Total pion yields and pi(-)/pi(-) ratios in two Sn+Sn collision systems, Sn-132+Sn-124 (neutron Sn-108+ Sn-112 rich) and n (neutron poor) at E = 270A MeV, are significant observables in SAMURAI Pion-Reconstruction and Ion-Tracker (S pi RIT) experiments. Based on a recently developed transport model, DaeJeon Boltzmann-Uehling-Uhlenbeck (DJBUU), we investigate the isospin-dependent inmedium effects by including density- and isospin-dependent cross sections for Delta baryon productions. We compare our results with the S pi RIT data by considering these effects. We find that the yields as well as the ratios strongly depend on the in-medium effect, especially isospin-dependent in-medium cross sections for Delta resonances.