A novel large-scale production system for modified basement membrane matrices using gene-swapped parietal endoderm cells

Parietal endoderm-like cells, including Engelbreth–Holm–Swarm tumor and differentiated F9 embryonal carcinoma cells, produce huge amounts of basement membrane components, including laminin-1 (α1β1γ1). We employed a double-lox system-based gene-swapping strategy in F9 cells to replace the laminin α1 gene with a laminin α5 minigene. The gene-swapped F9 cells secreted laminin-10 (α5β1γ1) consisting of the exogenous α5 subunit and endogenous β1 and γ1 subunits on differentiation. The laminin-10 concentration in the conditioned medium exceeded 10 mg/l, which is 10-fold higher than the concentrations achieved by conventional recombinant expression systems. The gene-swapped F9 cells deposited basement membrane-like matrices containing laminin-10 on culture dishes, offering a novel microenvironment for in vitro cell manipulation.