Five‑Year‑Old Brain Organoids Show Time‑Dependent Development

Researchers at Harvard have grown cortical organoids from human stem cells for five years, the longest period studied in detail. Genetic activity and epigenetic marks in the organoids matched those of a 4‑year‑old child’s cerebral cortex, indicating the structures record the passage of time. Earlier work had shown organoids could be maintained for up to two years, but this study extends that to five years and provides a reliable ageing profile. The long‑lived organoids could help scientists investigate how conditions such as autism and epilepsy emerge during later brain development and screen drugs that might alter disease progression. The work also highlights the need to develop methods that accelerate organoid ageing to broaden research possibilities.