Cerebral organoids model human brain development and microcephaly

The complexity of the human brain has made it difficult to study many brain disorders in model organisms, highlighting the need for an in vitro model of human brain development. Here we have developed a human pluripotent stem cell-derived three-dimensional organoid culture system, termed cerebral organoids, that develop various discrete, although interdependent, brain regions. These include a cerebral cortex containing progenitor populations that organize and produce mature cortical neuron subtypes. Furthermore, cerebral organoids are shown to recapitulate features of human cortical development, namely characteristic progenitor zone organization with abundant outer radial glial stem cells. Finally, we use RNA interference and patient-specific induced pluripotent stem cells to model microcephaly, a disorder that has been difficult to recapitulate in mice. We demonstrate premature neuronal differentiation in patient organoids, a defect that could help to explain the disease phenotype. Together, these data show that three-dimensional organoids can recapitulate development and disease even in this most complex human tissue. Here the authors present a human pluripotent stem cell-derived three-dimensional organoid culture system that is able to recapitulate several aspects of human brain development in addition to modelling the brain disorder microcephaly, which has been difficult to achieve using mouse models. Genetically altered mice are used widely to model human diseases, but as the organization of the human brain is so much more complicated than that of a rodent, brain development diseases have not been tackled. Juergen Knoblich and colleagues have developed an alternative model, a three-dimensional organoid culture system, using human pluripotent stem cells, that recapitulates several aspects of human brain development. The system mimics the temporal development of neuronal subtypes and the organization of the tissue into layers. In proof-of-principle experiments the authors produce a microcephaly model using patient-derived induced pluripotent stem cells and describe defects in neuronal differentiation not previously observed in rodent models.