We demonstrate that the appearance of the density isomers depends on the meson-nucleon coupling strengths in addition to the meson-delta coupling strengths within the mean field theory. Furthermore, the in-medium NN → NΔ cross section is studied with different values of the coupling strengths for deltas. We have found that the in-medium NN → NΔ cross section substantially increases with the increasing of scalar meson-delta coupling strength even for the case when the density isomers do not appear within the mean field theory, which shows the possibility of creating Δ-matter in energetic heavy-ion collisions.