In addition, unlike stem cells from other origins, we demonstrated that only FSCs cultured under established ex-vivo culture conditions simulating in vivo environment during pregnancy were induced to secrete IgM, a natural antibody (NAb) that binds to and removes various foreign antigens as soon as infection occurs 20, and IgG3 that has the broadest range of antigen-binding, variability capable of binding to various antigens, the highest activation capability of complement system after antigen binding, and binding affinity with various immune cells among other Igs 21. Here, IGHG3 is linked to infection.