Preferential expansion of umbilical cord blood-derived CD34-positive cells on human leukemia inhibitory factor transgenic feeder cells cultured on regenerated silk fibroin film.

In vitro expansion of transplantable hematopoietic stem cells (HSCs) is a very promising approach for different clinical applications. We have recently developed a new culture system that facilitates in vitro expansion of transplantable cord blood HSCs. In our study, we constructed a recombinant adenovirus Ad-GFP/human leukemia inhibitory factor (hLIF) expressing hLIF. The hLIF gene was delivered into human embryo lung fibroblast cell line WI-38 via infection with Ad-GFP/hLIF. Then, the transgenic cells were cultured on regenerated silk fibroin (SF) films as feeder layer cells for expansion of cord blood CD34(+) cells. Our results showed that the hLIF transgenic WI-38 cells cultured on SF could express hematopoiesis-related cytokines at higher levels compared with control groups. The hLIF-expressing feeder layer cells cultured on SF in combination with cytokines more efficiently expanded CD34(+) cells and CD34(+)CD38(-) cells. The percentages of adhesion molecules on the expanded CD34(+) cells in transgenic feeder layer cells cultured on SF were higher than those of control groups. Interestingly, the migration rate assessed by transwell assay was also significantly higher than those of control groups, which suggests that transgenic feeder layer cells cultured on SF has powerful ability to maintain the homing capacity of expanded CD34(+) cells. (c) 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.