Next, we explored the feasibility of in situ origami self-assembly in the presence of a more complex 3D tissue-like system. As a proof of principle, it was implemented during the formation of cerebral organoids from human induced pluripotent stem cells (hiPSCs), which is a multi-step process involving different medium exchanges bringing the necessary factors for embryoid body (EB) formation (day 0-5), neural induction (day 5-7), neuroepithelium expansion (day 7-10) and organoid maturation (from day 10). A molecular program coding for triangle origami was implemented during EB formation by a first addition of fresh medium containing all the DNA strands at day 2 (Fig. , Fig. ). Interestingly, we found that DNA origamis also successfully self-assembled in 15 min only in this complex system, and remained stable for at least a day (Fig. ). This process was repeated at day 4 of EB formation (Fig. ). Notably, at day 5, well-formed EBs with smooth spherical shapes were obtained (Fig.