Transforming growth factor beta 1 (TGF-β1) is a member of the TGF-β superfamily and regulates diverse cellular phenotypes. TGF-β1 binds to serine-threonine kinase type I and II receptors and activates signal transduction through SMAD2/3 proteins, thus regulating a variety of functions, including cell proliferation, differentiation, wound healing, apoptosis, and metabolism (Massagué; McDowell et al.). During human embryogenesis, TGF-β1 is expressed by endothelial and hematopoietic tissues and acts as an endogenous autocrine growth regulator in those cells (Gatherer et al.). Together with basic fibroblast growth factor (bFGF), TGF-β1 supports the culture of undifferentiated human embryonic stem cells and induced pluripotent stem cells (Amit et al.). TGF-β1 is produced in latent form by many blood cells and is present in high amounts in platelets and bones. Once activated, TGF-β1 helps to maintain immune homeostasis by modulating B cell response and mediating immunosuppressive effects on T cells and neutrophils (Letterio & Roberts).