Polymer-Coated Magnetic Microspheres Conjugated with Growth Factor Receptor Binding Peptides Enable Cell Sorting

The separation and sorting of human cells is an important step in the bioprocessing of cell-based therapeutics. Heterogeneous mixtures of cells must be sorted to isolate the desired cell type and purify the final product. This process is often achieved by antibody-based sorting techniques. In this work, we demonstrate that magnetic microspheres may be functionalized with peptides that selectively bind to cells on the basis of their relative concentration of specific surface proteins. Five-micrometer-magnetic microspheres were coated with the synthetic copolymer PVG (poly(poly(ethylene glycol)methyl ether methacrylate-ran-vinyl dimethyl azlactone-ran-glycidyl methacrylate) and functionalized with the vascular endothelial growth factor receptor binding peptide (VRBP), which binds to the vascular endothelial growth factor receptor (VEGFR). These microspheres exhibited low cytotoxicity and bind to cells depending on their relative surface protein expression. Finally, coated, magnetic microspheres were used to separate heterogeneous populations of cells dependent on their VEGFR expression through magnetic-assisted cell sorting (MACS), demonstrating that peptide-based cell sorting mechanisms may be useful in the bioprocessing of human-cell-based products.