In conclusion, we demonstrate a microfiltration isolation method that preserves the exosome structure, reduces contamination from higher abundant urinary proteins, and can be easily implemented into mass spectrometry analysis for biomarker discovery efforts or incorporation into routine clinical laboratory applications to yield higher sample throughput.

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SynopsisThe development of porous polysulfone hollow fibers and the spinning process used are discussed. An analysis is given of the spinning parameters which determine fiber mechanical properties and permeability. Hollow fibers were prepared which display high modulus and high tensile strength. These fibers can withstand hydraulic pressures of more than 1000 psi. They can thus serve as supports for dense, ultrathin membrane coatings, useful in high-pressure reverse osmosis and ultrafiltration processes.

SynopsisThe morphology of porous polysulfone hollow fibers which were spun by the dry-wet spinning process is discussed. It was demonstrated that a relatively moderate quenching medium should be employed in the bore of the nascent fiber in order to produce an isotropic fiber free of macrovoids and intrusion cells. A rather delicate quantitative balance between the internal precipitant and the spinning solution has to be maintained, especially when low-viscosity polymeric solutions are employed. Scanning electron micrographs of fiber cross sections display highly porous, spongestructured walls which in some instances exhibit a rather dense interface skin. However, control of the extrusion/coagulation procedure allows the formation of skinned, porous skinned, and nonskinned fibers.

A novel scheme for the separation and live recovery of one cell type from a mixture of cells using a cell affinity chromatography (CAC) system is demonstrated. An anti-murine IgG was chemically immobilized to a cellophane support via a carbonyldiimidazole (CDI) link. Murine splenocytes flowed over the support, and B-cells were allowed to attach at a shear rate of 15 s-1. Once loading was terminated, the support was washed at a shear rate of 315 s-1 to remove nonspecifically bound cells. Elution of the B-cells was initiated by the transmembrane diffusion of hydrochloric acid (pH 1), supplied to the side of the membrane opposite the cells. At the same time, a shear flow of normal saline was established on the cell side of the membrane, and cells, freed by acid, were retrieved. Results showed that, on average, 250 cells/mm2 attached to antibody immobilized on cellophane surfaces, at a shear rate of 15 s-1, and that attached cells were successfully displaced by acid supplied to the side of the membrane opposite that holding the cells. On average, at least 60% of the B-cells removed by this elution appeared viable, based on a Trypan Blue dye exclusion assay.