The use of leukemia inhibitory factor immobilized on virus-derived polyhedra to support the proliferation of mouse embryonic and induced pluripotent stem cells.

Human leukemia inhibitory factor (LIF) was immobilized into insect virus-derived microcrystals (polyhedra) to generate LIF polyhedra (LIF-PH) that can slowly release LIF into embryonic stem (ES) cell culture media and thus maintain ES cells in an undifferentiated state. Assays of the biological activities of LIF-PH indicated that a single addition of LIF-PH to the ES cell culture medium can support the proliferation of mouse ES and induced pluripotent stem (iPS) cells continuously for 14 days, and suggest that LIF-PH can be successfully used in the place of a periodic addition of recombinant LIF to the media every 2-3 days. The release of LIF protein from LIF-PH was determined by enzyme-linked immunosorbent assay (ELISA). Maintenance of undifferentiated state of mouse ES and iPS cells cultured with LIF-PH was determined by the detection of pluripotency-related biomarkers Oct3/4 and stage-specific embryonic antigen-1 (SSEA-1) through immunostaining and measurement of alkaline phosphatase activity. In this paper, we propose a closed culture system for mass production of ES and iPS cells that utilize a slow-releasing agent of LIF.