven support. The thermally stable PET nonwoven is chosen as a mechanical support and contributes to improving the thermal shrinkage of the composite nonwoven separator. The microporous PVdF-HFP gel polymer electrolyte serves as a pore size controller for the composite nonwoven separator. In order to provide a theoretical basis for this approach, an investigation of the phase diagram for coating solutions consisting of PVdF-HFP, solvent (acetone), and nonsolvent (water) is preceded. Based on this understanding of the phase behavior, the effects of phase inversion, more specifically, the water content in the coating solutions, on the morphology evolution of the composite nonwoven separators are identified. The phase inversion-governed microporous structures of the composite nonwoven separators play a crucial role in determining electrochemical performances of cells. The composite nonwoven separator is expected to be a promising alternative to a commercialized polyethylene (PE) separator, particularly in next-generation lithium-ion batteries necessitating superior battery safety and performance.

Benzalkonium Chloride Sterilization of Nonwoven Fibrous Scaffolds for Astrocyte Culture

Tissue engineering is an emerging field in biomedicine, holding enormous promise for regenerative medicine. Scaffolds, within which cells proliferate, are a controlling factor in tissue engineering applications. Upon fabrication, tissue scaffolds must undergo appropriate sterilization to eliminate contaminants. Current sterilization methods are either costly, time consuming, or ineffective. In this study, a quaternary salt, benzalkonium chloride (BAC), was used as a chemical agent for sterilization of nonwoven polyethylene terephthalate (PET) fibers and polylactic acid nanofibers. Treating the PET scaffolds with 0.1% (w/v) BAC for only 2 minutes was effective to eliminate bacterial contaminants in the fibrous matrices. In addition, astrocyte cells were successfully cultured in the PET scaffolds following BAC sterilization, demonstrating the suitability of BAC as a sterilization agent. This chemical sterilization method is also mild and nonabrasive to nanostructured materials such as electrospun polylactic acid nanofibers.

Functionalization of Textile Materials by Plasma Enhanced Modification

Textile materials are increasingly used in various industries. In these applications, the surfaces of textile materials play a key role, because a range of performance properties depends on surface characteristics. As with many other types of materials, the surface properties of textiles can be readily altered by the treatment of the materials with gas plasma, without impairment of their bulk mechanical properties. This article presents examples of new approaches to functionalization of textiles using plasma-enhanced modifications. Examples are given of the work on polyethylene terephthalate (PET) nonwoven materials. Micrographs, obtained by scanning probe microscopy (SPM) and environmental scanning electron microscopy (ESEM) are presented to demonstrate changes in the surface topography, surface chemistry, and surface wettability of PET nonwovens. The great potential for significant improvements in the properties of textiles by plasma-enhanced modification is highly promising.

Effects of mixing intensity on cell seeding and proliferation in three‐dimensional fibrous matrices

Nonwoven fibrous matrices have been widely used in cell and tissue cultures because their three-dimensional (3-D) structures with large surface areas and pore spaces can support high-density cell growth. Although cell adherence and growth on 2-D surfaces have been thoroughly investigated, very little is known for cells cultured in 3-D matrices. The effects of mixing intensity on cell seeding, adherence, and growth in fibrous matrices were thus investigated. Chinese Hamster Ovary and osteosarcoma cells were inoculated into nonwoven polyethylene terephthalate matrices by dynamic and static seeding methods, of which the former was found to be superior in seeding efficiency and cell distribution in the matrices. Dynamic seeding increased seeding efficiency from approximately 40% to more than 90%. When higher mixing intensities were applied, both cell attachment and detachment rates increased. Cell attachment was transport limited, as indicated by the increased attachment rate with increasing the mass transfer coefficient of the cells. Meanwhile, cell detachment from the 3-D matrix can be described by the Bell model. The effects of matrix pore size on cell adherence and proliferation were also investigated. In general, the smaller pore size is favorable to cell attachment and proliferation. Further analysis revealed that the interaction between mixing intensity and pore size played a vital role in hydrodynamic damage to cells, which was found to be significant when the Kolomogorov eddy size was smaller than the matrix pores. Increasing mixing intensity also increased oxygen transfer, decreased the lactate yield from glucose, and improved cell growth.

