Five-Year-Old Brain Organoids Reveal Epigenetic Aging Mirroring Human Development

Five Years Inside Harvard’s Labs

Human brain organoids cultured in a laboratory for five years have developed epigenetic aging dynamics and transcriptional profiles that mirror postnatal brain development.

Researchers led by Paola Arlotta at Harvard University analyzed tiny versions of the cerebral cortex grown from human stem cells over an extended period. According to reporting from New Scientist, the five-year-old organoids are the longest-lived brain organoids studied in detail to date. The team examined epigenetic marks—chemical tags on DNA that regulate gene activity and shift with age—and found that the cellular structures evolved from resembling fetal brains to matching the genetic activity typically seen in the cerebral cortex of a four-year-old child.

Overcoming the One-Year Barrier

To achieve this longevity, the research team had to adapt their laboratory methods. The organoids initially started losing neuronal signals around the one-year mark.

By modifying the culture medium, the Harvard team successfully grew a new set of organoids that featured more mature excitatory neurons, greater neuronal complexity, and enhanced electrical activity.

A First for Neurological Science

Before this long-term cultivation, organoids typically modeled only pre- and perinatal brains. They usually fell off in quality after three to four months of growth, which is equivalent to a second-trimester fetal brain.

András Lakatos at the University of Cambridge, who was not involved with the study, noted in New Scientist that the work demonstrates for the first time that organoids show an aging profile corresponding with a developing brain of a similar age.

Screening for Epilepsy and Autism

Researchers suggest that these long-lived organoids will serve as a valuable platform for studying how conditions such as autism and epilepsy emerge during later stages of brain development.

Arlotta noted that her team is already using the structures to screen for drugs that might alter the progression of disorders like epilepsy. However, experts point out that maintaining organoids for five years remains labor-intensive and impractical for routine screening. Consequently, finding methods to accelerate organoid aging in culture will remain an important focus for future neuroscience research.