Ex vivo HPC to DC expansion and development system. (A) Schematic representation of the LSC culture system and the lentivector constructs. The two LSC lines, LSC-KFT63b and LSC-KFT-GM15, produce the specified hematopoietic growth factors, which support the expansion of HPCs and DCPs. (B) and (C) Semi-quantitative RT-PCR analyses of lentiviral transgene expression in the LSC lines. All of the growth factor genes are human origin except for the mouse GM-CSF (mGM-CSF); the control endogenous mouse GAPDH (mGAPDH) gene expression is shown at bottom.