Preparation of PEG-grafted immunomagnetoliposomes and their application in cell sorting

Immunomagnetic systems have been used for positive selection of the cell fraction from a mixture using appropiate surface markers with satisfactory results, as hematopoietic CD34+ cells. In this work, we report the development of poly(ethylene glycol) (PEG)-grafted immunoliposomes loaded with dextran-magne-tite particles as the separation vehicles for immunomagnetic separation techniques. The magnetic ferrofluid was encapsulated into PEG-liposomes by the FTS methodology. The magnetoliposomes had a liposomal size around 800 nm and a Fe/lipid molar ratio of 0.87±0.30, and were retained in the magnetic field created by the MiniMACS system. Anti-CD34 immunomagnetoliposomes were prepared by coupling the My10 mAb and bound specifically to CD34+ KG-1a cells in culture and in mixtures with CD34- CHO cells. The magnetic cell sorting was carried out in cell mixtures KG-1a/CHO with a 10% initial of CD34+ KG-1a cells. The purity of the MiniMACS-positive fraction and the capture efficiency depended on the liposome concentration and antibody density used, related to the nonspecific cell binding of immunomagnetoliposomes due to the ferrofluid adsorbed and to the presence of whole antibody molecules in the liposome surface. The CD34+ cells isolated retained viability with an estimated recovery of 45-50%.