TMPRSS2 and infection: Cells exposed to an MOI of 2 failed to show signs of SARS-CoV-2 infection; however, using a higher MOI of 10, infection in i3Ns was detected (Figure 1B), albeit low compared to other cells highly susceptible to SARS-CoV-2 infection, such as Vero and VeroE6/TMPRSS2 [52].