Functional finishing of nonwoven fabrics. I. Accessibility of surface modified PET spunbond by atmospheric pressure He/O2 plasma treatment

AbstractThe surface of a polyethylene terephthalate (PET) spunbond nonwoven was modified by using atmospheric pressure He/O2 plasma treatment. Accessibility of the modified PET nonwoven has been investigated in terms of crystallinity, surface chemical composition, hydrophilicity, and dye uptake. Differential scanning calorimetry (DSC) for crystallinity measurement and X‐ray photoelectron spectroscopy (XPS) for chemical composition measurement were used. Surface morphology was studied by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Percentage crystallinity increased due to the depletion of amorphous region by plasma etching. Redeposition of etched particles was observed. Oxygen‐based functional groups on the surface of PET increase from 27 to about 32% after 90 s exposure. Wettability increases by more than 10 times and moisture regain increases by three times, compared with the untreated sample. Dye uptake was not changed significantly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4306–4310, 2006

Development of a 3D Perfusion Bioreactor System for Continuous Production of Hematopoietic and Blood Cells.

The recipient of expanded hematopoietic cells, especially cord cells, could benefit from both self-renewing and differentiated cells, to enhance the speed and durability of engraftment. For this and other clinical and laboratory purposes, we developed a modular perfusion bioreactor system using a 3D scaffold for cell growth. The polycarbonate bioreactor body design allows media to flow over and under but not through disks of nonwoven polyethylene terephthalate (PET) fabric scaffold, and allows nonadherent progeny to fall from the matrix into the flow path. Gas-permeable membranes over and under the media path allow gas exchange. We developed several media supply and cell collection methods, including recirculating (R) and single pass (SP) modes. A modified recirculating mode (MR), in which the external gas exchanger and cell settler used in the recirculating mode were eliminated, also was tested, with or without a fluid reservoir in the flow loop. We tested the system using light density marrow cells or cd34 positively selected marrow or cord cells seeded directly or on preestablished marrow stromal cells (MSCs) or the HS-5 cell line, during runs lasting over 60 days. We analyzed nonadherent cells and cell-matrix constructs using flow cytometry; bright field, phase, confocal, and scanning electron microscopy of cytospins, the constructs themselves, and constructs embedded in wax and sectioned, using conventional and immunofluorescent staining; and clonogenic assays for committed hematopoietic cells. Harvested nonadherent cell output increased with experience with the developing bioreactor system, reaching up to 100x the number put into the device, with CD34+ % ranging from 0.3 to 14.3.Selected experimental results, in chronologic order. All counts are per bioreactor module.ExptMethodNonfeeder Cells In x106Total Nonadherent Cells Out x106 over (days)Viability (%)CD34+ %CD34+ lineage-%1Marrow CD34+ on MSC, R0.98.7(68)3.8 to 960.8 to 12Marrow CD34+ on MSC, SP0.91(54)38 to 930.240.22Same,R0.97.1(55)70 to 980.5–7.40.1 to 1.73Marrow CD34+ on MSC, R0.568(68)55 to 990.4–3.40.2 to 2.44Marrow CD34+ on MSC, MR0.513(68)14 to 940.4 to 3.2.3 to 1.45Marrow light density, MR+2351(38)78 to 1001.6 to 2.6.3 to 2.36Cord CD34 + on MSC, MR0.921(60)68 to 950.3 to 14.37Cord CD34 + on HS-5, MR0.930(59)4 to 68Seventy to 100 % of cells collected were CD45+, CD14+ 20–48%, CD41 0.5–9%, CD19+ 0–2.6%, and CD3+ 0–1.6%. Confocal and SEM studies of the cell-matrix constructs demonstrated extracellular matrix deposits containing collagen, predominately types I and II, and fibronectin. This was most concentrated over the surfaces of the cell-matrix constructs, possible due to oxygenation gradients. CFU-GM were identified in the output for up to 65 days. This modular 3D perfusion bioreactor allows continued hematopoiesis over 60 days, with evidence of maintenance of early progenitors (by continued CFU-GM and CD34+ cell output) during that time. It may be an ideal device for studies of normal and perturbed hematopoiesis and for clinical use.

Surface engineering of electrospun polyethylene terephthalate (PET) nanofibers towards development of a new material for blood vessel engineering

Non-woven polyethylene terephthalate nanofiber mats (PET NFM) were prepared by electrospinning technology and were surface modified to mimic the fibrous proteins in native extracellular matrix towards constructing a biocompatible surface for endothelial cells (ECs). The electrospun PET NFM was first treated in formaldehyde to yield hydroxyl groups on the surface, followed by the grafting polymerization of methacrylic acid (MAA) initiated by Ce(IV). Finally, the PMAA-grafted PET NFM was grafted with gelatin using water-soluble carbodiimide as coupling agent. Plane PET film was also surface modified and characterized for basic understanding of the surface modification process. The grafting of PMAA and gelatin on PET surface was confirmed by XPS spectroscopy and quantitatively analyzed by colorimetric methods. ECs were cultured on the original and gelatin-modified PET NFM and the cell morphology, proliferation and viability were studied. Three characteristic surface makers expressed by ECs were studied using immuno-florescent microscopy. The gelatin grafting method can obviously improve the spreading and proliferation of the ECs on the PET NFM, and moreover, can preserve the EC's phenotype.

