Fig. 5

The luminal differentiation repertoire of myoepithelial progenitors is directed by interaction with specialized fibroblasts. a Comparison of capacity of fibroblasts to direct epithelial progenitor capacity. Myoepithelial cells co-cultured with iHBFC^CD105 or iHBFC^CD26 were passaged and subjected to luminal differentiation conditions at clonal density and peroxidase stained for K19. While the induced K19 appeared mainly scattered when derived from iHBFC^CD105 co-culture (left), additional rather homogenous islets presented from iHBFC^CD26 co-cultures (right). The distinct phenotypes were observed in five out of seven tests with absence of homogeneous islets from iHBFC^CD26 in two tests (bar = 500 μm). b Representative multicolor confocal images (K19, red; K14, green; nuclei, blue) of cryostat sections of xenografted NOG mice 8 weeks after orthotopic injection of myoepithelial cells from primary co-culture with iHBFC^CD105 or iHBFC^CD26. Bilayered epithelial structures were obtained in 6/10 and 5/8 injections from iHBFC^CD105 and iHBFC^CD26, respectively, although at limited numbers, down to a few per transplant. Whereas iHBFC^CD105 co-culture derived myoepithelial cells readily differentiated into luminal K14^−/low/K19⁺ cells, co-culture with iHBFC^CD26 resulted mainly in K14⁺/K19⁺ luminal cells (bar = 50 μm)