bioGenous^TM Human Brain (Expansion) Organoid Kit is a serum-free culture medium for human brain organoids (hFBs). In the human brain organoid expansion medium, human brain tissue self-organizes into hFBs under in vitro conditions, successfully replicating key features of in vivo cellular heterogeneity and intricate tissue architecture. These hFBs demonstrate capacity for prolonged expansion, a process fundamentally dependent on preserved tissue integrity. This structural preservation facilitates the generation of a native-like extracellular matrix microenvironment that critically enables sustained hFBs proliferation. hFBs may also have applications in regenerative biology and help understand developmental and disease-related biology.