Effect of the fiber diameter and porosity of non-woven PET fabrics on the osteogenic differentiation of mesenchymal stem cells

The proliferation and osteogenic differentiation of mesenchymal stem cells (MSCs) was investigated in three-dimensional non-woven fabrics prepared from polyethylene terephthalate (PET) fiber with different diameters. When seeded into the fabrics of cell scaffold, more MSC attached in the fabric of thicker PET fibers than that of thinner ones, irrespective of the fabric porosity. The morphology of cells attached became more spreaded with an increase in the fiber diameter of fabrics. The rate of MSC proliferation depended on the PET fiber diameter and porosity of fabrics: the bigger the fiber diameter of fabrics with higher porosity, the higher their proliferation rate. When the alkaline phosphatase (ALP) activity and osteocalcin content of MSC cultured in different types of fabrics was measured to evaluate the ostegenic differentiation, they became maximum for the non-woven fabrics with a fiber diameter of 9.0 μm, although the values of low-porous fabrics were significantly high compared with those of high porous fabrics. We concluded that the attachment, proliferation and bone differentiation of MSC was influenced by the fiber diameter and porosity of non-woven fabrics as the scaffold.

Stem cell collection filter system for human placental/umbilical cord blood processing.

The hydroxyethyl starch method and the Top & Bottom method have been used worldwide for the volume reduction of human placental/umbilical cord blood (PCB) units. To simplify the preparation of nucleated cell (NC) concentrates, we developed a new filter device--the stem cell collection filter system (SCF SYSTEM)--which can collect mononuclear cells (MNC) at a high recovery rate. The SCF SYSTEM consisted of a filter and two bags. Multilayered polyethylene terephthalate non-wovens, coated with a hydrophilic polymer, were used as filter media. PCB units were filtered by gravity (n = 12). Red blood cells, platelets and plasma were drained into the drain bag, and the NC trapped on the filter media was collected in the recovery bag by reverse washing. Recovered cell fractions were evaluated. The volume of cell concentrate recovered was 27.4 +/- 2.2 ml (mean +/- SD, n = 12). The whole time required for processing was less than 30 min, and handling was very simple. The viability of recovered NC was 97.8 +/- 3.2%. The recovery of lymphocytes, monocytes and granulocytes was 79.5 +/- 16.9%, 79.8 +/- 20.4% and 39.0 +/- 19.5%, respectively. The recovery rate of granulocytes was significantly lower than that of monocytes and lymphocytes (P < or = 0.0001). The recovery rates of CD3+ cells, CD19+ cells and CD56+ cells were almost the same as that of MNC. The recovery rates of CD34+ cells, total colony-forming cells and long-term culture-initiating cells were 81.7 +/- 27.0% (n = 11), 80.8 +/- 27.7% (n = 12) and 75.0 +/- 18.4% (n = 2), respectively. The new filter system was shown to be efficient for PCB processing, encompassing a very simple handling procedure with a good recovery of haematopoietic progenitor cells. Hence, the SCF SYSTEM is potentially useful for the volume reduction of PCB units for cord blood banking.

Thermal compression and characterization of three-dimensional nonwoven PET matrices as tissue engineering scaffolds

Nonwoven fibrous matrices have been widely used as scaffolds in tissue engineering, and modification of microstructure of these matrices is needed to organize cells in three-dimensional space with spatially balanced proliferation and differentiation required for functional tissue development. The method of thermal compression of nonwoven polyethylene terephthalate (PET) fabrics was developed and key parameters of temperature, pressure, and compression duration were evaluated in this study. The permanent deformation was obtained at elevated temperature under pressure and the viscoelastic compressional behaviors were observed, characterized by a distinct apparent modulus change in glass transition temperature region. A liquid extrusion method was further employed to analyze both pore size and its distribution for matrices with porosity ranging from 84 to 93%. It is also found that a more uniformly distributed pore size was resulted from thermal compression and the isotropic nature of nonwoven fabrics was preserved because of the proportional reduction of the pore by compression. The thermally compressed fabric matrices with two different pore sizes (15 and 20 μm in pore radius) were used to culture human trophoblast ED 27 and NIH 3T3 cells. It was found that cells cultured in the different pore-size PET matrices had different cell spatial organization and proliferation rates. The smaller pores in the matrix allowed cells to spread better and proliferate faster, while cells in the larger pores tended to form large aggregates and had lower proliferation rate. The thermal compression technique also can be applied to other synthetic fibrous matrices including biodegradable polymers used in tissue engineering to modify the microstructure according to their viscoelastic properties.